Merged rt44535 (relay port)

[thirdparty/dhcp.git] / server / dhcpv6.c

/*
 * Copyright (C) 2006-2017 by Internet Systems Consortium, Inc. ("ISC")
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

/*! \file server/dhcpv6.c */

#include "dhcpd.h"

#ifdef DHCPv6

#ifdef DHCP4o6
static void forw_dhcpv4_query(struct packet *packet);
static void send_dhcpv4_response(struct data_string *raw);

static void recv_dhcpv4_query(struct data_string *raw);
static void dhcp4o6_dhcpv4_query(struct data_string *reply_ret,
                                 struct packet *packet);

struct udp_data4o6 {
        u_int16_t src_port;
        u_int8_t  rsp_opt_exist;
        u_int8_t  reserved;
};

static int offset_data4o6 = 36; /* 16+16+4 */
#endif

/*
 * We use print_hex_1() to output DUID values. We could actually output
 * the DUID with more information... MAC address if using type 1 or 3,
 * and so on. However, RFC 3315 contains Grave Warnings against actually
 * attempting to understand a DUID.
 */

/*
 * TODO: gettext() or other method of localization for the messages
 *       for status codes (and probably for log formats eventually)
 * TODO: refactoring (simplify, simplify, simplify)
 * TODO: support multiple shared_networks on each interface (this
 *       will allow the server to issue multiple IPv6 addresses to
 *       a single interface)
 */

/*
 * DHCPv6 Reply workflow assist.  A Reply packet is built by various
 * different functions; this gives us one location where we keep state
 * regarding a reply.
 */
struct reply_state {
        /* root level persistent state */
        struct shared_network *shared;
        struct host_decl *host;
        struct subnet *subnet; /* Used to match fixed-addrs to subnet scopes. */
        struct option_state *opt_state;
        struct packet *packet;
        struct data_string client_id;

        /* IA level persistent state */
        unsigned ia_count;
        unsigned pd_count;
        unsigned client_resources;
        isc_boolean_t resources_included;
        isc_boolean_t static_lease;
        unsigned static_prefixes;
        struct ia_xx *ia;
        struct ia_xx *old_ia;
        struct option_state *reply_ia;
        struct data_string fixed;
        struct iaddrcidrnet fixed_pref; /* static prefix for logging */

        /* IAADDR/PREFIX level persistent state */
        struct iasubopt *lease;

        /*
         * "t1", "t2", preferred, and valid lifetimes records for calculating
         * t1 and t2 (min/max).
         */
        u_int32_t renew, rebind, min_prefer, min_valid;

        /* Client-requested valid and preferred lifetimes. */
        u_int32_t client_valid, client_prefer;

        /* Chosen values to transmit for valid and preferred lifetimes. */
        u_int32_t send_valid, send_prefer;

        /* Preferred prefix length (-1 is any). */
        int preflen;

        /* Index into the data field that has been consumed. */
        unsigned cursor;

        /* Space for the on commit statements for a fixed host */
        struct on_star on_star;

        union reply_buffer {
                unsigned char data[65536];
                struct dhcpv6_packet reply;
        } buf;
};

/*
 * Prototypes local to this file.
 */
static int get_encapsulated_IA_state(struct option_state **enc_opt_state,
                                     struct data_string *enc_opt_data,
                                     struct packet *packet,
                                     struct option_cache *oc,
                                     int offset);
static void build_dhcpv6_reply(struct data_string *, struct packet *);
static isc_result_t shared_network_from_packet6(struct shared_network **shared,
                                                struct packet *packet);
static void seek_shared_host(struct host_decl **hp,
                             struct shared_network *shared);
static isc_boolean_t fixed_matches_shared(struct host_decl *host,
                                          struct shared_network *shared);
static isc_result_t reply_process_ia_na(struct reply_state *reply,
                                        struct option_cache *ia);
static isc_result_t reply_process_ia_ta(struct reply_state *reply,
                                        struct option_cache *ia);
static isc_result_t reply_process_addr(struct reply_state *reply,
                                       struct option_cache *addr);
static isc_boolean_t address_is_owned(struct reply_state *reply,
                                      struct iaddr *addr);
static isc_boolean_t temporary_is_available(struct reply_state *reply,
                                            struct iaddr *addr);
static isc_result_t find_client_temporaries(struct reply_state *reply);
static isc_result_t reply_process_try_addr(struct reply_state *reply,
                                           struct iaddr *addr);
static isc_result_t find_client_address(struct reply_state *reply);
static isc_result_t reply_process_is_addressed(struct reply_state *reply,
                                               struct binding_scope **scope,
                                               struct group *group);
static isc_result_t reply_process_send_addr(struct reply_state *reply,
                                            struct iaddr *addr);
static struct iasubopt *lease_compare(struct iasubopt *alpha,
                                      struct iasubopt *beta);
static isc_result_t reply_process_ia_pd(struct reply_state *reply,
                                        struct option_cache *ia_pd);
static struct group *find_group_by_prefix(struct reply_state *reply);
static isc_result_t reply_process_prefix(struct reply_state *reply,
                                         struct option_cache *pref);
static isc_boolean_t prefix_is_owned(struct reply_state *reply,
                                     struct iaddrcidrnet *pref);
static isc_result_t find_client_prefix(struct reply_state *reply);
static isc_result_t reply_process_try_prefix(struct reply_state *reply,
                                             struct iaddrcidrnet *pref);
static isc_result_t reply_process_is_prefixed(struct reply_state *reply,
                                              struct binding_scope **scope,
                                              struct group *group);
static isc_result_t reply_process_send_prefix(struct reply_state *reply,
                                              struct iaddrcidrnet *pref);
static struct iasubopt *prefix_compare(struct reply_state *reply,
                                       struct iasubopt *alpha,
                                       struct iasubopt *beta);
static void schedule_lease_timeout_reply(struct reply_state *reply);

static int eval_prefix_mode(int thislen, int preflen, int prefix_mode);
static isc_result_t pick_v6_prefix_helper(struct reply_state *reply,
                                          int prefix_mode);

static void unicast_reject(struct data_string *reply_ret, struct packet *packet,
                  const struct data_string *client_id,
                  const struct data_string *server_id);

static isc_boolean_t is_unicast_option_defined(struct packet *packet);
static isc_result_t shared_network_from_requested_addr (struct shared_network
                                                        **shared,
                                                        struct packet* packet);
static isc_result_t get_first_ia_addr_val (struct packet* packet, int addr_type,
                                           struct iaddr* iaddr);

static void
set_reply_tee_times(struct reply_state* reply, unsigned ia_cursor);

static const char *iasubopt_plen_str(struct iasubopt *lease);
static int release_on_roam(struct reply_state *reply);

static int reuse_lease6(struct reply_state *reply, struct iasubopt *lease);
static void shorten_lifetimes(struct reply_state *reply, struct iasubopt *lease,
                              time_t age, int threshold);
static void write_to_packet(struct reply_state *reply, unsigned ia_cursor);
static const char *iasubopt_plen_str(struct iasubopt *lease);

#ifdef NSUPDATE
static void ddns_update_static6(struct reply_state* reply);
#endif

#ifdef DHCP4o6
/*
 * \brief Omapi I/O handler
 *
 * The inter-process communication receive handler.
 * Get the message, put it into the raw data_string
 * and call \ref send_dhcpv4_response() (DHCPv6 side) or
 * \ref recv_dhcpv4_query() (DHCPv4 side)
 *
 * \param h the OMAPI object
 * \return a result for I/O success or error (used by the I/O subsystem)
 */
isc_result_t dhcpv4o6_handler(omapi_object_t *h) {
        char buf[65536];
        struct data_string raw;
        int cc;

        if (h->type != dhcp4o6_type)
                return DHCP_R_INVALIDARG;

        cc = recv(dhcp4o6_fd, buf, sizeof(buf), 0);

        if (cc < DHCP_FIXED_NON_UDP + offset_data4o6)
                return ISC_R_UNEXPECTED;
        memset(&raw, 0, sizeof(raw));
        if (!buffer_allocate(&raw.buffer, cc, MDL)) {
                log_error("dhcpv4o6_handler: no memory buffer.");
                return ISC_R_NOMEMORY;
        }
        raw.data = raw.buffer->data;
        raw.len = cc;
        memcpy(raw.buffer->data, buf, cc);

        if (local_family == AF_INET6) {
                send_dhcpv4_response(&raw);
        } else {
                recv_dhcpv4_query(&raw);
        }

        data_string_forget(&raw, MDL);

        return ISC_R_SUCCESS;
}

/*
 * \brief Send the DHCPv4-response back to the DHCPv6 side
 *  (DHCPv6 server function)
 *
 * Format: interface:16 + address:16 + udp:4 + DHCPv6 DHCPv4-response message
 *
 * \param raw the IPC message content
 */
static void send_dhcpv4_response(struct data_string *raw) {
        struct interface_info *ip;
        char name[16 + 1];
        struct sockaddr_in6 to_addr;
        char pbuf[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")];
        struct udp_data4o6 udp_data;
        int send_ret;

        memset(name, 0, sizeof(name));
        memcpy(name, raw->data, 16);
        for (ip = interfaces; ip != NULL; ip = ip->next) {
                if (!strcmp(name, ip->name))
                        break;
        }
        if (ip == NULL) {
                log_error("send_dhcpv4_response: can't find interface %s.",
                          name);
                return;
        }

        memset(&to_addr, 0, sizeof(to_addr));
        to_addr.sin6_family = AF_INET6;
        memcpy(&to_addr.sin6_addr, raw->data + 16, 16);
        memset(&udp_data, 0, sizeof(udp_data));
        memcpy(&udp_data, raw->data + 32, 4);
        if ((raw->data[36] == DHCPV6_RELAY_FORW) ||
            (raw->data[36] == DHCPV6_RELAY_REPL)) {
                if (udp_data.rsp_opt_exist) {
                        to_addr.sin6_port = udp_data.src_port;
                } else {
                        to_addr.sin6_port = local_port;
                }
        } else {
                to_addr.sin6_port = remote_port;
        }

        log_info("send_dhcpv4_response(): sending %s on %s to %s port %d",
                 dhcpv6_type_names[raw->data[36]],
                 name,
                 inet_ntop(AF_INET6, raw->data + 16, pbuf, sizeof(pbuf)),
                 ntohs(to_addr.sin6_port));

        send_ret = send_packet6(ip, raw->data + 36, raw->len - 36, &to_addr);
        if (send_ret < 0) {
                log_error("send_dhcpv4_response: send_packet6(): %m");
        } else if (send_ret != raw->len - 36) {
                log_error("send_dhcpv4_response: send_packet6() "
                          "sent %d of %d bytes",
                          send_ret, raw->len - 36);
        }
}
#endif /* DHCP4o6 */

/*
 * Schedule lease timeouts for all of the iasubopts in the reply.
 * This is currently used to schedule timeouts for soft leases.
 */

static void
schedule_lease_timeout_reply(struct reply_state *reply) {
        struct iasubopt *tmp;
        int i;

        /* sanity check the reply */
        if ((reply == NULL) || (reply->ia == NULL) || (reply->ia->iasubopt == NULL))
                return;

        /* walk through the list, scheduling as we go */
        for (i = 0 ; i < reply->ia->num_iasubopt ; i++) {
                tmp = reply->ia->iasubopt[i];
                schedule_lease_timeout(tmp->ipv6_pool);
        }
}

/*
 * This function returns the time since DUID time start for the
 * given time_t value.
 */
static u_int32_t
duid_time(time_t when) {
        /*
         * This time is modulo 2^32.
         */
        while ((when - DUID_TIME_EPOCH) > 4294967295u) {
                /* use 2^31 to avoid spurious compiler warnings */
                when -= 2147483648u;
                when -= 2147483648u;
        }

        return when - DUID_TIME_EPOCH;
}


/*
 * Server DUID.
 *
 * This must remain the same for the lifetime of this server, because
 * clients return the server DUID that we sent them in Request packets.
 *
 * We pick the server DUID like this:
 *
 * 1. Check dhcpd.conf - any value the administrator has configured
 *    overrides any possible values.
 * 2. Check the leases.txt - we want to use the previous value if
 *    possible.
 * 3. Check if dhcpd.conf specifies a type of server DUID to use,
 *    and generate that type.
 * 4. Generate a type 1 (time + hardware address) DUID.
 */
static struct data_string server_duid;

/*
 * Check if the server_duid has been set.
 */
isc_boolean_t
server_duid_isset(void) {
        return (server_duid.data != NULL);
}

/*
 * Return the server_duid.
 */
void
copy_server_duid(struct data_string *ds, const char *file, int line) {
        data_string_copy(ds, &server_duid, file, line);
}

/*
 * Set the server DUID to a specified value. This is used when
 * the server DUID is stored in persistent memory (basically the
 * leases.txt file).
 */
void
set_server_duid(struct data_string *new_duid) {
        /* INSIST(new_duid != NULL); */
        /* INSIST(new_duid->data != NULL); */

        if (server_duid_isset()) {
                data_string_forget(&server_duid, MDL);
        }
        data_string_copy(&server_duid, new_duid, MDL);
}


/*
 * Set the server DUID based on the D6O_SERVERID option. This handles
 * the case where the administrator explicitly put it in the dhcpd.conf
 * file.
 */
isc_result_t
set_server_duid_from_option(void) {
        struct option_state *opt_state;
        struct option_cache *oc;
        struct data_string option_duid;
        isc_result_t ret_val;

        opt_state = NULL;
        if (!option_state_allocate(&opt_state, MDL)) {
                log_fatal("No memory for server DUID.");
        }

        execute_statements_in_scope(NULL, NULL, NULL, NULL, NULL,
                                    opt_state, &global_scope, root_group,
                                    NULL, NULL);

        oc = lookup_option(&dhcpv6_universe, opt_state, D6O_SERVERID);
        if (oc == NULL) {
                ret_val = ISC_R_NOTFOUND;
        } else {
                memset(&option_duid, 0, sizeof(option_duid));
                if (!evaluate_option_cache(&option_duid, NULL, NULL, NULL,
                                           opt_state, NULL, &global_scope,
                                           oc, MDL)) {
                        ret_val = ISC_R_UNEXPECTED;
                } else {
                        set_server_duid(&option_duid);
                        data_string_forget(&option_duid, MDL);
                        ret_val = ISC_R_SUCCESS;
                }
        }

        option_state_dereference(&opt_state, MDL);

        return ret_val;
}

/*
 * DUID layout, as defined in RFC 3315, section 9.
 *
 * We support type 1 (hardware address plus time) and type 3 (hardware
 * address).
 *
 * We can support type 2 for specific vendors in the future, if they
 * publish the specification. And of course there may be additional
 * types later.
 */
static int server_duid_type = DUID_LLT;

/*
 * Set the DUID type.
 */
void
set_server_duid_type(int type) {
        server_duid_type = type;
}

/*
 * Generate a new server DUID. This is done if there was no DUID in
 * the leases.txt or in the dhcpd.conf file.
 */
isc_result_t
generate_new_server_duid(void) {
        struct interface_info *p;
        u_int32_t time_val;
        struct data_string generated_duid;

        /*
         * Verify we have a type that we support.
         */
        if ((server_duid_type != DUID_LL) && (server_duid_type != DUID_LLT)) {
                log_error("Invalid DUID type %d specified, "
                          "only LL and LLT types supported", server_duid_type);
                return DHCP_R_INVALIDARG;
        }

        /*
         * Find an interface with a hardware address.
         * Any will do. :)
         */
        for (p = interfaces; p != NULL; p = p->next) {
                if (p->hw_address.hlen > 0) {
                        break;
                }
        }
        if (p == NULL) {
                return ISC_R_UNEXPECTED;
        }

        /*
         * Build our DUID.
         */
        memset(&generated_duid, 0, sizeof(generated_duid));
        if (server_duid_type == DUID_LLT) {
                time_val = duid_time(time(NULL));
                generated_duid.len = 8 + p->hw_address.hlen - 1;
                if (!buffer_allocate(&generated_duid.buffer,
                                     generated_duid.len, MDL)) {
                        log_fatal("No memory for server DUID.");
                }
                generated_duid.data = generated_duid.buffer->data;
                putUShort(generated_duid.buffer->data, DUID_LLT);
                putUShort(generated_duid.buffer->data + 2,
                          p->hw_address.hbuf[0]);
                putULong(generated_duid.buffer->data + 4, time_val);
                memcpy(generated_duid.buffer->data + 8,
                       p->hw_address.hbuf+1, p->hw_address.hlen-1);
        } else if (server_duid_type == DUID_LL) {
                generated_duid.len = 4 + p->hw_address.hlen - 1;
                if (!buffer_allocate(&generated_duid.buffer,
                                     generated_duid.len, MDL)) {
                        log_fatal("No memory for server DUID.");
                }
                generated_duid.data = generated_duid.buffer->data;
                putUShort(generated_duid.buffer->data, DUID_LL);
                putUShort(generated_duid.buffer->data + 2,
                          p->hw_address.hbuf[0]);
                memcpy(generated_duid.buffer->data + 4,
                       p->hw_address.hbuf+1, p->hw_address.hlen-1);
        } else {
                log_fatal("Unsupported server DUID type %d.", server_duid_type);
        }

        set_server_duid(&generated_duid);
        data_string_forget(&generated_duid, MDL);

        return ISC_R_SUCCESS;
}

/*
 * Get the client identifier from the packet.
 */
isc_result_t
get_client_id(struct packet *packet, struct data_string *client_id) {
        struct option_cache *oc;

        /*
         * Verify our client_id structure is empty.
         */
        if ((client_id->data != NULL) || (client_id->len != 0)) {
                return DHCP_R_INVALIDARG;
        }

        oc = lookup_option(&dhcpv6_universe, packet->options, D6O_CLIENTID);
        if (oc == NULL) {
                return ISC_R_NOTFOUND;
        }

        if (!evaluate_option_cache(client_id, packet, NULL, NULL,
                                   packet->options, NULL,
                                   &global_scope, oc, MDL)) {
                return ISC_R_FAILURE;
        }

        return ISC_R_SUCCESS;
}

/*
 * Message validation, defined in RFC 3315, sections 15.2, 15.5, 15.7:
 *
 *    Servers MUST discard any Solicit messages that do not include a
 *    Client Identifier option or that do include a Server Identifier
 *    option.
 */
int
valid_client_msg(struct packet *packet, struct data_string *client_id) {
        int ret_val;
        struct option_cache *oc;
        struct data_string data;

        ret_val = 0;
        memset(client_id, 0, sizeof(*client_id));
        memset(&data, 0, sizeof(data));

        switch (get_client_id(packet, client_id)) {
                case ISC_R_SUCCESS:
                        break;
                case ISC_R_NOTFOUND:
                        log_debug("Discarding %s from %s; "
                                  "client identifier missing",
                                  dhcpv6_type_names[packet->dhcpv6_msg_type],
                                  piaddr(packet->client_addr));
                        goto exit;
                default:
                        log_error("Error processing %s from %s; "
                                  "unable to evaluate Client Identifier",
                                  dhcpv6_type_names[packet->dhcpv6_msg_type],
                                  piaddr(packet->client_addr));
                        goto exit;
        }

        /*
         * Required by RFC 3315, section 15.
         */
        if (packet->unicast) {
                log_debug("Discarding %s from %s; packet sent unicast "
                          "(CLIENTID %s)",
                          dhcpv6_type_names[packet->dhcpv6_msg_type],
                          piaddr(packet->client_addr),
                          print_hex_1(client_id->len, client_id->data, 60));
                goto exit;
        }


        oc = lookup_option(&dhcpv6_universe, packet->options, D6O_SERVERID);
        if (oc != NULL) {
                if (evaluate_option_cache(&data, packet, NULL, NULL,
                                          packet->options, NULL,
                                          &global_scope, oc, MDL)) {
                        log_debug("Discarding %s from %s; "
                                  "server identifier found "
                                  "(CLIENTID %s, SERVERID %s)",
                                  dhcpv6_type_names[packet->dhcpv6_msg_type],
                                  piaddr(packet->client_addr),
                                  print_hex_1(client_id->len,
                                              client_id->data, 60),
                                  print_hex_2(data.len,
                                              data.data, 60));
                } else {
                        log_debug("Discarding %s from %s; "
                                  "server identifier found "
                                  "(CLIENTID %s)",
                                  dhcpv6_type_names[packet->dhcpv6_msg_type],
                                  print_hex_1(client_id->len,
                                              client_id->data, 60),
                                  piaddr(packet->client_addr));
                }
                goto exit;
        }

        /* looks good */
        ret_val = 1;

exit:
        if (data.len > 0) {
                data_string_forget(&data, MDL);
        }
        if (!ret_val) {
                if (client_id->len > 0) {
                        data_string_forget(client_id, MDL);
                }
        }
        return ret_val;
}

/*
 * Response validation, defined in RFC 3315, sections 15.4, 15.6, 15.8,
 * 15.9 (slightly different wording, but same meaning):
 *
 *   Servers MUST discard any received Request message that meet any of
 *   the following conditions:
 *
 *   -  the message does not include a Server Identifier option.
 *   -  the contents of the Server Identifier option do not match the
 *      server's DUID.
 *   -  the message does not include a Client Identifier option.
 */
int
valid_client_resp(struct packet *packet,
                  struct data_string *client_id,
                  struct data_string *server_id)
{
        int ret_val;
        struct option_cache *oc;

        /* INSIST((duid.data != NULL) && (duid.len > 0)); */

        ret_val = 0;
        memset(client_id, 0, sizeof(*client_id));
        memset(server_id, 0, sizeof(*server_id));

        switch (get_client_id(packet, client_id)) {
                case ISC_R_SUCCESS:
                        break;
                case ISC_R_NOTFOUND:
                        log_debug("Discarding %s from %s; "
                                  "client identifier missing",
                                  dhcpv6_type_names[packet->dhcpv6_msg_type],
                                  piaddr(packet->client_addr));
                        goto exit;
                default:
                        log_error("Error processing %s from %s; "
                                  "unable to evaluate Client Identifier",
                                  dhcpv6_type_names[packet->dhcpv6_msg_type],
                                  piaddr(packet->client_addr));
                        goto exit;
        }

        oc = lookup_option(&dhcpv6_universe, packet->options, D6O_SERVERID);
        if (oc == NULL) {
                log_debug("Discarding %s from %s: "
                          "server identifier missing (CLIENTID %s)",
                          dhcpv6_type_names[packet->dhcpv6_msg_type],
                          piaddr(packet->client_addr),
                          print_hex_1(client_id->len, client_id->data, 60));
                goto exit;
        }
        if (!evaluate_option_cache(server_id, packet, NULL, NULL,
                                   packet->options, NULL,
                                   &global_scope, oc, MDL)) {
                log_error("Error processing %s from %s; "
                          "unable to evaluate Server Identifier (CLIENTID %s)",
                          dhcpv6_type_names[packet->dhcpv6_msg_type],
                          piaddr(packet->client_addr),
                          print_hex_1(client_id->len, client_id->data, 60));
                goto exit;
        }
        if ((server_duid.len != server_id->len) ||
            (memcmp(server_duid.data, server_id->data, server_duid.len) != 0)) {
                log_debug("Discarding %s from %s; "
                          "not our server identifier "
                          "(CLIENTID %s, SERVERID %s, server DUID %s)",
                          dhcpv6_type_names[packet->dhcpv6_msg_type],
                          piaddr(packet->client_addr),
                          print_hex_1(client_id->len, client_id->data, 60),
                          print_hex_2(server_id->len, server_id->data, 60),
                          print_hex_3(server_duid.len, server_duid.data, 60));
                goto exit;
        }

        /* looks good */
        ret_val = 1;

exit:
        if (!ret_val) {
                if (server_id->len > 0) {
                        data_string_forget(server_id, MDL);
                }
                if (client_id->len > 0) {
                        data_string_forget(client_id, MDL);
                }
        }
        return ret_val;
}

/*
 * Information request validation, defined in RFC 3315, section 15.12:
 *
 *   Servers MUST discard any received Information-request message that
 *   meets any of the following conditions:
 *
 *   -  The message includes a Server Identifier option and the DUID in
 *      the option does not match the server's DUID.
 *
 *   -  The message includes an IA option.
 */
int
valid_client_info_req(struct packet *packet, struct data_string *server_id) {
        int ret_val;
        struct option_cache *oc;
        struct data_string client_id;
        char client_id_str[80]; /* print_hex_1() uses maximum 60 characters,
                                   plus a few more for extra information */

        ret_val = 0;
        memset(server_id, 0, sizeof(*server_id));
        memset(&client_id, 0, sizeof(client_id));

        /*
         * Make a string that we can print out to give more
         * information about the client if we need to.
         *
         * By RFC 3315, Section 18.1.5 clients SHOULD have a
         * client-id on an Information-request packet, but it
         * is not strictly necessary.
         */
        if (get_client_id(packet, &client_id) == ISC_R_SUCCESS) {
                snprintf(client_id_str, sizeof(client_id_str), " (CLIENTID %s)",
                         print_hex_1(client_id.len, client_id.data, 60));
                data_string_forget(&client_id, MDL);
        } else {
                client_id_str[0] = '\0';
        }

        /*
         * Required by RFC 3315, section 15.
         */
        if (packet->unicast) {
                log_debug("Discarding %s from %s; packet sent unicast%s",
                          dhcpv6_type_names[packet->dhcpv6_msg_type],
                          piaddr(packet->client_addr), client_id_str);
                goto exit;
        }

        oc = lookup_option(&dhcpv6_universe, packet->options, D6O_IA_NA);
        if (oc != NULL) {
                log_debug("Discarding %s from %s; "
                          "IA_NA option present%s",
                          dhcpv6_type_names[packet->dhcpv6_msg_type],
                          piaddr(packet->client_addr), client_id_str);
                goto exit;
        }
        oc = lookup_option(&dhcpv6_universe, packet->options, D6O_IA_TA);
        if (oc != NULL) {
                log_debug("Discarding %s from %s; "
                          "IA_TA option present%s",
                          dhcpv6_type_names[packet->dhcpv6_msg_type],
                          piaddr(packet->client_addr), client_id_str);
                goto exit;
        }
        oc = lookup_option(&dhcpv6_universe, packet->options, D6O_IA_PD);
        if (oc != NULL) {
                log_debug("Discarding %s from %s; "
                          "IA_PD option present%s",
                          dhcpv6_type_names[packet->dhcpv6_msg_type],
                          piaddr(packet->client_addr), client_id_str);
                goto exit;
        }

        oc = lookup_option(&dhcpv6_universe, packet->options, D6O_SERVERID);
        if (oc != NULL) {
                if (!evaluate_option_cache(server_id, packet, NULL, NULL,
                                           packet->options, NULL,
                                           &global_scope, oc, MDL)) {
                        log_error("Error processing %s from %s; "
                                  "unable to evaluate Server Identifier%s",
                                  dhcpv6_type_names[packet->dhcpv6_msg_type],
                                  piaddr(packet->client_addr), client_id_str);
                        goto exit;
                }
                if ((server_duid.len != server_id->len) ||
                    (memcmp(server_duid.data, server_id->data,
                            server_duid.len) != 0)) {
                        log_debug("Discarding %s from %s; "
                                  "not our server identifier "
                                  "(SERVERID %s, server DUID %s)%s",
                                  dhcpv6_type_names[packet->dhcpv6_msg_type],
                                  piaddr(packet->client_addr),
                                  print_hex_1(server_id->len,
                                              server_id->data, 60),
                                  print_hex_2(server_duid.len,
                                              server_duid.data, 60),
                                  client_id_str);
                        goto exit;
                }
        }

        /* looks good */
        ret_val = 1;

exit:
        if (!ret_val) {
                if (server_id->len > 0) {
                        data_string_forget(server_id, MDL);
                }
        }
        return ret_val;
}

/*
 * Options that we want to send, in addition to what was requested
 * via the ORO.
 */
static const int required_opts[] = {
        D6O_CLIENTID,
        D6O_SERVERID,
        D6O_STATUS_CODE,
        D6O_PREFERENCE,
        0
};
static const int required_opts_solicit[] = {
        D6O_CLIENTID,
        D6O_SERVERID,
        D6O_IA_NA,
        D6O_IA_TA,
        D6O_IA_PD,
        D6O_RAPID_COMMIT,
        D6O_STATUS_CODE,
        D6O_RECONF_ACCEPT,
        D6O_PREFERENCE,
        0
};
static const int required_opts_agent[] = {
        D6O_INTERFACE_ID,
#if defined(RELAY_PORT)
        D6O_RELAY_SOURCE_PORT,
#endif
        D6O_RELAY_MSG,
        0
};
static const int required_opts_IA[] = {
        D6O_IAADDR,
        D6O_STATUS_CODE,
        0
};
static const int required_opts_IA_PD[] = {
        D6O_IAPREFIX,
        D6O_STATUS_CODE,
        0
};
static const int required_opts_STATUS_CODE[] = {
        D6O_STATUS_CODE,
        0
};
#ifdef DHCP4o6
static const int required_opts_4o6[] = {
        D6O_DHCPV4_MSG,
        0
};
#endif

static const int unicast_reject_opts[] = {
        D6O_CLIENTID,
        D6O_SERVERID,
        D6O_STATUS_CODE,
        0
};


/*
 * Extracts from packet contents an IA_* option, storing the IA structure
 * in its entirety in enc_opt_data, and storing any decoded DHCPv6 options
 * in enc_opt_state for later lookup and evaluation.  The 'offset' indicates
 * where in the IA_* the DHCPv6 options commence.
 */
static int
get_encapsulated_IA_state(struct option_state **enc_opt_state,
                          struct data_string *enc_opt_data,
                          struct packet *packet,
                          struct option_cache *oc,
                          int offset)
{
        /*
         * Get the raw data for the encapsulated options.
         */
        memset(enc_opt_data, 0, sizeof(*enc_opt_data));
        if (!evaluate_option_cache(enc_opt_data, packet,
                                   NULL, NULL, packet->options, NULL,
                                   &global_scope, oc, MDL)) {
                log_error("get_encapsulated_IA_state: "
                          "error evaluating raw option.");
                return 0;
        }
        if (enc_opt_data->len < offset) {
                log_error("get_encapsulated_IA_state: raw option too small.");
                data_string_forget(enc_opt_data, MDL);
                return 0;
        }

        /*
         * Now create the option state structure, and pass it to the
         * function that parses options.
         */
        *enc_opt_state = NULL;
        if (!option_state_allocate(enc_opt_state, MDL)) {
                log_error("get_encapsulated_IA_state: no memory for options.");
                data_string_forget(enc_opt_data, MDL);
                return 0;
        }
        if (!parse_option_buffer(*enc_opt_state,
                                 enc_opt_data->data + offset,
                                 enc_opt_data->len - offset,
                                 &dhcpv6_universe)) {
                log_error("get_encapsulated_IA_state: error parsing options.");
                option_state_dereference(enc_opt_state, MDL);
                data_string_forget(enc_opt_data, MDL);
                return 0;
        }

        return 1;
}

static int
set_status_code(u_int16_t status_code, const char *status_message,
                struct option_state *opt_state)
{
        struct data_string d;
        int ret_val;

        memset(&d, 0, sizeof(d));
        d.len = sizeof(status_code) + strlen(status_message);
        if (!buffer_allocate(&d.buffer, d.len, MDL)) {
                log_fatal("set_status_code: no memory for status code.");
        }
        d.data = d.buffer->data;
        putUShort(d.buffer->data, status_code);
        memcpy(d.buffer->data + sizeof(status_code),
               status_message, d.len - sizeof(status_code));
        if (!save_option_buffer(&dhcpv6_universe, opt_state,
                                d.buffer, (unsigned char *)d.data, d.len,
                                D6O_STATUS_CODE, 0)) {
                log_error("set_status_code: error saving status code.");
                ret_val = 0;
        } else {
                ret_val = 1;
        }
        data_string_forget(&d, MDL);
        return ret_val;
}

void check_pool6_threshold(struct reply_state *reply,
                           struct iasubopt *lease)
{
        struct ipv6_pond *pond;
        isc_uint64_t used, count, high_threshold;
        int poolhigh = 0, poollow = 0;
        char *shared_name = "no name";
        char tmp_addr[INET6_ADDRSTRLEN];

        if ((lease->ipv6_pool == NULL) || (lease->ipv6_pool->ipv6_pond == NULL))
                return;
        pond = lease->ipv6_pool->ipv6_pond;

        /* If the address range is too large to track, just skip all this. */
        if (pond->jumbo_range == 1) {
                return;
        }

        count = pond->num_total;
        used = pond->num_active;

        /* get network name for logging */
        if ((pond->shared_network != NULL) &&
            (pond->shared_network->name != NULL)) {
                shared_name = pond->shared_network->name;
        }

        /* The logged flag indicates if we have already crossed the high
         * threshold and emitted a log message.  If it is set we check to
         * see if we have re-crossed the low threshold and need to reset
         * things.  When we cross the high threshold we determine what
         * the low threshold is and save it into the low_threshold value.
         * When we cross that threshold we reset the logged flag and
         * the low_threshold to 0 which allows the high threshold message
         * to be emitted once again.
         * if we haven't recrossed the boundry we don't need to do anything.
         */
        if (pond->logged !=0) {
                if (used <= pond->low_threshold) {
                        pond->low_threshold = 0;
                        pond->logged = 0;
                        log_error("Pool threshold reset - shared subnet: %s; "
                                  "address: %s; low threshold %llu/%llu.",
                                  shared_name,
                                  inet_ntop(AF_INET6, &lease->addr,
                                            tmp_addr, sizeof(tmp_addr)),
                                  used, count);
                }
                return;
        }

        /* find the high threshold */
        if (get_option_int(&poolhigh, &server_universe, reply->packet, NULL,
                           NULL, reply->packet->options, reply->opt_state,
                           reply->opt_state, &lease->scope,
                           SV_LOG_THRESHOLD_HIGH, MDL) == 0) {
                /* no threshold bail out */
                return;
        }

        /* We do have a threshold for this pool, see if its valid */
        if ((poolhigh <= 0) || (poolhigh > 100)) {
                /* not valid */
                return;
        }

        /* we have a valid value, have we exceeded it */
        high_threshold = FIND_POND6_PERCENT(count, poolhigh);
        if (used < high_threshold) {
                /* nope, no more to do */
                return;
        }

        /* we've exceeded it, output a message */
        log_error("Pool threshold exceeded - shared subnet: %s; "
                  "address: %s; high threshold %d%% %llu/%llu.",
                  shared_name,
                  inet_ntop(AF_INET6, &lease->addr, tmp_addr, sizeof(tmp_addr)),
                  poolhigh, used, count);

        /* handle the low threshold now, if we don't
         * have one we default to 0. */
        if ((get_option_int(&poollow, &server_universe, reply->packet, NULL,
                            NULL, reply->packet->options, reply->opt_state,
                            reply->opt_state, &lease->scope,
                            SV_LOG_THRESHOLD_LOW, MDL) == 0) ||
            (poollow > 100)) {
                poollow = 0;
        }

        /*
         * If the low theshold is higher than the high threshold we continue to log
         * If it isn't then we set the flag saying we already logged and determine
         * what the reset threshold is.
         */
        if (poollow < poolhigh) {
                pond->logged = 1;
                pond->low_threshold = FIND_POND6_PERCENT(count, poollow);
        }
}

/*
 * We have a set of operations we do to set up the reply packet, which
 * is the same for many message types.
 */
static int
start_reply(struct packet *packet,
            const struct data_string *client_id,
            const struct data_string *server_id,
            struct option_state **opt_state,
            struct dhcpv6_packet *reply)
{
        struct option_cache *oc;
        const unsigned char *server_id_data;
        int server_id_len;

        /*
         * Build our option state for reply.
         */
        *opt_state = NULL;
        if (!option_state_allocate(opt_state, MDL)) {
                log_error("start_reply: no memory for option_state.");
                return 0;
        }
        execute_statements_in_scope(NULL, packet, NULL, NULL,
                                    packet->options, *opt_state,
                                    &global_scope, root_group, NULL, NULL);

        /*
         * A small bit of special handling for Solicit messages.
         *
         * We could move the logic into a flag, but for now just check
         * explicitly.
         */
        if (packet->dhcpv6_msg_type == DHCPV6_SOLICIT) {
                reply->msg_type = DHCPV6_ADVERTISE;

                /*
                 * If:
                 * - this message type supports rapid commit (Solicit), and
                 * - the server is configured to supply a rapid commit, and
                 * - the client requests a rapid commit,
                 * Then we add a rapid commit option, and send Reply (instead
                 * of an Advertise).
                 */
                oc = lookup_option(&dhcpv6_universe,
                                   *opt_state, D6O_RAPID_COMMIT);
                if (oc != NULL) {
                        oc = lookup_option(&dhcpv6_universe,
                                           packet->options, D6O_RAPID_COMMIT);
                        if (oc != NULL) {
                                /* Rapid-commit in action. */
                                reply->msg_type = DHCPV6_REPLY;
                        } else {
                                /* Don't want a rapid-commit in advertise. */
                                delete_option(&dhcpv6_universe,
                                              *opt_state, D6O_RAPID_COMMIT);
                        }
                }
        } else {
                reply->msg_type = DHCPV6_REPLY;
                /* Delete the rapid-commit from the sent options. */
                oc = lookup_option(&dhcpv6_universe,
                                   *opt_state, D6O_RAPID_COMMIT);
                if (oc != NULL) {
                        delete_option(&dhcpv6_universe,
                                      *opt_state, D6O_RAPID_COMMIT);
                }
        }

        /*
         * Use the client's transaction identifier for the reply.
         */
        memcpy(reply->transaction_id, packet->dhcpv6_transaction_id,
               sizeof(reply->transaction_id));

        /*
         * RFC 3315, section 18.2 says we need server identifier and
         * client identifier.
         *
         * If the server ID is defined via the configuration file, then
         * it will already be present in the option state at this point,
         * so we don't need to set it.
         *
         * If we have a server ID passed in from the caller,
         * use that, otherwise use the global DUID.
         */
        oc = lookup_option(&dhcpv6_universe, *opt_state, D6O_SERVERID);
        if (oc == NULL) {
                if (server_id == NULL) {
                        server_id_data = server_duid.data;
                        server_id_len = server_duid.len;
                } else {
                        server_id_data = server_id->data;
                        server_id_len = server_id->len;
                }
                if (!save_option_buffer(&dhcpv6_universe, *opt_state,
                                        NULL, (unsigned char *)server_id_data,
                                        server_id_len, D6O_SERVERID, 0)) {
                                log_error("start_reply: "
                                          "error saving server identifier.");
                                return 0;
                }
        }

        if (client_id->buffer != NULL) {
                if (!save_option_buffer(&dhcpv6_universe, *opt_state,
                                        client_id->buffer,
                                        (unsigned char *)client_id->data,
                                        client_id->len,
                                        D6O_CLIENTID, 0)) {
                        log_error("start_reply: error saving "
                                  "client identifier.");
                        return 0;
                }
        }

        /*
         * If the client accepts reconfiguration, let it know that we
         * will send them.
         *
         * Note: we don't actually do this yet, but DOCSIS requires we
         *       claim to.
         */
        oc = lookup_option(&dhcpv6_universe, packet->options,
                           D6O_RECONF_ACCEPT);
        if (oc != NULL) {
                if (!save_option_buffer(&dhcpv6_universe, *opt_state,
                                        NULL, (unsigned char *)"", 0,
                                        D6O_RECONF_ACCEPT, 0)) {
                        log_error("start_reply: "
                                  "error saving RECONF_ACCEPT option.");
                        option_state_dereference(opt_state, MDL);
                        return 0;
                }
        }

        return 1;
}

/*
 * Try to get the IPv6 address the client asked for from the
 * pool.
 *
 * addr is the result (should be a pointer to NULL on entry)
 * pool is the pool to search in
 * requested_addr is the address the client wants
 */
static isc_result_t
try_client_v6_address(struct iasubopt **addr,
                      struct ipv6_pool *pool,
                      const struct data_string *requested_addr)
{
        struct in6_addr tmp_addr;
        isc_result_t result;

        if (requested_addr->len < sizeof(tmp_addr)) {
                return DHCP_R_INVALIDARG;
        }
        memcpy(&tmp_addr, requested_addr->data, sizeof(tmp_addr));
        if (IN6_IS_ADDR_UNSPECIFIED(&tmp_addr)) {
                return ISC_R_FAILURE;
        }

        /*
         * The address is not covered by this (or possibly any) dynamic
         * range.
         */
        if (!ipv6_in_pool(&tmp_addr, pool)) {
                return ISC_R_ADDRNOTAVAIL;
        }

        if (lease6_exists(pool, &tmp_addr)) {
                return ISC_R_ADDRINUSE;
        }

        result = iasubopt_allocate(addr, MDL);
        if (result != ISC_R_SUCCESS) {
                return result;
        }
        (*addr)->addr = tmp_addr;
        (*addr)->plen = 0;

        /* Default is soft binding for 2 minutes. */
        result = add_lease6(pool, *addr, cur_time + 120);
        if (result != ISC_R_SUCCESS) {
                iasubopt_dereference(addr, MDL);
        }
        return result;
}

/*!
 *
 * \brief  Get an IPv6 address for the client.
 *
 * Attempt to find a usable address for the client.  We walk through
 * the ponds checking for permit and deny then through the pools
 * seeing if they have an available address.
 *
 * \param reply = the state structure for the current work on this request
 *                if we create a lease we return it using reply->lease
 *
 * \return
 * ISC_R_SUCCESS = we were able to find an address and are returning a
 *                 pointer to the lease
 * ISC_R_NORESOURCES = there don't appear to be any free addresses.  This
 *                     is probabalistic.  We don't exhaustively try the
 *                     address range, instead we hash the duid and if
 *                     the address derived from the hash is in use we
 *                     hash the address.  After a number of failures we
 *                     conclude the pool is basically full.
 */
static isc_result_t
pick_v6_address(struct reply_state *reply)
{
        struct ipv6_pool *p = NULL;
        struct ipv6_pond *pond;
        int i;
        int start_pool;
        unsigned int attempts;
        char tmp_buf[INET6_ADDRSTRLEN];
        struct iasubopt **addr = &reply->lease;
        isc_uint64_t total = 0;
        isc_uint64_t active = 0;
        isc_uint64_t abandoned = 0;
        int jumbo_range = 0;
        char *shared_name = (reply->shared->name ?
                             reply->shared->name : "(no name)");

        /*
         * Do a quick walk through of the ponds and pools
         * to see if we have any NA address pools
         */
        for (pond = reply->shared->ipv6_pond; pond != NULL; pond = pond->next) {
                if (pond->ipv6_pools == NULL)
                        continue;

                for (i = 0; (p = pond->ipv6_pools[i]) != NULL; i++) {
                        if (p->pool_type == D6O_IA_NA)
                                break;
                }
                if (p != NULL)
                        break;
        }

        /* If we get here and p is NULL we have no useful pools */
        if (p == NULL) {
                log_debug("Unable to pick client address: "
                          "no IPv6 pools on this shared network");
                return ISC_R_NORESOURCES;
        }

        /*
         * We have at least one pool that could provide an address
         * Now we walk through the ponds and pools again and check
         * to see if the client is permitted and if an address is
         * available
         *
         * Within a given pond we start looking at the last pool we
         * allocated from, unless it had a collision trying to allocate
         * an address. This will tend to move us into less-filled pools.
         */

        for (pond = reply->shared->ipv6_pond; pond != NULL; pond = pond->next) {
                isc_result_t result = ISC_R_FAILURE;

                if (((pond->prohibit_list != NULL) &&
                     (permitted(reply->packet, pond->prohibit_list))) ||
                    ((pond->permit_list != NULL) &&
                     (!permitted(reply->packet, pond->permit_list))))
                        continue;

#ifdef EUI_64
                /* If pond is EUI-64 but client duid isn't a valid EUI-64
                 * id, then skip this pond */
                if (pond->use_eui_64 &&
                    !valid_eui_64_duid(&reply->ia->iaid_duid, IAID_LEN)) {
                        continue;
                }
#endif

                start_pool = pond->last_ipv6_pool;
                i = start_pool;
                do {
                        p = pond->ipv6_pools[i];
                        if (p->pool_type == D6O_IA_NA) {
#ifdef EUI_64
                                if (pond->use_eui_64) {
                                        result =
                                        create_lease6_eui_64(p, addr,
                                                      &reply->ia->iaid_duid,
                                                      cur_time + 120);
                                }
                                else
#endif
                                {
                                        result =
                                        create_lease6(p, addr, &attempts,
                                                      &reply->ia->iaid_duid,
                                                      cur_time + 120);

                                }

                                if (result == ISC_R_SUCCESS) {
                                        /*
                                         * Record the pool used (or next one if
                                         * there was a collision).
                                         */
                                        if (attempts > 1) {
                                                i++;
                                                if (pond->ipv6_pools[i]
                                                    == NULL) {
                                                        i = 0;
                                                }
                                        }

                                        pond->last_ipv6_pool = i;

                                        log_debug("Picking pool address %s",
                                                  inet_ntop(AF_INET6,
                                                  &((*addr)->addr),
                                                  tmp_buf, sizeof(tmp_buf)));
                                        return (ISC_R_SUCCESS);
                                }
                        }

                        i++;
                        if (pond->ipv6_pools[i] == NULL) {
                                i = 0;
                        }
                } while (i != start_pool);

                if (result == ISC_R_NORESOURCES) {
                        jumbo_range += pond->jumbo_range;
                        total += pond->num_total;
                        active += pond->num_active;
                        abandoned += pond->num_abandoned;
                }
        }

        /*
         * If we failed to pick an IPv6 address from any of the subnets.
         * Presumably that means we have no addresses for the client.
         */
        if (jumbo_range != 0) {
                log_debug("Unable to pick client address: "
                          "no addresses available  - shared network %s: "
                          " 2^64-1 < total, %llu active,  %llu abandoned",
                          shared_name, active - abandoned, abandoned);
        } else {
                log_debug("Unable to pick client address: "
                          "no addresses available  - shared network %s: "
                          "%llu total, %llu active,  %llu abandoned",
                          shared_name, total, active - abandoned, abandoned);
        }

        return ISC_R_NORESOURCES;
}

/*
 * Try to get the IPv6 prefix the client asked for from the
 * prefix pool.
 *
 * pref is the result (should be a pointer to NULL on entry)
 * pool is the prefix pool to search in
 * requested_pref is the address the client wants
 */
static isc_result_t
try_client_v6_prefix(struct iasubopt **pref,
                     struct ipv6_pool *pool,
                     const struct data_string *requested_pref)
{
        u_int8_t tmp_plen;
        struct in6_addr tmp_pref;
        struct iaddr ia;
        isc_result_t result;

        if (requested_pref->len < sizeof(tmp_plen) + sizeof(tmp_pref)) {
                return DHCP_R_INVALIDARG;
        }

        tmp_plen = (int) requested_pref->data[0];
        if ((tmp_plen < 3) || (tmp_plen > 128)) {
                return ISC_R_FAILURE;
        }

        memcpy(&tmp_pref, requested_pref->data + 1, sizeof(tmp_pref));
        if (IN6_IS_ADDR_UNSPECIFIED(&tmp_pref)) {
                return ISC_R_FAILURE;
        }

        ia.len = 16;
        memcpy(&ia.iabuf, &tmp_pref, 16);
        if (!is_cidr_mask_valid(&ia, (int) tmp_plen)) {
                return ISC_R_FAILURE;
        }

        if (!ipv6_in_pool(&tmp_pref, pool) ||
            ((int)tmp_plen != pool->units)) {
                return ISC_R_ADDRNOTAVAIL;
        }

        if (prefix6_exists(pool, &tmp_pref, tmp_plen)) {
                return ISC_R_ADDRINUSE;
        }

        result = iasubopt_allocate(pref, MDL);
        if (result != ISC_R_SUCCESS) {
                return result;
        }

        (*pref)->addr = tmp_pref;
        (*pref)->plen = tmp_plen;

        /* Default is soft binding for 2 minutes. */
        result = add_lease6(pool, *pref, cur_time + 120);
        if (result != ISC_R_SUCCESS) {
                iasubopt_dereference(pref, MDL);
        }

        return result;
}

/*!
 *
 * \brief  Get an IPv6 prefix for the client.
 *
 * Attempt to find a usable prefix for the client.  Based upon the prefix
 * length mode and the plen supplied by the client (if one), we make one
 * or more calls to pick_v6_prefix_helper() to find a prefix as follows:
 *
 * PLM_IGNORE or client specifies a plen of zero, use the first available
 * prefix regardless of it's length.
 *
 * PLM_PREFER – look for an exact match to client's plen first, if none
 * found, use the first available prefix of any length
 *
 * PLM_EXACT – look for an exact match first, if none found then fail. This
 * is the default behavior.
 *
 * PLM_MAXIMUM  - look for an exact match first, then the first available whose
 * prefix length is less than client's plen, otherwise fail.
 *
 * PLM_MINIMUM  - look for an exact match first, then the first available whose
 * prefix length is greater than client's plen, otherwise fail.
 *
 * Note that the selection mode is configurable at the global scope only via
 * prefix-len-mode.
 *
 * \param reply = the state structure for the current work on this request
 *                if we create a lease we return it using reply->lease
 *
 * \return
 * ISC_R_SUCCESS = we were able to find an prefix and are returning a
 *                 pointer to the lease
 * ISC_R_NORESOURCES = there don't appear to be any free addresses.  This
 *                     is probabalistic.  We don't exhaustively try the
 *                     address range, instead we hash the duid and if
 *                     the address derived from the hash is in use we
 *                     hash the address.  After a number of failures we
 *                     conclude the pool is basically full.
 */
static isc_result_t
pick_v6_prefix(struct reply_state *reply) {
        struct ipv6_pool *p = NULL;
        struct ipv6_pond *pond;
        int i;
        isc_result_t result;

        /*
         * Do a quick walk through of the ponds and pools
         * to see if we have any prefix pools
        */
        for (pond = reply->shared->ipv6_pond; pond != NULL; pond = pond->next) {
                if (pond->ipv6_pools == NULL)
                        continue;

                for (i = 0; (p = pond->ipv6_pools[i]) != NULL; i++) {
                        if (p->pool_type == D6O_IA_PD)
                                break;
                }
                if (p != NULL)
                        break;
        }

        /* If we get here and p is NULL we have no useful pools */
        if (p == NULL) {
                log_debug("Unable to pick client prefix: "
                          "no IPv6 pools on this shared network");
                return ISC_R_NORESOURCES;
        }

        if (reply->preflen <= 0) {
                /* If we didn't get a plen (-1) or client plen is 0, then just
                 * select first available (same as PLM_INGORE) */
                result = pick_v6_prefix_helper(reply, PLM_IGNORE);
        } else {
                switch (prefix_length_mode) {
                case PLM_PREFER:
                        /* First we look for an exact match, if not found
                         * then first available */
                        result = pick_v6_prefix_helper(reply, PLM_EXACT);
                        if (result != ISC_R_SUCCESS) {
                                result = pick_v6_prefix_helper(reply,
                                                              PLM_IGNORE);
                        }
                        break;

                case PLM_EXACT:
                        /* Match exactly or fail */
                        result = pick_v6_prefix_helper(reply, PLM_EXACT);
                        break;

                case PLM_MINIMUM:
                case PLM_MAXIMUM:
                        /* First we look for an exact match, if not found
                         * then first available by mode */
                        result = pick_v6_prefix_helper(reply, PLM_EXACT);
                        if (result != ISC_R_SUCCESS) {
                                result = pick_v6_prefix_helper(reply,
                                                            prefix_length_mode);
                        }
                        break;

                default:
                        /* First available */
                        result = pick_v6_prefix_helper(reply, PLM_IGNORE);
                        break;
                }
        }

        if (result == ISC_R_SUCCESS) {
                char tmp_buf[INET6_ADDRSTRLEN];

                log_debug("Picking pool prefix %s/%u",
                          inet_ntop(AF_INET6, &(reply->lease->addr),
                                    tmp_buf, sizeof(tmp_buf)),
                                    (unsigned)(reply->lease->plen));
                return (ISC_R_SUCCESS);
        }

        /*
         * If we failed to pick an IPv6 prefix
         * Presumably that means we have no prefixes for the client.
        */
        log_debug("Unable to pick client prefix: no prefixes available");
        return ISC_R_NORESOURCES;
}

/*!
 *
 * \brief  Get an IPv6 prefix for the client based upon selection mode.
 *
 * We walk through the ponds checking for permit and deny. If a pond is
 * permissable to use, loop through its PD pools checking prefix lengths
 * against the client plen based on the prefix length mode, looking for
 * available prefixes.
 *
 * \param reply = the state structure for the current work on this request
 *                if we create a lease we return it using reply->lease
 * \prefix_mode = selection mode to use
 *
 * \return
 * ISC_R_SUCCESS = we were able to find a prefix and are returning a
 *                 pointer to the lease
 * ISC_R_NORESOURCES = there don't appear to be any free addresses.  This
 *                     is probabalistic.  We don't exhaustively try the
 *                     address range, instead we hash the duid and if
 *                     the address derived from the hash is in use we
 *                     hash the address.  After a number of failures we
 *                     conclude the pool is basically full.
 */
isc_result_t
pick_v6_prefix_helper(struct reply_state *reply, int prefix_mode) {
        struct ipv6_pool *p = NULL;
        struct ipv6_pond *pond;
        int i;
        unsigned int attempts;
        struct iasubopt **pref = &reply->lease;

        for (pond = reply->shared->ipv6_pond; pond != NULL; pond = pond->next) {
                if (((pond->prohibit_list != NULL) &&
                     (permitted(reply->packet, pond->prohibit_list))) ||
                    ((pond->permit_list != NULL) &&
                     (!permitted(reply->packet, pond->permit_list))))
                        continue;

                for (i = 0; (p = pond->ipv6_pools[i]) != NULL; i++) {
                        if ((p->pool_type == D6O_IA_PD) &&
                            (eval_prefix_mode(p->units, reply->preflen,
                                              prefix_mode) == 1) &&
                            (create_prefix6(p, pref, &attempts,
                                            &reply->ia->iaid_duid,
                                            cur_time + 120) == ISC_R_SUCCESS)) {
                                return (ISC_R_SUCCESS);
                        }
                }
        }

        return ISC_R_NORESOURCES;
}

/*!
 *
 * \brief Test a prefix length against another based on prefix length mode
 *
 * \param len - prefix length to test
 * \param preflen - preferred prefix length against which to test
 * \param prefix_mode - prefix selection mode with which to test
 *
 * Note that the case of preferred length of 0 is not short-cut here as it
 * is assumed to be done at a higher level.
 *
 * \return 1 if the given length is usable based upon mode and a preferred
 * length, 0 if not.
 */
int
eval_prefix_mode(int len, int preflen, int prefix_mode) {
        int use_it = 1;
        switch (prefix_mode) {
        case PLM_EXACT:
                use_it = (len == preflen);
                break;
        case PLM_MINIMUM:
                /* they asked for a prefix length no "shorter" than preflen */
                use_it = (len >= preflen);
                break;
        case PLM_MAXIMUM:
                /* they asked for a prefix length no "longer" than preflen */
                use_it = (len <= preflen);
                break;
        default:
                /* otherwise use it */
                break;
        }

        return (use_it);
}

/*
 *! \file server/dhcpv6.c
 *
 * \brief construct a reply containing information about a client's lease
 *
 * lease_to_client() is called from several messages to construct a
 * reply that contains all that we know about the client's correct lease
 * (or projected lease).
 *
 * Solicit - "Soft" binding, ignore unknown addresses or bindings, just
 *           send what we "may" give them on a request.
 *
 * Request - "Hard" binding, but ignore supplied addresses (just provide what
 *           the client should really use).
 *
 * Renew   - "Hard" binding, but client-supplied addresses are 'real'.  Error
 * Rebind    out any "wrong" addresses the client sends.  This means we send
 *           an empty IA_NA with a status code of NoBinding or NotOnLink or
 *           possibly send the address with zeroed lifetimes.
 *
 * Information-Request - No binding.
 *
 * The basic structure is to traverse the client-supplied data first, and
 * validate and echo back any contents that can be.  If the client-supplied
 * data does not error out (on renew/rebind as above), but we did not send
 * any addresses, attempt to allocate one.
 *
 * At the end of the this function we call commit_leases_timed() to
 * fsync and rotate the file as necessary.  commit_leases_timed() will
 * check that we have written at least one lease to the file and that
 * some time has passed before doing any fsync or file rewrite so we
 * don't bother tracking if we did a write_ia during this function.
 */
/* TODO: look at client hints for lease times */

static void
lease_to_client(struct data_string *reply_ret,
                struct packet *packet,
                const struct data_string *client_id,
                const struct data_string *server_id)
{
        static struct reply_state reply;
        struct option_cache *oc;
        struct data_string packet_oro;
        int i;

        memset(&packet_oro, 0, sizeof(packet_oro));

        /* Locate the client.  */
        if (shared_network_from_packet6(&reply.shared,
                                        packet) != ISC_R_SUCCESS)
                goto exit;

        /*
         * Initialize the reply.
         */
        packet_reference(&reply.packet, packet, MDL);
        data_string_copy(&reply.client_id, client_id, MDL);

        if (!start_reply(packet, client_id, server_id, &reply.opt_state,
                         &reply.buf.reply))
                goto exit;

        /* Set the write cursor to just past the reply header. */
        reply.cursor = REPLY_OPTIONS_INDEX;

        /*
         * Get the ORO from the packet, if any.
         */
        oc = lookup_option(&dhcpv6_universe, packet->options, D6O_ORO);
        if (oc != NULL) {
                if (!evaluate_option_cache(&packet_oro, packet,
                                           NULL, NULL,
                                           packet->options, NULL,
                                           &global_scope, oc, MDL)) {
                        log_error("lease_to_client: error evaluating ORO.");
                        goto exit;
                }
        }

        /*
         * Find a host record that matches the packet, if any, and is
         * valid for the shared network the client is on.
         */
        if (find_hosts6(&reply.host, packet, client_id, MDL)) {
                packet->known = 1;
                seek_shared_host(&reply.host, reply.shared);
        }

        /* Process the client supplied IA's onto the reply buffer. */
        reply.ia_count = 0;
        oc = lookup_option(&dhcpv6_universe, packet->options, D6O_IA_NA);

        for (; oc != NULL ; oc = oc->next) {
                isc_result_t status;

                /* Start counting resources (addresses) offered. */
                reply.client_resources = 0;
                reply.resources_included = ISC_FALSE;

                status = reply_process_ia_na(&reply, oc);

                /*
                 * We continue to try other IA's whether we can address
                 * this one or not.  Any other result is an immediate fail.
                 */
                if ((status != ISC_R_SUCCESS) &&
                    (status != ISC_R_NORESOURCES))
                        goto exit;
        }
        oc = lookup_option(&dhcpv6_universe, packet->options, D6O_IA_TA);
        for (; oc != NULL ; oc = oc->next) {
                isc_result_t status;

                /* Start counting resources (addresses) offered. */
                reply.client_resources = 0;
                reply.resources_included = ISC_FALSE;

                status = reply_process_ia_ta(&reply, oc);

                /*
                 * We continue to try other IA's whether we can address
                 * this one or not.  Any other result is an immediate fail.
                 */
                if ((status != ISC_R_SUCCESS) &&
                    (status != ISC_R_NORESOURCES))
                        goto exit;
        }

        /* Same for IA_PD's. */
        reply.pd_count = 0;
        oc = lookup_option(&dhcpv6_universe, packet->options, D6O_IA_PD);
        for (; oc != NULL ; oc = oc->next) {
                isc_result_t status;

                /* Start counting resources (prefixes) offered. */
                reply.client_resources = 0;
                reply.resources_included = ISC_FALSE;

                status = reply_process_ia_pd(&reply, oc);

                /*
                 * We continue to try other IA_PD's whether we can address
                 * this one or not.  Any other result is an immediate fail.
                 */
                if ((status != ISC_R_SUCCESS) &&
                    (status != ISC_R_NORESOURCES))
                        goto exit;
        }

        /*
         * Make no reply if we gave no resources and is not
         * for Information-Request.
         */
        if ((reply.ia_count == 0) && (reply.pd_count == 0)) {
                if (reply.packet->dhcpv6_msg_type !=
                                            DHCPV6_INFORMATION_REQUEST)
                        goto exit;

                /*
                 * Because we only execute statements on a per-IA basis,
                 * we need to execute statements in any non-IA reply to
                 * source configuration.
                 */
                execute_statements_in_scope(NULL, reply.packet, NULL, NULL,
                                            reply.packet->options,
                                            reply.opt_state, &global_scope,
                                            reply.shared->group, root_group,
                                            NULL);

                /* Execute statements from class scopes. */
                for (i = reply.packet->class_count; i > 0; i--) {
                        execute_statements_in_scope(NULL, reply.packet,
                                                    NULL, NULL,
                                                    reply.packet->options,
                                                    reply.opt_state,
                                                    &global_scope,
                                                    reply.packet->classes[i - 1]->group,
                                                    reply.shared->group, NULL);
                }

                /* Bring in any configuration from a host record. */
                if (reply.host != NULL)
                        execute_statements_in_scope(NULL, reply.packet,
                                                    NULL, NULL,
                                                    reply.packet->options,
                                                    reply.opt_state,
                                                    &global_scope,
                                                    reply.host->group,
                                                    reply.shared->group, NULL);
        }

        /*
         * RFC3315 section 17.2.2 (Solicit):
         *
         * If the server will not assign any addresses to any IAs in a
         * subsequent Request from the client, the server MUST send an
         * Advertise message to the client that includes only a Status
         * Code option with code NoAddrsAvail and a status message for
         * the user, a Server Identifier option with the server's DUID,
         * and a Client Identifier option with the client's DUID.
         *
         * This has been updated by an errata such that the server
         * can always send an IA.
         *
         * Section 18.2.1 (Request):
         *
         * If the server cannot assign any addresses to an IA in the
         * message from the client, the server MUST include the IA in
         * the Reply message with no addresses in the IA and a Status
         * Code option in the IA containing status code NoAddrsAvail.
         *
         * Section 18.1.8 (Client Behavior):
         *
         * Leave unchanged any information about addresses the client has
         * recorded in the IA but that were not included in the IA from
         * the server.
         * Sends a Renew/Rebind if the IA is not in the Reply message.
         */

        /*
         * Having stored the client's IA's, store any options that
         * will fit in the remaining space.
         */
        reply.cursor += store_options6((char *)reply.buf.data + reply.cursor,
                                       sizeof(reply.buf) - reply.cursor,
                                       reply.opt_state, reply.packet,
                                       required_opts_solicit,
                                       &packet_oro);

        /* Return our reply to the caller. */
        reply_ret->len = reply.cursor;
        reply_ret->buffer = NULL;
        if (!buffer_allocate(&reply_ret->buffer, reply.cursor, MDL)) {
                log_fatal("No memory to store Reply.");
        }
        memcpy(reply_ret->buffer->data, reply.buf.data, reply.cursor);
        reply_ret->data = reply_ret->buffer->data;

        /* If appropriate commit and rotate the lease file */
        (void) commit_leases_timed();

      exit:
        /* Cleanup. */
        if (reply.shared != NULL)
                shared_network_dereference(&reply.shared, MDL);
        if (reply.host != NULL)
                host_dereference(&reply.host, MDL);
        if (reply.opt_state != NULL)
                option_state_dereference(&reply.opt_state, MDL);
        if (reply.packet != NULL)
                packet_dereference(&reply.packet, MDL);
        if (reply.client_id.data != NULL)
                data_string_forget(&reply.client_id, MDL);
        if (packet_oro.buffer != NULL)
                data_string_forget(&packet_oro, MDL);
        reply.renew = reply.rebind = reply.min_prefer = reply.min_valid = 0;
        reply.cursor = 0;
}

/* Process a client-supplied IA_NA.  This may append options to the tail of
 * the reply packet being built in the reply_state structure.
 */
static isc_result_t
reply_process_ia_na(struct reply_state *reply, struct option_cache *ia) {
        isc_result_t status = ISC_R_SUCCESS;
        u_int32_t iaid;
        unsigned ia_cursor;
        struct option_state *packet_ia;
        struct option_cache *oc;
        struct data_string ia_data, data;

        /* Initialize values that will get cleaned up on return. */
        packet_ia = NULL;
        memset(&ia_data, 0, sizeof(ia_data));
        memset(&data, 0, sizeof(data));
        /*
         * Note that find_client_address() may set reply->lease.
         */

        /* Make sure there is at least room for the header. */
        if ((reply->cursor + IA_NA_OFFSET + 4) > sizeof(reply->buf)) {
                log_error("reply_process_ia_na: Reply too long for IA.");
                return ISC_R_NOSPACE;
        }


        /* Fetch the IA_NA contents. */
        if (!get_encapsulated_IA_state(&packet_ia, &ia_data, reply->packet,
                                       ia, IA_NA_OFFSET)) {
                log_error("reply_process_ia_na: error evaluating ia");
                status = ISC_R_FAILURE;
                goto cleanup;
        }

        /* Extract IA_NA header contents. */
        iaid = getULong(ia_data.data);
        reply->renew = getULong(ia_data.data + 4);
        reply->rebind = getULong(ia_data.data + 8);

        /* Create an IA_NA structure. */
        if (ia_allocate(&reply->ia, iaid, (char *)reply->client_id.data,
                        reply->client_id.len, MDL) != ISC_R_SUCCESS) {
                log_error("reply_process_ia_na: no memory for ia.");
                status = ISC_R_NOMEMORY;
                goto cleanup;
        }
        reply->ia->ia_type = D6O_IA_NA;

        /* Cache pre-existing IA, if any. */
        ia_hash_lookup(&reply->old_ia, ia_na_active,
                       (unsigned char *)reply->ia->iaid_duid.data,
                       reply->ia->iaid_duid.len, MDL);

        /*
         * Create an option cache to carry the IA_NA option contents, and
         * execute any user-supplied values into it.
         */
        if (!option_state_allocate(&reply->reply_ia, MDL)) {
                status = ISC_R_NOMEMORY;
                goto cleanup;
        }

        /* Check & cache the fixed host record. */
        if ((reply->host != NULL) && (reply->host->fixed_addr != NULL)) {
                struct iaddr tmp_addr;

                if (!evaluate_option_cache(&reply->fixed, NULL, NULL, NULL,
                                           NULL, NULL, &global_scope,
                                           reply->host->fixed_addr, MDL)) {
                        log_error("reply_process_ia_na: unable to evaluate "
                                  "fixed address.");
                        status = ISC_R_FAILURE;
                        goto cleanup;
                }

                if (reply->fixed.len < 16) {
                        log_error("reply_process_ia_na: invalid fixed address.");
                        status = DHCP_R_INVALIDARG;
                        goto cleanup;
                }

                /* Find the static lease's subnet. */
                tmp_addr.len = 16;
                memcpy(tmp_addr.iabuf, reply->fixed.data, 16);

                if (find_grouped_subnet(&reply->subnet, reply->shared,
                                        tmp_addr, MDL) == 0)
                        log_fatal("Impossible condition at %s:%d.", MDL);

                reply->static_lease = ISC_TRUE;
        } else
                reply->static_lease = ISC_FALSE;

        /*
         * Save the cursor position at the start of the IA, so we can
         * set length and adjust t1/t2 values later.  We write a temporary
         * header out now just in case we decide to adjust the packet
         * within sub-process functions.
         */
        ia_cursor = reply->cursor;

        /* Initialize the IA_NA header.  First the code. */
        putUShort(reply->buf.data + reply->cursor, (unsigned)D6O_IA_NA);
        reply->cursor += 2;

        /* Then option length. */
        putUShort(reply->buf.data + reply->cursor, 0x0Cu);
        reply->cursor += 2;

        /* Then IA_NA header contents; IAID. */
        putULong(reply->buf.data + reply->cursor, iaid);
        reply->cursor += 4;

        /* We store the client's t1 for now, and may over-ride it later. */
        putULong(reply->buf.data + reply->cursor, reply->renew);
        reply->cursor += 4;

        /* We store the client's t2 for now, and may over-ride it later. */
        putULong(reply->buf.data + reply->cursor, reply->rebind);
        reply->cursor += 4;

        /*
         * For each address in this IA_NA, decide what to do about it.
         *
         * Guidelines:
         *
         * The client leaves unchanged any information about addresses
         * it has recorded but are not included ("cancel/break" below).
         * A not included IA ("cleanup" below) could give a Renew/Rebind.
         */
        oc = lookup_option(&dhcpv6_universe, packet_ia, D6O_IAADDR);
        reply->min_valid = reply->min_prefer = INFINITE_TIME;
        reply->client_valid = reply->client_prefer = 0;
        for (; oc != NULL ; oc = oc->next) {
                status = reply_process_addr(reply, oc);

                /*
                 * Canceled means we did not allocate addresses to the
                 * client, but we're "done" with this IA - we set a status
                 * code.  So transmit this reply, e.g., move on to the next
                 * IA.
                 */
                if (status == ISC_R_CANCELED)
                        break;

                if ((status != ISC_R_SUCCESS) &&
                    (status != ISC_R_ADDRINUSE) &&
                    (status != ISC_R_ADDRNOTAVAIL))
                        goto cleanup;
        }

        reply->ia_count++;

        /*
         * If we fell through the above and never gave the client
         * an address, give it one now.
         */
        if ((status != ISC_R_CANCELED) && (reply->client_resources == 0)) {
                status = find_client_address(reply);

                if (status == ISC_R_NORESOURCES) {
                        switch (reply->packet->dhcpv6_msg_type) {
                              case DHCPV6_SOLICIT:
                                /*
                                 * No address for any IA is handled
                                 * by the caller.
                                 */
                                /* FALL THROUGH */

                              case DHCPV6_REQUEST:
                                /* Section 18.2.1 (Request):
                                 *
                                 * If the server cannot assign any addresses to
                                 * an IA in the message from the client, the
                                 * server MUST include the IA in the Reply
                                 * message with no addresses in the IA and a
                                 * Status Code option in the IA containing
                                 * status code NoAddrsAvail.
                                 */
                                option_state_dereference(&reply->reply_ia, MDL);
                                if (!option_state_allocate(&reply->reply_ia,
                                                           MDL))
                                {
                                        log_error("reply_process_ia_na: No "
                                                  "memory for option state "
                                                  "wipe.");
                                        status = ISC_R_NOMEMORY;
                                        goto cleanup;
                                }

                                if (!set_status_code(STATUS_NoAddrsAvail,
                                                     "No addresses available "
                                                     "for this interface.",
                                                      reply->reply_ia)) {
                                        log_error("reply_process_ia_na: Unable "
                                                  "to set NoAddrsAvail status "
                                                  "code.");
                                        status = ISC_R_FAILURE;
                                        goto cleanup;
                                }

                                status = ISC_R_SUCCESS;
                                break;

                              default:
                                /*
                                 * RFC 3315 does not tell us to emit a status
                                 * code in this condition, or anything else.
                                 *
                                 * If we included non-allocated addresses
                                 * (zeroed lifetimes) in an IA, then the client
                                 * will deconfigure them.
                                 *
                                 * So we want to include the IA even if we
                                 * can't give it a new address if it includes
                                 * zeroed lifetime addresses.
                                 *
                                 * We don't want to include the IA if we
                                 * provide zero addresses including zeroed
                                 * lifetimes.
                                 */
                                if (reply->resources_included)
                                        status = ISC_R_SUCCESS;
                                else
                                        goto cleanup;
                                break;
                        }
                }

                if (status != ISC_R_SUCCESS)
                        goto cleanup;
        }

        /*
         * yes, goto's aren't the best but we also want to avoid extra
         * indents
         */
        if (status == ISC_R_CANCELED) {
                /* We're replying with a status code so we still need to
                 * write it out in wire-format to the outbound buffer */
                write_to_packet(reply, ia_cursor);
                goto cleanup;
        }

        /*
         * Handle static leases, we always log stuff and if it's
         * a hard binding we run any commit statements that we have
         */
        if (reply->static_lease) {
                char tmp_addr[INET6_ADDRSTRLEN];
                log_info("%s NA: address %s to client with duid %s iaid = %d "
                         "static",
                         dhcpv6_type_names[reply->buf.reply.msg_type],
                         inet_ntop(AF_INET6, reply->fixed.data, tmp_addr,
                                   sizeof(tmp_addr)),
                         print_hex_1(reply->client_id.len,
                                     reply->client_id.data, 60),
                         iaid);

                /* Write the lease out in wire-format to the outbound buffer */
                write_to_packet(reply, ia_cursor);
#ifdef NSUPDATE
                /* Performs DDNS updates if we're configured to do them */
                ddns_update_static6(reply);
#endif
                if ((reply->buf.reply.msg_type == DHCPV6_REPLY) &&
                    (reply->on_star.on_commit != NULL)) {
                        execute_statements(NULL, reply->packet, NULL, NULL,
                                           reply->packet->options,
                                           reply->opt_state, NULL,
                                           reply->on_star.on_commit, NULL);
                        executable_statement_dereference
                                (&reply->on_star.on_commit, MDL);
                }
                goto cleanup;
        }

        /*
         * If we have any addresses log what we are doing.
         */
        if (reply->ia->num_iasubopt != 0) {
                struct iasubopt *tmp;
                int i;
                char tmp_addr[INET6_ADDRSTRLEN];

                for (i = 0 ; i < reply->ia->num_iasubopt ; i++) {
                        tmp = reply->ia->iasubopt[i];

                        log_info("%s NA: address %s to client with duid %s "
                                 "iaid = %d valid for %u seconds",
                                 dhcpv6_type_names[reply->buf.reply.msg_type],
                                 inet_ntop(AF_INET6, &tmp->addr,
                                           tmp_addr, sizeof(tmp_addr)),
                                 print_hex_1(reply->client_id.len,
                                             reply->client_id.data, 60),
                                 iaid, tmp->valid);
                }
        }

        /*
         * If this is not a 'soft' binding, consume the new changes into
         * the database (if any have been attached to the ia_na).
         *
         * Loop through the assigned dynamic addresses, referencing the
         * leases onto this IA_NA rather than any old ones, and updating
         * pool timers for each (if any).
         *
         * Note that we must do ddns_updates() before we test for lease
         * reuse (so we'll know if DNS entries are different).  To ensure
         * we don't break any configs, we run on_commit statements before
         * we do ddns_updates() just in case the former affects the later.
         * This is symetrical with v4 logic.  We always run on_commit and
         * ddns_udpates() whether a lease is reused or renewed.
         */
        if ((reply->ia->num_iasubopt != 0) &&
            (reply->buf.reply.msg_type == DHCPV6_REPLY)) {
                int must_commit = 0;
                struct iasubopt *tmp;
                struct data_string *ia_id;
                int i;

                for (i = 0 ; i < reply->ia->num_iasubopt ; i++) {
                        tmp = reply->ia->iasubopt[i];
                        if (tmp->ia != NULL) {
                                ia_dereference(&tmp->ia, MDL);
                        }

                        ia_reference(&tmp->ia, reply->ia, MDL);

                        /* If we have anything to do on commit do it now */
                        if (tmp->on_star.on_commit != NULL) {
                                execute_statements(NULL, reply->packet,
                                                   NULL, NULL,
                                                   reply->packet->options,
                                                   reply->opt_state,
                                                   &tmp->scope,
                                                   tmp->on_star.on_commit,
                                                   &tmp->on_star);
                                executable_statement_dereference
                                        (&tmp->on_star.on_commit, MDL);
                        }

#if defined (NSUPDATE)

                        /* Perform ddns updates */
                        oc = lookup_option(&server_universe, reply->opt_state,
                                           SV_DDNS_UPDATES);
                        if ((oc == NULL) ||
                            evaluate_boolean_option_cache(NULL, reply->packet,
                                                          NULL, NULL,
                                                        reply->packet->options,
                                                          reply->opt_state,
                                                          &tmp->scope,
                                                          oc, MDL)) {
                                ddns_updates(reply->packet, NULL, NULL,
                                             tmp, NULL, reply->opt_state);
                        }
#endif
                        if (!reuse_lease6(reply, tmp)) {
                                /* Commit 'hard' bindings. */
                                must_commit = 1;
                                renew_lease6(tmp->ipv6_pool, tmp);
                                schedule_lease_timeout(tmp->ipv6_pool);

                                /* Do our threshold check. */
                                check_pool6_threshold(reply, tmp);
                        }
                }

                /* write the IA_NA in wire-format to the outbound buffer */
                write_to_packet(reply, ia_cursor);

                /* Remove any old ia from the hash. */
                if (reply->old_ia != NULL) {
                        if (!release_on_roam(reply)) {
                                ia_id = &reply->old_ia->iaid_duid;
                                ia_hash_delete(ia_na_active,
                                               (unsigned char *)ia_id->data,
                                               ia_id->len, MDL);
                        }

                        ia_dereference(&reply->old_ia, MDL);
                }

                /* Put new ia into the hash. */
                reply->ia->cltt = cur_time;
                ia_id = &reply->ia->iaid_duid;
                ia_hash_add(ia_na_active, (unsigned char *)ia_id->data,
                            ia_id->len, reply->ia, MDL);

                /* If we couldn't reuse all of the iasubopts, we
                * must update udpate the lease db */
                if (must_commit) {
                        write_ia(reply->ia);
                }
        } else {
                /* write the IA_NA in wire-format to the outbound buffer */
                write_to_packet(reply, ia_cursor);
                schedule_lease_timeout_reply(reply);
        }

      cleanup:
        if (packet_ia != NULL)
                option_state_dereference(&packet_ia, MDL);
        if (reply->reply_ia != NULL)
                option_state_dereference(&reply->reply_ia, MDL);
        if (ia_data.data != NULL)
                data_string_forget(&ia_data, MDL);
        if (data.data != NULL)
                data_string_forget(&data, MDL);
        if (reply->ia != NULL)
                ia_dereference(&reply->ia, MDL);
        if (reply->old_ia != NULL)
                ia_dereference(&reply->old_ia, MDL);
        if (reply->lease != NULL)
                iasubopt_dereference(&reply->lease, MDL);
        if (reply->fixed.data != NULL)
                data_string_forget(&reply->fixed, MDL);
        if (reply->subnet != NULL)
                subnet_dereference(&reply->subnet, MDL);
        if (reply->on_star.on_expiry != NULL)
                executable_statement_dereference
                        (&reply->on_star.on_expiry, MDL);
        if (reply->on_star.on_release != NULL)
                executable_statement_dereference
                        (&reply->on_star.on_release, MDL);

        /*
         * ISC_R_CANCELED is a status code used by the addr processing to
         * indicate we're replying with a status code.  This is still a
         * success at higher layers.
         */
        return((status == ISC_R_CANCELED) ? ISC_R_SUCCESS : status);
}

/*
 * Writes the populated IA_xx in wire format to the reply buffer
 */
void
write_to_packet(struct reply_state *reply, unsigned ia_cursor) {
        reply->cursor += store_options6((char *)reply->buf.data + reply->cursor,
                                        sizeof(reply->buf) - reply->cursor,
                                        reply->reply_ia, reply->packet,
                                        (reply->ia->ia_type != D6O_IA_PD ?
                                        required_opts_IA : required_opts_IA_PD),
                                        NULL);

        /* Reset the length of this IA to match what was just written. */
        putUShort(reply->buf.data + ia_cursor + 2,
                  reply->cursor - (ia_cursor + 4));

        if (reply->ia->ia_type != D6O_IA_TA) {
                /* Calculate T1/T2 and stuff them in the reply */
                set_reply_tee_times(reply, ia_cursor);
        }
}

/*
 * Process an IAADDR within a given IA_xA, storing any IAADDR reply contents
 * into the reply's current ia-scoped option cache.  Returns ISC_R_CANCELED
 * in the event we are replying with a status code and do not wish to process
 * more IAADDRs within this IA.
 */
static isc_result_t
reply_process_addr(struct reply_state *reply, struct option_cache *addr) {
        u_int32_t pref_life, valid_life;
        struct binding_scope **scope;
        struct group *group;
        struct subnet *subnet;
        struct iaddr tmp_addr;
        struct option_cache *oc;
        struct data_string iaaddr, data;
        isc_result_t status = ISC_R_SUCCESS;
#ifdef EUI_64
        int invalid_for_eui_64 = 0;
#endif

        /* Initializes values that will be cleaned up. */
        memset(&iaaddr, 0, sizeof(iaaddr));
        memset(&data, 0, sizeof(data));
        /* Note that reply->lease may be set by address_is_owned() */

        /*
         * There is no point trying to process an incoming address if there
         * is no room for an outgoing address.
         */
        if ((reply->cursor + 28) > sizeof(reply->buf)) {
                log_error("reply_process_addr: Out of room for address.");
                return ISC_R_NOSPACE;
        }

        /* Extract this IAADDR option. */
        if (!evaluate_option_cache(&iaaddr, reply->packet, NULL, NULL,
                                   reply->packet->options, NULL, &global_scope,
                                   addr, MDL) ||
            (iaaddr.len < IAADDR_OFFSET)) {
                log_error("reply_process_addr: error evaluating IAADDR.");
                status = ISC_R_FAILURE;
                goto cleanup;
        }

        /* The first 16 bytes are the IPv6 address. */
        pref_life = getULong(iaaddr.data + 16);
        valid_life = getULong(iaaddr.data + 20);

        if ((reply->client_valid == 0) ||
            (reply->client_valid > valid_life))
                reply->client_valid = valid_life;

        if ((reply->client_prefer == 0) ||
            (reply->client_prefer > pref_life))
                reply->client_prefer = pref_life;

        /*
         * Clients may choose to send :: as an address, with the idea to give
         * hints about preferred-lifetime or valid-lifetime.
         */
        tmp_addr.len = 16;
        memset(tmp_addr.iabuf, 0, 16);
        if (!memcmp(iaaddr.data, tmp_addr.iabuf, 16)) {
                /* Status remains success; we just ignore this one. */
                goto cleanup;
        }

        /* tmp_addr len remains 16 */
        memcpy(tmp_addr.iabuf, iaaddr.data, 16);

        /*
         * Verify that this address is on the client's network.
         */
        for (subnet = reply->shared->subnets ; subnet != NULL ;
             subnet = subnet->next_sibling) {
                if (addr_eq(subnet_number(tmp_addr, subnet->netmask),
                            subnet->net))
                        break;
        }

#ifdef EUI_64
        if (subnet) {
                /* If the requested address falls into an EUI-64 pool, then
                 * we need to verify if it has EUI-64 duid AND the requested
                 * address is correct for that duid.  If not we treat it just
                 * like an not-on-link request. */
                struct ipv6_pool* pool = NULL;
                struct in6_addr* addr = (struct in6_addr*)(iaaddr.data);
                if ((find_ipv6_pool(&pool, D6O_IA_NA, addr) == ISC_R_SUCCESS)
                    && (pool->ipv6_pond->use_eui_64) &&
                   (!valid_for_eui_64_pool(pool, &reply->client_id, 0, addr))) {
                        log_debug ("Requested address: %s,"
                                   " not valid for EUI-64 pool",
                                   pin6_addr(addr));
                        invalid_for_eui_64 = 1;
                }
        }
#endif

        /* Address not found on shared network. */
#ifdef EUI_64
        if ((subnet == NULL) || invalid_for_eui_64) {
#else
        if (subnet == NULL) {
#endif
                /* Ignore this address on 'soft' bindings. */
                if (reply->packet->dhcpv6_msg_type == DHCPV6_SOLICIT) {
                        /* disable rapid commit */
                        reply->buf.reply.msg_type = DHCPV6_ADVERTISE;
                        delete_option(&dhcpv6_universe,
                                      reply->opt_state,
                                      D6O_RAPID_COMMIT);
                        /* status remains success */
                        goto cleanup;
                }

                /*
                 * RFC3315 section 18.2.1:
                 *
                 * If the server finds that the prefix on one or more IP
                 * addresses in any IA in the message from the client is not
                 * appropriate for the link to which the client is connected,
                 * the server MUST return the IA to the client with a Status
                 * Code option with the value NotOnLink.
                 */
                if (reply->packet->dhcpv6_msg_type == DHCPV6_REQUEST) {
                        /* Rewind the IA_NA to empty. */
                        option_state_dereference(&reply->reply_ia, MDL);
                        if (!option_state_allocate(&reply->reply_ia, MDL)) {
                                log_error("reply_process_addr: No memory for "
                                          "option state wipe.");
                                status = ISC_R_NOMEMORY;
                                goto cleanup;
                        }

                        /* Append a NotOnLink status code. */
                        if (!set_status_code(STATUS_NotOnLink,
                                             "Address not for use on this "
                                             "link.", reply->reply_ia)) {
                                log_error("reply_process_addr: Failure "
                                          "setting status code.");
                                status = ISC_R_FAILURE;
                                goto cleanup;
                        }

                        /* Fin (no more IAADDRs). */
                        status = ISC_R_CANCELED;
                        goto cleanup;
                }

                /*
                 * RFC3315 sections 18.2.3 and 18.2.4 have identical language:
                 *
                 * If the server finds that any of the addresses are not
                 * appropriate for the link to which the client is attached,
                 * the server returns the address to the client with lifetimes
                 * of 0.
                 */
                if ((reply->packet->dhcpv6_msg_type != DHCPV6_RENEW) &&
                    (reply->packet->dhcpv6_msg_type != DHCPV6_REBIND)) {
                        log_error("It is impossible to lease a client that is "
                                  "not sending a solicit, request, renew, or "
                                  "rebind.");
                        status = ISC_R_FAILURE;
                        goto cleanup;
                }

                reply->send_prefer = reply->send_valid = 0;
                goto send_addr;
        }


        /* Verify the address belongs to the client. */
        if (!address_is_owned(reply, &tmp_addr)) {
                /*
                 * For solicit and request, any addresses included are
                 * 'requested' addresses.  For rebind, we actually have
                 * no direction on what to do from 3315 section 18.2.4!
                 * So I think the best bet is to try and give it out, and if
                 * we can't, zero lifetimes.
                 */
                if ((reply->packet->dhcpv6_msg_type == DHCPV6_SOLICIT) ||
                    (reply->packet->dhcpv6_msg_type == DHCPV6_REQUEST) ||
                    (reply->packet->dhcpv6_msg_type == DHCPV6_REBIND)) {
                        status = reply_process_try_addr(reply, &tmp_addr);

                        /*
                         * If the address is in use, or isn't in any dynamic
                         * range, continue as normal.  If any other error was
                         * found, error out.
                         */
                        if ((status != ISC_R_SUCCESS) &&
                            (status != ISC_R_ADDRINUSE) &&
                            (status != ISC_R_ADDRNOTAVAIL))
                                goto cleanup;

                        /*
                         * If we didn't honor this lease, for solicit and
                         * request we simply omit it from our answer.  For
                         * rebind, we send it with zeroed lifetimes.
                         */
                        if (reply->lease == NULL) {
                                if (reply->packet->dhcpv6_msg_type ==
                                                        DHCPV6_REBIND) {
                                        reply->send_prefer = 0;
                                        reply->send_valid = 0;
                                        goto send_addr;
                                }

                                /* status remains success - ignore */
                                goto cleanup;
                        }
                /*
                 * RFC3315 section 18.2.3:
                 *
                 * If the server cannot find a client entry for the IA the
                 * server returns the IA containing no addresses with a Status
                 * Code option set to NoBinding in the Reply message.
                 *
                 * On mismatch we (ab)use this pretending we have not the IA
                 * as soon as we have not an address.
                 */
                } else if (reply->packet->dhcpv6_msg_type == DHCPV6_RENEW) {
                        /* Rewind the IA_NA to empty. */
                        option_state_dereference(&reply->reply_ia, MDL);
                        if (!option_state_allocate(&reply->reply_ia, MDL)) {
                                log_error("reply_process_addr: No memory for "
                                          "option state wipe.");
                                status = ISC_R_NOMEMORY;
                                goto cleanup;
                        }

                        /* Append a NoBinding status code.  */
                        if (!set_status_code(STATUS_NoBinding,
                                             "Address not bound to this "
                                             "interface.", reply->reply_ia)) {
                                log_error("reply_process_addr: Unable to "
                                          "attach status code.");
                                status = ISC_R_FAILURE;
                                goto cleanup;
                        }

                        /* Fin (no more IAADDRs). */
                        status = ISC_R_CANCELED;
                        goto cleanup;
                } else {
                        log_error("It is impossible to lease a client that is "
                                  "not sending a solicit, request, renew, or "
                                  "rebind message.");
                        status = ISC_R_FAILURE;
                        goto cleanup;
                }
        }

        if (reply->static_lease) {
                if (reply->host == NULL)
                        log_fatal("Impossible condition at %s:%d.", MDL);

                scope = &global_scope;
                group = reply->subnet->group;
        } else {
                if (reply->lease == NULL)
                        log_fatal("Impossible condition at %s:%d.", MDL);

                scope = &reply->lease->scope;
                group = reply->lease->ipv6_pool->ipv6_pond->group;
        }

        /*
         * If client_resources is nonzero, then the reply_process_is_addressed
         * function has executed configuration state into the reply option
         * cache.  We will use that valid cache to derive configuration for
         * whether or not to engage in additional addresses, and similar.
         */
        if (reply->client_resources != 0) {
                unsigned limit = 1;

                /*
                 * Does this client have "enough" addresses already?  Default
                 * to one.  Everybody gets one, and one should be enough for
                 * anybody.
                 */
                oc = lookup_option(&server_universe, reply->opt_state,
                                   SV_LIMIT_ADDRS_PER_IA);
                if (oc != NULL) {
                        if (!evaluate_option_cache(&data, reply->packet,
                                                   NULL, NULL,
                                                   reply->packet->options,
                                                   reply->opt_state,
                                                   scope, oc, MDL) ||
                            (data.len != 4)) {
                                log_error("reply_process_addr: unable to "
                                          "evaluate addrs-per-ia value.");
                                status = ISC_R_FAILURE;
                                goto cleanup;
                        }

                        limit = getULong(data.data);
                        data_string_forget(&data, MDL);
                }

                /*
                 * If we wish to limit the client to a certain number of
                 * addresses, then omit the address from the reply.
                 */
                if (reply->client_resources >= limit)
                        goto cleanup;
        }

        status = reply_process_is_addressed(reply, scope, group);
        if (status != ISC_R_SUCCESS)
                goto cleanup;

      send_addr:
        status = reply_process_send_addr(reply, &tmp_addr);

      cleanup:
        if (iaaddr.data != NULL)
                data_string_forget(&iaaddr, MDL);
        if (data.data != NULL)
                data_string_forget(&data, MDL);
        if (reply->lease != NULL)
                iasubopt_dereference(&reply->lease, MDL);

        return status;
}

/*
 * Verify the address belongs to the client.  If we've got a host
 * record with a fixed address, it has to be the assigned address
 * (fault out all else).  Otherwise it's a dynamic address, so lookup
 * that address and make sure it belongs to this DUID:IAID pair.
 */
static isc_boolean_t
address_is_owned(struct reply_state *reply, struct iaddr *addr) {
        int i;
        struct ipv6_pond *pond;

        /*
         * This faults out addresses that don't match fixed addresses.
         */
        if (reply->static_lease) {
                if (reply->fixed.data == NULL)
                        log_fatal("Impossible condition at %s:%d.", MDL);

                if (memcmp(addr->iabuf, reply->fixed.data, 16) == 0)
                        return (ISC_TRUE);

                return (ISC_FALSE);
        }

        if ((reply->old_ia == NULL) || (reply->old_ia->num_iasubopt == 0))
                return (ISC_FALSE);

        for (i = 0 ; i < reply->old_ia->num_iasubopt ; i++) {
                struct iasubopt *tmp;

                tmp = reply->old_ia->iasubopt[i];

                if (memcmp(addr->iabuf, &tmp->addr, 16) == 0) {
                        if (lease6_usable(tmp) == ISC_FALSE) {
                                return (ISC_FALSE);
                        }

                        pond = tmp->ipv6_pool->ipv6_pond;
                        if (((pond->prohibit_list != NULL) &&
                             (permitted(reply->packet, pond->prohibit_list))) ||
                            ((pond->permit_list != NULL) &&
                             (!permitted(reply->packet, pond->permit_list))))
                                return (ISC_FALSE);

                        iasubopt_reference(&reply->lease, tmp, MDL);

                        return (ISC_TRUE);
                }
        }

        return (ISC_FALSE);
}

/* Process a client-supplied IA_TA.  This may append options to the tail of
 * the reply packet being built in the reply_state structure.
 */
static isc_result_t
reply_process_ia_ta(struct reply_state *reply, struct option_cache *ia) {
        isc_result_t status = ISC_R_SUCCESS;
        u_int32_t iaid;
        unsigned ia_cursor;
        struct option_state *packet_ia;
        struct option_cache *oc;
        struct data_string ia_data, data;
        struct data_string iaaddr;
        u_int32_t pref_life, valid_life;
        struct iaddr tmp_addr;

        /* Initialize values that will get cleaned up on return. */
        packet_ia = NULL;
        memset(&ia_data, 0, sizeof(ia_data));
        memset(&data, 0, sizeof(data));
        memset(&iaaddr, 0, sizeof(iaaddr));

        /* Make sure there is at least room for the header. */
        if ((reply->cursor + IA_TA_OFFSET + 4) > sizeof(reply->buf)) {
                log_error("reply_process_ia_ta: Reply too long for IA.");
                return ISC_R_NOSPACE;
        }


        /* Fetch the IA_TA contents. */
        if (!get_encapsulated_IA_state(&packet_ia, &ia_data, reply->packet,
                                       ia, IA_TA_OFFSET)) {
                log_error("reply_process_ia_ta: error evaluating ia");
                status = ISC_R_FAILURE;
                goto cleanup;
        }

        /* Extract IA_TA header contents. */
        iaid = getULong(ia_data.data);

        /* Create an IA_TA structure. */
        if (ia_allocate(&reply->ia, iaid, (char *)reply->client_id.data,
                        reply->client_id.len, MDL) != ISC_R_SUCCESS) {
                log_error("reply_process_ia_ta: no memory for ia.");
                status = ISC_R_NOMEMORY;
                goto cleanup;
        }
        reply->ia->ia_type = D6O_IA_TA;

        /* Cache pre-existing IA, if any. */
        ia_hash_lookup(&reply->old_ia, ia_ta_active,
                       (unsigned char *)reply->ia->iaid_duid.data,
                       reply->ia->iaid_duid.len, MDL);

        /*
         * Create an option cache to carry the IA_TA option contents, and
         * execute any user-supplied values into it.
         */
        if (!option_state_allocate(&reply->reply_ia, MDL)) {
                status = ISC_R_NOMEMORY;
                goto cleanup;
        }

        /*
         * Temporary leases are dynamic by definition.
         */
        reply->static_lease = ISC_FALSE;

        /*
         * Save the cursor position at the start of the IA, so we can
         * set length later.  We write a temporary
         * header out now just in case we decide to adjust the packet
         * within sub-process functions.
         */
        ia_cursor = reply->cursor;

        /* Initialize the IA_TA header.  First the code. */
        putUShort(reply->buf.data + reply->cursor, (unsigned)D6O_IA_TA);
        reply->cursor += 2;

        /* Then option length. */
        putUShort(reply->buf.data + reply->cursor, 0x04u);
        reply->cursor += 2;

        /* Then IA_TA header contents; IAID. */
        putULong(reply->buf.data + reply->cursor, iaid);
        reply->cursor += 4;

        /*
         * Deal with an IAADDR for lifetimes.
         * For all or none, process IAADDRs as hints.
         */
        reply->min_valid = reply->min_prefer = INFINITE_TIME;
        reply->client_valid = reply->client_prefer = 0;
        oc = lookup_option(&dhcpv6_universe, packet_ia, D6O_IAADDR);
        for (; oc != NULL; oc = oc->next) {
                memset(&iaaddr, 0, sizeof(iaaddr));
                if (!evaluate_option_cache(&iaaddr, reply->packet,
                                           NULL, NULL,
                                           reply->packet->options, NULL,
                                           &global_scope, oc, MDL) ||
                    (iaaddr.len < IAADDR_OFFSET)) {
                        log_error("reply_process_ia_ta: error "
                                  "evaluating IAADDR.");
                        status = ISC_R_FAILURE;
                        goto cleanup;
                }
                /* The first 16 bytes are the IPv6 address. */
                pref_life = getULong(iaaddr.data + 16);
                valid_life = getULong(iaaddr.data + 20);

                if ((reply->client_valid == 0) ||
                    (reply->client_valid > valid_life))
                        reply->client_valid = valid_life;

                if ((reply->client_prefer == 0) ||
                    (reply->client_prefer > pref_life))
                        reply->client_prefer = pref_life;

                /* Nothing more if something has failed. */
                if (status == ISC_R_CANCELED)
                        continue;

                tmp_addr.len = 16;
                memcpy(tmp_addr.iabuf, iaaddr.data, 16);
                if (!temporary_is_available(reply, &tmp_addr))
                        goto bad_temp;
                status = reply_process_is_addressed(reply,
                                                    &reply->lease->scope,
                                                    reply->lease->ipv6_pool->ipv6_pond->group);
                if (status != ISC_R_SUCCESS)
                        goto bad_temp;
                status = reply_process_send_addr(reply, &tmp_addr);
                if (status != ISC_R_SUCCESS)
                        goto bad_temp;
                if (reply->lease != NULL)
                        iasubopt_dereference(&reply->lease, MDL);
                continue;

        bad_temp:
                /* Rewind the IA_TA to empty. */
                option_state_dereference(&reply->reply_ia, MDL);
                if (!option_state_allocate(&reply->reply_ia, MDL)) {
                        status = ISC_R_NOMEMORY;
                        goto cleanup;
                }
                status = ISC_R_CANCELED;
                reply->client_resources = 0;
                reply->resources_included = ISC_FALSE;
                if (reply->lease != NULL)
                        iasubopt_dereference(&reply->lease, MDL);
        }
        reply->ia_count++;

        /*
         * Give the client temporary addresses.
         */
        if (reply->client_resources != 0)
                goto store;
        status = find_client_temporaries(reply);
        if (status == ISC_R_NORESOURCES) {
                switch (reply->packet->dhcpv6_msg_type) {
                      case DHCPV6_SOLICIT:
                        /*
                         * No address for any IA is handled
                         * by the caller.
                         */
                        /* FALL THROUGH */

                      case DHCPV6_REQUEST:
                        /* Section 18.2.1 (Request):
                         *
                         * If the server cannot assign any addresses to
                         * an IA in the message from the client, the
                         * server MUST include the IA in the Reply
                         * message with no addresses in the IA and a
                         * Status Code option in the IA containing
                         * status code NoAddrsAvail.
                         */
                        option_state_dereference(&reply->reply_ia, MDL);
                        if (!option_state_allocate(&reply->reply_ia,  MDL)) {
                                log_error("reply_process_ia_ta: No "
                                          "memory for option state wipe.");
                                status = ISC_R_NOMEMORY;
                                goto cleanup;
                        }

                        if (!set_status_code(STATUS_NoAddrsAvail,
                                             "No addresses available "
                                             "for this interface.",
                                              reply->reply_ia)) {
                                log_error("reply_process_ia_ta: Unable "
                                          "to set NoAddrsAvail status code.");
                                status = ISC_R_FAILURE;
                                goto cleanup;
                        }

                        status = ISC_R_SUCCESS;
                        break;

                      default:
                        /*
                         * We don't want to include the IA if we
                         * provide zero addresses including zeroed
                         * lifetimes.
                         */
                        if (reply->resources_included)
                                status = ISC_R_SUCCESS;
                        else
                                goto cleanup;
                        break;
                }
        } else if (status != ISC_R_SUCCESS)
                goto cleanup;

      store:

        /*
         * yes, goto's aren't the best but we also want to avoid extra
         * indents
         */
        if (status == ISC_R_CANCELED) {
                /* We're replying with a status code so we still need to
                * write it out in wire-format to the outbound buffer */
                write_to_packet(reply, ia_cursor);
                goto cleanup;
        }

        /*
         * If we have any addresses log what we are doing.
         */
        if (reply->ia->num_iasubopt != 0) {
                struct iasubopt *tmp;
                int i;
                char tmp_addr[INET6_ADDRSTRLEN];

                for (i = 0 ; i < reply->ia->num_iasubopt ; i++) {
                        tmp = reply->ia->iasubopt[i];

                        log_info("%s TA: address %s to client with duid %s "
                                 "iaid = %d valid for %u seconds",
                                 dhcpv6_type_names[reply->buf.reply.msg_type],
                                 inet_ntop(AF_INET6, &tmp->addr,
                                           tmp_addr, sizeof(tmp_addr)),
                                 print_hex_1(reply->client_id.len,
                                             reply->client_id.data, 60),
                                 iaid,
                                 tmp->valid);
                }
        }

        /*
         * For hard bindings we consume the new changes into
         * the database (if any have been attached to the ia_ta).
         *
         * Loop through the assigned dynamic addresses, referencing the
         * leases onto this IA_TA rather than any old ones, and updating
         * pool timers for each (if any).
         */
        if ((reply->ia->num_iasubopt != 0) &&
            (reply->buf.reply.msg_type == DHCPV6_REPLY)) {
                int must_commit = 0;
                struct iasubopt *tmp;
                struct data_string *ia_id;
                int i;

                for (i = 0 ; i < reply->ia->num_iasubopt ; i++) {
                        tmp = reply->ia->iasubopt[i];

                        if (tmp->ia != NULL)
                                ia_dereference(&tmp->ia, MDL);
                        ia_reference(&tmp->ia, reply->ia, MDL);

                        /* If we have anything to do on commit do it now */
                        if (tmp->on_star.on_commit != NULL) {
                                execute_statements(NULL, reply->packet,
                                                   NULL, NULL,
                                                   reply->packet->options,
                                                   reply->opt_state,
                                                   &tmp->scope,
                                                   tmp->on_star.on_commit,
                                                   &tmp->on_star);
                                executable_statement_dereference
                                        (&tmp->on_star.on_commit, MDL);
                        }

#if defined (NSUPDATE)
                        /*
                         * Perform ddns updates.
                         */
                        oc = lookup_option(&server_universe, reply->opt_state,
                                           SV_DDNS_UPDATES);
                        if ((oc == NULL) ||
                            evaluate_boolean_option_cache(NULL, reply->packet,
                                                          NULL, NULL,
                                                        reply->packet->options,
                                                          reply->opt_state,
                                                          &tmp->scope,
                                                          oc, MDL)) {
                                ddns_updates(reply->packet, NULL, NULL,
                                             tmp, NULL, reply->opt_state);
                        }
#endif

                        if (!reuse_lease6(reply, tmp)) {
                                /* Commit 'hard' bindings. */
                                must_commit = 1;
                                renew_lease6(tmp->ipv6_pool, tmp);
                                schedule_lease_timeout(tmp->ipv6_pool);

                                /* Do our threshold check. */
                                check_pool6_threshold(reply, tmp);
                        }
                }

                /* write the IA_TA in wire-format to the outbound buffer */
                write_to_packet(reply, ia_cursor);

                /* Remove any old ia from the hash. */
                if (reply->old_ia != NULL) {
                        if (!release_on_roam(reply)) {
                                ia_id = &reply->old_ia->iaid_duid;
                                ia_hash_delete(ia_ta_active,
                                               (unsigned char *)ia_id->data,
                                               ia_id->len, MDL);
                        }

                        ia_dereference(&reply->old_ia, MDL);
                }

                /* Put new ia into the hash. */
                reply->ia->cltt = cur_time;
                ia_id = &reply->ia->iaid_duid;
                ia_hash_add(ia_ta_active, (unsigned char *)ia_id->data,
                            ia_id->len, reply->ia, MDL);

                /* If we couldn't reuse all of the iasubopts, we
                * must update udpate the lease db */
                if (must_commit) {
                        write_ia(reply->ia);
                }
        } else {
                /* write the IA_TA in wire-format to the outbound buffer */
                write_to_packet(reply, ia_cursor);
                schedule_lease_timeout_reply(reply);
        }

      cleanup:
        if (packet_ia != NULL)
                option_state_dereference(&packet_ia, MDL);
        if (iaaddr.data != NULL)
                data_string_forget(&iaaddr, MDL);
        if (reply->reply_ia != NULL)
                option_state_dereference(&reply->reply_ia, MDL);
        if (ia_data.data != NULL)
                data_string_forget(&ia_data, MDL);
        if (data.data != NULL)
                data_string_forget(&data, MDL);
        if (reply->ia != NULL)
                ia_dereference(&reply->ia, MDL);
        if (reply->old_ia != NULL)
                ia_dereference(&reply->old_ia, MDL);
        if (reply->lease != NULL)
                iasubopt_dereference(&reply->lease, MDL);

        /*
         * ISC_R_CANCELED is a status code used by the addr processing to
         * indicate we're replying with other addresses.  This is still a
         * success at higher layers.
         */
        return((status == ISC_R_CANCELED) ? ISC_R_SUCCESS : status);
}
/*
 * Determines if a lease (iasubopt) can be reused without extending it.
 * If dhcp-cache-threshold is greater than zero (i.e enabled) then
 * a lease may be reused without going through a full renewal if
 * it meets all the requirements.  In short it must be active, younger
 * than the threshold, and not have DNS changes.
 *
 * If it is determined that it can be reused, that a call to
 * shorten_lifetimes() is made to reduce the valid and preferred lifetimes
 * sent to the client by the age of the lease.
 *
 * Returns 1 if lease can be reused, 0 otherwise
 */
int
reuse_lease6(struct reply_state *reply, struct iasubopt *lease) {
        int threshold = DEFAULT_CACHE_THRESHOLD;
        struct option_cache* oc = NULL;
        struct data_string d1;
        time_t age;
        time_t limit;
        int reuse_it = 0;

        /* In order to even qualify for reuse consideration:
         * 1. Lease must be active
         * 2. It must have been accepted at least once
         * 3. DNS info must not have changed */
        if ((lease->state != FTS_ACTIVE) ||
            (lease->hard_lifetime_end_time == 0) ||
            (lease->ddns_cb != NULL)) {
                return (0);
        }

        /* Look up threshold value */
        memset(&d1, 0, sizeof(struct data_string));
        oc = lookup_option(&server_universe, reply->opt_state,
                           SV_CACHE_THRESHOLD);
        if (oc &&
            evaluate_option_cache(&d1, reply->packet, NULL, NULL,
                                  reply->packet->options, reply->opt_state,
                                  &lease->scope, oc, MDL)) {
                        if (d1.len == 1 && (d1.data[0] < 100)) {
                                threshold = d1.data[0];
                        }

                data_string_forget(&d1, MDL);
        }

        if (threshold <= 0) {
                return (0);
        }

        if (lease->valid >= MAX_TIME) {
                /* Infinite leases are always reused.  We have to make
                * a choice because we cannot determine when they actually
                * began, so we either always reuse them or we never do. */
                log_debug ("reusing infinite lease for: %s%s",
                            pin6_addr(&lease->addr), iasubopt_plen_str(lease));
                return (1);
        }

        age = cur_tv.tv_sec - (lease->hard_lifetime_end_time - lease->valid);
        if (lease->valid <= (INT_MAX / threshold))
                limit = lease->valid * threshold / 100;
        else
                limit = lease->valid / 100 * threshold;

        if (age < limit) {
                /* Reduce valid/preferred going to the client by age */
                shorten_lifetimes(reply, lease, age, threshold);
                reuse_it = 1;
        }

        return (reuse_it);
}

/*
 * Reduces the valid and preferred lifetimes for a given lease (iasubopt)
 *
 * We cannot determine until after a iasubopt has been added to
 * the reply if the lease can be reused. Therefore, when we do reuse a
 * lease we need a way to alter the lifetimes that will be sent to the client.
 * That's where this function comes in handy:
 *
 * Locate the iasubopt by it's address within the reply the reduce both
 * the preferred and valid lifetimes by the given number of seconds.
 *
 * Note that this function, by necessity, works directly with the
 * option_cache data. Sort of a no-no but I don't have any better ideas.
 */
void shorten_lifetimes(struct reply_state *reply, struct iasubopt *lease,
                       time_t age, int threshold) {
        struct option_cache* oc = NULL;
        int subopt_type;
        int addr_offset;
        int pref_offset;
        int val_offset;
        int exp_length;

        if (reply->ia->ia_type != D6O_IA_PD) {
                subopt_type = D6O_IAADDR;
                addr_offset = IASUBOPT_NA_ADDR_OFFSET;
                pref_offset = IASUBOPT_NA_PREF_OFFSET;
                val_offset = IASUBOPT_NA_VALID_OFFSET;
                exp_length = IASUBOPT_NA_LEN;
        }
        else {
                subopt_type = D6O_IAPREFIX;
                addr_offset = IASUBOPT_PD_PREFIX_OFFSET;
                pref_offset = IASUBOPT_PD_PREF_OFFSET;
                val_offset = IASUBOPT_PD_VALID_OFFSET;
                exp_length = IASUBOPT_PD_LEN;
        }

        // loop through the iasubopts for the one that matches this lease
        oc = lookup_option(&dhcpv6_universe, reply->reply_ia, subopt_type);
        for (; oc != NULL ; oc = oc->next) {
                if (oc->data.data == NULL || oc->data.len != exp_length) {
                        /* shouldn't happen */
                        continue;
                }

                /* If address matches (and for PDs the prefix len matches)
                * we assume this is our subopt, so update the lifetimes */
                if (!memcmp(oc->data.data + addr_offset, &lease->addr, 16) &&
                    (subopt_type != D6O_IAPREFIX ||
                     (oc->data.data[IASUBOPT_PD_PREFLEN_OFFSET] ==
                      lease->plen))) {
                        u_int32_t pref_life = getULong(oc->data.data +
                                                       pref_offset);
                        u_int32_t valid_life = getULong(oc->data.data +
                                                        val_offset);

                        if (pref_life < MAX_TIME && pref_life > age) {
                                pref_life -= age;
                                putULong((unsigned char*)(oc->data.data) +
                                          pref_offset, pref_life);

                                if (reply->min_prefer > pref_life) {
                                        reply->min_prefer = pref_life;
                                }
                        }

                        if (valid_life < MAX_TIME && valid_life > age) {
                                valid_life -= age;
                                putULong((unsigned char*)(oc->data.data) +
                                         val_offset, valid_life);

                                if (reply->min_valid > reply->send_valid) {
                                        reply->min_valid = valid_life;
                                }
                        }

                        log_debug ("Reusing lease for: %s%s, "
                                   "age %ld secs < %d%%,"
                                   " sending shortened lifetimes -"
                                   " preferred: %u, valid %u",
                                   pin6_addr(&lease->addr),
                                   iasubopt_plen_str(lease),
                                   (long)age, threshold,
                                   pref_life, valid_life);
                        break;
                }
        }
}

/*
 * Verify the temporary address is available.
 */
static isc_boolean_t
temporary_is_available(struct reply_state *reply, struct iaddr *addr) {
        struct in6_addr tmp_addr;
        struct subnet *subnet;
        struct ipv6_pool *pool = NULL;
        struct ipv6_pond *pond = NULL;
        int i;

        memcpy(&tmp_addr, addr->iabuf, sizeof(tmp_addr));
        /*
         * Clients may choose to send :: as an address, with the idea to give
         * hints about preferred-lifetime or valid-lifetime.
         * So this is not a request for this address.
         */
        if (IN6_IS_ADDR_UNSPECIFIED(&tmp_addr))
                return ISC_FALSE;

        /*
         * Verify that this address is on the client's network.
         */
        for (subnet = reply->shared->subnets ; subnet != NULL ;
             subnet = subnet->next_sibling) {
                if (addr_eq(subnet_number(*addr, subnet->netmask),
                            subnet->net))
                        break;
        }

        /* Address not found on shared network. */
        if (subnet == NULL)
                return ISC_FALSE;

        /*
         * Check if this address is owned (must be before next step).
         */
        if (address_is_owned(reply, addr))
                return ISC_TRUE;

        /*
         * Verify that this address is in a temporary pool and try to get it.
         */
        for (pond = reply->shared->ipv6_pond; pond != NULL; pond = pond->next) {
                if (((pond->prohibit_list != NULL) &&
                     (permitted(reply->packet, pond->prohibit_list))) ||
                    ((pond->permit_list != NULL) &&
                     (!permitted(reply->packet, pond->permit_list))))
                        continue;

                for (i = 0 ; (pool = pond->ipv6_pools[i]) != NULL ; i++) {
                        if (pool->pool_type != D6O_IA_TA)
                                continue;

                        if (ipv6_in_pool(&tmp_addr, pool))
                                break;
                }

                if (pool != NULL)
                        break;
        }

        if (pool == NULL)
                return ISC_FALSE;
        if (lease6_exists(pool, &tmp_addr))
                return ISC_FALSE;
        if (iasubopt_allocate(&reply->lease, MDL) != ISC_R_SUCCESS)
                return ISC_FALSE;
        reply->lease->addr = tmp_addr;
        reply->lease->plen = 0;
        /* Default is soft binding for 2 minutes. */
        if (add_lease6(pool, reply->lease, cur_time + 120) != ISC_R_SUCCESS)
                return ISC_FALSE;

        return ISC_TRUE;
}

/*
 * Get a temporary address per prefix.
 */
static isc_result_t
find_client_temporaries(struct reply_state *reply) {
        int i;
        struct ipv6_pool *p = NULL;
        struct ipv6_pond *pond;
        isc_result_t status = ISC_R_NORESOURCES;;
        unsigned int attempts;
        struct iaddr send_addr;

        /*
         * Do a quick walk through of the ponds and pools
         * to see if we have any prefix pools
         */
        for (pond = reply->shared->ipv6_pond; pond != NULL; pond = pond->next) {
                if (pond->ipv6_pools == NULL)
                        continue;

                for (i = 0; (p = pond->ipv6_pools[i]) != NULL; i++) {
                        if (p->pool_type == D6O_IA_TA)
                                break;
                }
                if (p != NULL)
                        break;
        }

        /* If we get here and p is NULL we have no useful pools */
        if (p == NULL) {
                log_debug("Unable to get client addresses: "
                          "no IPv6 pools on this shared network");
                return ISC_R_NORESOURCES;
        }

        /*
         * We have at least one pool that could provide an address
         * Now we walk through the ponds and pools again and check
         * to see if the client is permitted and if an address is
         * available
         */

        for (pond = reply->shared->ipv6_pond; pond != NULL; pond = pond->next) {
                if (((pond->prohibit_list != NULL) &&
                     (permitted(reply->packet, pond->prohibit_list))) ||
                    ((pond->permit_list != NULL) &&
                     (!permitted(reply->packet, pond->permit_list))))
                        continue;

                for (i = 0; (p = pond->ipv6_pools[i]) != NULL; i++) {
                        if (p->pool_type != D6O_IA_TA) {
                                continue;
                        }

                        /*
                         * Get an address in this temporary pool.
                         */
                        status = create_lease6(p, &reply->lease, &attempts,
                                               &reply->client_id,
                                               cur_time + 120);

                        if (status != ISC_R_SUCCESS) {
                                log_debug("Unable to get a temporary address.");
                                goto cleanup;
                        }

                        status = reply_process_is_addressed(reply,
                                                            &reply->lease->scope,
                                                            pond->group);
                        if (status != ISC_R_SUCCESS) {
                                goto cleanup;
                        }
                        send_addr.len = 16;
                        memcpy(send_addr.iabuf, &reply->lease->addr, 16);
                        status = reply_process_send_addr(reply, &send_addr);
                        if (status != ISC_R_SUCCESS) {
                                goto cleanup;
                        }
                        /*
                         * reply->lease can't be null as we use it above
                         * add check if that changes
                         */
                        iasubopt_dereference(&reply->lease, MDL);
                }
        }

      cleanup:
        if (reply->lease != NULL) {
                iasubopt_dereference(&reply->lease, MDL);
        }
        return status;
}

/*
 * This function only returns failure on 'hard' failures.  If it succeeds,
 * it will leave a lease structure behind.
 */
static isc_result_t
reply_process_try_addr(struct reply_state *reply, struct iaddr *addr) {
        isc_result_t status = ISC_R_ADDRNOTAVAIL;
        struct ipv6_pool *pool = NULL;
        struct ipv6_pond *pond = NULL;
        int i;
        struct data_string data_addr;

        if ((reply == NULL) || (reply->shared == NULL) ||
            (addr == NULL) || (reply->lease != NULL))
                return (DHCP_R_INVALIDARG);

        /*
         * Do a quick walk through of the ponds and pools
         * to see if we have any NA address pools
         */
        for (pond = reply->shared->ipv6_pond; pond != NULL; pond = pond->next) {
                if (pond->ipv6_pools == NULL)
                        continue;

                for (i = 0; ; i++) {
                        pool = pond->ipv6_pools[i];
                        if ((pool == NULL) ||
                            (pool->pool_type == D6O_IA_NA))
                                break;
                }
                if (pool != NULL)
                        break;
        }

        /* If we get here and p is NULL we have no useful pools */
        if (pool == NULL) {
                return (ISC_R_ADDRNOTAVAIL);
        }

        memset(&data_addr, 0, sizeof(data_addr));
        data_addr.len = addr->len;
        data_addr.data = addr->iabuf;

        /*
         * We have at least one pool that could provide an address
         * Now we walk through the ponds and pools again and check
         * to see if the client is permitted and if an address is
         * available
         *
         * Within a given pond we start looking at the last pool we
         * allocated from, unless it had a collision trying to allocate
         * an address. This will tend to move us into less-filled pools.
         */

        for (pond = reply->shared->ipv6_pond; pond != NULL; pond = pond->next) {
                if (((pond->prohibit_list != NULL) &&
                     (permitted(reply->packet, pond->prohibit_list))) ||
                    ((pond->permit_list != NULL) &&
                     (!permitted(reply->packet, pond->permit_list))))
                        continue;

                for (i = 0 ; (pool = pond->ipv6_pools[i]) != NULL ; i++) {
                        if (pool->pool_type != D6O_IA_NA)
                                continue;

                        status = try_client_v6_address(&reply->lease, pool,
                                                       &data_addr);
                        if (status == ISC_R_SUCCESS)
                                break;
                }

                if (status == ISC_R_SUCCESS)
                        break;
        }

        /* Note that this is just pedantry.  There is no allocation to free. */
        data_string_forget(&data_addr, MDL);
        /* Return just the most recent status... */
        return (status);
}

/* Look around for an address to give the client.  First, look through the
 * old IA for addresses we can extend.  Second, try to allocate a new address.
 * Finally, actually add that address into the current reply IA.
 */
static isc_result_t
find_client_address(struct reply_state *reply) {
        struct iaddr send_addr;
        isc_result_t status = ISC_R_NORESOURCES;
        struct iasubopt *lease, *best_lease = NULL;
        struct binding_scope **scope;
        struct group *group;
        int i;

        if (reply->static_lease) {
                if (reply->host == NULL)
                        return DHCP_R_INVALIDARG;

                send_addr.len = 16;
                memcpy(send_addr.iabuf, reply->fixed.data, 16);

                scope = &global_scope;
                group = reply->subnet->group;
                goto send_addr;
        }

        if (reply->old_ia != NULL)  {
                for (i = 0 ; i < reply->old_ia->num_iasubopt ; i++) {
                        struct shared_network *candidate_shared;
                        struct ipv6_pond *pond;

                        lease = reply->old_ia->iasubopt[i];
                        candidate_shared = lease->ipv6_pool->shared_network;
                        pond = lease->ipv6_pool->ipv6_pond;

                        /*
                         * Look for the best lease on the client's shared
                         * network, that is still permitted
                         */

                        if ((candidate_shared != reply->shared) ||
                            (lease6_usable(lease) != ISC_TRUE))
                                continue;

                        if (((pond->prohibit_list != NULL) &&
                             (permitted(reply->packet, pond->prohibit_list))) ||
                            ((pond->permit_list != NULL) &&
                             (!permitted(reply->packet, pond->permit_list))))
                                continue;

                        best_lease = lease_compare(lease, best_lease);
                }
        }

        /* Try to pick a new address if we didn't find one, or if we found an
         * abandoned lease.
         */
        if ((best_lease == NULL) || (best_lease->state == FTS_ABANDONED)) {
                status = pick_v6_address(reply);
        } else if (best_lease != NULL) {
                iasubopt_reference(&reply->lease, best_lease, MDL);
                status = ISC_R_SUCCESS;
        }

        /* Pick the abandoned lease as a last resort. */
        if ((status == ISC_R_NORESOURCES) && (best_lease != NULL)) {
                /* I don't see how this is supposed to be done right now. */
                log_error("Best match for DUID %s is an abandoned address,"
                          " This may be a result of multiple clients attempting"
                          " to use this DUID",
                         print_hex_1(reply->client_id.len,
                                     reply->client_id.data, 60));
                /* iasubopt_reference(&reply->lease, best_lease, MDL); */
        }

        /* Give up now if we didn't find a lease. */
        if (status != ISC_R_SUCCESS)
                return status;

        if (reply->lease == NULL)
                log_fatal("Impossible condition at %s:%d.", MDL);

        /* Draw binding scopes from the lease's binding scope, and config
         * from the lease's containing subnet and higher.  Note that it may
         * be desirable to place the group attachment directly in the pool.
         */
        scope = &reply->lease->scope;
        group = reply->lease->ipv6_pool->ipv6_pond->group;

        send_addr.len = 16;
        memcpy(send_addr.iabuf, &reply->lease->addr, 16);

      send_addr:
        status = reply_process_is_addressed(reply, scope, group);
        if (status != ISC_R_SUCCESS)
                return status;

        status = reply_process_send_addr(reply, &send_addr);
        return status;
}

/* Once an address is found for a client, perform several common functions;
 * Calculate and store valid and preferred lease times, draw client options
 * into the option state.
 */
static isc_result_t
reply_process_is_addressed(struct reply_state *reply,
                           struct binding_scope **scope, struct group *group)
{
        isc_result_t status = ISC_R_SUCCESS;
        struct data_string data;
        struct option_cache *oc;
        struct option_state *tmp_options = NULL;
        struct on_star *on_star;
        int i;

        /* Initialize values we will cleanup. */
        memset(&data, 0, sizeof(data));

        /*
         * Find the proper on_star block to use.  We use the
         * one in the lease if we have a lease or the one in
         * the reply if we don't have a lease because this is
         * a static instance
         */
        if (reply->lease) {
                on_star = &reply->lease->on_star;
        } else {
                on_star = &reply->on_star;
        }

        /*
         * Bring in the root configuration.  We only do this to bring
         * in the on * statements, as we didn't have the lease available
         * we did it the first time.
         */
        option_state_allocate(&tmp_options, MDL);
        execute_statements_in_scope(NULL, reply->packet, NULL, NULL,
                                    reply->packet->options, tmp_options,
                                    &global_scope, root_group, NULL,
                                    on_star);
        if (tmp_options != NULL) {
                option_state_dereference(&tmp_options, MDL);
        }

        /*
         * Bring configured options into the root packet level cache - start
         * with the lease's closest enclosing group (passed in by the caller
         * as 'group').
         */
        execute_statements_in_scope(NULL, reply->packet, NULL, NULL,
                                    reply->packet->options, reply->opt_state,
                                    scope, group, root_group, on_star);

        /* Execute statements from class scopes. */
        for (i = reply->packet->class_count; i > 0; i--) {
                execute_statements_in_scope(NULL, reply->packet, NULL, NULL,
                                            reply->packet->options,
                                            reply->opt_state, scope,
                                            reply->packet->classes[i - 1]->group,
                                            group, on_star);
        }

        /*
         * If there is a host record, over-ride with values configured there,
         * without re-evaluating configuration from the previously executed
         * group or its common enclosers.
         */
        if (reply->host != NULL)
                execute_statements_in_scope(NULL, reply->packet, NULL, NULL,
                                            reply->packet->options,
                                            reply->opt_state, scope,
                                            reply->host->group, group,
                                            on_star);

        /* Determine valid lifetime. */
        if (reply->client_valid == 0)
                reply->send_valid = DEFAULT_DEFAULT_LEASE_TIME;
        else
                reply->send_valid = reply->client_valid;

        oc = lookup_option(&server_universe, reply->opt_state,
                           SV_DEFAULT_LEASE_TIME);
        if (oc != NULL) {
                if (!evaluate_option_cache(&data, reply->packet, NULL, NULL,
                                           reply->packet->options,
                                           reply->opt_state,
                                           scope, oc, MDL) ||
                    (data.len != 4)) {
                        log_error("reply_process_is_addressed: unable to "
                                  "evaluate default lease time");
                        status = ISC_R_FAILURE;
                        goto cleanup;
                }

                reply->send_valid = getULong(data.data);
                data_string_forget(&data, MDL);
        }

        /* Check to see if the lease time would cause us to wrap
         * in which case we make it infinite.
         * The following doesn't work on at least some systems:
         * (cur_time + reply->send_valid < cur_time)
         */
        if (reply->send_valid != INFINITE_TIME) {
                time_t test_time = cur_time + reply->send_valid;
                if (test_time < cur_time)
                        reply->send_valid = INFINITE_TIME;
        }

        if (reply->client_prefer == 0)
                reply->send_prefer = reply->send_valid;
        else
                reply->send_prefer = reply->client_prefer;

        if ((reply->send_prefer >= reply->send_valid) &&
            (reply->send_valid != INFINITE_TIME))
                reply->send_prefer = (reply->send_valid / 2) +
                                     (reply->send_valid / 8);

        oc = lookup_option(&server_universe, reply->opt_state,
                           SV_PREFER_LIFETIME);
        if (oc != NULL) {
                if (!evaluate_option_cache(&data, reply->packet, NULL, NULL,
                                           reply->packet->options,
                                           reply->opt_state,
                                           scope, oc, MDL) ||
                    (data.len != 4)) {
                        log_error("reply_process_is_addressed: unable to "
                                  "evaluate preferred lease time");
                        status = ISC_R_FAILURE;
                        goto cleanup;
                }

                reply->send_prefer = getULong(data.data);
                data_string_forget(&data, MDL);
        }

        /* Note lowest values for later calculation of renew/rebind times. */
        if (reply->min_prefer > reply->send_prefer)
                reply->min_prefer = reply->send_prefer;

        if (reply->min_valid > reply->send_valid)
                reply->min_valid = reply->send_valid;

#if 0
        /*
         * XXX: Old 4.0.0 alpha code would change the host {} record
         * XXX: uid upon lease assignment.  This was intended to cover the
         * XXX: case where a client first identifies itself using vendor
         * XXX: options in a solicit, or request, but later neglects to include
         * XXX: these options in a Renew or Rebind.  It is not clear that this
         * XXX: is required, and has some startling ramifications (such as
         * XXX: how to recover this dynamic host {} state across restarts).
         */
        if (reply->host != NULL)
                change_host_uid(host, reply->client_id->data,
                                reply->client_id->len);
#endif /* 0 */

        /* Perform dynamic lease related update work. */
        if (reply->lease != NULL) {
                /* Cached lifetimes */
                reply->lease->prefer = reply->send_prefer;
                reply->lease->valid = reply->send_valid;

                /* Advance (or rewind) the valid lifetime.
                 * In the protocol 0xFFFFFFFF is infinite
                 * when connecting to the lease file MAX_TIME is
                 */
                if (reply->buf.reply.msg_type == DHCPV6_REPLY) {
                        if (reply->send_valid == INFINITE_TIME) {
                                reply->lease->soft_lifetime_end_time = MAX_TIME;
                        } else {
                                reply->lease->soft_lifetime_end_time =
                                  cur_time + reply->send_valid;
                        }
                        /* Wait before renew! */
                }

                status = ia_add_iasubopt(reply->ia, reply->lease, MDL);
                if (status != ISC_R_SUCCESS) {
                        log_fatal("reply_process_is_addressed: Unable to "
                                  "attach lease to new IA: %s",
                                  isc_result_totext(status));
                }

                /*
                 * If this is a new lease, make sure it is attached somewhere.
                 */
                if (reply->lease->ia == NULL) {
                        ia_reference(&reply->lease->ia, reply->ia, MDL);
                }
        }

        /* Bring a copy of the relevant options into the IA scope. */
        execute_statements_in_scope(NULL, reply->packet, NULL, NULL,
                                    reply->packet->options, reply->reply_ia,
                                    scope, group, root_group, NULL);

        /* Execute statements from class scopes. */
        for (i = reply->packet->class_count; i > 0; i--) {
                execute_statements_in_scope(NULL, reply->packet, NULL, NULL,
                                            reply->packet->options,
                                            reply->reply_ia, scope,
                                            reply->packet->classes[i - 1]->group,
                                            group, NULL);
        }

        /*
         * And bring in host record configuration, if any, but not to overlap
         * the previous group or its common enclosers.
         */
        if (reply->host != NULL)
                execute_statements_in_scope(NULL, reply->packet, NULL, NULL,
                                            reply->packet->options,
                                            reply->reply_ia, scope,
                                            reply->host->group, group, NULL);

      cleanup:
        if (data.data != NULL)
                data_string_forget(&data, MDL);

        if (status == ISC_R_SUCCESS)
                reply->client_resources++;

        return status;
}

/* Simply send an IAADDR within the IA scope as described. */
static isc_result_t
reply_process_send_addr(struct reply_state *reply, struct iaddr *addr) {
        isc_result_t status = ISC_R_SUCCESS;
        struct data_string data;

        memset(&data, 0, sizeof(data));

        /* Now append the lease. */
        data.len = IAADDR_OFFSET;
        if (!buffer_allocate(&data.buffer, data.len, MDL)) {
                log_error("reply_process_send_addr: out of memory"
                          "allocating new IAADDR buffer.");
                status = ISC_R_NOMEMORY;
                goto cleanup;
        }
        data.data = data.buffer->data;

        memcpy(data.buffer->data, addr->iabuf, 16);
        putULong(data.buffer->data + 16, reply->send_prefer);
        putULong(data.buffer->data + 20, reply->send_valid);

        if (!append_option_buffer(&dhcpv6_universe, reply->reply_ia,
                                  data.buffer, data.buffer->data,
                                  data.len, D6O_IAADDR, 0)) {
                log_error("reply_process_send_addr: unable "
                          "to save IAADDR option");
                status = ISC_R_FAILURE;
                goto cleanup;
        }

        reply->resources_included = ISC_TRUE;

      cleanup:
        if (data.data != NULL)
                data_string_forget(&data, MDL);

        return status;
}

/* Choose the better of two leases. */
static struct iasubopt *
lease_compare(struct iasubopt *alpha, struct iasubopt *beta) {
        if (alpha == NULL)
                return beta;
        if (beta == NULL)
                return alpha;

        switch(alpha->state) {
              case FTS_ACTIVE:
                switch(beta->state) {
                      case FTS_ACTIVE:
                        /* Choose the lease with the longest lifetime (most
                         * likely the most recently allocated).
                         */
                        if (alpha->hard_lifetime_end_time <
                            beta->hard_lifetime_end_time)
                                return beta;
                        else
                                return alpha;

                      case FTS_EXPIRED:
                      case FTS_ABANDONED:
                        return alpha;

                      default:
                        log_fatal("Impossible condition at %s:%d.", MDL);
                }
                break;

              case FTS_EXPIRED:
                switch (beta->state) {
                      case FTS_ACTIVE:
                        return beta;

                      case FTS_EXPIRED:
                        /* Choose the most recently expired lease. */
                        if (alpha->hard_lifetime_end_time <
                            beta->hard_lifetime_end_time)
                                return beta;
                        else if ((alpha->hard_lifetime_end_time ==
                                  beta->hard_lifetime_end_time) &&
                                 (alpha->soft_lifetime_end_time <
                                  beta->soft_lifetime_end_time))
                                return beta;
                        else
                                return alpha;

                      case FTS_ABANDONED:
                        return alpha;

                      default:
                        log_fatal("Impossible condition at %s:%d.", MDL);
                }
                break;

              case FTS_ABANDONED:
                switch (beta->state) {
                      case FTS_ACTIVE:
                      case FTS_EXPIRED:
                        return alpha;

                      case FTS_ABANDONED:
                        /* Choose the lease that was abandoned longest ago. */
                        if (alpha->hard_lifetime_end_time <
                            beta->hard_lifetime_end_time)
                                return alpha;
                        else
                                return beta;

                      default:
                        log_fatal("Impossible condition at %s:%d.", MDL);
                }
                break;

              default:
                log_fatal("Impossible condition at %s:%d.", MDL);
        }

        log_fatal("Triple impossible condition at %s:%d.", MDL);
        return NULL;
}

/* Process a client-supplied IA_PD.  This may append options to the tail of
 * the reply packet being built in the reply_state structure.
 */
static isc_result_t
reply_process_ia_pd(struct reply_state *reply, struct option_cache *ia) {
        isc_result_t status = ISC_R_SUCCESS;
        u_int32_t iaid;
        unsigned ia_cursor;
        struct option_state *packet_ia;
        struct option_cache *oc;
        struct data_string ia_data, data;

        /* Initialize values that will get cleaned up on return. */
        packet_ia = NULL;
        memset(&ia_data, 0, sizeof(ia_data));
        memset(&data, 0, sizeof(data));
        /*
         * Note that find_client_prefix() may set reply->lease.
         */

        /* Make sure there is at least room for the header. */
        if ((reply->cursor + IA_PD_OFFSET + 4) > sizeof(reply->buf)) {
                log_error("reply_process_ia_pd: Reply too long for IA.");
                return ISC_R_NOSPACE;
        }


        /* Fetch the IA_PD contents. */
        if (!get_encapsulated_IA_state(&packet_ia, &ia_data, reply->packet,
                                       ia, IA_PD_OFFSET)) {
                log_error("reply_process_ia_pd: error evaluating ia");
                status = ISC_R_FAILURE;
                goto cleanup;
        }

        /* Extract IA_PD header contents. */
        iaid = getULong(ia_data.data);
        reply->renew = getULong(ia_data.data + 4);
        reply->rebind = getULong(ia_data.data + 8);

        /* Create an IA_PD structure. */
        if (ia_allocate(&reply->ia, iaid, (char *)reply->client_id.data,
                        reply->client_id.len, MDL) != ISC_R_SUCCESS) {
                log_error("reply_process_ia_pd: no memory for ia.");
                status = ISC_R_NOMEMORY;
                goto cleanup;
        }
        reply->ia->ia_type = D6O_IA_PD;

        /* Cache pre-existing IA_PD, if any. */
        ia_hash_lookup(&reply->old_ia, ia_pd_active,
                       (unsigned char *)reply->ia->iaid_duid.data,
                       reply->ia->iaid_duid.len, MDL);

        /*
         * Create an option cache to carry the IA_PD option contents, and
         * execute any user-supplied values into it.
         */
        if (!option_state_allocate(&reply->reply_ia, MDL)) {
                status = ISC_R_NOMEMORY;
                goto cleanup;
        }

        /* Check & count the fixed prefix host records. */
        reply->static_prefixes = 0;
        if ((reply->host != NULL) && (reply->host->fixed_prefix != NULL)) {
                struct iaddrcidrnetlist *fp;

                for (fp = reply->host->fixed_prefix; fp != NULL;
                     fp = fp->next) {
                        reply->static_prefixes += 1;
                }
        }

        /*
         * Save the cursor position at the start of the IA_PD, so we can
         * set length and adjust t1/t2 values later.  We write a temporary
         * header out now just in case we decide to adjust the packet
         * within sub-process functions.
         */
        ia_cursor = reply->cursor;

        /* Initialize the IA_PD header.  First the code. */
        putUShort(reply->buf.data + reply->cursor, (unsigned)D6O_IA_PD);
        reply->cursor += 2;

        /* Then option length. */
        putUShort(reply->buf.data + reply->cursor, 0x0Cu);
        reply->cursor += 2;

        /* Then IA_PD header contents; IAID. */
        putULong(reply->buf.data + reply->cursor, iaid);
        reply->cursor += 4;

        /* We store the client's t1 for now, and may over-ride it later. */
        putULong(reply->buf.data + reply->cursor, reply->renew);
        reply->cursor += 4;

        /* We store the client's t2 for now, and may over-ride it later. */
        putULong(reply->buf.data + reply->cursor, reply->rebind);
        reply->cursor += 4;

        /*
         * For each prefix in this IA_PD, decide what to do about it.
         */
        oc = lookup_option(&dhcpv6_universe, packet_ia, D6O_IAPREFIX);
        reply->min_valid = reply->min_prefer = INFINITE_TIME;
        reply->client_valid = reply->client_prefer = 0;
        reply->preflen = -1;
        for (; oc != NULL ; oc = oc->next) {
                status = reply_process_prefix(reply, oc);

                /*
                 * Canceled means we did not allocate prefixes to the
                 * client, but we're "done" with this IA - we set a status
                 * code.  So transmit this reply, e.g., move on to the next
                 * IA.
                 */
                if (status == ISC_R_CANCELED)
                        break;

                if ((status != ISC_R_SUCCESS) &&
                    (status != ISC_R_ADDRINUSE) &&
                    (status != ISC_R_ADDRNOTAVAIL))
                        goto cleanup;
        }

        reply->pd_count++;

        /*
         * If we fell through the above and never gave the client
         * a prefix, give it one now.
         */
        if ((status != ISC_R_CANCELED) && (reply->client_resources == 0)) {
                status = find_client_prefix(reply);

                if (status == ISC_R_NORESOURCES) {
                        switch (reply->packet->dhcpv6_msg_type) {
                              case DHCPV6_SOLICIT:
                                /*
                                 * No prefix for any IA is handled
                                 * by the caller.
                                 */
                                /* FALL THROUGH */

                              case DHCPV6_REQUEST:
                                /* Same than for addresses. */
                                option_state_dereference(&reply->reply_ia, MDL);
                                if (!option_state_allocate(&reply->reply_ia,
                                                           MDL))
                                {
                                        log_error("reply_process_ia_pd: No "
                                                  "memory for option state "
                                                  "wipe.");
                                        status = ISC_R_NOMEMORY;
                                        goto cleanup;
                                }

                                if (!set_status_code(STATUS_NoPrefixAvail,
                                                     "No prefixes available "
                                                     "for this interface.",
                                                      reply->reply_ia)) {
                                        log_error("reply_process_ia_pd: "
                                                  "Unable to set "
                                                  "NoPrefixAvail status "
                                                  "code.");
                                        status = ISC_R_FAILURE;
                                        goto cleanup;
                                }

                                status = ISC_R_SUCCESS;
                                break;

                              default:
                                if (reply->resources_included)
                                        status = ISC_R_SUCCESS;
                                else
                                        goto cleanup;
                                break;
                        }
                }

                if (status != ISC_R_SUCCESS)
                        goto cleanup;
        }

        /*
         * yes, goto's aren't the best but we also want to avoid extra
         * indents
         */
        if (status == ISC_R_CANCELED) {
                /* We're replying with a status code so we still need to
                 * write it out in wire-format to the outbound buffer */
                write_to_packet(reply, ia_cursor);
                goto cleanup;
        }

        /*
         * Handle static prefixes, we always log stuff and if it's
         * a hard binding we run any commit statements that we have
         */
        if (reply->static_prefixes != 0) {
                char tmp_addr[INET6_ADDRSTRLEN];
                log_info("%s PD: address %s/%d to client with duid %s "
                         "iaid = %d static",
                         dhcpv6_type_names[reply->buf.reply.msg_type],
                         inet_ntop(AF_INET6, reply->fixed_pref.lo_addr.iabuf,
                                   tmp_addr, sizeof(tmp_addr)),
                         reply->fixed_pref.bits,
                         print_hex_1(reply->client_id.len,
                                     reply->client_id.data, 60),
                         iaid);

                /* Write the lease out in wire-format to the outbound buffer */
                write_to_packet(reply, ia_cursor);

                if ((reply->buf.reply.msg_type == DHCPV6_REPLY) &&
                    (reply->on_star.on_commit != NULL)) {
                        execute_statements(NULL, reply->packet, NULL, NULL,
                                           reply->packet->options,
                                           reply->opt_state,
                                           NULL, reply->on_star.on_commit,
                                           NULL);
                        executable_statement_dereference
                                (&reply->on_star.on_commit, MDL);
                }
                goto cleanup;
        }

        /*
         * If we have any addresses log what we are doing.
         */
        if (reply->ia->num_iasubopt != 0) {
                struct iasubopt *tmp;
                int i;
                char tmp_addr[INET6_ADDRSTRLEN];

                for (i = 0 ; i < reply->ia->num_iasubopt ; i++) {
                        tmp = reply->ia->iasubopt[i];

                        log_info("%s PD: address %s/%d to client with duid %s"
                                 " iaid = %d valid for %u seconds",
                                 dhcpv6_type_names[reply->buf.reply.msg_type],
                                 inet_ntop(AF_INET6, &tmp->addr,
                                           tmp_addr, sizeof(tmp_addr)),
                                 (int)tmp->plen,
                                 print_hex_1(reply->client_id.len,
                                             reply->client_id.data, 60),
                                 iaid, tmp->valid);
                }
        }

        /*
         * If this is not a 'soft' binding, consume the new changes into
         * the database (if any have been attached to the ia_pd).
         *
         * Loop through the assigned dynamic prefixes, referencing the
         * prefixes onto this IA_PD rather than any old ones, and updating
         * prefix pool timers for each (if any).
         *
         * If a lease can be reused we skip renewing it or checking the
         * pool threshold. If it can't we flag that the IA must be commited
         * to the db and do the renewal and pool check.
         */
        if ((reply->buf.reply.msg_type == DHCPV6_REPLY) &&
            (reply->ia->num_iasubopt != 0)) {
                int must_commit = 0;
                struct iasubopt *tmp;
                struct data_string *ia_id;
                int i;

                for (i = 0 ; i < reply->ia->num_iasubopt ; i++) {
                        tmp = reply->ia->iasubopt[i];

                        if (tmp->ia != NULL)
                                ia_dereference(&tmp->ia, MDL);
                        ia_reference(&tmp->ia, reply->ia, MDL);

                        /* If we have anything to do on commit do it now */
                        if (tmp->on_star.on_commit != NULL) {
                                execute_statements(NULL, reply->packet,
                                                   NULL, NULL,
                                                   reply->packet->options,
                                                   reply->opt_state,
                                                   &tmp->scope,
                                                   tmp->on_star.on_commit,
                                                   &tmp->on_star);
                                executable_statement_dereference
                                        (&tmp->on_star.on_commit, MDL);
                        }

                        if (!reuse_lease6(reply, tmp)) {
                                /* Commit 'hard' bindings. */
                                must_commit = 1;
                                renew_lease6(tmp->ipv6_pool, tmp);
                                schedule_lease_timeout(tmp->ipv6_pool);

                                /* Do our threshold check. */
                                check_pool6_threshold(reply, tmp);
                        }
                }

                /* write the IA_PD in wire-format to the outbound buffer */
                write_to_packet(reply, ia_cursor);

                /* Remove any old ia from the hash. */
                if (reply->old_ia != NULL) {
                        if (!release_on_roam(reply)) {
                                ia_id = &reply->old_ia->iaid_duid;
                                ia_hash_delete(ia_pd_active,
                                               (unsigned char *)ia_id->data,
                                               ia_id->len, MDL);
                        }

                        ia_dereference(&reply->old_ia, MDL);
                }

                /* Put new ia into the hash. */
                reply->ia->cltt = cur_time;
                ia_id = &reply->ia->iaid_duid;
                ia_hash_add(ia_pd_active, (unsigned char *)ia_id->data,
                            ia_id->len, reply->ia, MDL);

                /* If we couldn't reuse all of the iasubopts, we
                * must udpate the lease db */
                if (must_commit) {
                        write_ia(reply->ia);
                }
        } else {
                /* write the IA_PD in wire-format to the outbound buffer */
                write_to_packet(reply, ia_cursor);
                schedule_lease_timeout_reply(reply);
        }

      cleanup:
        if (packet_ia != NULL)
                option_state_dereference(&packet_ia, MDL);
        if (reply->reply_ia != NULL)
                option_state_dereference(&reply->reply_ia, MDL);
        if (ia_data.data != NULL)
                data_string_forget(&ia_data, MDL);
        if (data.data != NULL)
                data_string_forget(&data, MDL);
        if (reply->ia != NULL)
                ia_dereference(&reply->ia, MDL);
        if (reply->old_ia != NULL)
                ia_dereference(&reply->old_ia, MDL);
        if (reply->lease != NULL)
                iasubopt_dereference(&reply->lease, MDL);
        if (reply->on_star.on_expiry != NULL)
                executable_statement_dereference
                        (&reply->on_star.on_expiry, MDL);
        if (reply->on_star.on_release != NULL)
                executable_statement_dereference
                        (&reply->on_star.on_release, MDL);

        /*
         * ISC_R_CANCELED is a status code used by the prefix processing to
         * indicate we're replying with a status code.  This is still a
         * success at higher layers.
         */
        return((status == ISC_R_CANCELED) ? ISC_R_SUCCESS : status);
}

/*!
 *
 * \brief Find the proper scoping group for use with a v6 static prefix.
 *
 * We start by trying to find a subnet based on the given prefix and
 * the shared network.  If we don't find one then the prefix has been
 * declared outside of any subnets.  If there is a static address
 * associated with the host we use it to try and find a subnet (this
 * should succeed).  If there isn't a static address we fall back
 * to the shared subnet itself.
 * Once we have a subnet we extract the group from it and return it.
 *
 * \param reply - the reply structure we use to collect information
 *                we will use the fields shared, fixed_pref and host
 *                from the structure
 *
 * \return a pointer to the group structure to use for scoping
 */

static struct group *
find_group_by_prefix(struct reply_state *reply) {
        /* default group if we don't find anything better */
        struct group *group = reply->shared->group;
        struct subnet *subnet = NULL;
        struct iaddr tmp_addr;
        struct data_string fixed_addr;

        /* Try with the prefix first */
        if (find_grouped_subnet(&subnet, reply->shared,
                                reply->fixed_pref.lo_addr, MDL) != 0) {
                group = subnet->group;
                subnet_dereference(&subnet, MDL);
                return (group);
        }

        /* Didn't find a subnet via prefix, what about fixed address */
        /* The caller has already tested reply->host != NULL */

        memset(&fixed_addr, 0, sizeof(fixed_addr));

        if ((reply->host->fixed_addr != NULL) &&
            (evaluate_option_cache(&fixed_addr, NULL, NULL, NULL,
                                   NULL, NULL, &global_scope,
                                   reply->host->fixed_addr, MDL))) {
                if (fixed_addr.len >= 16) {
                        tmp_addr.len = 16;
                        memcpy(tmp_addr.iabuf, fixed_addr.data, 16);
                        if (find_grouped_subnet(&subnet, reply->shared,
                                                tmp_addr, MDL) != 0) {
                                group = subnet->group;
                                subnet_dereference(&subnet, MDL);
                        }
                }
                data_string_forget(&fixed_addr, MDL);
        }

        /* return whatever we got */
        return (group);
}

/*
 * Process an IAPREFIX within a given IA_PD, storing any IAPREFIX reply
 * contents into the reply's current ia_pd-scoped option cache.  Returns
 * ISC_R_CANCELED in the event we are replying with a status code and do
 * not wish to process more IAPREFIXes within this IA_PD.
 */
static isc_result_t
reply_process_prefix(struct reply_state *reply, struct option_cache *pref) {
        u_int32_t pref_life, valid_life;
        struct binding_scope **scope;
        struct iaddrcidrnet tmp_pref;
        struct option_cache *oc;
        struct data_string iapref, data;
        isc_result_t status = ISC_R_SUCCESS;
        struct group *group;

        /* Initializes values that will be cleaned up. */
        memset(&iapref, 0, sizeof(iapref));
        memset(&data, 0, sizeof(data));
        /* Note that reply->lease may be set by prefix_is_owned() */

        /*
         * There is no point trying to process an incoming prefix if there
         * is no room for an outgoing prefix.
         */
        if ((reply->cursor + 29) > sizeof(reply->buf)) {
                log_error("reply_process_prefix: Out of room for prefix.");
                return ISC_R_NOSPACE;
        }

        /* Extract this IAPREFIX option. */
        if (!evaluate_option_cache(&iapref, reply->packet, NULL, NULL,
                                   reply->packet->options, NULL, &global_scope,
                                   pref, MDL) ||
            (iapref.len < IAPREFIX_OFFSET)) {
                log_error("reply_process_prefix: error evaluating IAPREFIX.");
                status = ISC_R_FAILURE;
                goto cleanup;
        }

        /*
         * Layout: preferred and valid lifetimes followed by the prefix
         * length and the IPv6 address.
         */
        pref_life = getULong(iapref.data);
        valid_life = getULong(iapref.data + 4);

        if ((reply->client_valid == 0) ||
            (reply->client_valid > valid_life))
                reply->client_valid = valid_life;

        if ((reply->client_prefer == 0) ||
            (reply->client_prefer > pref_life))
                reply->client_prefer = pref_life;

        /*
         * Clients may choose to send ::/0 as a prefix, with the idea to give
         * hints about preferred-lifetime or valid-lifetime.
         */
        tmp_pref.lo_addr.len = 16;
        memset(tmp_pref.lo_addr.iabuf, 0, 16);
        if ((iapref.data[8] == 0) &&
            (memcmp(iapref.data + 9, tmp_pref.lo_addr.iabuf, 16) == 0)) {
                /* Status remains success; we just ignore this one. */
                goto cleanup;
        }

        /*
         * Clients may choose to send ::/X as a prefix to specify a
         * preferred/requested prefix length. Note X is never zero here.
         */
        tmp_pref.bits = (int) iapref.data[8];
        if (reply->preflen < 0) {
                /* Cache the first preferred prefix length. */
                reply->preflen = tmp_pref.bits;
        }
        if (memcmp(iapref.data + 9, tmp_pref.lo_addr.iabuf, 16) == 0) {
                goto cleanup;
        }

        memcpy(tmp_pref.lo_addr.iabuf, iapref.data + 9, 16);

        /* Verify the prefix belongs to the client. */
        if (!prefix_is_owned(reply, &tmp_pref)) {
                /* Same than for addresses. */
                if ((reply->packet->dhcpv6_msg_type == DHCPV6_SOLICIT) ||
                    (reply->packet->dhcpv6_msg_type == DHCPV6_REQUEST) ||
                    (reply->packet->dhcpv6_msg_type == DHCPV6_REBIND)) {
                        status = reply_process_try_prefix(reply, &tmp_pref);

                        /* Either error out or skip this prefix. */
                        if ((status != ISC_R_SUCCESS) &&
                            (status != ISC_R_ADDRINUSE) &&
                            (status != ISC_R_ADDRNOTAVAIL))
                                goto cleanup;

                        if (reply->lease == NULL) {
                                if (reply->packet->dhcpv6_msg_type ==
                                                        DHCPV6_REBIND) {
                                        reply->send_prefer = 0;
                                        reply->send_valid = 0;
                                        goto send_pref;
                                }

                                /* status remains success - ignore */
                                goto cleanup;
                        }
                /*
                 * RFC3633 section 18.2.3:
                 *
                 * If the delegating router cannot find a binding
                 * for the requesting router's IA_PD the delegating
                 * router returns the IA_PD containing no prefixes
                 * with a Status Code option set to NoBinding in the
                 * Reply message.
                 *
                 * On mismatch we (ab)use this pretending we have not the IA
                 * as soon as we have not a prefix.
                 */
                } else if (reply->packet->dhcpv6_msg_type == DHCPV6_RENEW) {
                        /* Rewind the IA_PD to empty. */
                        option_state_dereference(&reply->reply_ia, MDL);
                        if (!option_state_allocate(&reply->reply_ia, MDL)) {
                                log_error("reply_process_prefix: No memory "
                                          "for option state wipe.");
                                status = ISC_R_NOMEMORY;
                                goto cleanup;
                        }

                        /* Append a NoBinding status code.  */
                        if (!set_status_code(STATUS_NoBinding,
                                             "Prefix not bound to this "
                                             "interface.", reply->reply_ia)) {
                                log_error("reply_process_prefix: Unable to "
                                          "attach status code.");
                                status = ISC_R_FAILURE;
                                goto cleanup;
                        }

                        /* Fin (no more IAPREFIXes). */
                        status = ISC_R_CANCELED;
                        goto cleanup;
                } else {
                        log_error("It is impossible to lease a client that is "
                                  "not sending a solicit, request, renew, or "
                                  "rebind message.");
                        status = ISC_R_FAILURE;
                        goto cleanup;
                }
        }

        if (reply->static_prefixes > 0) {
                if (reply->host == NULL)
                        log_fatal("Impossible condition at %s:%d.", MDL);

                scope = &global_scope;

                /* Copy the static prefix for logging and finding the group */
                memcpy(&reply->fixed_pref, &tmp_pref, sizeof(tmp_pref));

                /* Try to find a group for the static prefix */
                group = find_group_by_prefix(reply);
        } else {
                if (reply->lease == NULL)
                        log_fatal("Impossible condition at %s:%d.", MDL);

                scope = &reply->lease->scope;
                group = reply->lease->ipv6_pool->ipv6_pond->group;
        }

        /*
         * If client_resources is nonzero, then the reply_process_is_prefixed
         * function has executed configuration state into the reply option
         * cache.  We will use that valid cache to derive configuration for
         * whether or not to engage in additional prefixes, and similar.
         */
        if (reply->client_resources != 0) {
                unsigned limit = 1;

                /*
                 * Does this client have "enough" prefixes already?  Default
                 * to one.  Everybody gets one, and one should be enough for
                 * anybody.
                 */
                oc = lookup_option(&server_universe, reply->opt_state,
                                   SV_LIMIT_PREFS_PER_IA);
                if (oc != NULL) {
                        if (!evaluate_option_cache(&data, reply->packet,
                                                   NULL, NULL,
                                                   reply->packet->options,
                                                   reply->opt_state,
                                                   scope, oc, MDL) ||
                            (data.len != 4)) {
                                log_error("reply_process_prefix: unable to "
                                          "evaluate prefs-per-ia value.");
                                status = ISC_R_FAILURE;
                                goto cleanup;
                        }

                        limit = getULong(data.data);
                        data_string_forget(&data, MDL);
                }

                /*
                 * If we wish to limit the client to a certain number of
                 * prefixes, then omit the prefix from the reply.
                 */
                if (reply->client_resources >= limit)
                        goto cleanup;
        }

        status = reply_process_is_prefixed(reply, scope, group);
        if (status != ISC_R_SUCCESS)
                goto cleanup;

      send_pref:
        status = reply_process_send_prefix(reply, &tmp_pref);

      cleanup:
        if (iapref.data != NULL)
                data_string_forget(&iapref, MDL);
        if (data.data != NULL)
                data_string_forget(&data, MDL);
        if (reply->lease != NULL)
                iasubopt_dereference(&reply->lease, MDL);

        return status;
}

/*
 * Verify the prefix belongs to the client.  If we've got a host
 * record with fixed prefixes, it has to be an assigned prefix
 * (fault out all else).  Otherwise it's a dynamic prefix, so lookup
 * that prefix and make sure it belongs to this DUID:IAID pair.
 */
static isc_boolean_t
prefix_is_owned(struct reply_state *reply, struct iaddrcidrnet *pref) {
        struct iaddrcidrnetlist *l;
        int i;
        struct ipv6_pond *pond;

        /*
         * This faults out prefixes that don't match fixed prefixes.
         */
        if (reply->static_prefixes > 0) {
                for (l = reply->host->fixed_prefix; l != NULL; l = l->next) {
                        if ((pref->bits == l->cidrnet.bits) &&
                            (memcmp(pref->lo_addr.iabuf,
                                    l->cidrnet.lo_addr.iabuf, 16) == 0))
                                return (ISC_TRUE);
                }
                return (ISC_FALSE);
        }

        if ((reply->old_ia == NULL) ||
            (reply->old_ia->num_iasubopt == 0))
                return (ISC_FALSE);

        for (i = 0 ; i < reply->old_ia->num_iasubopt ; i++) {
                struct iasubopt *tmp;

                tmp = reply->old_ia->iasubopt[i];

                if ((pref->bits == (int) tmp->plen) &&
                    (memcmp(pref->lo_addr.iabuf, &tmp->addr, 16) == 0)) {
                        if (lease6_usable(tmp) == ISC_FALSE) {
                                return (ISC_FALSE);
                        }

                        pond = tmp->ipv6_pool->ipv6_pond;
                        if (((pond->prohibit_list != NULL) &&
                             (permitted(reply->packet, pond->prohibit_list))) ||
                            ((pond->permit_list != NULL) &&
                             (!permitted(reply->packet, pond->permit_list))))
                                return (ISC_FALSE);

                        iasubopt_reference(&reply->lease, tmp, MDL);
                        return (ISC_TRUE);
                }
        }

        return (ISC_FALSE);
}

/*
 * This function only returns failure on 'hard' failures.  If it succeeds,
 * it will leave a prefix structure behind.
 */
static isc_result_t
reply_process_try_prefix(struct reply_state *reply,
                         struct iaddrcidrnet *pref) {
        isc_result_t status = ISC_R_ADDRNOTAVAIL;
        struct ipv6_pool *pool = NULL;
        struct ipv6_pond *pond = NULL;
        int i;
        struct data_string data_pref;

        if ((reply == NULL) || (reply->shared == NULL) ||
            (pref == NULL) || (reply->lease != NULL))
                return (DHCP_R_INVALIDARG);

        /*
         * Do a quick walk through of the ponds and pools
         * to see if we have any prefix pools
         */
        for (pond = reply->shared->ipv6_pond; pond != NULL; pond = pond->next) {
                if (pond->ipv6_pools == NULL)
                        continue;

                for (i = 0; (pool = pond->ipv6_pools[i]) != NULL; i++) {
                        if (pool->pool_type == D6O_IA_PD)
                                break;
                }
                if (pool != NULL)
                        break;
        }

        /* If we get here and p is NULL we have no useful pools */
        if (pool == NULL) {
                return (ISC_R_ADDRNOTAVAIL);
        }

        memset(&data_pref, 0, sizeof(data_pref));
        data_pref.len = 17;
        if (!buffer_allocate(&data_pref.buffer, data_pref.len, MDL)) {
                log_error("reply_process_try_prefix: out of memory.");
                return (ISC_R_NOMEMORY);
        }
        data_pref.data = data_pref.buffer->data;
        data_pref.buffer->data[0] = (u_int8_t) pref->bits;
        memcpy(data_pref.buffer->data + 1, pref->lo_addr.iabuf, 16);

        /*
         * We have at least one pool that could provide a prefix
         * Now we walk through the ponds and pools again and check
         * to see if the client is permitted and if an prefix is
         * available
         *
         */

        for (pond = reply->shared->ipv6_pond; pond != NULL; pond = pond->next) {
                if (((pond->prohibit_list != NULL) &&
                     (permitted(reply->packet, pond->prohibit_list))) ||
                    ((pond->permit_list != NULL) &&
                     (!permitted(reply->packet, pond->permit_list))))
                        continue;

                for (i = 0; (pool = pond->ipv6_pools[i]) != NULL; i++) {
                        if (pool->pool_type != D6O_IA_PD) {
                                continue;
                        }

                        status = try_client_v6_prefix(&reply->lease, pool,
                                                      &data_pref);
                        /* If we found it in this pool (either in use or available),
                           there is no need to look further. */
                        if ( (status == ISC_R_SUCCESS) || (status == ISC_R_ADDRINUSE) )
                                break;
                        }
                if ( (status == ISC_R_SUCCESS) || (status == ISC_R_ADDRINUSE) )
                        break;
        }

        data_string_forget(&data_pref, MDL);
        /* Return just the most recent status... */
        return (status);
}

/* Look around for a prefix to give the client.  First, look through the old
 * IA_PD for prefixes we can extend.  Second, try to allocate a new prefix.
 * Finally, actually add that prefix into the current reply IA_PD.
 */
static isc_result_t
find_client_prefix(struct reply_state *reply) {
        struct iaddrcidrnet send_pref;
        isc_result_t status = ISC_R_NORESOURCES;
        struct iasubopt *prefix, *best_prefix = NULL;
        struct binding_scope **scope;
        int i;
        struct group *group;

        if (reply->static_prefixes > 0) {
                struct iaddrcidrnetlist *l;

                if (reply->host == NULL)
                        return DHCP_R_INVALIDARG;

                for (l = reply->host->fixed_prefix; l != NULL; l = l->next) {
                        if (l->cidrnet.bits == reply->preflen)
                                break;
                }
                if (l == NULL) {
                        /*
                         * If no fixed prefix has the preferred length,
                         * get the first one.
                         */
                        l = reply->host->fixed_prefix;
                }
                memcpy(&send_pref, &l->cidrnet, sizeof(send_pref));

                scope = &global_scope;

                /* Copy the prefix for logging purposes */
                memcpy(&reply->fixed_pref, &l->cidrnet, sizeof(send_pref));

                /* Try to find a group for the static prefix */
                group = find_group_by_prefix(reply);

                goto send_pref;
        }

        if (reply->old_ia != NULL)  {
                for (i = 0 ; i < reply->old_ia->num_iasubopt ; i++) {
                        struct shared_network *candidate_shared;
                        struct ipv6_pond *pond;

                        prefix = reply->old_ia->iasubopt[i];
                        candidate_shared = prefix->ipv6_pool->shared_network;
                        pond = prefix->ipv6_pool->ipv6_pond;

                        /*
                         * Consider this prefix if it is in a global pool or
                         * if it is scoped in a pool under the client's shared
                         * network.
                         */
                        if (((candidate_shared != NULL) &&
                             (candidate_shared != reply->shared)) ||
                            (lease6_usable(prefix) != ISC_TRUE))
                                continue;

                        /*
                         * And check if the prefix is still permitted
                         */

                        if (((pond->prohibit_list != NULL) &&
                             (permitted(reply->packet, pond->prohibit_list))) ||
                            ((pond->permit_list != NULL) &&
                             (!permitted(reply->packet, pond->permit_list))))
                                continue;

                        best_prefix = prefix_compare(reply, prefix,
                                                     best_prefix);
                }

                /*
                 * If we have prefix length hint and we're not igoring them,
                 * then toss the best match if it doesn't match the hint,
                 * unless this is in response to a rebind.  In the latter
                 * case we're supposed to return it with zero lifetimes.
                 * (See rt45780) */
                if (best_prefix && (reply->preflen > 0)
                    && (prefix_length_mode != PLM_IGNORE)
                    && (reply->preflen != best_prefix->plen)
                    && (reply->packet->dhcpv6_msg_type != DHCPV6_REBIND)) {
                        best_prefix = NULL;
                }
        }

        /* Try to pick a new prefix if we didn't find one, or if we found an
         * abandoned prefix.
         */
        if ((best_prefix == NULL) || (best_prefix->state == FTS_ABANDONED)) {
                status = pick_v6_prefix(reply);
        } else if (best_prefix != NULL) {
                iasubopt_reference(&reply->lease, best_prefix, MDL);
                status = ISC_R_SUCCESS;
        }

        /* Pick the abandoned prefix as a last resort. */
        if ((status == ISC_R_NORESOURCES) && (best_prefix != NULL)) {
                /* I don't see how this is supposed to be done right now. */
                log_error("Reclaiming abandoned prefixes is not yet "
                          "supported.  Treating this as an out of space "
                          "condition.");
                /* iasubopt_reference(&reply->lease, best_prefix, MDL); */
        }

        /* Give up now if we didn't find a prefix. */
        if (status != ISC_R_SUCCESS)
                return status;

        if (reply->lease == NULL)
                log_fatal("Impossible condition at %s:%d.", MDL);

        scope = &reply->lease->scope;
        group = reply->lease->ipv6_pool->ipv6_pond->group;

        send_pref.lo_addr.len = 16;
        memcpy(send_pref.lo_addr.iabuf, &reply->lease->addr, 16);
        send_pref.bits = (int) reply->lease->plen;

      send_pref:
        status = reply_process_is_prefixed(reply, scope, group);
        if (status != ISC_R_SUCCESS)
                return status;

        status = reply_process_send_prefix(reply, &send_pref);
        return status;
}

/* Once a prefix is found for a client, perform several common functions;
 * Calculate and store valid and preferred prefix times, draw client options
 * into the option state.
 */
static isc_result_t
reply_process_is_prefixed(struct reply_state *reply,
                          struct binding_scope **scope, struct group *group)
{
        isc_result_t status = ISC_R_SUCCESS;
        struct data_string data;
        struct option_cache *oc;
        struct option_state *tmp_options = NULL;
        struct on_star *on_star;
        int i;

        /* Initialize values we will cleanup. */
        memset(&data, 0, sizeof(data));

        /*
         * Find the proper on_star block to use.  We use the
         * one in the lease if we have a lease or the one in
         * the reply if we don't have a lease because this is
         * a static instance
         */
        if (reply->lease) {
                on_star = &reply->lease->on_star;
        } else {
                on_star = &reply->on_star;
        }

        /*
         * Bring in the root configuration.  We only do this to bring
         * in the on * statements, as we didn't have the lease available
         * we we did it the first time.
         */
        option_state_allocate(&tmp_options, MDL);
        execute_statements_in_scope(NULL, reply->packet, NULL, NULL,
                                    reply->packet->options, tmp_options,
                                    &global_scope, root_group, NULL,
                                    on_star);
        if (tmp_options != NULL) {
                option_state_dereference(&tmp_options, MDL);
        }

        /*
         * Bring configured options into the root packet level cache - start
         * with the lease's closest enclosing group (passed in by the caller
         * as 'group').
         */
        execute_statements_in_scope(NULL, reply->packet, NULL, NULL,
                                    reply->packet->options, reply->opt_state,
                                    scope, group, root_group, on_star);

        /* Execute statements from class scopes. */
        for (i = reply->packet->class_count; i > 0; i--) {
                execute_statements_in_scope(NULL, reply->packet, NULL, NULL,
                                            reply->packet->options,
                                            reply->opt_state, scope,
                                            reply->packet->classes[i - 1]->group,
                                            group, on_star);
        }

        /*
         * If there is a host record, over-ride with values configured there,
         * without re-evaluating configuration from the previously executed
         * group or its common enclosers.
         */
        if (reply->host != NULL)
                execute_statements_in_scope(NULL, reply->packet, NULL, NULL,
                                            reply->packet->options,
                                            reply->opt_state, scope,
                                            reply->host->group, group,
                                            on_star);

        /* Determine valid lifetime. */
        if (reply->client_valid == 0)
                reply->send_valid = DEFAULT_DEFAULT_LEASE_TIME;
        else
                reply->send_valid = reply->client_valid;

        oc = lookup_option(&server_universe, reply->opt_state,
                           SV_DEFAULT_LEASE_TIME);
        if (oc != NULL) {
                if (!evaluate_option_cache(&data, reply->packet, NULL, NULL,
                                           reply->packet->options,
                                           reply->opt_state,
                                           scope, oc, MDL) ||
                    (data.len != 4)) {
                        log_error("reply_process_is_prefixed: unable to "
                                  "evaluate default prefix time");
                        status = ISC_R_FAILURE;
                        goto cleanup;
                }

                reply->send_valid = getULong(data.data);
                data_string_forget(&data, MDL);
        }

        /* Check to see if the lease time would cause us to wrap
         * in which case we make it infinite.
         * The following doesn't work on at least some systems:
         * (cur_time + reply->send_valid < cur_time)
         */
        if (reply->send_valid != INFINITE_TIME) {
                time_t test_time = cur_time + reply->send_valid;
                if (test_time < cur_time)
                        reply->send_valid = INFINITE_TIME;
        }

        if (reply->client_prefer == 0)
                reply->send_prefer = reply->send_valid;
        else
                reply->send_prefer = reply->client_prefer;

        if ((reply->send_prefer >= reply->send_valid) &&
            (reply->send_valid != INFINITE_TIME))
                reply->send_prefer = (reply->send_valid / 2) +
                                     (reply->send_valid / 8);

        oc = lookup_option(&server_universe, reply->opt_state,
                           SV_PREFER_LIFETIME);
        if (oc != NULL) {
                if (!evaluate_option_cache(&data, reply->packet, NULL, NULL,
                                           reply->packet->options,
                                           reply->opt_state,
                                           scope, oc, MDL) ||
                    (data.len != 4)) {
                        log_error("reply_process_is_prefixed: unable to "
                                  "evaluate preferred prefix time");
                        status = ISC_R_FAILURE;
                        goto cleanup;
                }

                reply->send_prefer = getULong(data.data);
                data_string_forget(&data, MDL);
        }

        /* Note lowest values for later calculation of renew/rebind times. */
        if (reply->min_prefer > reply->send_prefer)
                reply->min_prefer = reply->send_prefer;

        if (reply->min_valid > reply->send_valid)
                reply->min_valid = reply->send_valid;

        /* Perform dynamic prefix related update work. */
        if (reply->lease != NULL) {
                /* Cached lifetimes */
                reply->lease->prefer = reply->send_prefer;
                reply->lease->valid = reply->send_valid;

                /* Advance (or rewind) the valid lifetime.
                 * In the protocol 0xFFFFFFFF is infinite
                 * when connecting to the lease file MAX_TIME is
                 */
                if (reply->buf.reply.msg_type == DHCPV6_REPLY) {
                        if (reply->send_valid == INFINITE_TIME) {
                                reply->lease->soft_lifetime_end_time = MAX_TIME;
                        } else {
                                reply->lease->soft_lifetime_end_time =
                                  cur_time + reply->send_valid;
                        }
                        /* Wait before renew! */
                }

                status = ia_add_iasubopt(reply->ia, reply->lease, MDL);
                if (status != ISC_R_SUCCESS) {
                        log_fatal("reply_process_is_prefixed: Unable to "
                                  "attach prefix to new IA_PD: %s",
                                  isc_result_totext(status));
                }

                /*
                 * If this is a new prefix, make sure it is attached somewhere.
                 */
                if (reply->lease->ia == NULL) {
                        ia_reference(&reply->lease->ia, reply->ia, MDL);
                }
        }

        /* Bring a copy of the relevant options into the IA_PD scope. */
        execute_statements_in_scope(NULL, reply->packet, NULL, NULL,
                                    reply->packet->options, reply->reply_ia,
                                    scope, group, root_group, NULL);

        /* Execute statements from class scopes. */
        for (i = reply->packet->class_count; i > 0; i--) {
                execute_statements_in_scope(NULL, reply->packet, NULL, NULL,
                                            reply->packet->options,
                                            reply->reply_ia, scope,
                                            reply->packet->classes[i - 1]->group,
                                            group, NULL);
        }

        /*
         * And bring in host record configuration, if any, but not to overlap
         * the previous group or its common enclosers.
         */
        if (reply->host != NULL)
                execute_statements_in_scope(NULL, reply->packet, NULL, NULL,
                                            reply->packet->options,
                                            reply->reply_ia, scope,
                                            reply->host->group, group, NULL);

      cleanup:
        if (data.data != NULL)
                data_string_forget(&data, MDL);

        if (status == ISC_R_SUCCESS)
                reply->client_resources++;

        return status;
}

/* Simply send an IAPREFIX within the IA_PD scope as described. */
static isc_result_t
reply_process_send_prefix(struct reply_state *reply,
                          struct iaddrcidrnet *pref) {
        isc_result_t status = ISC_R_SUCCESS;
        struct data_string data;

        memset(&data, 0, sizeof(data));

        /* Now append the prefix. */
        data.len = IAPREFIX_OFFSET;
        if (!buffer_allocate(&data.buffer, data.len, MDL)) {
                log_error("reply_process_send_prefix: out of memory"
                          "allocating new IAPREFIX buffer.");
                status = ISC_R_NOMEMORY;
                goto cleanup;
        }
        data.data = data.buffer->data;

        putULong(data.buffer->data, reply->send_prefer);
        putULong(data.buffer->data + 4, reply->send_valid);
        data.buffer->data[8] = pref->bits;
        memcpy(data.buffer->data + 9, pref->lo_addr.iabuf, 16);

        if (!append_option_buffer(&dhcpv6_universe, reply->reply_ia,
                                  data.buffer, data.buffer->data,
                                  data.len, D6O_IAPREFIX, 0)) {
                log_error("reply_process_send_prefix: unable "
                          "to save IAPREFIX option");
                status = ISC_R_FAILURE;
                goto cleanup;
        }

        reply->resources_included = ISC_TRUE;

      cleanup:
        if (data.data != NULL)
                data_string_forget(&data, MDL);

        return status;
}

/* Choose the better of two prefixes. */
static struct iasubopt *
prefix_compare(struct reply_state *reply,
               struct iasubopt *alpha, struct iasubopt *beta) {
        if (alpha == NULL)
                return beta;
        if (beta == NULL)
                return alpha;

        if (reply->preflen >= 0) {
                if ((alpha->plen == reply->preflen) &&
                    (beta->plen != reply->preflen))
                        return alpha;
                if ((beta->plen == reply->preflen) &&
                    (alpha->plen != reply->preflen))
                        return beta;
        }

        switch(alpha->state) {
              case FTS_ACTIVE:
                switch(beta->state) {
                      case FTS_ACTIVE:
                        /* Choose the prefix with the longest lifetime (most
                         * likely the most recently allocated).
                         */
                        if (alpha->hard_lifetime_end_time <
                            beta->hard_lifetime_end_time)
                                return beta;
                        else
                                return alpha;

                      case FTS_EXPIRED:
                      case FTS_ABANDONED:
                        return alpha;

                      default:
                        log_fatal("Impossible condition at %s:%d.", MDL);
                }
                break;

              case FTS_EXPIRED:
                switch (beta->state) {
                      case FTS_ACTIVE:
                        return beta;

                      case FTS_EXPIRED:
                        /* Choose the most recently expired prefix. */
                        if (alpha->hard_lifetime_end_time <
                            beta->hard_lifetime_end_time)
                                return beta;
                        else if ((alpha->hard_lifetime_end_time ==
                                  beta->hard_lifetime_end_time) &&
                                 (alpha->soft_lifetime_end_time <
                                  beta->soft_lifetime_end_time))
                                return beta;
                        else
                                return alpha;

                      case FTS_ABANDONED:
                        return alpha;

                      default:
                        log_fatal("Impossible condition at %s:%d.", MDL);
                }
                break;

              case FTS_ABANDONED:
                switch (beta->state) {
                      case FTS_ACTIVE:
                      case FTS_EXPIRED:
                        return alpha;

                      case FTS_ABANDONED:
                        /* Choose the prefix that was abandoned longest ago. */
                        if (alpha->hard_lifetime_end_time <
                            beta->hard_lifetime_end_time)
                                return alpha;
                        else
                                return beta;

                      default:
                        log_fatal("Impossible condition at %s:%d.", MDL);
                }
                break;

              default:
                log_fatal("Impossible condition at %s:%d.", MDL);
        }

        log_fatal("Triple impossible condition at %s:%d.", MDL);
        return NULL;
}

/*
 * Solicit is how a client starts requesting addresses.
 *
 * If the client asks for rapid commit, and we support it, we will
 * allocate the addresses and reply.
 *
 * Otherwise we will send an advertise message.
 */

static void
dhcpv6_solicit(struct data_string *reply_ret, struct packet *packet) {
        struct data_string client_id;

        /*
         * Validate our input.
         */
        if (!valid_client_msg(packet, &client_id)) {
                return;
        }

        lease_to_client(reply_ret, packet, &client_id, NULL);

        /*
         * Clean up.
         */
        data_string_forget(&client_id, MDL);
}

/*
 * Request is how a client actually requests addresses.
 *
 * Very similar to Solicit handling, except the server DUID is required.
 */

static void
dhcpv6_request(struct data_string *reply_ret, struct packet *packet) {
        struct data_string client_id;
        struct data_string server_id;

        /*
         * Validate our input.
         */
        if (!valid_client_resp(packet, &client_id, &server_id)) {
                return;
        }

        /* If the REQUEST arrived via unicast and unicast option isn't set,
         * reject it per RFC 3315, Sec 18.2.1 */
        if (packet->unicast == ISC_TRUE &&
            is_unicast_option_defined(packet) == ISC_FALSE) {
                unicast_reject(reply_ret, packet, &client_id, &server_id);
        } else {
                /*
                 * Issue our lease.
                 */
                lease_to_client(reply_ret, packet, &client_id, &server_id);
        }

        /*
         * Cleanup.
         */
        data_string_forget(&client_id, MDL);
        data_string_forget(&server_id, MDL);
}

/* Find a DHCPv6 packet's shared network from hints in the packet.
 */
static isc_result_t
shared_network_from_packet6(struct shared_network **shared,
                            struct packet *packet)
{
        const struct packet *chk_packet;
        const struct in6_addr *link_addr, *first_link_addr;
        struct iaddr tmp_addr;
        struct subnet *subnet;
        isc_result_t status;

        if ((shared == NULL) || (*shared != NULL) || (packet == NULL))
                return DHCP_R_INVALIDARG;

        /*
         * First, find the link address where the packet from the client
         * first appeared (if this packet was relayed).
         */
        first_link_addr = NULL;
        chk_packet = packet->dhcpv6_container_packet;
        while (chk_packet != NULL) {
                link_addr = &chk_packet->dhcpv6_link_address;
                if (!IN6_IS_ADDR_UNSPECIFIED(link_addr) &&
                    !IN6_IS_ADDR_LINKLOCAL(link_addr)) {
                        first_link_addr = link_addr;
                        break;
                }
                chk_packet = chk_packet->dhcpv6_container_packet;
        }

        /*
         * If there is a relayed link address, find the subnet associated
         * with that, and use that to get the appropriate
         * shared_network.
         */
        if (first_link_addr != NULL) {
                tmp_addr.len = sizeof(*first_link_addr);
                memcpy(tmp_addr.iabuf,
                       first_link_addr, sizeof(*first_link_addr));
                subnet = NULL;
                if (!find_subnet(&subnet, tmp_addr, MDL)) {
                        log_debug("No subnet found for link-address %s.",
                                  piaddr(tmp_addr));
                        return ISC_R_NOTFOUND;
                }
                status = shared_network_reference(shared,
                                                  subnet->shared_network, MDL);
                subnet_dereference(&subnet, MDL);

        /*
         * If there is no link address, we will use the interface
         * that this packet came in on to pick the shared_network.
         */
        } else if (packet->interface != NULL) {
                status = shared_network_reference(shared,
                                         packet->interface->shared_network,
                                         MDL);
                if (packet->dhcpv6_container_packet != NULL) {
                        log_info("[L2 Relay] No link address in relay packet "
                                 "assuming L2 relay and using receiving "
                                 "interface");
                }

        } else {
                /*
                 * We shouldn't be able to get here but if there is no link
                 * address and no interface we don't know where to get the
                 * pool from log an error and return an error.
                 */
                log_error("No interface and no link address "
                          "can't determine pool");
                status = DHCP_R_INVALIDARG;
        }

        return status;
}

/*
 * When a client thinks it might be on a new link, it sends a
 * Confirm message.
 *
 * From RFC3315 section 18.2.2:
 *
 *   When the server receives a Confirm message, the server determines
 *   whether the addresses in the Confirm message are appropriate for the
 *   link to which the client is attached.  If all of the addresses in the
 *   Confirm message pass this test, the server returns a status of
 *   Success.  If any of the addresses do not pass this test, the server
 *   returns a status of NotOnLink.  If the server is unable to perform
 *   this test (for example, the server does not have information about
 *   prefixes on the link to which the client is connected), or there were
 *   no addresses in any of the IAs sent by the client, the server MUST
 *   NOT send a reply to the client.
 */

static void
dhcpv6_confirm(struct data_string *reply_ret, struct packet *packet) {
        struct shared_network *shared;
        struct subnet *subnet;
        struct option_cache *ia, *ta, *oc;
        struct data_string cli_enc_opt_data, iaaddr, client_id, packet_oro;
        struct option_state *cli_enc_opt_state, *opt_state;
        struct iaddr cli_addr;
        int pass;
        isc_boolean_t inappropriate, has_addrs;
        char reply_data[65536];
        struct dhcpv6_packet *reply = (struct dhcpv6_packet *)reply_data;
        int reply_ofs = (int)(offsetof(struct dhcpv6_packet, options));

        /*
         * Basic client message validation.
         */
        memset(&client_id, 0, sizeof(client_id));
        if (!valid_client_msg(packet, &client_id)) {
                return;
        }

        /*
         * Do not process Confirms that do not have IA's we do not recognize.
         */
        ia = lookup_option(&dhcpv6_universe, packet->options, D6O_IA_NA);
        ta = lookup_option(&dhcpv6_universe, packet->options, D6O_IA_TA);
        if ((ia == NULL) && (ta == NULL))
                return;

        /*
         * IA_PD's are simply ignored.
         */
        delete_option(&dhcpv6_universe, packet->options, D6O_IA_PD);

        /*
         * Bit of variable initialization.
         */
        opt_state = cli_enc_opt_state = NULL;
        memset(&cli_enc_opt_data, 0, sizeof(cli_enc_opt_data));
        memset(&iaaddr, 0, sizeof(iaaddr));
        memset(&packet_oro, 0, sizeof(packet_oro));

        /* Determine what shared network the client is connected to.  We
         * must not respond if we don't have any information about the
         * network the client is on.
         */
        shared = NULL;
        if ((shared_network_from_packet6(&shared, packet) != ISC_R_SUCCESS) ||
            (shared == NULL))
                goto exit;

        /* If there are no recorded subnets, then we have no
         * information about this subnet - ignore Confirms.
         */
        subnet = shared->subnets;
        if (subnet == NULL)
                goto exit;

        /* Are the addresses in all the IA's appropriate for that link? */
        has_addrs = inappropriate = ISC_FALSE;
        pass = D6O_IA_NA;
        while(!inappropriate) {
                /* If we've reached the end of the IA_NA pass, move to the
                 * IA_TA pass.
                 */
                if ((pass == D6O_IA_NA) && (ia == NULL)) {
                        pass = D6O_IA_TA;
                        ia = ta;
                }

                /* If we've reached the end of all passes, we're done. */
                if (ia == NULL)
                        break;

                if (((pass == D6O_IA_NA) &&
                     !get_encapsulated_IA_state(&cli_enc_opt_state,
                                                &cli_enc_opt_data,
                                                packet, ia, IA_NA_OFFSET)) ||
                    ((pass == D6O_IA_TA) &&
                     !get_encapsulated_IA_state(&cli_enc_opt_state,
                                                &cli_enc_opt_data,
                                                packet, ia, IA_TA_OFFSET))) {
                        goto exit;
                }

                oc = lookup_option(&dhcpv6_universe, cli_enc_opt_state,
                                   D6O_IAADDR);

                for ( ; oc != NULL ; oc = oc->next) {
                        if (!evaluate_option_cache(&iaaddr, packet, NULL, NULL,
                                                   packet->options, NULL,
                                                   &global_scope, oc, MDL) ||
                            (iaaddr.len < IAADDR_OFFSET)) {
                                log_error("dhcpv6_confirm: "
                                          "error evaluating IAADDR.");
                                goto exit;
                        }

                        /* Copy out the IPv6 address for processing. */
                        cli_addr.len = 16;
                        memcpy(cli_addr.iabuf, iaaddr.data, 16);

                        data_string_forget(&iaaddr, MDL);

                        /* Record that we've processed at least one address. */
                        has_addrs = ISC_TRUE;

                        /* Find out if any subnets cover this address. */
                        for (subnet = shared->subnets ; subnet != NULL ;
                             subnet = subnet->next_sibling) {
                                if (addr_eq(subnet_number(cli_addr,
                                                          subnet->netmask),
                                            subnet->net))
                                        break;
                        }

                        /* If we reach the end of the subnet list, and no
                         * subnet matches the client address, then it must
                         * be inappropriate to the link (so far as our
                         * configuration says).  Once we've found one
                         * inappropriate address, there is no reason to
                         * continue searching.
                         */
                        if (subnet == NULL) {
                                inappropriate = ISC_TRUE;
                                break;
                        }
                }

                option_state_dereference(&cli_enc_opt_state, MDL);
                data_string_forget(&cli_enc_opt_data, MDL);

                /* Advance to the next IA_*. */
                ia = ia->next;
        }

        /* If the client supplied no addresses, do not reply. */
        if (!has_addrs)
                goto exit;

        /*
         * Set up reply.
         */
        if (!start_reply(packet, &client_id, NULL, &opt_state, reply)) {
                goto exit;
        }

        /*
         * Set our status.
         */
        if (inappropriate) {
                if (!set_status_code(STATUS_NotOnLink,
                                     "Some of the addresses are not on link.",
                                     opt_state)) {
                        goto exit;
                }
        } else {
                if (!set_status_code(STATUS_Success,
                                     "All addresses still on link.",
                                     opt_state)) {
                        goto exit;
                }
        }

        /*
         * Only one option: add it.
         */
        reply_ofs += store_options6(reply_data+reply_ofs,
                                    sizeof(reply_data)-reply_ofs,
                                    opt_state, packet,
                                    required_opts, &packet_oro);

        /*
         * Return our reply to the caller.
         */
        reply_ret->len = reply_ofs;
        reply_ret->buffer = NULL;
        if (!buffer_allocate(&reply_ret->buffer, reply_ofs, MDL)) {
                log_fatal("No memory to store reply.");
        }
        reply_ret->data = reply_ret->buffer->data;
        memcpy(reply_ret->buffer->data, reply, reply_ofs);

exit:
        /* Cleanup any stale data strings. */
        if (cli_enc_opt_data.buffer != NULL)
                data_string_forget(&cli_enc_opt_data, MDL);
        if (iaaddr.buffer != NULL)
                data_string_forget(&iaaddr, MDL);
        if (client_id.buffer != NULL)
                data_string_forget(&client_id, MDL);
        if (packet_oro.buffer != NULL)
                data_string_forget(&packet_oro, MDL);

        /* Release any stale option states. */
        if (cli_enc_opt_state != NULL)
                option_state_dereference(&cli_enc_opt_state, MDL);
        if (opt_state != NULL)
                option_state_dereference(&opt_state, MDL);
}

/*
 * Renew is when a client wants to extend its lease/prefix, at time T1.
 *
 * We handle this the same as if the client wants a new lease/prefix,
 * except for the error code of when addresses don't match.
 */

static void
dhcpv6_renew(struct data_string *reply, struct packet *packet) {
        struct data_string client_id;
        struct data_string server_id;

        /*
         * Validate the request.
         */
        if (!valid_client_resp(packet, &client_id, &server_id)) {
                return;
        }

        /* If the RENEW arrived via unicast and unicast option isn't set,
         * reject it per RFC 3315, Sec 18.2.3 */
        if (packet->unicast == ISC_TRUE &&
            is_unicast_option_defined(packet) == ISC_FALSE) {
                unicast_reject(reply, packet, &client_id, &server_id);
        } else {
                /*
                 * Renew our lease.
                 */
                lease_to_client(reply, packet, &client_id, &server_id);
        }

        /*
         * Cleanup.
         */
        data_string_forget(&server_id, MDL);
        data_string_forget(&client_id, MDL);
}

/*
 * Rebind is when a client wants to extend its lease, at time T2.
 *
 * We handle this the same as if the client wants a new lease, except
 * for the error code of when addresses don't match.
 */

static void
dhcpv6_rebind(struct data_string *reply, struct packet *packet) {
        struct data_string client_id;

        if (!valid_client_msg(packet, &client_id)) {
                return;
        }

        lease_to_client(reply, packet, &client_id, NULL);

        data_string_forget(&client_id, MDL);
}

static void
ia_na_match_decline(const struct data_string *client_id,
                    const struct data_string *iaaddr,
                    struct iasubopt *lease)
{
        char tmp_addr[INET6_ADDRSTRLEN];

        log_error("Client %s reports address %s is "
                  "already in use by another host!",
                  print_hex_1(client_id->len, client_id->data, 60),
                  inet_ntop(AF_INET6, iaaddr->data,
                            tmp_addr, sizeof(tmp_addr)));
        if (lease != NULL) {
                decline_lease6(lease->ipv6_pool, lease);
                lease->ia->cltt = cur_time;
                write_ia(lease->ia);
        }
}

static void
ia_na_nomatch_decline(const struct data_string *client_id,
                      const struct data_string *iaaddr,
                      u_int32_t *ia_na_id,
                      struct packet *packet,
                      char *reply_data,
                      int *reply_ofs,
                      int reply_len)
{
        char tmp_addr[INET6_ADDRSTRLEN];
        struct option_state *host_opt_state;
        int len;

        log_info("Client %s declines address %s, which is not offered to it.",
                 print_hex_1(client_id->len, client_id->data, 60),
                 inet_ntop(AF_INET6, iaaddr->data, tmp_addr, sizeof(tmp_addr)));

        /*
         * Create state for this IA_NA.
         */
        host_opt_state = NULL;
        if (!option_state_allocate(&host_opt_state, MDL)) {
                log_error("ia_na_nomatch_decline: out of memory "
                          "allocating option_state.");
                goto exit;
        }

        if (!set_status_code(STATUS_NoBinding, "Decline for unknown address.",
                             host_opt_state)) {
                goto exit;
        }

        /*
         * Insure we have enough space
         */
        if (reply_len < (*reply_ofs + 16)) {
                log_error("ia_na_nomatch_decline: "
                          "out of space for reply packet.");
                goto exit;
        }

        /*
         * Put our status code into the reply packet.
         */
        len = store_options6(reply_data+(*reply_ofs)+16,
                             reply_len-(*reply_ofs)-16,
                             host_opt_state, packet,
                             required_opts_STATUS_CODE, NULL);

        /*
         * Store the non-encapsulated option data for this
         * IA_NA into our reply packet. Defined in RFC 3315,
         * section 22.4.
         */
        /* option number */
        putUShort((unsigned char *)reply_data+(*reply_ofs), D6O_IA_NA);
        /* option length */
        putUShort((unsigned char *)reply_data+(*reply_ofs)+2, len + 12);
        /* IA_NA, copied from the client */
        memcpy(reply_data+(*reply_ofs)+4, ia_na_id, 4);
        /* t1 and t2, odd that we need them, but here it is */
        putULong((unsigned char *)reply_data+(*reply_ofs)+8, 0);
        putULong((unsigned char *)reply_data+(*reply_ofs)+12, 0);

        /*
         * Get ready for next IA_NA.
         */
        *reply_ofs += (len + 16);

exit:
        option_state_dereference(&host_opt_state, MDL);
}

static void
iterate_over_ia_na(struct data_string *reply_ret,
                   struct packet *packet,
                   const struct data_string *client_id,
                   const struct data_string *server_id,
                   const char *packet_type,
                   void (*ia_na_match)(),
                   void (*ia_na_nomatch)())
{
        struct option_state *opt_state;
        struct host_decl *packet_host;
        struct option_cache *ia;
        struct option_cache *oc;
        /* cli_enc_... variables come from the IA_NA/IA_TA options */
        struct data_string cli_enc_opt_data;
        struct option_state *cli_enc_opt_state;
        struct host_decl *host;
        struct data_string iaaddr;
        struct data_string fixed_addr;
        char reply_data[65536];
        struct dhcpv6_packet *reply = (struct dhcpv6_packet *)reply_data;
        int reply_ofs = (int)(offsetof(struct dhcpv6_packet, options));
        char status_msg[32];
        struct iasubopt *lease;
        struct ia_xx *existing_ia_na;
        int i;
        struct data_string key;
        u_int32_t iaid;

        /*
         * Initialize to empty values, in case we have to exit early.
         */
        opt_state = NULL;
        memset(&cli_enc_opt_data, 0, sizeof(cli_enc_opt_data));
        cli_enc_opt_state = NULL;
        memset(&iaaddr, 0, sizeof(iaaddr));
        memset(&fixed_addr, 0, sizeof(fixed_addr));
        lease = NULL;

        /*
         * Find the host record that matches from the packet, if any.
         */
        packet_host = NULL;
        find_hosts6(&packet_host, packet, client_id, MDL);

        /*
         * Set our reply information.
         */
        reply->msg_type = DHCPV6_REPLY;
        memcpy(reply->transaction_id, packet->dhcpv6_transaction_id,
               sizeof(reply->transaction_id));

        /*
         * Build our option state for reply.
         */
        opt_state = NULL;
        if (!option_state_allocate(&opt_state, MDL)) {
                log_error("iterate_over_ia_na: no memory for option_state.");
                goto exit;
        }
        execute_statements_in_scope(NULL, packet, NULL, NULL,
                                    packet->options, opt_state,
                                    &global_scope, root_group, NULL, NULL);

        /*
         * RFC 3315, section 18.2.7 tells us which options to include.
         */
        oc = lookup_option(&dhcpv6_universe, opt_state, D6O_SERVERID);
        if (oc == NULL) {
                if (!save_option_buffer(&dhcpv6_universe, opt_state, NULL,
                                        (unsigned char *)server_duid.data,
                                        server_duid.len, D6O_SERVERID, 0)) {
                        log_error("iterate_over_ia_na: "
                                  "error saving server identifier.");
                        goto exit;
                }
        }

        if (!save_option_buffer(&dhcpv6_universe, opt_state,
                                client_id->buffer,
                                (unsigned char *)client_id->data,
                                client_id->len,
                                D6O_CLIENTID, 0)) {
                log_error("iterate_over_ia_na: "
                          "error saving client identifier.");
                goto exit;
        }

        snprintf(status_msg, sizeof(status_msg), "%s received.", packet_type);
        if (!set_status_code(STATUS_Success, status_msg, opt_state)) {
                goto exit;
        }

        /*
         * Add our options that are not associated with any IA_NA or IA_TA.
         */
        reply_ofs += store_options6(reply_data+reply_ofs,
                                    sizeof(reply_data)-reply_ofs,
                                    opt_state, packet,
                                    required_opts, NULL);

        /*
         * Loop through the IA_NA reported by the client, and deal with
         * addresses reported as already in use.
         */
        for (ia = lookup_option(&dhcpv6_universe, packet->options, D6O_IA_NA);
             ia != NULL; ia = ia->next) {

                if (!get_encapsulated_IA_state(&cli_enc_opt_state,
                                               &cli_enc_opt_data,
                                               packet, ia, IA_NA_OFFSET)) {
                        goto exit;
                }

                iaid = getULong(cli_enc_opt_data.data);

                /*
                 * XXX: It is possible that we can get multiple addresses
                 *      sent by the client. We don't send multiple
                 *      addresses, so this indicates a client error.
                 *      We should check for multiple IAADDR options, log
                 *      if found, and set as an error.
                 */
                oc = lookup_option(&dhcpv6_universe, cli_enc_opt_state,
                                   D6O_IAADDR);
                if (oc == NULL) {
                        /* no address given for this IA, ignore */
                        option_state_dereference(&cli_enc_opt_state, MDL);
                        data_string_forget(&cli_enc_opt_data, MDL);
                        continue;
                }

                memset(&iaaddr, 0, sizeof(iaaddr));
                if (!evaluate_option_cache(&iaaddr, packet, NULL, NULL,
                                           packet->options, NULL,
                                           &global_scope, oc, MDL)) {
                        log_error("iterate_over_ia_na: "
                                  "error evaluating IAADDR.");
                        goto exit;
                }

                /*
                 * Now we need to figure out which host record matches
                 * this IA_NA and IAADDR (encapsulated option contents
                 * matching a host record by option).
                 *
                 * XXX: We don't currently track IA_NA separately, but
                 *      we will need to do this!
                 */
                host = NULL;
                if (!find_hosts_by_option(&host, packet,
                                          cli_enc_opt_state, MDL)) {
                        if (packet_host != NULL) {
                                host = packet_host;
                        } else {
                                host = NULL;
                        }
                }
                while (host != NULL) {
                        if (host->fixed_addr != NULL) {
                                if (!evaluate_option_cache(&fixed_addr, NULL,
                                                           NULL, NULL, NULL,
                                                           NULL, &global_scope,
                                                           host->fixed_addr,
                                                           MDL)) {
                                        log_error("iterate_over_ia_na: error "
                                                  "evaluating host address.");
                                        goto exit;
                                }
                                if ((iaaddr.len >= 16) &&
                                    !memcmp(fixed_addr.data, iaaddr.data, 16)) {
                                        data_string_forget(&fixed_addr, MDL);
                                        break;
                                }
                                data_string_forget(&fixed_addr, MDL);
                        }
                        host = host->n_ipaddr;
                }

                if ((host == NULL) && (iaaddr.len >= IAADDR_OFFSET)) {
                        /*
                         * Find existing IA_NA.
                         */
                        if (ia_make_key(&key, iaid,
                                        (char *)client_id->data,
                                        client_id->len,
                                        MDL) != ISC_R_SUCCESS) {
                                log_fatal("iterate_over_ia_na: no memory for "
                                          "key.");
                        }

                        existing_ia_na = NULL;
                        if (ia_hash_lookup(&existing_ia_na, ia_na_active,
                                           (unsigned char *)key.data,
                                           key.len, MDL)) {
                                /*
                                 * Make sure this address is in the IA_NA.
                                 */
                                for (i=0; i<existing_ia_na->num_iasubopt; i++) {
                                        struct iasubopt *tmp;
                                        struct in6_addr *in6_addr;

                                        tmp = existing_ia_na->iasubopt[i];
                                        in6_addr = &tmp->addr;
                                        if (memcmp(in6_addr,
                                                   iaaddr.data, 16) == 0) {
                                                iasubopt_reference(&lease,
                                                                   tmp, MDL);
                                                break;
                                        }
                                }
                        }

                        data_string_forget(&key, MDL);
                }

                if ((host != NULL) || (lease != NULL)) {
                        ia_na_match(client_id, &iaaddr, lease);
                } else {
                        ia_na_nomatch(client_id, &iaaddr,
                                      (u_int32_t *)cli_enc_opt_data.data,
                                      packet, reply_data, &reply_ofs,
                                      sizeof(reply_data));
                }

                if (lease != NULL) {
                        iasubopt_dereference(&lease, MDL);
                }

                data_string_forget(&iaaddr, MDL);
                option_state_dereference(&cli_enc_opt_state, MDL);
                data_string_forget(&cli_enc_opt_data, MDL);
        }

        /*
         * Return our reply to the caller.
         */
        reply_ret->len = reply_ofs;
        reply_ret->buffer = NULL;
        if (!buffer_allocate(&reply_ret->buffer, reply_ofs, MDL)) {
                log_fatal("No memory to store reply.");
        }
        reply_ret->data = reply_ret->buffer->data;
        memcpy(reply_ret->buffer->data, reply, reply_ofs);

exit:
        if (lease != NULL) {
                iasubopt_dereference(&lease, MDL);
        }
        if (fixed_addr.buffer != NULL) {
                data_string_forget(&fixed_addr, MDL);
        }
        if (iaaddr.buffer != NULL) {
                data_string_forget(&iaaddr, MDL);
        }
        if (cli_enc_opt_state != NULL) {
                option_state_dereference(&cli_enc_opt_state, MDL);
        }
        if (cli_enc_opt_data.buffer != NULL) {
                data_string_forget(&cli_enc_opt_data, MDL);
        }
        if (opt_state != NULL) {
                option_state_dereference(&opt_state, MDL);
        }
}

/*
 * Decline means a client has detected that something else is using an
 * address we gave it.
 *
 * Since we're only dealing with fixed leases for now, there's not
 * much we can do, other that log the occurrence.
 *
 * When we start issuing addresses from pools, then we will have to
 * record our declined addresses and issue another. In general with
 * IPv6 there is no worry about DoS by clients exhausting space, but
 * we still need to be aware of this possibility.
 */

/* TODO: IA_TA */
static void
dhcpv6_decline(struct data_string *reply, struct packet *packet) {
        struct data_string client_id;
        struct data_string server_id;

        /*
         * Validate our input.
         */
        if (!valid_client_resp(packet, &client_id, &server_id)) {
                return;
        }

        /* If the DECLINE arrived via unicast and unicast option isn't set,
         * reject it per RFC 3315, Sec 18.2.7 */
        if (packet->unicast == ISC_TRUE &&
            is_unicast_option_defined(packet) == ISC_FALSE) {
                unicast_reject(reply, packet, &client_id, &server_id);
        } else {
                /*
                 * Undefined for IA_PD.
                 */
                delete_option(&dhcpv6_universe, packet->options, D6O_IA_PD);

                /*
                 * And operate on each IA_NA in this packet.
                 */
                iterate_over_ia_na(reply, packet, &client_id, &server_id,
                                   "Decline", ia_na_match_decline,
                                   ia_na_nomatch_decline);

        }

        data_string_forget(&server_id, MDL);
        data_string_forget(&client_id, MDL);
}

static void
ia_na_match_release(const struct data_string *client_id,
                    const struct data_string *iaaddr,
                    struct iasubopt *lease)
{
        char tmp_addr[INET6_ADDRSTRLEN];

        log_info("Client %s releases address %s",
                 print_hex_1(client_id->len, client_id->data, 60),
                 inet_ntop(AF_INET6, iaaddr->data, tmp_addr, sizeof(tmp_addr)));
        if (lease != NULL) {
                release_lease6(lease->ipv6_pool, lease);
                lease->ia->cltt = cur_time;
                write_ia(lease->ia);
        }
}

static void
ia_na_nomatch_release(const struct data_string *client_id,
                      const struct data_string *iaaddr,
                      u_int32_t *ia_na_id,
                      struct packet *packet,
                      char *reply_data,
                      int *reply_ofs,
                      int reply_len)
{
        char tmp_addr[INET6_ADDRSTRLEN];
        struct option_state *host_opt_state;
        int len;

        log_info("Client %s releases address %s, which is not leased to it.",
                 print_hex_1(client_id->len, client_id->data, 60),
                 inet_ntop(AF_INET6, iaaddr->data, tmp_addr, sizeof(tmp_addr)));

        /*
         * Create state for this IA_NA.
         */
        host_opt_state = NULL;
        if (!option_state_allocate(&host_opt_state, MDL)) {
                log_error("ia_na_nomatch_release: out of memory "
                          "allocating option_state.");
                goto exit;
        }

        if (!set_status_code(STATUS_NoBinding,
                             "Release for non-leased address.",
                             host_opt_state)) {
                goto exit;
        }

        /*
         * Insure we have enough space
         */
        if (reply_len < (*reply_ofs + 16)) {
                log_error("ia_na_nomatch_release: "
                          "out of space for reply packet.");
                goto exit;
        }

        /*
         * Put our status code into the reply packet.
         */
        len = store_options6(reply_data+(*reply_ofs)+16,
                             reply_len-(*reply_ofs)-16,
                             host_opt_state, packet,
                             required_opts_STATUS_CODE, NULL);

        /*
         * Store the non-encapsulated option data for this
         * IA_NA into our reply packet. Defined in RFC 3315,
         * section 22.4.
         */
        /* option number */
        putUShort((unsigned char *)reply_data+(*reply_ofs), D6O_IA_NA);
        /* option length */
        putUShort((unsigned char *)reply_data+(*reply_ofs)+2, len + 12);
        /* IA_NA, copied from the client */
        memcpy(reply_data+(*reply_ofs)+4, ia_na_id, 4);
        /* t1 and t2, odd that we need them, but here it is */
        putULong((unsigned char *)reply_data+(*reply_ofs)+8, 0);
        putULong((unsigned char *)reply_data+(*reply_ofs)+12, 0);

        /*
         * Get ready for next IA_NA.
         */
        *reply_ofs += (len + 16);

exit:
        option_state_dereference(&host_opt_state, MDL);
}

static void
ia_pd_match_release(const struct data_string *client_id,
                    const struct data_string *iapref,
                    struct iasubopt *prefix)
{
        char tmp_addr[INET6_ADDRSTRLEN];

        log_info("Client %s releases prefix %s/%u",
                 print_hex_1(client_id->len, client_id->data, 60),
                 inet_ntop(AF_INET6, iapref->data + 9,
                           tmp_addr, sizeof(tmp_addr)),
                 (unsigned) getUChar(iapref->data + 8));
        if (prefix != NULL) {
                release_lease6(prefix->ipv6_pool, prefix);
                prefix->ia->cltt = cur_time;
                write_ia(prefix->ia);
        }
}

static void
ia_pd_nomatch_release(const struct data_string *client_id,
                      const struct data_string *iapref,
                      u_int32_t *ia_pd_id,
                      struct packet *packet,
                      char *reply_data,
                      int *reply_ofs,
                      int reply_len)
{
        char tmp_addr[INET6_ADDRSTRLEN];
        struct option_state *host_opt_state;
        int len;

        log_info("Client %s releases prefix %s/%u, which is not leased to it.",
                 print_hex_1(client_id->len, client_id->data, 60),
                 inet_ntop(AF_INET6, iapref->data + 9,
                           tmp_addr, sizeof(tmp_addr)),
                 (unsigned) getUChar(iapref->data + 8));

        /*
         * Create state for this IA_PD.
         */
        host_opt_state = NULL;
        if (!option_state_allocate(&host_opt_state, MDL)) {
                log_error("ia_pd_nomatch_release: out of memory "
                          "allocating option_state.");
                goto exit;
        }

        if (!set_status_code(STATUS_NoBinding,
                             "Release for non-leased prefix.",
                             host_opt_state)) {
                goto exit;
        }

        /*
         * Insure we have enough space
         */
        if (reply_len < (*reply_ofs + 16)) {
                log_error("ia_pd_nomatch_release: "
                          "out of space for reply packet.");
                goto exit;
        }

        /*
         * Put our status code into the reply packet.
         */
        len = store_options6(reply_data+(*reply_ofs)+16,
                             reply_len-(*reply_ofs)-16,
                             host_opt_state, packet,
                             required_opts_STATUS_CODE, NULL);

        /*
         * Store the non-encapsulated option data for this
         * IA_PD into our reply packet. Defined in RFC 3315,
         * section 22.4.
         */
        /* option number */
        putUShort((unsigned char *)reply_data+(*reply_ofs), D6O_IA_PD);
        /* option length */
        putUShort((unsigned char *)reply_data+(*reply_ofs)+2, len + 12);
        /* IA_PD, copied from the client */
        memcpy(reply_data+(*reply_ofs)+4, ia_pd_id, 4);
        /* t1 and t2, odd that we need them, but here it is */
        putULong((unsigned char *)reply_data+(*reply_ofs)+8, 0);
        putULong((unsigned char *)reply_data+(*reply_ofs)+12, 0);

        /*
         * Get ready for next IA_PD.
         */
        *reply_ofs += (len + 16);

exit:
        option_state_dereference(&host_opt_state, MDL);
}

static void
iterate_over_ia_pd(struct data_string *reply_ret,
                   struct packet *packet,
                   const struct data_string *client_id,
                   const struct data_string *server_id,
                   const char *packet_type,
                   void (*ia_pd_match)(),
                   void (*ia_pd_nomatch)())
{
        struct data_string reply_new;
        int reply_len;
        struct option_state *opt_state;
        struct host_decl *packet_host;
        struct option_cache *ia;
        struct option_cache *oc;
        /* cli_enc_... variables come from the IA_PD options */
        struct data_string cli_enc_opt_data;
        struct option_state *cli_enc_opt_state;
        struct host_decl *host;
        struct data_string iaprefix;
        char reply_data[65536];
        int reply_ofs;
        struct iasubopt *prefix;
        struct ia_xx *existing_ia_pd;
        int i;
        struct data_string key;
        u_int32_t iaid;

        /*
         * Initialize to empty values, in case we have to exit early.
         */
        memset(&reply_new, 0, sizeof(reply_new));
        opt_state = NULL;
        memset(&cli_enc_opt_data, 0, sizeof(cli_enc_opt_data));
        cli_enc_opt_state = NULL;
        memset(&iaprefix, 0, sizeof(iaprefix));
        prefix = NULL;

        /*
         * Compute the available length for the reply.
         */
        reply_len = sizeof(reply_data) - reply_ret->len;
        reply_ofs = 0;

        /*
         * Find the host record that matches from the packet, if any.
         */
        packet_host = NULL;
        find_hosts6(&packet_host, packet, client_id, MDL);

        /*
         * Build our option state for reply.
         */
        opt_state = NULL;
        if (!option_state_allocate(&opt_state, MDL)) {
                log_error("iterate_over_ia_pd: no memory for option_state.");
                goto exit;
        }
        execute_statements_in_scope(NULL, packet, NULL, NULL,
                                    packet->options, opt_state,
                                    &global_scope, root_group, NULL, NULL);

        /*
         * Loop through the IA_PD reported by the client, and deal with
         * prefixes reported as already in use.
         */
        for (ia = lookup_option(&dhcpv6_universe, packet->options, D6O_IA_PD);
             ia != NULL; ia = ia->next) {

            if (!get_encapsulated_IA_state(&cli_enc_opt_state,
                                           &cli_enc_opt_data,
                                           packet, ia, IA_PD_OFFSET)) {
                goto exit;
            }

            iaid = getULong(cli_enc_opt_data.data);

            oc = lookup_option(&dhcpv6_universe, cli_enc_opt_state,
                               D6O_IAPREFIX);
            if (oc == NULL) {
                /* no prefix given for this IA_PD, ignore */
                option_state_dereference(&cli_enc_opt_state, MDL);
                data_string_forget(&cli_enc_opt_data, MDL);
                continue;
            }

            for (; oc != NULL; oc = oc->next) {
                memset(&iaprefix, 0, sizeof(iaprefix));
                if (!evaluate_option_cache(&iaprefix, packet, NULL, NULL,
                                           packet->options, NULL,
                                           &global_scope, oc, MDL)) {
                        log_error("iterate_over_ia_pd: "
                                  "error evaluating IAPREFIX.");
                        goto exit;
                }

                /*
                 * Now we need to figure out which host record matches
                 * this IA_PD and IAPREFIX (encapsulated option contents
                 * matching a host record by option).
                 *
                 * XXX: We don't currently track IA_PD separately, but
                 *      we will need to do this!
                 */
                host = NULL;
                if (!find_hosts_by_option(&host, packet,
                                          cli_enc_opt_state, MDL)) {
                        if (packet_host != NULL) {
                                host = packet_host;
                        } else {
                                host = NULL;
                        }
                }
                while (host != NULL) {
                        if (host->fixed_prefix != NULL) {
                                struct iaddrcidrnetlist *l;
                                int plen = (int) getUChar(iaprefix.data + 8);

                                for (l = host->fixed_prefix; l != NULL;
                                     l = l->next) {
                                        if (plen != l->cidrnet.bits)
                                                continue;
                                        if (memcmp(iaprefix.data + 9,
                                                   l->cidrnet.lo_addr.iabuf,
                                                   16) == 0)
                                                break;
                                }
                                if ((l != NULL) && (iaprefix.len >= 17))
                                        break;
                        }
                        host = host->n_ipaddr;
                }

                if ((host == NULL) && (iaprefix.len >= IAPREFIX_OFFSET)) {
                        /*
                         * Find existing IA_PD.
                         */
                        if (ia_make_key(&key, iaid,
                                        (char *)client_id->data,
                                        client_id->len,
                                        MDL) != ISC_R_SUCCESS) {
                                log_fatal("iterate_over_ia_pd: no memory for "
                                          "key.");
                        }

                        existing_ia_pd = NULL;
                        if (ia_hash_lookup(&existing_ia_pd, ia_pd_active,
                                           (unsigned char *)key.data,
                                           key.len, MDL)) {
                                /*
                                 * Make sure this prefix is in the IA_PD.
                                 */
                                for (i = 0;
                                     i < existing_ia_pd->num_iasubopt;
                                     i++) {
                                        struct iasubopt *tmp;
                                        u_int8_t plen;

                                        plen = getUChar(iaprefix.data + 8);
                                        tmp = existing_ia_pd->iasubopt[i];
                                        if ((tmp->plen == plen) &&
                                            (memcmp(&tmp->addr,
                                                    iaprefix.data + 9,
                                                    16) == 0)) {
                                                iasubopt_reference(&prefix,
                                                                   tmp, MDL);
                                                break;
                                        }
                                }
                        }

                        data_string_forget(&key, MDL);
                }

                if ((host != NULL) || (prefix != NULL)) {
                        ia_pd_match(client_id, &iaprefix, prefix);
                } else {
                        ia_pd_nomatch(client_id, &iaprefix,
                                      (u_int32_t *)cli_enc_opt_data.data,
                                      packet, reply_data, &reply_ofs,
                                      reply_len - reply_ofs);
                }

                if (prefix != NULL) {
                        iasubopt_dereference(&prefix, MDL);
                }

                data_string_forget(&iaprefix, MDL);
            }

            option_state_dereference(&cli_enc_opt_state, MDL);
            data_string_forget(&cli_enc_opt_data, MDL);
        }

        /*
         * Return our reply to the caller.
         * The IA_NA routine has already filled at least the header.
         */
        reply_new.len = reply_ret->len + reply_ofs;
        if (!buffer_allocate(&reply_new.buffer, reply_new.len, MDL)) {
                log_fatal("No memory to store reply.");
        }
        reply_new.data = reply_new.buffer->data;
        memcpy(reply_new.buffer->data,
               reply_ret->buffer->data, reply_ret->len);
        memcpy(reply_new.buffer->data + reply_ret->len,
               reply_data, reply_ofs);
        data_string_forget(reply_ret, MDL);
        data_string_copy(reply_ret, &reply_new, MDL);
        data_string_forget(&reply_new, MDL);

exit:
        if (prefix != NULL) {
                iasubopt_dereference(&prefix, MDL);
        }
        if (iaprefix.buffer != NULL) {
                data_string_forget(&iaprefix, MDL);
        }
        if (cli_enc_opt_state != NULL) {
                option_state_dereference(&cli_enc_opt_state, MDL);
        }
        if (cli_enc_opt_data.buffer != NULL) {
                data_string_forget(&cli_enc_opt_data, MDL);
        }
        if (opt_state != NULL) {
                option_state_dereference(&opt_state, MDL);
        }
}

/*
 * Release means a client is done with the leases.
 */

static void
dhcpv6_release(struct data_string *reply, struct packet *packet) {
        struct data_string client_id;
        struct data_string server_id;

        /*
         * Validate our input.
         */
        if (!valid_client_resp(packet, &client_id, &server_id)) {
                return;
        }

        /* If the RELEASE arrived via unicast and unicast option isn't set,
         * reject it per RFC 3315, Sec 18.2.6 */
        if (packet->unicast == ISC_TRUE &&
            is_unicast_option_defined(packet) == ISC_FALSE) {
                unicast_reject(reply, packet, &client_id, &server_id);
        } else {
                /*
                 * And operate on each IA_NA in this packet.
                 */
                iterate_over_ia_na(reply, packet, &client_id, &server_id,
                                   "Release", ia_na_match_release,
                                   ia_na_nomatch_release);

                /*
                 * And operate on each IA_PD in this packet.
                 */
                iterate_over_ia_pd(reply, packet, &client_id, &server_id,
                                   "Release", ia_pd_match_release,
                                   ia_pd_nomatch_release);
        }

        data_string_forget(&server_id, MDL);
        data_string_forget(&client_id, MDL);
}

/*
 * Information-Request is used by clients who have obtained an address
 * from other means, but want configuration information from the server.
 */

static void
dhcpv6_information_request(struct data_string *reply, struct packet *packet) {
        struct data_string client_id;
        struct data_string server_id;

        /*
         * Validate our input.
         */
        if (!valid_client_info_req(packet, &server_id)) {
                return;
        }

        /*
         * Get our client ID, if there is one.
         */
        memset(&client_id, 0, sizeof(client_id));
        if (get_client_id(packet, &client_id) != ISC_R_SUCCESS) {
                data_string_forget(&client_id, MDL);
        }

        /*
         * Use the lease_to_client() function. This will work fine,
         * because the valid_client_info_req() insures that we
         * don't have any IA that would cause us to allocate
         * resources to the client.
         */
        lease_to_client(reply, packet, &client_id,
                        server_id.data != NULL ? &server_id : NULL);

        /*
         * Cleanup.
         */
        if (client_id.data != NULL) {
                data_string_forget(&client_id, MDL);
        }
        data_string_forget(&server_id, MDL);
}

/*
 * The Relay-forw message is sent by relays. It typically contains a
 * single option, which encapsulates an entire packet.
 *
 * We need to build an encapsulated reply.
 */

/* XXX: this is very, very similar to do_packet6(), and should probably
        be combined in a clever way */
/* DHCPv6 server side */
static void
dhcpv6_relay_forw(struct data_string *reply_ret, struct packet *packet) {
        struct option_cache *oc;
        struct data_string enc_opt_data;
        struct packet *enc_packet;
        unsigned char msg_type;
        const struct dhcpv6_packet *msg;
        const struct dhcpv6_relay_packet *relay;
        struct data_string enc_reply;
        char link_addr[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")];
        char peer_addr[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")];
        struct data_string a_opt, packet_ero;
        struct option_state *opt_state;
        static char reply_data[65536];
        struct dhcpv6_relay_packet *reply;
        int reply_ofs;

        /*
         * Initialize variables for early exit.
         */
        opt_state = NULL;
        memset(&a_opt, 0, sizeof(a_opt));
        memset(&packet_ero, 0, sizeof(packet_ero));
        memset(&enc_reply, 0, sizeof(enc_reply));
        memset(&enc_opt_data, 0, sizeof(enc_opt_data));
        enc_packet = NULL;

        /*
         * Get our encapsulated relay message.
         */
        oc = lookup_option(&dhcpv6_universe, packet->options, D6O_RELAY_MSG);
        if (oc == NULL) {
                inet_ntop(AF_INET6, &packet->dhcpv6_link_address,
                          link_addr, sizeof(link_addr));
                inet_ntop(AF_INET6, &packet->dhcpv6_peer_address,
                          peer_addr, sizeof(peer_addr));
                log_info("Relay-forward from %s with link address=%s and "
                         "peer address=%s missing Relay Message option.",
                          piaddr(packet->client_addr), link_addr, peer_addr);
                goto exit;
        }

        if (!evaluate_option_cache(&enc_opt_data, NULL, NULL, NULL,
                                   NULL, NULL, &global_scope, oc, MDL)) {
                /* should be dhcpv6_relay_forw */
                log_error("dhcpv6_forw_relay: error evaluating "
                          "relayed message.");
                goto exit;
        }

        if (!packet6_len_okay((char *)enc_opt_data.data, enc_opt_data.len)) {
                /* should be dhcpv6_relay_forw */
                log_error("dhcpv6_forw_relay: encapsulated packet too short.");
                goto exit;
        }

        /*
         * Build a packet structure from this encapsulated packet.
         */
        enc_packet = NULL;
        if (!packet_allocate(&enc_packet, MDL)) {
                /* should be dhcpv6_relay_forw */
                log_error("dhcpv6_forw_relay: "
                          "no memory for encapsulated packet.");
                goto exit;
        }

        if (!option_state_allocate(&enc_packet->options, MDL)) {
                /* should be dhcpv6_relay_forw */
                log_error("dhcpv6_forw_relay: "
                          "no memory for encapsulated packet's options.");
                goto exit;
        }

        enc_packet->client_port = packet->client_port;
        enc_packet->client_addr = packet->client_addr;
        interface_reference(&enc_packet->interface, packet->interface, MDL);
        enc_packet->dhcpv6_container_packet = packet;

        msg_type = enc_opt_data.data[0];
        if ((msg_type == DHCPV6_RELAY_FORW) ||
            (msg_type == DHCPV6_RELAY_REPL)) {
                int relaylen = (int)(offsetof(struct dhcpv6_relay_packet, options));
                relay = (struct dhcpv6_relay_packet *)enc_opt_data.data;
                enc_packet->dhcpv6_msg_type = relay->msg_type;

                /* relay-specific data */
                enc_packet->dhcpv6_hop_count = relay->hop_count;
                memcpy(&enc_packet->dhcpv6_link_address,
                       relay->link_address, sizeof(relay->link_address));
                memcpy(&enc_packet->dhcpv6_peer_address,
                       relay->peer_address, sizeof(relay->peer_address));

                if (!parse_option_buffer(enc_packet->options,
                                         relay->options,
                                         enc_opt_data.len - relaylen,
                                         &dhcpv6_universe)) {
                        /* no logging here, as parse_option_buffer() logs all
                           cases where it fails */
                        goto exit;
                }
        } else if ((msg_type == DHCPV6_DHCPV4_QUERY) ||
                   (msg_type == DHCPV6_DHCPV4_RESPONSE)) {
#ifdef DHCP4o6
                if (!dhcpv4_over_dhcpv6 ||
                    (msg_type == DHCPV6_DHCPV4_RESPONSE)) {
                        log_error("dhcpv6_relay_forw: "
                                  "unsupported %s message type.",
                                  dhcpv6_type_names[msg_type]);
                        goto exit;
                }
                forw_dhcpv4_query(packet);
                goto exit;
#else /* DHCP4o6 */
                log_error("dhcpv6_relay_forw: unsupported %s message type.",
                          dhcpv6_type_names[msg_type]);
                goto exit;
#endif /* DHCP4o6 */
        } else {
                int msglen = (int)(offsetof(struct dhcpv6_packet, options));
                msg = (struct dhcpv6_packet *)enc_opt_data.data;
                enc_packet->dhcpv6_msg_type = msg->msg_type;

                /* message-specific data */
                memcpy(enc_packet->dhcpv6_transaction_id,
                       msg->transaction_id,
                       sizeof(enc_packet->dhcpv6_transaction_id));

                if (!parse_option_buffer(enc_packet->options,
                                         msg->options,
                                         enc_opt_data.len - msglen,
                                         &dhcpv6_universe)) {
                        /* no logging here, as parse_option_buffer() logs all
                           cases where it fails */
                        goto exit;
                }
        }

        /*
         * This is recursive. It is possible to exceed maximum packet size.
         * XXX: This will cause the packet send to fail.
         */
        build_dhcpv6_reply(&enc_reply, enc_packet);

        /*
         * If we got no encapsulated data, then it is discarded, and
         * our reply-forw is also discarded.
         */
        if (enc_reply.data == NULL) {
                goto exit;
        }

        /*
         * Now we can use the reply_data buffer.
         * Packet header stuff all comes from the forward message.
         */
        reply = (struct dhcpv6_relay_packet *)reply_data;
        reply->msg_type = DHCPV6_RELAY_REPL;
        reply->hop_count = packet->dhcpv6_hop_count;
        memcpy(reply->link_address, &packet->dhcpv6_link_address,
               sizeof(reply->link_address));
        memcpy(reply->peer_address, &packet->dhcpv6_peer_address,
               sizeof(reply->peer_address));
        reply_ofs = (int)(offsetof(struct dhcpv6_relay_packet, options));

        /*
         * Get the reply option state.
         */
        opt_state = NULL;
        if (!option_state_allocate(&opt_state, MDL)) {
                log_error("dhcpv6_relay_forw: no memory for option state.");
                goto exit;
        }

        /*
         * Append the interface-id if present.
         */
        oc = lookup_option(&dhcpv6_universe, packet->options,
                           D6O_INTERFACE_ID);
        if (oc != NULL) {
                if (!evaluate_option_cache(&a_opt, packet,
                                           NULL, NULL,
                                           packet->options, NULL,
                                           &global_scope, oc, MDL)) {
                        log_error("dhcpv6_relay_forw: error evaluating "
                                  "Interface ID.");
                        goto exit;
                }
                if (!save_option_buffer(&dhcpv6_universe, opt_state, NULL,
                                        (unsigned char *)a_opt.data,
                                        a_opt.len,
                                        D6O_INTERFACE_ID, 0)) {
                        log_error("dhcpv6_relay_forw: error saving "
                                  "Interface ID.");
                        goto exit;
                }
                data_string_forget(&a_opt, MDL);
        }

#if defined(RELAY_PORT)
        /*
         * Append the relay_source_port option if present.
         */
        oc = lookup_option(&dhcpv6_universe, packet->options,
                           D6O_RELAY_SOURCE_PORT);
        if (oc != NULL) {
                if (!evaluate_option_cache(&a_opt, packet,
                                           NULL, NULL,
                                           packet->options, NULL,
                                           &global_scope, oc, MDL)) {
                        log_error("dhcpv6_relay_forw: error evaluating "
                                  "Relay Source Port.");
                        goto exit;
                }
                if (!save_option_buffer(&dhcpv6_universe, opt_state, NULL,
                                        (unsigned char *)a_opt.data,
                                        a_opt.len,
                                        D6O_RELAY_SOURCE_PORT, 0)) {
                        log_error("dhcpv6_relay_forw: error saving "
                                  "Relay Source Port.");
                        goto exit;
                }
                data_string_forget(&a_opt, MDL);

                packet->relay_source_port = ISC_TRUE;
        }
#endif

        /*
         * Append our encapsulated stuff for caller.
         */
        if (!save_option_buffer(&dhcpv6_universe, opt_state, NULL,
                                (unsigned char *)enc_reply.data,
                                enc_reply.len,
                                D6O_RELAY_MSG, 0)) {
                log_error("dhcpv6_relay_forw: error saving Relay MSG.");
                goto exit;
        }

        /*
         * Get the ERO if any.
         */
        oc = lookup_option(&dhcpv6_universe, packet->options, D6O_ERO);
        if (oc != NULL) {
                unsigned req;
                int i;

                if (!evaluate_option_cache(&packet_ero, packet,
                                           NULL, NULL,
                                           packet->options, NULL,
                                           &global_scope, oc, MDL) ||
                        (packet_ero.len & 1)) {
                        log_error("dhcpv6_relay_forw: error evaluating ERO.");
                        goto exit;
                }

                /* Decode and apply the ERO. */
                for (i = 0; i < packet_ero.len; i += 2) {
                        req = getUShort(packet_ero.data + i);
                        /* Already in the reply? */
                        oc = lookup_option(&dhcpv6_universe, opt_state, req);
                        if (oc != NULL)
                                continue;
                        /* Get it from the packet if present. */
                        oc = lookup_option(&dhcpv6_universe,
                                           packet->options,
                                           req);
                        if (oc == NULL)
                                continue;
                        if (!evaluate_option_cache(&a_opt, packet,
                                                   NULL, NULL,
                                                   packet->options, NULL,
                                                   &global_scope, oc, MDL)) {
                                log_error("dhcpv6_relay_forw: error "
                                          "evaluating option %u.", req);
                                goto exit;
                        }
                        if (!save_option_buffer(&dhcpv6_universe,
                                                opt_state,
                                                NULL,
                                                (unsigned char *)a_opt.data,
                                                a_opt.len,
                                                req,
                                                0)) {
                                log_error("dhcpv6_relay_forw: error saving "
                                          "option %u.", req);
                                goto exit;
                        }
                        data_string_forget(&a_opt, MDL);
                }
        }

        reply_ofs += store_options6(reply_data + reply_ofs,
                                    sizeof(reply_data) - reply_ofs,
                                    opt_state, packet,
                                    required_opts_agent, &packet_ero);

        /*
         * Return our reply to the caller.
         */
        reply_ret->len = reply_ofs;
        reply_ret->buffer = NULL;
        if (!buffer_allocate(&reply_ret->buffer, reply_ret->len, MDL)) {
                log_fatal("No memory to store reply.");
        }
        reply_ret->data = reply_ret->buffer->data;
        memcpy(reply_ret->buffer->data, reply_data, reply_ofs);

exit:
        if (opt_state != NULL)
                option_state_dereference(&opt_state, MDL);
        if (a_opt.data != NULL) {
                data_string_forget(&a_opt, MDL);
        }
        if (packet_ero.data != NULL) {
                data_string_forget(&packet_ero, MDL);
        }
        if (enc_reply.data != NULL) {
                data_string_forget(&enc_reply, MDL);
        }
        if (enc_opt_data.data != NULL) {
                data_string_forget(&enc_opt_data, MDL);
        }
        if (enc_packet != NULL) {
                packet_dereference(&enc_packet, MDL);
        }
}

#ifdef DHCP4o6
/* \brief Internal processing of a relayed DHCPv4-query
 *  (DHCPv4 server side)
 *
 * Code copied from \ref dhcpv6_relay_forw() which itself is
 * from \ref do_packet6().
 *
 * \param reply_ret pointer to the response
 * \param packet the query
 */
static void
dhcp4o6_relay_forw(struct data_string *reply_ret, struct packet *packet) {
        struct option_cache *oc;
        struct data_string enc_opt_data;
        struct packet *enc_packet;
        unsigned char msg_type;
        const struct dhcpv6_relay_packet *relay;
        const struct dhcpv4_over_dhcpv6_packet *msg;
        struct data_string enc_reply;
        char link_addr[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")];
        char peer_addr[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")];
        struct data_string a_opt, packet_ero;
        struct option_state *opt_state;
        static char reply_data[65536];
        struct dhcpv6_relay_packet *reply;
        int reply_ofs;

        /*
         * Initialize variables for early exit.
         */
        opt_state = NULL;
        memset(&a_opt, 0, sizeof(a_opt));
        memset(&packet_ero, 0, sizeof(packet_ero));
        memset(&enc_reply, 0, sizeof(enc_reply));
        memset(&enc_opt_data, 0, sizeof(enc_opt_data));
        enc_packet = NULL;

        /*
         * Get our encapsulated relay message.
         */
        oc = lookup_option(&dhcpv6_universe, packet->options, D6O_RELAY_MSG);
        if (oc == NULL) {
                inet_ntop(AF_INET6, &packet->dhcpv6_link_address,
                          link_addr, sizeof(link_addr));
                inet_ntop(AF_INET6, &packet->dhcpv6_peer_address,
                          peer_addr, sizeof(peer_addr));
                log_info("Relay-forward from %s with link address=%s and "
                         "peer address=%s missing Relay Message option.",
                          piaddr(packet->client_addr), link_addr, peer_addr);
                goto exit;
        }

        if (!evaluate_option_cache(&enc_opt_data, NULL, NULL, NULL,
                                   NULL, NULL, &global_scope, oc, MDL)) {
                log_error("dhcp4o6_relay_forw: error evaluating "
                          "relayed message.");
                goto exit;
        }

        if (!packet6_len_okay((char *)enc_opt_data.data, enc_opt_data.len)) {
                log_error("dhcp4o6_relay_forw: "
                          "encapsulated packet too short.");
                goto exit;
        }

        /*
         * Build a packet structure from this encapsulated packet.
         */
        if (!packet_allocate(&enc_packet, MDL)) {
                log_error("dhcp4o6_relay_forw: "
                          "no memory for encapsulated packet.");
                goto exit;
        }

        if (!option_state_allocate(&enc_packet->options, MDL)) {
                log_error("dhcp4o6_relay_forw: "
                          "no memory for encapsulated packet's options.");
                goto exit;
        }

        enc_packet->client_port = packet->client_port;
        enc_packet->client_addr = packet->client_addr;
        interface_reference(&enc_packet->interface, packet->interface, MDL);
        enc_packet->dhcpv6_container_packet = packet;

        msg_type = enc_opt_data.data[0];
        if ((msg_type == DHCPV6_RELAY_FORW) ||
            (msg_type == DHCPV6_RELAY_REPL)) {
                int relaylen = (int)(offsetof(struct dhcpv6_relay_packet, options));
                relay = (struct dhcpv6_relay_packet *)enc_opt_data.data;
                enc_packet->dhcpv6_msg_type = relay->msg_type;

                /* relay-specific data */
                enc_packet->dhcpv6_hop_count = relay->hop_count;
                memcpy(&enc_packet->dhcpv6_link_address,
                       relay->link_address, sizeof(relay->link_address));
                memcpy(&enc_packet->dhcpv6_peer_address,
                       relay->peer_address, sizeof(relay->peer_address));

                if (!parse_option_buffer(enc_packet->options,
                                         relay->options,
                                         enc_opt_data.len - relaylen,
                                         &dhcpv6_universe)) {
                        /* no logging here, as parse_option_buffer() logs all
                           cases where it fails */
                        goto exit;
                }
        } else if ((msg_type == DHCPV6_DHCPV4_QUERY) ||
                   (msg_type == DHCPV6_DHCPV4_RESPONSE)) {
                int msglen =
                    (int)(offsetof(struct dhcpv4_over_dhcpv6_packet, options));
                msg = (struct dhcpv4_over_dhcpv6_packet *)enc_opt_data.data;
                enc_packet->dhcpv6_msg_type = msg->msg_type;

                /* message-specific data */
                memcpy(enc_packet->dhcp4o6_flags,
                       msg->flags,
                       sizeof(enc_packet->dhcp4o6_flags));

                if (!parse_option_buffer(enc_packet->options,
                                         msg->options,
                                         enc_opt_data.len - msglen,
                                         &dhcpv6_universe)) {
                        /* no logging here, as parse_option_buffer() logs all
                           cases where it fails */
                        goto exit;
                }
        } else {
                log_error("dhcp4o6_relay_forw: unexpected message of type %d.",
                          (int)msg_type);
                goto exit;
        }

        /*
         * This is recursive. It is possible to exceed maximum packet size.
         * XXX: This will cause the packet send to fail.
         */
        build_dhcpv6_reply(&enc_reply, enc_packet);

        /*
         * If we got no encapsulated data, then it is discarded, and
         * our reply-forw is also discarded.
         */
        if (enc_reply.data == NULL) {
                goto exit;
        }

        /*
         * Now we can use the reply_data buffer.
         * Packet header stuff all comes from the forward message.
         */
        reply = (struct dhcpv6_relay_packet *)reply_data;
        reply->msg_type = DHCPV6_RELAY_REPL;
        reply->hop_count = packet->dhcpv6_hop_count;
        memcpy(reply->link_address, &packet->dhcpv6_link_address,
               sizeof(reply->link_address));
        memcpy(reply->peer_address, &packet->dhcpv6_peer_address,
               sizeof(reply->peer_address));
        reply_ofs = (int)(offsetof(struct dhcpv6_relay_packet, options));

        /*
         * Get the reply option state.
         */
        if (!option_state_allocate(&opt_state, MDL)) {
                log_error("dhcp4o6_relay_forw: no memory for option state.");
                goto exit;
        }

        /*
         * Append the interface-id if present.
         */
        oc = lookup_option(&dhcpv6_universe, packet->options,
                           D6O_INTERFACE_ID);
        if (oc != NULL) {
                if (!evaluate_option_cache(&a_opt, packet,
                                           NULL, NULL,
                                           packet->options, NULL,
                                           &global_scope, oc, MDL)) {
                        log_error("dhcp4o6_relay_forw: error evaluating "
                                  "Interface ID.");
                        goto exit;
                }
                if (!save_option_buffer(&dhcpv6_universe, opt_state, NULL,
                                        (unsigned char *)a_opt.data,
                                        a_opt.len,
                                        D6O_INTERFACE_ID, 0)) {
                        log_error("dhcp4o6_relay_forw: error saving "
                                  "Interface ID.");
                        goto exit;
                }
                data_string_forget(&a_opt, MDL);
        }

#if defined(RELAY_PORT)
        /*
         * Append the relay_source_port option if present.
         */
        oc = lookup_option(&dhcpv6_universe, packet->options,
                           D6O_RELAY_SOURCE_PORT);
        if (oc != NULL) {
                if (!evaluate_option_cache(&a_opt, packet,
                                           NULL, NULL,
                                           packet->options, NULL,
                                           &global_scope, oc, MDL)) {
                        log_error("dhcpv4o6_relay_forw: error evaluating "
                                  "Relay Source Port.");
                        goto exit;
                }
                if (!save_option_buffer(&dhcpv6_universe, opt_state, NULL,
                                        (unsigned char *)a_opt.data,
                                        a_opt.len,
                                        D6O_RELAY_SOURCE_PORT, 0)) {
                        log_error("dhcpv4o6_relay_forw: error saving "
                                  "Relay Source Port.");
                        goto exit;
                }
                data_string_forget(&a_opt, MDL);

                packet->relay_source_port = ISC_TRUE;
        }
#endif

        /*
         * Append our encapsulated stuff for caller.
         */
        if (!save_option_buffer(&dhcpv6_universe, opt_state, NULL,
                                (unsigned char *)enc_reply.data,
                                enc_reply.len,
                                D6O_RELAY_MSG, 0)) {
                log_error("dhcp4o6_relay_forw: error saving Relay MSG.");
                goto exit;
        }

        /*
         * Get the ERO if any.
         */
        oc = lookup_option(&dhcpv6_universe, packet->options, D6O_ERO);
        if (oc != NULL) {
                unsigned req;
                int i;

                if (!evaluate_option_cache(&packet_ero, packet,
                                           NULL, NULL,
                                           packet->options, NULL,
                                           &global_scope, oc, MDL) ||
                        (packet_ero.len & 1)) {
                        log_error("dhcp4o6_relay_forw: error evaluating ERO.");
                        goto exit;
                }

                /* Decode and apply the ERO. */
                for (i = 0; i < packet_ero.len; i += 2) {
                        req = getUShort(packet_ero.data + i);
                        /* Already in the reply? */
                        oc = lookup_option(&dhcpv6_universe, opt_state, req);
                        if (oc != NULL)
                                continue;
                        /* Get it from the packet if present. */
                        oc = lookup_option(&dhcpv6_universe,
                                           packet->options,
                                           req);
                        if (oc == NULL)
                                continue;
                        if (!evaluate_option_cache(&a_opt, packet,
                                                   NULL, NULL,
                                                   packet->options, NULL,
                                                   &global_scope, oc, MDL)) {
                                log_error("dhcp4o6_relay_forw: error "
                                          "evaluating option %u.", req);
                                goto exit;
                        }
                        if (!save_option_buffer(&dhcpv6_universe,
                                                opt_state,
                                                NULL,
                                                (unsigned char *)a_opt.data,
                                                a_opt.len,
                                                req,
                                                0)) {
                                log_error("dhcp4o6_relay_forw: error saving "
                                          "option %u.", req);
                                goto exit;
                        }
                        data_string_forget(&a_opt, MDL);
                }
        }

        reply_ofs += store_options6(reply_data + reply_ofs,
                                    sizeof(reply_data) - reply_ofs,
                                    opt_state, packet,
                                    required_opts_agent, &packet_ero);

        /*
         * Return our reply to the caller.
         */
        reply_ret->len = reply_ofs;
        reply_ret->buffer = NULL;
        if (!buffer_allocate(&reply_ret->buffer, reply_ret->len, MDL)) {
                log_fatal("No memory to store reply.");
        }
        reply_ret->data = reply_ret->buffer->data;
        memcpy(reply_ret->buffer->data, reply_data, reply_ofs);

exit:
        if (opt_state != NULL)
                option_state_dereference(&opt_state, MDL);
        if (a_opt.data != NULL) {
                data_string_forget(&a_opt, MDL);
        }
        if (packet_ero.data != NULL) {
                data_string_forget(&packet_ero, MDL);
        }
        if (enc_reply.data != NULL) {
                data_string_forget(&enc_reply, MDL);
        }
        if (enc_opt_data.data != NULL) {
                data_string_forget(&enc_opt_data, MDL);
        }
        if (enc_packet != NULL) {
                packet_dereference(&enc_packet, MDL);
        }
}

/*
 * \brief Internal processing of a DHCPv4-query
 *  (DHCPv4 server function)
 *
 * Code copied from \ref do_packet().
 *
 * \param reply_ret pointer to the response
 * \param packet the query
 */
static void
dhcp4o6_dhcpv4_query(struct data_string *reply_ret, struct packet *packet) {
        struct option_cache *oc;
        struct data_string enc_opt_data;
        struct packet *enc_packet;
        struct data_string enc_response;
        struct option_state *opt_state;
        static char response_data[65536];
        struct dhcpv4_over_dhcpv6_packet *response;
        int response_ofs;

        /*
         * Initialize variables for early exit.
         */
        opt_state = NULL;
        memset(&enc_response, 0, sizeof(enc_response));
        memset(&enc_opt_data, 0, sizeof(enc_opt_data));
        enc_packet = NULL;

        /*
         * Get our encapsulated relay message.
         */
        oc = lookup_option(&dhcpv6_universe, packet->options, D6O_DHCPV4_MSG);
        if (oc == NULL) {
                log_info("DHCPv4-query from %s missing DHCPv4 Message option.",
                         piaddr(packet->client_addr));
                goto exit;
        }

        if (!evaluate_option_cache(&enc_opt_data, NULL, NULL, NULL,
                                   NULL, NULL, &global_scope, oc, MDL)) {
                log_error("dhcp4o6_dhcpv4_query: error evaluating "
                          "DHCPv4 message.");
                goto exit;
        }

        if (enc_opt_data.len < DHCP_FIXED_NON_UDP) {
                log_error("dhcp4o6_dhcpv4_query: DHCPv4 packet too short.");
                goto exit;
        }

        /*
         * Build a packet structure from this encapsulated packet.
         */
        if (!packet_allocate(&enc_packet, MDL)) {
                log_error("dhcp4o6_dhcpv4_query: "
                          "no memory for encapsulated packet.");
                goto exit;
        }

        enc_packet->raw = (struct dhcp_packet *)enc_opt_data.data;
        enc_packet->packet_length = enc_opt_data.len;
        enc_packet->dhcp4o6_response = &enc_response;
        enc_packet->client_port = packet->client_port;
        enc_packet->client_addr = packet->client_addr;
        interface_reference(&enc_packet->interface, packet->interface, MDL);
        enc_packet->dhcpv6_container_packet = packet;
        if (packet->dhcp4o6_flags[0] & DHCP4O6_QUERY_UNICAST)
                enc_packet->unicast = 1;

        if (enc_packet->raw->hlen > sizeof(enc_packet->raw->chaddr)) {
                log_info("dhcp4o6_dhcpv4_query: "
                         "discarding packet with bogus hlen.");
                goto exit;
        }

        /* Allocate packet->options now so it is non-null for all packets */
        if (!option_state_allocate (&enc_packet->options, MDL)) {
                log_error("dhcp4o6_dhcpv4_query: no memory for options.");
                goto exit;
        }

        /* If there's an option buffer, try to parse it. */
        if (enc_packet->packet_length >= DHCP_FIXED_NON_UDP + 4) {
                struct option_cache *op;
                if (!parse_options(enc_packet)) {
                        if (enc_packet->options)
                                option_state_dereference
                                        (&enc_packet->options, MDL);
                        packet_dereference (&enc_packet, MDL);
                        goto exit;
                }

                if (enc_packet->options_valid &&
                    (op = lookup_option(&dhcp_universe,
                                        enc_packet->options,
                                        DHO_DHCP_MESSAGE_TYPE))) {
                        struct data_string dp;
                        memset(&dp, 0, sizeof dp);
                        evaluate_option_cache(&dp, enc_packet, NULL, NULL,
                                              enc_packet->options, NULL,
                                              NULL, op, MDL);
                        if (dp.len > 0)
                                enc_packet->packet_type = dp.data[0];
                        else
                                enc_packet->packet_type = 0;
                        data_string_forget(&dp, MDL);
                }
        }

        if (validate_packet(enc_packet) != 0) {
                if (enc_packet->packet_type)
                        dhcp(enc_packet);
                else
                        bootp(enc_packet);
        }

        /* If the caller kept the packet, they'll have upped the refcnt. */
        packet_dereference(&enc_packet, MDL);

        /*
         * If we got no response data, then it is discarded, and
         * our DHCPv4-response is also discarded.
         */
        if (enc_response.data == NULL) {
                goto exit;
        }

        /*
         * Now we can use the response_data buffer.
         */
        response = (struct dhcpv4_over_dhcpv6_packet *)response_data;
        response->msg_type = DHCPV6_DHCPV4_RESPONSE;
        response->flags[0] = response->flags[1] = response->flags[2] = 0;
        response_ofs =
                (int)(offsetof(struct dhcpv4_over_dhcpv6_packet, options));

        /*
         * Get the response option state.
         */
        if (!option_state_allocate(&opt_state, MDL)) {
                log_error("dhcp4o6_dhcpv4_query: no memory for option state.");
                goto exit;
        }

        /*
         * Append our encapsulated stuff for caller.
         */
        if (!save_option_buffer(&dhcpv6_universe, opt_state, NULL,
                                (unsigned char *)enc_response.data,
                                enc_response.len,
                                D6O_DHCPV4_MSG, 0)) {
                log_error("dhcp4o6_dhcpv4_query: error saving DHCPv4 MSG.");
                goto exit;
        }

        response_ofs += store_options6(response_data + response_ofs,
                                       sizeof(response_data) - response_ofs,
                                       opt_state, packet,
                                       required_opts_4o6, NULL);

        /*
         * Return our response to the caller.
         */
        reply_ret->len = response_ofs;
        reply_ret->buffer = NULL;
        if (!buffer_allocate(&reply_ret->buffer, reply_ret->len, MDL)) {
                log_fatal("dhcp4o6_dhcpv4_query: no memory to store reply.");
        }
        reply_ret->data = reply_ret->buffer->data;
        memcpy(reply_ret->buffer->data, response_data, response_ofs);

exit:
        if (opt_state != NULL)
                option_state_dereference(&opt_state, MDL);
        if (enc_response.data != NULL) {
                data_string_forget(&enc_response, MDL);
        }
        if (enc_opt_data.data != NULL) {
                data_string_forget(&enc_opt_data, MDL);
        }
        if (enc_packet != NULL) {
                packet_dereference(&enc_packet, MDL);
        }
}

/*
 * \brief Forward a DHCPv4-query message to the DHCPv4 side
 *  (DHCPv6 server function)
 *
 * Format: interface:16 + address:16 + udp:4 + DHCPv6 DHCPv4-query message
 *
 * \brief packet the DHCPv6 DHCPv4-query message
 */
static void forw_dhcpv4_query(struct packet *packet) {
        struct data_string ds;
        struct udp_data4o6 udp_data;
        unsigned len;
        int cc;

        /* Get the initial message. */
        while (packet->dhcpv6_container_packet != NULL)
                packet = packet->dhcpv6_container_packet;

        /* Check the initial message. */
        if ((packet->raw == NULL) ||
            (packet->client_addr.len != 16) ||
            (packet->interface == NULL)) {
                log_error("forw_dhcpv4_query: can't find initial message.");
                return;
        }

        /* Get a buffer. */
        len = packet->packet_length + 36;
        memset(&ds, 0, sizeof(ds));
        if (!buffer_allocate(&ds.buffer, len, MDL)) {
                log_error("forw_dhcpv4_query: "
                          "no memory for encapsulating packet.");
                return;
        }
        ds.data = ds.buffer->data;
        ds.len = len;

        /* Fill the buffer. */
        strncpy((char *)ds.buffer->data, packet->interface->name, 16);
        memcpy(ds.buffer->data + 16,
               packet->client_addr.iabuf, 16);
        memset(&udp_data, 0, sizeof(udp_data));
        udp_data.src_port = packet->client_port;
        memcpy(ds.buffer->data + 32, &udp_data, 4);
        memcpy(ds.buffer->data + 36,
               (unsigned char *)packet->raw,
               packet->packet_length);

        /* Forward to the DHCPv4 server. */
        cc = send(dhcp4o6_fd, ds.data, ds.len, 0);
        if (cc < 0)
                log_error("forw_dhcpv4_query: send(): %m");
        data_string_forget(&ds, MDL);
}
#endif

static void
dhcpv6_discard(struct packet *packet) {
        /* INSIST(packet->msg_type > 0); */
        /* INSIST(packet->msg_type < dhcpv6_type_name_max); */

        log_debug("Discarding %s from %s; message type not handled by server",
                  dhcpv6_type_names[packet->dhcpv6_msg_type],
                  piaddr(packet->client_addr));
}

static void
build_dhcpv6_reply(struct data_string *reply, struct packet *packet) {
        memset(reply, 0, sizeof(*reply));

        /* I would like to classify the client once here, but
         * as I don't want to classify all of the incoming packets
         * I need to do it before handling specific types.
         * We don't need to classify if we are tossing the packet
         * or if it is a relay - the classification step will get
         * done when we process the inner client packet.
         */

        switch (packet->dhcpv6_msg_type) {
                case DHCPV6_SOLICIT:
                        classify_client(packet);
                        dhcpv6_solicit(reply, packet);
                        break;
                case DHCPV6_ADVERTISE:
                        dhcpv6_discard(packet);
                        break;
                case DHCPV6_REQUEST:
                        classify_client(packet);
                        dhcpv6_request(reply, packet);
                        break;
                case DHCPV6_CONFIRM:
                        classify_client(packet);
                        dhcpv6_confirm(reply, packet);
                        break;
                case DHCPV6_RENEW:
                        classify_client(packet);
                        dhcpv6_renew(reply, packet);
                        break;
                case DHCPV6_REBIND:
                        classify_client(packet);
                        dhcpv6_rebind(reply, packet);
                        break;
                case DHCPV6_REPLY:
                        dhcpv6_discard(packet);
                        break;
                case DHCPV6_RELEASE:
                        classify_client(packet);
                        dhcpv6_release(reply, packet);
                        break;
                case DHCPV6_DECLINE:
                        classify_client(packet);
                        dhcpv6_decline(reply, packet);
                        break;
                case DHCPV6_RECONFIGURE:
                        dhcpv6_discard(packet);
                        break;
                case DHCPV6_INFORMATION_REQUEST:
                        classify_client(packet);
                        dhcpv6_information_request(reply, packet);
                        break;
                case DHCPV6_RELAY_FORW:
#ifdef DHCP4o6
                        if (dhcpv4_over_dhcpv6 && (local_family == AF_INET))
                                dhcp4o6_relay_forw(reply, packet);
                        else
#endif /* DHCP4o6 */
                        dhcpv6_relay_forw(reply, packet);
                        break;
                case DHCPV6_RELAY_REPL:
                        dhcpv6_discard(packet);
                        break;
                case DHCPV6_LEASEQUERY:
                        classify_client(packet);
                        dhcpv6_leasequery(reply, packet);
                        break;
                case DHCPV6_LEASEQUERY_REPLY:
                        dhcpv6_discard(packet);
                        break;
                case DHCPV6_DHCPV4_QUERY:
#ifdef DHCP4o6
                        if (dhcpv4_over_dhcpv6) {
                                if (local_family == AF_INET6) {
                                        forw_dhcpv4_query(packet);
                                } else {
                                        dhcp4o6_dhcpv4_query(reply, packet);
                                }
                        } else
#endif /* DHCP4o6 */
                        dhcpv6_discard(packet);
                        break;
                case DHCPV6_DHCPV4_RESPONSE:
                        dhcpv6_discard(packet);
                        break;
                default:
                        /* XXX: would be nice if we had "notice" level,
                                as syslog, for this */
                        log_info("Discarding unknown DHCPv6 message type %d "
                                 "from %s", packet->dhcpv6_msg_type,
                                 piaddr(packet->client_addr));
        }
}

static void
log_packet_in(const struct packet *packet) {
        struct data_string s;
        u_int32_t tid;
        char tmp_addr[INET6_ADDRSTRLEN];
        const void *addr;

        memset(&s, 0, sizeof(s));

        if (packet->dhcpv6_msg_type < dhcpv6_type_name_max) {
                data_string_sprintfa(&s, "%s message from %s port %d",
                                     dhcpv6_type_names[packet->dhcpv6_msg_type],
                                     piaddr(packet->client_addr),
                                     ntohs(packet->client_port));
        } else {
                data_string_sprintfa(&s,
                                     "Unknown message type %d from %s port %d",
                                     packet->dhcpv6_msg_type,
                                     piaddr(packet->client_addr),
                                     ntohs(packet->client_port));
        }
        if ((packet->dhcpv6_msg_type == DHCPV6_RELAY_FORW) ||
            (packet->dhcpv6_msg_type == DHCPV6_RELAY_REPL)) {
                addr = &packet->dhcpv6_link_address;
                data_string_sprintfa(&s, ", link address %s",
                                     inet_ntop(AF_INET6, addr,
                                               tmp_addr, sizeof(tmp_addr)));
                addr = &packet->dhcpv6_peer_address;
                data_string_sprintfa(&s, ", peer address %s",
                                     inet_ntop(AF_INET6, addr,
                                               tmp_addr, sizeof(tmp_addr)));
        } else if ((packet->dhcpv6_msg_type != DHCPV6_DHCPV4_QUERY) &&
                   (packet->dhcpv6_msg_type != DHCPV6_DHCPV4_RESPONSE)) {
                tid = 0;
                memcpy(((char *)&tid)+1, packet->dhcpv6_transaction_id, 3);
                data_string_sprintfa(&s, ", transaction ID 0x%06X", tid);

/*
                oc = lookup_option(&dhcpv6_universe, packet->options,
                                   D6O_CLIENTID);
                if (oc != NULL) {
                        memset(&tmp_ds, 0, sizeof(tmp_ds_));
                        if (!evaluate_option_cache(&tmp_ds, packet, NULL, NULL,
                                                   packet->options, NULL,
                                                   &global_scope, oc, MDL)) {
                                log_error("Error evaluating Client Identifier");
                        } else {
                                data_strint_sprintf(&s, ", client ID %s",

                                data_string_forget(&tmp_ds, MDL);
                        }
                }
*/

        }
        log_info("%s", s.data);

        data_string_forget(&s, MDL);
}

void
dhcpv6(struct packet *packet) {
        struct data_string reply;
        struct sockaddr_in6 to_addr;
        int send_ret;

        /*
         * Log a message that we received this packet.
         */
        log_packet_in(packet);

        /*
         * Build our reply packet.
         */
        build_dhcpv6_reply(&reply, packet);

        if (reply.data != NULL) {
                /*
                 * Send our reply, if we have one.
                 */
                memset(&to_addr, 0, sizeof(to_addr));
                to_addr.sin6_family = AF_INET6;
                if ((packet->dhcpv6_msg_type == DHCPV6_RELAY_FORW) ||
                    (packet->dhcpv6_msg_type == DHCPV6_RELAY_REPL)) {
                        to_addr.sin6_port = local_port;
                } else {
                        to_addr.sin6_port = remote_port;
                }

#if defined (REPLY_TO_SOURCE_PORT)
                /*
                 * This appears to have been included for testing so we would
                 * not need a root client, but was accidently left in the
                 * final code.  We continue to include it in case
                 * some users have come to rely upon it, but leave
                 * it off by default as it's a bad idea.
                 */
                to_addr.sin6_port = packet->client_port;
#endif

#if defined(RELAY_PORT)
                /*
                 * Check relay source port.
                 */
                if (packet->relay_source_port) {
                        to_addr.sin6_port = packet->client_port;
                }
#endif

                memcpy(&to_addr.sin6_addr, packet->client_addr.iabuf,
                       sizeof(to_addr.sin6_addr));

                log_info("Sending %s to %s port %d",
                         dhcpv6_type_names[reply.data[0]],
                         piaddr(packet->client_addr),
                         ntohs(to_addr.sin6_port));

                send_ret = send_packet6(packet->interface,
                                        reply.data, reply.len, &to_addr);
                if (send_ret != reply.len) {
                        log_error("dhcpv6: send_packet6() sent %d of %d bytes",
                                  send_ret, reply.len);
                }
                data_string_forget(&reply, MDL);
        }
}

#ifdef DHCP4o6
/*
 * \brief Receive a DHCPv4-query message from the DHCPv6 side
 *  (DHCPv4 server function)
 *
 * Receive a message with a DHCPv4-query inside from the DHCPv6 server.
 * (code copied from \ref do_packet6() \ref and dhcpv6())
 *
 * Format: interface:16 + address:16 + udp:4 + DHCPv6 DHCPv4-query message
 *
 * \param raw the DHCPv6 DHCPv4-query message raw content
 */
static void recv_dhcpv4_query(struct data_string *raw) {
        struct interface_info *ip;
        char name[16 + 1];
        struct iaddr iaddr;
        struct packet *packet;
        unsigned char msg_type;
        const struct dhcpv6_relay_packet *relay;
        const struct dhcpv4_over_dhcpv6_packet *msg;
        struct data_string reply;
        struct data_string ds;
        struct udp_data4o6 udp_data;
        unsigned len;
        int cc;

        memset(name, 0, sizeof(name));
        memcpy(name, raw->data, 16);
        for (ip = interfaces; ip != NULL; ip = ip->next) {
                if (!strcmp(name, ip->name))
                        break;
        }
        if (ip == NULL) {
                log_error("recv_dhcpv4_query: can't find interface %s.",
                          name);
                return;
        }

        iaddr.len = 16;
        memcpy(iaddr.iabuf, raw->data + 16, 16);

        memset(&udp_data, 0, sizeof(udp_data));
        memcpy(&udp_data, raw->data + 32, 4);

        /*
         * From do_packet6().
         */

        if (!packet6_len_okay((char *)raw->data + 36, raw->len - 36)) {
                log_error("recv_dhcpv4_query: "
                         "short packet from %s, len %d, dropped",
                         piaddr(iaddr), raw->len - 36);
                return;
        }

        /*
         * Build a packet structure.
         */
        packet = NULL;
        if (!packet_allocate(&packet, MDL)) {
                log_error("recv_dhcpv4_query: no memory for packet.");
                return;
        }

        if (!option_state_allocate(&packet->options, MDL)) {
                log_error("recv_dhcpv4_query: no memory for options.");
                packet_dereference(&packet, MDL);
                return;
        }

        packet->raw = (struct dhcp_packet *)(raw->data + 36);
        packet->packet_length = raw->len - 36;
        packet->client_port = udp_data.src_port;
        packet->client_addr = iaddr;
        interface_reference(&packet->interface, ip, MDL);

        msg_type = raw->data[36];
        if ((msg_type == DHCPV6_RELAY_FORW) ||
            (msg_type == DHCPV6_RELAY_REPL)) {
                int relaylen =
                    (int)(offsetof(struct dhcpv6_relay_packet, options));
                relay = (const struct dhcpv6_relay_packet *)(raw->data + 36);
                packet->dhcpv6_msg_type = relay->msg_type;

                /* relay-specific data */
                packet->dhcpv6_hop_count = relay->hop_count;
                memcpy(&packet->dhcpv6_link_address,
                       relay->link_address, sizeof(relay->link_address));
                memcpy(&packet->dhcpv6_peer_address,
                       relay->peer_address, sizeof(relay->peer_address));

                if (!parse_option_buffer(packet->options,
                                         relay->options,
                                         raw->len - 36 - relaylen,
                                         &dhcpv6_universe)) {
                        /* no logging here, as parse_option_buffer() logs all
                           cases where it fails */
                        packet_dereference(&packet, MDL);
                        return;
                }
        } else if ((msg_type == DHCPV6_DHCPV4_QUERY) ||
                   (msg_type == DHCPV6_DHCPV4_RESPONSE)) {
                int msglen =
                    (int)(offsetof(struct dhcpv4_over_dhcpv6_packet, options));
                msg = (struct dhcpv4_over_dhcpv6_packet *)(raw->data + 36);
                packet->dhcpv6_msg_type = msg->msg_type;

                /* message-specific data */
                memcpy(packet->dhcp4o6_flags, msg->flags,
                       sizeof(packet->dhcp4o6_flags));

                if (!parse_option_buffer(packet->options,
                                         msg->options,
                                         raw->len - 36 - msglen,
                                         &dhcpv6_universe)) {
                        /* no logging here, as parse_option_buffer() logs all
                           cases where it fails */
                        packet_dereference(&packet, MDL);
                        return;
                }
        } else {
                log_error("recv_dhcpv4_query: unexpected message of type %d.",
                          (int)msg_type);
                packet_dereference(&packet, MDL);
                return;
        }

        /*
         * From dhcpv6().
         */

        /*
         * Log a message that we received this packet.
         */
        /* log_packet_in(packet); */
        memset(&ds, 0, sizeof(ds));
        if (packet->dhcpv6_msg_type < dhcpv6_type_name_max) {
                data_string_sprintfa(&ds, "%s message from %s",
                                     dhcpv6_type_names[packet->dhcpv6_msg_type],
                                     piaddr(packet->client_addr));
        } else {
                data_string_sprintfa(&ds,
                                     "Unknown message type %d from %s",
                                     packet->dhcpv6_msg_type,
                                     piaddr(packet->client_addr));
        }
        if ((packet->dhcpv6_msg_type == DHCPV6_RELAY_FORW) ||
            (packet->dhcpv6_msg_type == DHCPV6_RELAY_REPL)) {
                char tmp_addr[INET6_ADDRSTRLEN];
                const void *addr;

                addr = &packet->dhcpv6_link_address;
                data_string_sprintfa(&ds, ", link address %s",
                                     inet_ntop(AF_INET6, addr,
                                               tmp_addr, sizeof(tmp_addr)));
                addr = &packet->dhcpv6_peer_address;
                data_string_sprintfa(&ds, ", peer address %s",
                                     inet_ntop(AF_INET6, addr,
                                               tmp_addr, sizeof(tmp_addr)));
        } else if ((packet->dhcpv6_msg_type != DHCPV6_DHCPV4_QUERY) &&
                   (packet->dhcpv6_msg_type != DHCPV6_DHCPV4_RESPONSE)) {
                u_int32_t tid = 0;

                memcpy(((char *)&tid)+1, packet->dhcpv6_transaction_id, 3);
                data_string_sprintfa(&ds, ", transaction ID 0x%06X", tid);
        }
        log_info("%s", ds.data);
        data_string_forget(&ds, MDL);

        /*
         * Build our reply packet.
         */
        build_dhcpv6_reply(&reply, packet);

        if (reply.data == NULL) {
                packet_dereference(&packet, MDL);
                return;
        }

        /*
         * Forward the response.
         */
        len = reply.len + 36;
        memset(&ds, 0, sizeof(ds));
        if (!buffer_allocate(&ds.buffer, len, MDL)) {
                log_error("recv_dhcpv4_query: no memory.");
                packet_dereference(&packet, MDL);
                return;
        }
        ds.data = ds.buffer->data;
        ds.len = len;

        memcpy(ds.buffer->data, name, 16);
        memcpy(ds.buffer->data + 16, iaddr.iabuf, 16);
        udp_data.rsp_opt_exist = packet->relay_source_port ? 1 : 0;
        memcpy(ds.buffer->data + 32, &udp_data, 4);
        memcpy(ds.buffer->data + 36, reply.data, reply.len);

        /*
         * Now we can release the packet.
         */
        packet_dereference(&packet, MDL);

        cc = send(dhcp4o6_fd, ds.data, ds.len, 0);
        if (cc < 0)
                log_error("recv_dhcpv4_query: send(): %m");
        data_string_forget(&ds, MDL);
}
#endif /* DHCP4o6 */

static void
seek_shared_host(struct host_decl **hp, struct shared_network *shared) {
        struct host_decl *nofixed = NULL;
        struct host_decl *seek, *hold = NULL;

        /*
         * Seek forward through fixed addresses for the right link.
         *
         * Note: how to do this for fixed prefixes???
         */
        host_reference(&hold, *hp, MDL);
        host_dereference(hp, MDL);
        seek = hold;
        while (seek != NULL) {
                if (seek->fixed_addr == NULL)
                        nofixed = seek;
                else if (fixed_matches_shared(seek, shared))
                        break;

                seek = seek->n_ipaddr;
        }

        if ((seek == NULL) && (nofixed != NULL))
                seek = nofixed;

        if (seek != NULL)
                host_reference(hp, seek, MDL);
}

static isc_boolean_t
fixed_matches_shared(struct host_decl *host, struct shared_network *shared) {
        struct subnet *subnet;
        struct data_string addr;
        isc_boolean_t matched;
        struct iaddr fixed;

        if (host->fixed_addr == NULL)
                return ISC_FALSE;

        memset(&addr, 0, sizeof(addr));
        if (!evaluate_option_cache(&addr, NULL, NULL, NULL, NULL, NULL,
                                   &global_scope, host->fixed_addr, MDL))
                return ISC_FALSE;

        if (addr.len < 16) {
                data_string_forget(&addr, MDL);
                return ISC_FALSE;
        }

        fixed.len = 16;
        memcpy(fixed.iabuf, addr.data, 16);

        matched = ISC_FALSE;
        for (subnet = shared->subnets ; subnet != NULL ;
             subnet = subnet->next_sibling) {
                if (addr_eq(subnet_number(fixed, subnet->netmask),
                            subnet->net)) {
                        matched = ISC_TRUE;
                        break;
                }
        }

        data_string_forget(&addr, MDL);
        return matched;
}

/*!
 *
 * \brief Constructs a REPLY with status of UseMulticast to a given packet
 *
 * Per RFC 3315 Secs 18.2.1,3,6 & 7, when a server rejects a client's
 * unicast-sent packet, the response must only contain the client id,
 * server id, and a status code option of 5 (UseMulticast).  This function
 * constructs such a packet and returns it as a data_string.
 *
 * \param reply_ret = data_string which will receive the newly constructed
 * reply
 * \param packet = client request which is being rejected
 * \param client_id = data_string which contains the client id
 * \param server_id = data_string which which contains the server id
 *
 */
void
unicast_reject(struct data_string *reply_ret,
             struct packet *packet,
             const struct data_string *client_id,
             const struct data_string *server_id)
{
        struct reply_state reply;
        memset(&reply, 0x0, sizeof(struct reply_state));

        /* Locate the client. */
        if (shared_network_from_packet6(&reply.shared, packet)
                != ISC_R_SUCCESS) {
                log_error("unicast_reject: could not locate client.");
                return;
        }

        /* Initialize the reply. */
        packet_reference(&reply.packet, packet, MDL);
        data_string_copy(&reply.client_id, client_id, MDL);

        if (start_reply(packet, client_id, server_id, &reply.opt_state,
                         &reply.buf.reply)) {
                /* Set the UseMulticast status code. */
                if (!set_status_code(STATUS_UseMulticast,
                                     "Unicast not allowed by server.",
                                     reply.opt_state)) {
                        log_error("unicast_reject: Unable to set status code.");
                } else {
                        /* Set write cursor to just past the reply header. */
                        reply.cursor = REPLY_OPTIONS_INDEX;
                        reply.cursor += store_options6(((char *)reply.buf.data
                                                        + reply.cursor),
                                                       (sizeof(reply.buf)
                                                        - reply.cursor),
                                                       reply.opt_state,
                                                       reply.packet,
                                                       unicast_reject_opts,
                                                       NULL);

                        /* Return our reply to the caller. */
                        reply_ret->len = reply.cursor;
                        reply_ret->buffer = NULL;
                        if (!buffer_allocate(&reply_ret->buffer,
                                             reply.cursor, MDL)) {
                                log_fatal("unicast_reject:"
                                          "No memory to store Reply.");
                        }

                        memcpy(reply_ret->buffer->data, reply.buf.data,
                               reply.cursor);
                        reply_ret->data = reply_ret->buffer->data;
                }

        }

        /* Cleanup. */
        if (reply.shared != NULL)
                shared_network_dereference(&reply.shared, MDL);
        if (reply.opt_state != NULL)
                option_state_dereference(&reply.opt_state, MDL);
        if (reply.packet != NULL)
                packet_dereference(&reply.packet, MDL);
        if (reply.client_id.data != NULL)
                data_string_forget(&reply.client_id, MDL);
}

/*!
 *
 * \brief Checks if the dhcp6.unicast option has been defined
 *
 * Scans the option space for the presence of the dhcp6.unicast option. The
 * function attempts to map the inbound packet to a shared network first
 * by an ip address specified via an D6O_IA_XX option and if that fails then
 * by the packet's source information (e.g. relay link, link, or interace).
 * Once the packet is mapped to a shared network, the function executes all
 * statements from the network's group outward into a local option cache.
 * The option cache is then scanned for the presence of unicast option.  If
 * the packet cannot be mapped to a shared network, the function returns
 * ISC_FALSE.
 * \param packet inbound packet from the client
 *
 * \return ISC_TRUE if the dhcp6.unicast option is defined, false otherwise.
 *
 */
isc_boolean_t
is_unicast_option_defined(struct packet *packet) {
        isc_boolean_t is_defined = ISC_FALSE;
        struct option_state *opt_state = NULL;
        struct option_cache *oc = NULL;
        struct shared_network *shared = NULL;

        if (!option_state_allocate(&opt_state, MDL)) {
                log_fatal("is_unicast_option_defined:"
                          "No memory for option state.");
        }

        /* We try to map the packet to a network first by an IA_XX value.
         * If that fails, we try by packet source. */
        if (((shared_network_from_requested_addr(&shared, packet)
             != ISC_R_SUCCESS) &&
            (shared_network_from_packet6(&shared, packet) != ISC_R_SUCCESS))
            || (shared == NULL)) {
                /* @todo what would this really mean? I think wrong network
                 * logic will catch it */
                log_error("is_unicast_option_defined:"
                          "cannot attribute packet to a network.");
                return (ISC_FALSE);
        }

        /* Now that we've mapped it to a network, execute statments to that
         * scope, looking for the unicast option. We don't care about the
         * value of the option, only whether or not it is defined. */
        execute_statements_in_scope(NULL, NULL, NULL, NULL, NULL, opt_state,
                                    &global_scope, shared->group, NULL, NULL);

        oc = lookup_option(&dhcpv6_universe, opt_state, D6O_UNICAST);
        is_defined = (oc != NULL ? ISC_TRUE : ISC_FALSE);
        log_debug("is_unicast_option_defined: option found : %d", is_defined);

        if (shared != NULL) {
                shared_network_dereference(&shared, MDL);
        }

        if (opt_state != NULL) {
                option_state_dereference(&opt_state, MDL);
        }

        return (is_defined);
}

/*!
 *
 * \brief Maps a packet to a shared network based on the requested IP address
 *
 * The function attempts to find a subnet that matches the first requested IP
 * address contained within the given packet.  Note that it looks first for
 * D6O_IA_NAs, then D6O_IA_PDs and lastly D6O_IA_TAs.  If a matching network is
 * found, a reference to it is returned in the parameter, shared.
 *
 * \param shared shared_network pointer which will receive the matching network
 * \param packet inbound packet from the client
 *
 * \return ISC_R_SUCCESS if the packet can be mapped to a shared_network.
 *
 */
static isc_result_t
shared_network_from_requested_addr (struct shared_network **shared,
                                    struct packet* packet) {
        struct iaddr iaddr;
        struct subnet* subnet = NULL;
        isc_result_t status = ISC_R_FAILURE;

        /* Try to match first IA_ address or prefix we find to a subnet. In
         * theory all  IA_ values in a given request are supposed to be in the
         * same subnet so we only need to try one right? */
        if ((get_first_ia_addr_val(packet, D6O_IA_NA, &iaddr) != ISC_R_SUCCESS)
             && (get_first_ia_addr_val(packet, D6O_IA_PD, &iaddr)
                 != ISC_R_SUCCESS)
             && (get_first_ia_addr_val(packet, D6O_IA_TA, &iaddr)
                 != ISC_R_SUCCESS))  {
                /* we found nothing to match against */
                log_debug("share_network_from_request_addr: nothing to match");
                return (ISC_R_FAILURE);
        }

        if (!find_subnet(&subnet, iaddr, MDL)) {
                log_debug("shared_network_from_requested_addr:"
                          "No subnet found for addr %s.", piaddr(iaddr));
        } else {
                status = shared_network_reference(shared,
                                                  subnet->shared_network, MDL);
                subnet_dereference(&subnet, MDL);
                log_debug("shared_network_from_requested_addr:"
                          " found shared network %s for address %s.",
                          ((*shared)->name ? (*shared)->name : "unnamed"),
                          piaddr(iaddr));
                return (status);
        }

        return (ISC_R_FAILURE);
}

/*!
 *
 * \brief Retrieves the first IP address from a given packet of a given type
 *
 * Search a packet for options of a given type (D6O_IA_AN, D6O_IA_PD, or
 * D6O_IA_TA) for the first non-blank IA_XX value and return its IP address
 * component.
 *
 * \param packet packet received from the client
 * \param addr_type the address option type (D6O_IA_NA , D6O_IA_PD, or
 * D6O_IP_TA) to look for within the packet.
 * \param iaddr pointer to the iaddr structure which will receive the extracted
 * address.
 *
 * \return ISC_R_SUCCESS if an address was succesfully extracted, ISC_R_FALURE
 * otherwise.
 *
 */
static isc_result_t
get_first_ia_addr_val (struct packet* packet, int addr_type,
                       struct iaddr* iaddr)  {
        struct option_cache *ia;
        struct option_cache *oc = NULL;
        struct data_string cli_enc_opt_data;
        struct option_state *cli_enc_opt_state;
        int addr_opt_offset;
        int addr_opt;
        int addr_opt_data_len;
        int ip_addr_offset;

        isc_result_t status = ISC_R_FAILURE;
        memset(iaddr, 0, sizeof(struct iaddr));

        /* Set up address type specifics */
        switch (addr_type) {
        case D6O_IA_NA:
                addr_opt_offset = IA_NA_OFFSET;
                addr_opt = D6O_IAADDR;
                addr_opt_data_len = 24;
                ip_addr_offset = 0;
                break;
        case D6O_IA_TA:
                addr_opt_offset = IA_TA_OFFSET;
                addr_opt = D6O_IAADDR;
                addr_opt_data_len = 24;
                ip_addr_offset = 0;
                break;
        case D6O_IA_PD:
                addr_opt_offset = IA_PD_OFFSET;
                addr_opt = D6O_IAPREFIX;
                addr_opt_data_len = 25;
                ip_addr_offset = 9;
                break;
        default:
                /* shouldn't be here */
                log_error ("get_first_ia_addr_val: invalid opt type %d",
                           addr_type);
                return (ISC_R_FAILURE);
        }

        /* Find the first, non-blank IA_XX value within an D6O_IA_XX option. */
        for (ia = lookup_option(&dhcpv6_universe, packet->options, addr_type);
             ia != NULL && oc == NULL; ia = ia->next) {
                if (!get_encapsulated_IA_state(&cli_enc_opt_state,
                                               &cli_enc_opt_data,
                                               packet, ia, addr_opt_offset)) {
                        log_debug ("get_first_ia_addr_val:"
                                   " couldn't unroll enclosing option");
                        return (ISC_R_FAILURE);
                }

                oc = lookup_option(&dhcpv6_universe, cli_enc_opt_state,
                                   addr_opt);
                if (oc == NULL) {
                        /* no address given for this IA, ignore */
                        option_state_dereference(&cli_enc_opt_state, MDL);
                        data_string_forget(&cli_enc_opt_data, MDL);
                }
        }

        /* If we found a non-blank IA_XX then extract its ip address. */
        if (oc != NULL) {
                struct data_string iaddr_str;

                memset(&iaddr_str, 0, sizeof(iaddr_str));
                if (!evaluate_option_cache(&iaddr_str, packet, NULL, NULL,
                                          packet->options, NULL, &global_scope,
                                          oc, MDL)) {
                        log_error("get_first_ia_addr_val: "
                                  "error evaluating IA_XX option.");
                } else {
                        if (iaddr_str.len != addr_opt_data_len) {
                                log_error("shared_network_from_requested_addr:"
                                          " invalid length %d, expected %d",
                                          iaddr_str.len, addr_opt_data_len);
                        } else {
                                iaddr->len = 16;
                                memcpy (iaddr->iabuf,
                                        iaddr_str.data + ip_addr_offset, 16);
                                status = ISC_R_SUCCESS;
                        }
                        data_string_forget(&iaddr_str, MDL);
                }

                option_state_dereference(&cli_enc_opt_state, MDL);
                data_string_forget(&cli_enc_opt_data, MDL);
        }

        return (status);
}

/*
* \brief Calculates the reply T1/T2 times and stuffs them in outbound buffer
*
* T1/T2 time selection is kind of weird.  We actually use DHCP * (v4) scoped
* options, dhcp-renewal-time and dhcp-rebinding-time, as handy existing places
* where these can be configured by an administrator.  A value of zero tells the
* client it may choose its own value.
*
* When those options are not defined, the values will be set to zero unless
* the global option, dhcpv6-set-tee-times is enabled. When this option is
* enabled the values are calculated as recommended by RFC 3315, Section 22.4:
*
*       T1 will be set to 0.5 times the shortest preferred lifetime
*       in the IA_XX option.  If the "shortest" preferred lifetime is
*       0xFFFFFFFF,  T1 will set to 0xFFFFFFFF.
*
*       T2 will be set to 0.8 times the shortest preferred lifetime
*       in the IA_XX option.  If the "shortest" preferred lifetime is
*       0xFFFFFFFF,  T2 will set to 0xFFFFFFFF.
*
* Note that dhcpv6-set-tee-times is intended to be transitional and will
* likely be removed in 4.4.0, leaving the behavior as getting the values
* either from the configured parameters (if you want zeros, define them as
* zeros) or by calculating them per the RFC.
*
* \param reply - pointer to the reply_state structure
* \param ia_cursor - offset of the beginning of the IA_XX option within the
* reply's outbound data buffer
*/
static void
set_reply_tee_times(struct reply_state* reply, unsigned ia_cursor)
{
        struct option_cache *oc;
        int set_tee_times;

        /* Found out if calculated values are enabled. */
        oc = lookup_option(&server_universe, reply->opt_state,
                           SV_DHCPV6_SET_TEE_TIMES);
        set_tee_times = (oc &&
                         evaluate_boolean_option_cache(NULL, reply->packet,
                                                       NULL, NULL,
                                                       reply->packet->options,
                                                       reply->opt_state,
                                                       &global_scope, oc, MDL));

        oc = lookup_option(&dhcp_universe, reply->opt_state,
                           DHO_DHCP_RENEWAL_TIME);
        if (oc != NULL) {
                /* dhcp-renewal-time is defined, use it */
                struct data_string data;
                memset(&data, 0x00, sizeof(data));

                if (!evaluate_option_cache(&data, reply->packet, NULL, NULL,
                                           reply->packet->options,
                                           reply->opt_state, &global_scope,
                                           oc, MDL) ||
                    (data.len != 4)) {
                        log_error("Invalid renewal time.");
                        reply->renew = 0;
                } else {
                        reply->renew = getULong(data.data);
                }

                if (data.data != NULL)
                        data_string_forget(&data, MDL);
        } else if (set_tee_times) {
                /* Setting them is enabled so T1 is either infinite or
                 * 0.5 * the shortest preferred lifetime in the IA_XX  */
                if (reply->min_prefer == INFINITE_TIME)
                        reply->renew = INFINITE_TIME;
                else
                        reply->renew = reply->min_prefer / 2;
        } else {
                /* Default is to let the client choose */
                reply->renew = 0;
        }

        putULong(reply->buf.data + ia_cursor + 8, reply->renew);

        /* Now T2. */
        oc = lookup_option(&dhcp_universe, reply->opt_state,
                           DHO_DHCP_REBINDING_TIME);
        if (oc != NULL) {
                /* dhcp-rebinding-time is defined, use it */
                struct data_string data;
                memset(&data, 0x00, sizeof(data));

                if (!evaluate_option_cache(&data, reply->packet, NULL, NULL,
                                           reply->packet->options,
                                           reply->opt_state, &global_scope,
                                           oc, MDL) ||
                    (data.len != 4)) {
                        log_error("Invalid rebinding time.");
                        reply->rebind = 0;
                } else {
                        reply->rebind = getULong(data.data);
                }

                if (data.data != NULL)
                        data_string_forget(&data, MDL);
        } else if (set_tee_times) {
                /* Setting them is enabled so T2 is either infinite or
                 * 0.8 * the shortest preferred lifetime in the reply */
                if (reply->min_prefer == INFINITE_TIME)
                        reply->rebind = INFINITE_TIME;
                else
                        reply->rebind = (reply->min_prefer / 5) * 4;
        } else {
                /* Default is to let the client choose */
                reply->rebind = 0;
        }

        putULong(reply->buf.data + ia_cursor + 12, reply->rebind);
}

/*
 * Releases the iasubopts in the pre-existing IA, if they are not in
 * the same shared-network as the new IA.
 *
 * returns 1 if the release was done, 0 otherwise
 */
int
release_on_roam(struct reply_state* reply) {
        struct ia_xx* old_ia = reply->old_ia;
        struct iasubopt *lease = NULL;
        int i;

        if ((!do_release_on_roam) || old_ia == NULL
            || old_ia->num_iasubopt <= 0) {
                return(0);
        }

        /* If the old shared-network and new are the same, client hasn't
        * roamed, nothing to do. We only check the first one because you
        * cannot have iasubopts on different shared-networks within a
        * single ia. */
        lease = old_ia->iasubopt[0];
        if (lease->ipv6_pool->shared_network == reply->shared) {
                return (0);
        }

        /* Old and new are on different shared networks so the client must
        * roamed. Release the old leases. */
        for (i = 0;  i < old_ia->num_iasubopt; i++) {
                lease = old_ia->iasubopt[i];

                log_info("Client: %s roamed to new network,"
                         " releasing lease: %s%s",
                         print_hex_1(reply->client_id.len,
                                     reply->client_id.data, 60),
                         pin6_addr(&lease->addr), iasubopt_plen_str(lease));

                release_lease6(lease->ipv6_pool, lease);
                lease->ia->cltt = cur_time;
                write_ia(lease->ia);
        }

        return (1);
}

/*
 * Convenience function which returns a string (static buffer)
 * containing either a "/" followed by the prefix length or an
 * empty string depending on the lease type
 */
const char *iasubopt_plen_str(struct iasubopt *lease) {
        static char prefix_buf[16];
        *prefix_buf = 0;
        if ((lease->ia) && (lease->ia->ia_type == D6O_IA_PD)) {
                sprintf(prefix_buf, "/%-d", lease->plen);
        }

        return (prefix_buf);
}

#ifdef NSUPDATE
/*
 * Initiates DDNS updates for static v6 leases if configured to do so.
 *
 * The function, which must be called after the IA has been written to the
 * packet, adds an iasubopt to the IA for static lease.  This is done so we
 * have an iasubopt to pass into ddns_updates().  A reference to the IA is
 * added to the DDNS control block to ensure it and it's iasubopt remain in
 * scope until the update is complete.
 *
 */
void ddns_update_static6(struct reply_state* reply) {
        struct iasubopt *iasub = NULL;
        struct binding_scope *scope = NULL;
        struct option_cache *oc = NULL;

        oc = lookup_option(&server_universe, reply->opt_state, SV_DDNS_UPDATES);
        if ((oc != NULL) &&
                (evaluate_boolean_option_cache(NULL, reply->packet, NULL, NULL,
                                               reply->packet->options,
                                               reply->opt_state, NULL,
                                               oc, MDL) == 0)) {
                return;
        }

        oc = lookup_option(&server_universe, reply->opt_state,
                           SV_UPDATE_STATIC_LEASES);
        if ((oc == NULL) ||
                (evaluate_boolean_option_cache(NULL, reply->packet,
                                                     NULL, NULL,
                                                     reply->packet->options,
                                                     reply->opt_state, NULL,
                                                     oc, MDL) == 0)) {
                return;
        }

        if (iasubopt_allocate(&iasub, MDL) != ISC_R_SUCCESS) {
                log_fatal("No memory for iasubopt.");
        }

        if (ia_add_iasubopt(reply->ia, iasub, MDL) != ISC_R_SUCCESS) {
                log_fatal("Could not add iasubopt.");
        }

        ia_reference(&iasub->ia, reply->ia, MDL);

        memcpy(iasub->addr.s6_addr, reply->fixed.data, 16);
        iasub->plen = 0;
        iasub->prefer =  MAX_TIME;
        iasub->valid =  MAX_TIME;
        iasub->static_lease = 1;

        if (!binding_scope_allocate(&scope, MDL)) {
                log_fatal("Out of memory for binding scope.");
        }

        binding_scope_reference(&iasub->scope, scope, MDL);

        ddns_updates(reply->packet, NULL, NULL, iasub, NULL, reply->opt_state);
}
#endif /* NSUPDATE */

#endif /* DHCPv6 */