Merged rt35711c (DHCPv4-over-DHCPv6 support)

[thirdparty/dhcp.git] / client / dhc6.c

/* dhc6.c - DHCPv6 client routines. */

/*
 * Copyright (c) 2012-2016 by Internet Systems Consortium, Inc. ("ISC")
 * Copyright (c) 2006-2010 by Internet Systems Consortium, Inc. ("ISC")
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * 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.
 *
 *   Internet Systems Consortium, Inc.
 *   950 Charter Street
 *   Redwood City, CA 94063
 *   <info@isc.org>
 *   https://www.isc.org/
 */

#include "dhcpd.h"

#ifdef DHCPv6

struct sockaddr_in6 DHCPv6DestAddr;

/*
 * Option definition structures that are used by the software - declared
 * here once and assigned at startup to save lookups.
 */
struct option *clientid_option = NULL;
struct option *elapsed_option = NULL;
struct option *ia_na_option = NULL;
struct option *ia_ta_option = NULL;
struct option *ia_pd_option = NULL;
struct option *iaaddr_option = NULL;
struct option *iaprefix_option = NULL;
struct option *oro_option = NULL;
struct option *irt_option = NULL;

static struct dhc6_lease *dhc6_dup_lease(struct dhc6_lease *lease,
                                         const char *file, int line);
static struct dhc6_ia *dhc6_dup_ia(struct dhc6_ia *ia,
                                   const char *file, int line);
static struct dhc6_addr *dhc6_dup_addr(struct dhc6_addr *addr,
                                       const char *file, int line);
static void dhc6_ia_destroy(struct dhc6_ia **src, const char *file, int line);
static isc_result_t dhc6_parse_ia_na(struct dhc6_ia **pia,
                                     struct packet *packet,
                                     struct option_state *options,
                                     unsigned code);
static isc_result_t dhc6_parse_ia_ta(struct dhc6_ia **pia,
                                     struct packet *packet,
                                     struct option_state *options,
                                     unsigned code);
static isc_result_t dhc6_parse_ia_pd(struct dhc6_ia **pia,
                                     struct packet *packet,
                                     struct option_state *options,
                                     unsigned code);
static isc_result_t dhc6_parse_addrs(struct dhc6_addr **paddr,
                                     struct packet *packet,
                                     struct option_state *options);
static isc_result_t dhc6_parse_prefixes(struct dhc6_addr **ppref,
                                        struct packet *packet,
                                        struct option_state *options);
static struct dhc6_ia *find_ia(struct dhc6_ia *head,
                               u_int16_t type, const char *id);
static struct dhc6_addr *find_addr(struct dhc6_addr *head,
                                   struct iaddr *address);
static struct dhc6_addr *find_pref(struct dhc6_addr *head,
                                   struct iaddr *prefix, u_int8_t plen);
void init_handler(struct packet *packet, struct client_state *client);
void info_request_handler(struct packet *packet, struct client_state *client);
void rapid_commit_handler(struct packet *packet, struct client_state *client);
void do_init6(void *input);
void do_info_request6(void *input);
void do_confirm6(void *input);
void reply_handler(struct packet *packet, struct client_state *client);
static isc_result_t dhc6_create_iaid(struct client_state *client,
                                     struct data_string *ia,
                                     int idx,
                                     unsigned len);
static int dhc6_count_ia(struct dhc6_lease *lease,
                         u_int16_t ia_type);
static isc_result_t dhc6_bare_ia_xx(struct client_state *client,
                                    struct data_string *packet,
                                    int wanted,
                                    u_int16_t ia_type);
static isc_result_t dhc6_add_ia_na(struct client_state *client,
                                   struct data_string *packet,
                                   struct dhc6_lease *lease,
                                   u_int8_t message,
                                   int wanted,
                                   int *added);
static isc_result_t dhc6_add_ia_ta(struct client_state *client,
                                   struct data_string *packet,
                                   struct dhc6_lease *lease,
                                   u_int8_t message,
                                   int wanted,
                                   int *added);
static isc_result_t dhc6_add_ia_pd(struct client_state *client,
                                   struct data_string *packet,
                                   struct dhc6_lease *lease,
                                   u_int8_t message,
                                   int wanted,
                                   int *added);
static isc_boolean_t stopping_finished(void);
static void dhc6_merge_lease(struct dhc6_lease *src, struct dhc6_lease *dst);
void do_select6(void *input);
void do_refresh6(void *input);
static void do_release6(void *input);
static void start_bound(struct client_state *client);
static void start_informed(struct client_state *client);
void informed_handler(struct packet *packet, struct client_state *client);
void bound_handler(struct packet *packet, struct client_state *client);
void start_renew6(void *input);
void start_rebind6(void *input);
void do_depref(void *input);
void do_expire(void *input);
static void make_client6_options(struct client_state *client,
                                 struct option_state **op,
                                 struct dhc6_lease *lease, u_int8_t message);
static void script_write_params6(struct client_state *client,
                                 const char *prefix,
                                 struct option_state *options);
static void script_write_requested6(struct client_state *client);
static isc_boolean_t active_prefix(struct client_state *client);

static int check_timing6(struct client_state *client, u_int8_t msg_type,
                         char *msg_str, struct dhc6_lease *lease,
                         struct data_string *ds);
static isc_result_t dhc6_get_status_code(struct option_state *options,
                                         unsigned *code,
                                         struct data_string *msg);
static isc_result_t dhc6_check_status(isc_result_t rval,
                                      struct option_state *options,
                                      const char *scope,
                                      unsigned *code);

extern int onetry;
extern int stateless;

/*
 * Assign DHCPv6 port numbers as a client.
 */
void
dhcpv6_client_assignments(void)
{
        struct servent *ent;
        unsigned code;

        if (path_dhclient_pid == NULL)
                path_dhclient_pid = _PATH_DHCLIENT6_PID;
        if (path_dhclient_db == NULL)
                path_dhclient_db = _PATH_DHCLIENT6_DB;

        if (local_port == 0) {
                ent = getservbyname("dhcpv6-client", "udp");
                if (ent == NULL)
                        local_port = htons(546);
                else
                        local_port = ent->s_port;
        }

        if (remote_port == 0) {
                ent = getservbyname("dhcpv6-server", "udp");
                if (ent == NULL)
                        remote_port = htons(547);
                else
                        remote_port = ent->s_port;
        }

        memset(&DHCPv6DestAddr, 0, sizeof(DHCPv6DestAddr));
        DHCPv6DestAddr.sin6_family = AF_INET6;
        DHCPv6DestAddr.sin6_port = remote_port;
        if (inet_pton(AF_INET6, All_DHCP_Relay_Agents_and_Servers,
                      &DHCPv6DestAddr.sin6_addr) <= 0) {
                log_fatal("Bad address %s", All_DHCP_Relay_Agents_and_Servers);
        }

        code = D6O_CLIENTID;
        if (!option_code_hash_lookup(&clientid_option,
                                     dhcpv6_universe.code_hash, &code, 0, MDL))
                log_fatal("Unable to find the CLIENTID option definition.");

        code = D6O_ELAPSED_TIME;
        if (!option_code_hash_lookup(&elapsed_option,
                                     dhcpv6_universe.code_hash, &code, 0, MDL))
                log_fatal("Unable to find the ELAPSED_TIME option definition.");

        code = D6O_IA_NA;
        if (!option_code_hash_lookup(&ia_na_option, dhcpv6_universe.code_hash,
                                     &code, 0, MDL))
                log_fatal("Unable to find the IA_NA option definition.");

        code = D6O_IA_TA;
        if (!option_code_hash_lookup(&ia_ta_option, dhcpv6_universe.code_hash,
                                     &code, 0, MDL))
                log_fatal("Unable to find the IA_TA option definition.");

        code = D6O_IA_PD;
        if (!option_code_hash_lookup(&ia_pd_option, dhcpv6_universe.code_hash,
                                     &code, 0, MDL))
                log_fatal("Unable to find the IA_PD option definition.");

        code = D6O_IAADDR;
        if (!option_code_hash_lookup(&iaaddr_option, dhcpv6_universe.code_hash,
                                     &code, 0, MDL))
                log_fatal("Unable to find the IAADDR option definition.");

        code = D6O_IAPREFIX;
        if (!option_code_hash_lookup(&iaprefix_option,
                                     dhcpv6_universe.code_hash,
                                     &code, 0, MDL))
                log_fatal("Unable to find the IAPREFIX option definition.");

        code = D6O_ORO;
        if (!option_code_hash_lookup(&oro_option, dhcpv6_universe.code_hash,
                                     &code, 0, MDL))
                log_fatal("Unable to find the ORO option definition.");

        code = D6O_INFORMATION_REFRESH_TIME;
        if (!option_code_hash_lookup(&irt_option, dhcpv6_universe.code_hash,
                                     &code, 0, MDL))
                log_fatal("Unable to find the IRT option definition.");

#ifndef __CYGWIN32__ /* XXX */
        endservent();
#endif
}

/*
 * Instead of implementing RFC3315 RAND (section 14) as a float "between"
 * -0.1 and 0.1 non-inclusive, we implement it as an integer.
 *
 * The result is expected to follow this table:
 *
 *              split range answer
 *                  - ERROR -                 base <= 0
 *              0       1   0..0         1 <= base <= 10
 *              1       3  -1..1        11 <= base <= 20
 *              2       5  -2..2        21 <= base <= 30
 *              3       7  -3..3        31 <= base <= 40
 *              ...
 *
 * XXX: For this to make sense, we really need to do timing on a
 * XXX: usec scale...we currently can assume zero for any value less than
 * XXX: 11, which are very common in early stages of transmission for most
 * XXX: messages.
 */
static TIME
dhc6_rand(TIME base)
{
        TIME rval;
        TIME range;
        TIME split;

        /*
         * A zero or less timeout is a bad thing...we don't want to
         * DHCP-flood anyone.
         */
        if (base <= 0)
                log_fatal("Impossible condition at %s:%d.", MDL);

        /*
         * The first thing we do is count how many random integers we want
         * in either direction (best thought of as the maximum negative
         * integer, as we will subtract this potentially from a random 0).
         */
        split = (base - 1) / 10;

        /* Don't bother with the rest of the math if we know we'll get 0. */
        if (split == 0)
                return 0;

        /*
         * Then we count the total number of integers in this set.  This
         * is twice the number of integers in positive and negative
         * directions, plus zero (-1, 0, 1 is 3, -2..2 adds 2 to 5, so forth).
         */
        range = (split * 2) + 1;

        /* Take a random number from [0..(range-1)]. */
        rval = random();
        rval %= range;

        /* Offset it to uncover potential negative values. */
        rval -= split;

        return rval;
}

/* Initialize message exchange timers (set RT from Initial-RT). */
static void
dhc6_retrans_init(struct client_state *client)
{
        int xid;

        /* Initialize timers. */
        client->txcount = 0;
        client->RT = client->IRT + dhc6_rand(client->IRT);

        /* Generate a new random 24-bit transaction ID for this exchange. */

#if (RAND_MAX >= 0x00ffffff)
        xid = random();
#elif (RAND_MAX >= 0x0000ffff)
        xid = (random() << 16) ^ random();
#elif (RAND_MAX >= 0x000000ff)
        xid = (random() << 16) ^ (random() << 8) ^ random();
#else
# error "Random number generator of less than 8 bits not supported."
#endif

        client->dhcpv6_transaction_id[0] = (xid >> 16) & 0xff;
        client->dhcpv6_transaction_id[1] = (xid >>  8) & 0xff;
        client->dhcpv6_transaction_id[2] =  xid        & 0xff;
}

/* Advance the DHCPv6 retransmission state once. */
static void
dhc6_retrans_advance(struct client_state *client)
{
        struct timeval elapsed, elapsed_plus_rt;

        /* elapsed = cur - start */
        elapsed.tv_sec = cur_tv.tv_sec - client->start_time.tv_sec;
        elapsed.tv_usec = cur_tv.tv_usec - client->start_time.tv_usec;
        if (elapsed.tv_usec < 0) {
                elapsed.tv_sec -= 1;
                elapsed.tv_usec += 1000000;
        }
        /* retrans_advance is called after consuming client->RT. */
        /* elapsed += RT */
        elapsed.tv_sec += client->RT / 100;
        elapsed.tv_usec += (client->RT % 100) * 10000;
        if (elapsed.tv_usec >= 1000000) {
                elapsed.tv_sec += 1;
                elapsed.tv_usec -= 1000000;
        }
        /*
         * Save what the time will be after the current RT to determine
         * what the delta to MRD will be.
         */
        elapsed_plus_rt.tv_sec = elapsed.tv_sec;
        elapsed_plus_rt.tv_usec = elapsed.tv_usec;

        /*
         * RT for each subsequent message transmission is based on the previous
         * value of RT:
         *
         *    RT = 2*RTprev + RAND*RTprev
         */
        client->RT += client->RT + dhc6_rand(client->RT);

        /*
         * MRT specifies an upper bound on the value of RT (disregarding the
         * randomization added by the use of RAND).  If MRT has a value of 0,
         * there is no upper limit on the value of RT.  Otherwise:
         *
         *    if (RT > MRT)
         *       RT = MRT + RAND*MRT
         */
        if ((client->MRT != 0) && (client->RT > client->MRT))
                client->RT = client->MRT + dhc6_rand(client->MRT);

        /*
         * Further, if there's an MRD, we should wake up upon reaching
         * the MRD rather than at some point after it.
         */
        if (client->MRD == 0) {
                /* Done. */
                client->txcount++;
                return;
        }
        /* elapsed += client->RT */
        elapsed.tv_sec += client->RT / 100;
        elapsed.tv_usec += (client->RT % 100) * 10000;
        if (elapsed.tv_usec >= 1000000) {
                elapsed.tv_sec += 1;
                elapsed.tv_usec -= 1000000;
        }
        if (elapsed.tv_sec >= client->MRD) {
                /*
                 * The desired RT is the time that will be remaining in MRD
                 * when the current timeout finishes.  We then have
                 * desired RT = MRD - (elapsed time + previous RT); or
                 * desired RT = MRD - elapsed_plut_rt;
                 */
                client->RT = client->MRD - elapsed_plus_rt.tv_sec;
                client->RT = (client->RT * 100) -
                        (elapsed_plus_rt.tv_usec / 10000);
                if (client->RT < 0)
                        client->RT = 0;
        }
        client->txcount++;
}

/* Quick validation of DHCPv6 ADVERTISE packet contents. */
static int
valid_reply(struct packet *packet, struct client_state *client)
{
        struct data_string sid, cid;
        struct option_cache *oc;
        int rval = ISC_TRUE;

        memset(&sid, 0, sizeof(sid));
        memset(&cid, 0, sizeof(cid));

        if (!lookup_option(&dhcpv6_universe, packet->options, D6O_SERVERID)) {
                log_error("Response without a server identifier received.");
                rval = ISC_FALSE;
        }

        oc = lookup_option(&dhcpv6_universe, packet->options, D6O_CLIENTID);
        if (!oc ||
            !evaluate_option_cache(&sid, packet, NULL, client, packet->options,
                                   client->sent_options, &global_scope, oc,
                                   MDL)) {
                log_error("Response without a client identifier.");
                rval = ISC_FALSE;
        }

        oc = lookup_option(&dhcpv6_universe, client->sent_options,
                           D6O_CLIENTID);
        if (!oc ||
            !evaluate_option_cache(&cid, packet, NULL, client,
                                   client->sent_options, NULL, &global_scope,
                                   oc, MDL)) {
                log_error("Local client identifier is missing!");
                rval = ISC_FALSE;
        }

        if (sid.len == 0 ||
            sid.len != cid.len ||
            memcmp(sid.data, cid.data, sid.len)) {
                log_error("Advertise with matching transaction ID, but "
                          "mismatching client id.");
                rval = ISC_FALSE;
        }

        /* clean up pointers to the strings */
        if (sid.data != NULL)
                data_string_forget(&sid, MDL);
        if (cid.data != NULL)
                data_string_forget(&cid, MDL);

        return rval;
}

/*
 * Create a complete copy of a DHCPv6 lease structure.
 */
static struct dhc6_lease *
dhc6_dup_lease(struct dhc6_lease *lease, const char *file, int line)
{
        struct dhc6_lease *copy;
        struct dhc6_ia **insert_ia, *ia;

        copy = dmalloc(sizeof(*copy), file, line);
        if (copy == NULL) {
                log_error("Out of memory for v6 lease structure.");
                return NULL;
        }

        data_string_copy(&copy->server_id, &lease->server_id, file, line);
        copy->pref = lease->pref;

        memcpy(copy->dhcpv6_transaction_id, lease->dhcpv6_transaction_id,
               sizeof(copy->dhcpv6_transaction_id));

        option_state_reference(&copy->options, lease->options, file, line);

        insert_ia = &copy->bindings;
        for (ia = lease->bindings ; ia != NULL ; ia = ia->next) {
                *insert_ia = dhc6_dup_ia(ia, file, line);

                if (*insert_ia == NULL) {
                        dhc6_lease_destroy(&copy, file, line);
                        return NULL;
                }

                insert_ia = &(*insert_ia)->next;
        }

        return copy;
}

/*
 * Duplicate an IA structure.
 */
static struct dhc6_ia *
dhc6_dup_ia(struct dhc6_ia *ia, const char *file, int line)
{
        struct dhc6_ia *copy;
        struct dhc6_addr **insert_addr, *addr;

        copy = dmalloc(sizeof(*ia), file, line);
        if (copy == NULL) {
                log_error("Out of memory for v6 duplicate IA structure.");
                return NULL;
        }

        memcpy(copy->iaid, ia->iaid, sizeof(copy->iaid));

        copy->ia_type = ia->ia_type;
        copy->starts = ia->starts;
        copy->renew = ia->renew;
        copy->rebind = ia->rebind;

        insert_addr = &copy->addrs;
        for (addr = ia->addrs ; addr != NULL ; addr = addr->next) {
                *insert_addr = dhc6_dup_addr(addr, file, line);

                if (*insert_addr == NULL) {
                        dhc6_ia_destroy(&copy, file, line);
                        return NULL;
                }

                insert_addr = &(*insert_addr)->next;
        }

        if (ia->options != NULL)
                option_state_reference(&copy->options, ia->options,
                                       file, line);

        return copy;
}

/*
 * Duplicate an IAADDR or IAPREFIX structure.
 */
static struct dhc6_addr *
dhc6_dup_addr(struct dhc6_addr *addr, const char *file, int line)
{
        struct dhc6_addr *copy;

        copy = dmalloc(sizeof(*addr), file, line);

        if (copy == NULL)
                return NULL;

        memcpy(&copy->address, &addr->address, sizeof(copy->address));

        copy->plen = addr->plen;
        copy->flags = addr->flags;
        copy->starts = addr->starts;
        copy->preferred_life = addr->preferred_life;
        copy->max_life = addr->max_life;

        if (addr->options != NULL)
                option_state_reference(&copy->options, addr->options,
                                       file, line);

        return copy;
}

/*
 * Form a DHCPv6 lease structure based upon packet contents.  Creates and
 * populates IA's and any IAADDR/IAPREFIX's they contain.
 * Parsed options are deleted in order to not save them in the lease file.
 *
 * If we get a status code of NoAddrs or NoPrefix we toss the affected
 * IAs.  If it as at the top level we toss all IAs of that type.  If it
 * is in an IA we only toss that one.  According to the spec we shouldn't
 * get a NoPrefix status at the top level but we will allow it.
 *
 */
static struct dhc6_lease *
dhc6_leaseify(struct packet *packet, struct client_state* client)
{
        struct data_string ds;
        struct dhc6_lease *lease;
        struct option_cache *oc;
        unsigned code;

        lease = dmalloc(sizeof(*lease), MDL);
        if (lease == NULL) {
                log_error("Out of memory for v6 lease structure.");
                return NULL;
        }

        memcpy(lease->dhcpv6_transaction_id, packet->dhcpv6_transaction_id, 3);
        option_state_reference(&lease->options, packet->options, MDL);

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

        /* Determine preference (default zero). */
        oc = lookup_option(&dhcpv6_universe, lease->options, D6O_PREFERENCE);
        if (oc &&
            evaluate_option_cache(&ds, packet, NULL, NULL, lease->options,
                                  NULL, &global_scope, oc, MDL)) {
                if (ds.len != 1) {
                        log_error("Invalid length of DHCPv6 Preference option "
                                  "(%d != 1)", ds.len);
                        data_string_forget(&ds, MDL);
                        dhc6_lease_destroy(&lease, MDL);
                        return NULL;
                } else {
                        lease->pref = ds.data[0];
                        log_debug("RCV:  X-- Preference %u.",
                                  (unsigned)lease->pref);
                }

                data_string_forget(&ds, MDL);
        }
        delete_option(&dhcpv6_universe, lease->options, D6O_PREFERENCE);

        /* Get the top level status code.  If the code is NoAddrsAvail
         * or NoPrefixAvail strip it from the options as we don't
         * want it to show up in check_[advertise reply].  We
         * pass it along to the parse_ia_xx routines and they
         * will drop the affected IAs for NoAddrs or NoPrefix,
         * other status codes will be ignored and handled by
         * the check_[advertise reply] routines.
         */
        code = STATUS_Success;
        if ((dhc6_get_status_code(lease->options, &code, NULL) == ISC_R_SUCCESS)
            &&
            ((code == STATUS_NoAddrsAvail) || (code == STATUS_NoPrefixAvail))) {
                delete_option(&dhcpv6_universe, lease->options,
                              D6O_STATUS_CODE);
        }

        /*
         * Dig into recursive DHCPv6 pockets for IA_NA and contained IAADDR
         * options.
         */
        if (dhc6_parse_ia_na(&lease->bindings, packet,
                             lease->options, code) != ISC_R_SUCCESS) {
                /* Error conditions are logged by the caller. */
                dhc6_lease_destroy(&lease, MDL);
                return NULL;
        }
        /*
         * Dig into recursive DHCPv6 pockets for IA_TA and contained IAADDR
         * options.
         */
        if (dhc6_parse_ia_ta(&lease->bindings, packet,
                             lease->options, code) != ISC_R_SUCCESS) {
                /* Error conditions are logged by the caller. */
                dhc6_lease_destroy(&lease, MDL);
                return NULL;
        }
        /*
         * Dig into recursive DHCPv6 pockets for IA_PD and contained IAPREFIX
         * options.
         */
        if (dhc6_parse_ia_pd(&lease->bindings, packet,
                             lease->options, code) != ISC_R_SUCCESS) {
                /* Error conditions are logged by the caller. */
                dhc6_lease_destroy(&lease, MDL);
                return NULL;
        }

        /*
         * This is last because in the future we may want to make a different
         * key based upon additional information from the packet (we may need
         * to allow multiple leases in one client state per server, but we're
         * not sure based on what additional keys now).
         */
        oc = lookup_option(&dhcpv6_universe, packet->options, D6O_SERVERID);
        if ((oc == NULL) ||
            !evaluate_option_cache(&lease->server_id, packet, NULL, NULL,
                                   lease->options, NULL, &global_scope,
                                   oc, MDL) ||
            lease->server_id.len == 0) {
                /* This should be impossible due to validation checks earlier.
                 */
                log_error("Invalid SERVERID option cache.");
                dhc6_lease_destroy(&lease, MDL);
                return NULL;
        } else {
                log_debug("RCV:  X-- Server ID: %s",
                          print_hex_1(lease->server_id.len,
                                      lease->server_id.data, 52));
        }

        execute_statements_in_scope(NULL, (struct packet *)packet, NULL,
                                    client, lease->options, lease->options,
                                    &global_scope, client->config->on_receipt,
                                    NULL, NULL);

        return lease;
}

static isc_result_t
dhc6_parse_ia_na(struct dhc6_ia **pia, struct packet *packet,
                 struct option_state *options, unsigned code)
{
        struct data_string ds;
        struct dhc6_ia *ia;
        struct option_cache *oc;
        isc_result_t result;
        unsigned ia_code;

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

        oc = lookup_option(&dhcpv6_universe, options, D6O_IA_NA);
        for ( ; oc != NULL ; oc = oc->next) {
                ia = dmalloc(sizeof(*ia), MDL);
                if (ia == NULL) {
                        log_error("Out of memory allocating IA_NA structure.");
                        return ISC_R_NOMEMORY;
                } else if (evaluate_option_cache(&ds, packet, NULL, NULL,
                                                 options, NULL,
                                                 &global_scope, oc, MDL) &&
                           ds.len >= 12) {
                        memcpy(ia->iaid, ds.data, 4);
                        ia->ia_type = D6O_IA_NA;
                        ia->starts = cur_time;
                        ia->renew = getULong(ds.data + 4);
                        ia->rebind = getULong(ds.data + 8);

                        log_debug("RCV:  X-- IA_NA %s",
                                  print_hex_1(4, ia->iaid, 59));
                        /* XXX: This should be the printed time I think. */
                        log_debug("RCV:  | X-- starts %u",
                                  (unsigned)ia->starts);
                        log_debug("RCV:  | X-- t1 - renew  +%u", ia->renew);
                        log_debug("RCV:  | X-- t2 - rebind +%u", ia->rebind);

                        /*
                         * RFC3315 section 22.4, discard IA_NA's that
                         * have t1 greater than t2, and both not zero.
                         * Since RFC3315 defines this behaviour, it is not
                         * an error - just normal operation.
                         *
                         * Note that RFC3315 says we MUST honor these values
                         * if they are not zero.  So insane values are
                         * totally OK.
                         */
                        if ((ia->renew > 0) && (ia->rebind > 0) &&
                            (ia->renew > ia->rebind)) {
                                log_debug("RCV:  | !-- INVALID renew/rebind "
                                          "times, IA_NA discarded.");
                                dfree(ia, MDL);
                                data_string_forget(&ds, MDL);
                                continue;
                        }

                        if (ds.len > 12) {
                                log_debug("RCV:  | X-- [Options]");

                                if (!option_state_allocate(&ia->options,
                                                           MDL)) {
                                        log_error("Out of memory allocating "
                                                  "IA_NA option state.");
                                        dfree(ia, MDL);
                                        data_string_forget(&ds, MDL);
                                        return ISC_R_NOMEMORY;
                                }

                                if (!parse_option_buffer(ia->options,
                                                         ds.data + 12,
                                                         ds.len - 12,
                                                         &dhcpv6_universe)) {
                                        log_error("Corrupt IA_NA options.");
                                        option_state_dereference(&ia->options,
                                                                 MDL);
                                        dfree(ia, MDL);
                                        data_string_forget(&ds, MDL);
                                        return DHCP_R_BADPARSE;
                                }
                        }
                        data_string_forget(&ds, MDL);

                        if (ia->options != NULL) {
                                result = dhc6_parse_addrs(&ia->addrs, packet,
                                                          ia->options);
                                if (result != ISC_R_SUCCESS) {
                                        option_state_dereference(&ia->options,
                                                                 MDL);
                                        dfree(ia, MDL);
                                        return result;
                                }
                        }

                        /* If we have no addresses or the top level status code
                         * or the status code in this IA indicate no addresses
                         * toss the IA.
                         */
                        ia_code = STATUS_Success;
                        if ((ia->addrs == NULL) ||
                            (code == STATUS_NoAddrsAvail) ||
                            ((ia->options != NULL) &&
                             (dhc6_get_status_code(ia->options, &ia_code, NULL)
                              == ISC_R_SUCCESS) &&
                             (ia_code == STATUS_NoAddrsAvail))) {
                                log_debug("RCV:  | !-- Status code of "
                                          "no addrs, IA_NA discarded.");
                                dhc6_ia_destroy(&ia, MDL);
                                continue;
                        }

                        while (*pia != NULL)
                                pia = &(*pia)->next;
                        *pia = ia;
                        pia = &ia->next;
                } else {
                        log_error("Invalid IA_NA option cache.");
                        dfree(ia, MDL);
                        if (ds.len != 0)
                                data_string_forget(&ds, MDL);
                        return ISC_R_UNEXPECTED;
                }
        }
        delete_option(&dhcpv6_universe, options, D6O_IA_NA);

        return ISC_R_SUCCESS;
}

static isc_result_t
dhc6_parse_ia_ta(struct dhc6_ia **pia, struct packet *packet,
                 struct option_state *options, unsigned code)
{
        struct data_string ds;
        struct dhc6_ia *ia;
        struct option_cache *oc;
        isc_result_t result;
        unsigned ia_code;

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

        oc = lookup_option(&dhcpv6_universe, options, D6O_IA_TA);
        for ( ; oc != NULL ; oc = oc->next) {
                ia = dmalloc(sizeof(*ia), MDL);
                if (ia == NULL) {
                        log_error("Out of memory allocating IA_TA structure.");
                        return ISC_R_NOMEMORY;
                } else if (evaluate_option_cache(&ds, packet, NULL, NULL,
                                                 options, NULL,
                                                 &global_scope, oc, MDL) &&
                           ds.len >= 4) {
                        memcpy(ia->iaid, ds.data, 4);
                        ia->ia_type = D6O_IA_TA;
                        ia->starts = cur_time;

                        log_debug("RCV:  X-- IA_TA %s",
                                  print_hex_1(4, ia->iaid, 59));
                        /* XXX: This should be the printed time I think. */
                        log_debug("RCV:  | X-- starts %u",
                                  (unsigned)ia->starts);

                        if (ds.len > 4) {
                                log_debug("RCV:  | X-- [Options]");

                                if (!option_state_allocate(&ia->options,
                                                           MDL)) {
                                        log_error("Out of memory allocating "
                                                  "IA_TA option state.");
                                        dfree(ia, MDL);
                                        data_string_forget(&ds, MDL);
                                        return ISC_R_NOMEMORY;
                                }

                                if (!parse_option_buffer(ia->options,
                                                         ds.data + 4,
                                                         ds.len - 4,
                                                         &dhcpv6_universe)) {
                                        log_error("Corrupt IA_TA options.");
                                        option_state_dereference(&ia->options,
                                                                 MDL);
                                        dfree(ia, MDL);
                                        data_string_forget(&ds, MDL);
                                        return DHCP_R_BADPARSE;
                                }
                        }
                        data_string_forget(&ds, MDL);

                        if (ia->options != NULL) {
                                result = dhc6_parse_addrs(&ia->addrs, packet,
                                                          ia->options);
                                if (result != ISC_R_SUCCESS) {
                                        option_state_dereference(&ia->options,
                                                                 MDL);
                                        dfree(ia, MDL);
                                        return result;
                                }
                        }

                        /* If we have no addresses or the top level status code
                         * or the status code in this IA indicate no addresses
                         * toss the IA.
                         */
                        ia_code = STATUS_Success;
                        if ((ia->addrs == NULL) ||
                            (code == STATUS_NoAddrsAvail) ||
                            ((ia->options != NULL) &&
                             (dhc6_get_status_code(ia->options, &ia_code, NULL)
                              == ISC_R_SUCCESS) &&
                             (ia_code == STATUS_NoAddrsAvail))) {
                                log_debug("RCV:  | !-- Status code of "
                                          "no addrs, IA_TA discarded.");
                                dhc6_ia_destroy(&ia, MDL);
                                continue;
                        }

                        while (*pia != NULL)
                                pia = &(*pia)->next;
                        *pia = ia;
                        pia = &ia->next;
                } else {
                        log_error("Invalid IA_TA option cache.");
                        dfree(ia, MDL);
                        if (ds.len != 0)
                                data_string_forget(&ds, MDL);
                        return ISC_R_UNEXPECTED;
                }
        }
        delete_option(&dhcpv6_universe, options, D6O_IA_TA);

        return ISC_R_SUCCESS;
}

static isc_result_t
dhc6_parse_ia_pd(struct dhc6_ia **pia, struct packet *packet,
                 struct option_state *options, unsigned code)
{
        struct data_string ds;
        struct dhc6_ia *ia;
        struct option_cache *oc;
        isc_result_t result;
        unsigned ia_code;

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

        oc = lookup_option(&dhcpv6_universe, options, D6O_IA_PD);
        for ( ; oc != NULL ; oc = oc->next) {
                ia = dmalloc(sizeof(*ia), MDL);
                if (ia == NULL) {
                        log_error("Out of memory allocating IA_PD structure.");
                        return ISC_R_NOMEMORY;
                } else if (evaluate_option_cache(&ds, packet, NULL, NULL,
                                                 options, NULL,
                                                 &global_scope, oc, MDL) &&
                           ds.len >= 12) {
                        memcpy(ia->iaid, ds.data, 4);
                        ia->ia_type = D6O_IA_PD;
                        ia->starts = cur_time;
                        ia->renew = getULong(ds.data + 4);
                        ia->rebind = getULong(ds.data + 8);

                        log_debug("RCV:  X-- IA_PD %s",
                                  print_hex_1(4, ia->iaid, 59));
                        /* XXX: This should be the printed time I think. */
                        log_debug("RCV:  | X-- starts %u",
                                  (unsigned)ia->starts);
                        log_debug("RCV:  | X-- t1 - renew  +%u", ia->renew);
                        log_debug("RCV:  | X-- t2 - rebind +%u", ia->rebind);

                        /*
                         * RFC3633 section 9, discard IA_PD's that
                         * have t1 greater than t2, and both not zero.
                         * Since RFC3633 defines this behaviour, it is not
                         * an error - just normal operation.
                         */
                        if ((ia->renew > 0) && (ia->rebind > 0) &&
                            (ia->renew > ia->rebind)) {
                                log_debug("RCV:  | !-- INVALID renew/rebind "
                                          "times, IA_PD discarded.");
                                dfree(ia, MDL);
                                data_string_forget(&ds, MDL);
                                continue;
                        }

                        if (ds.len > 12) {
                                log_debug("RCV:  | X-- [Options]");

                                if (!option_state_allocate(&ia->options,
                                                           MDL)) {
                                        log_error("Out of memory allocating "
                                                  "IA_PD option state.");
                                        dfree(ia, MDL);
                                        data_string_forget(&ds, MDL);
                                        return ISC_R_NOMEMORY;
                                }

                                if (!parse_option_buffer(ia->options,
                                                         ds.data + 12,
                                                         ds.len - 12,
                                                         &dhcpv6_universe)) {
                                        log_error("Corrupt IA_PD options.");
                                        option_state_dereference(&ia->options,
                                                                 MDL);
                                        dfree(ia, MDL);
                                        data_string_forget(&ds, MDL);
                                        return DHCP_R_BADPARSE;
                                }
                        }
                        data_string_forget(&ds, MDL);

                        if (ia->options != NULL) {
                                result = dhc6_parse_prefixes(&ia->addrs,
                                                             packet,
                                                             ia->options);
                                if (result != ISC_R_SUCCESS) {
                                        option_state_dereference(&ia->options,
                                                                 MDL);
                                        dfree(ia, MDL);
                                        return result;
                                }
                        }

                        /* If we have no prefixes or the top level status code
                         * or the status code in this IA indicate no prefixes
                         * toss the IA.
                         */
                        ia_code = STATUS_Success;
                        if ((ia->addrs == NULL) ||
                            (code == STATUS_NoPrefixAvail) ||
                            ((ia->options != NULL) &&
                             (dhc6_get_status_code(ia->options, &ia_code, NULL)
                              == ISC_R_SUCCESS) &&
                             (ia_code == STATUS_NoPrefixAvail))) {
                                log_debug("RCV:  | !-- Status code of "
                                          "no prefix, IA_PD discarded.");
                                dhc6_ia_destroy(&ia, MDL);
                                continue;
                        }

                        while (*pia != NULL)
                                pia = &(*pia)->next;
                        *pia = ia;
                        pia = &ia->next;
                } else {
                        log_error("Invalid IA_PD option cache.");
                        dfree(ia, MDL);
                        if (ds.len != 0)
                                data_string_forget(&ds, MDL);
                        return ISC_R_UNEXPECTED;
                }
        }
        delete_option(&dhcpv6_universe, options, D6O_IA_PD);

        return ISC_R_SUCCESS;
}


static isc_result_t
dhc6_parse_addrs(struct dhc6_addr **paddr, struct packet *packet,
                 struct option_state *options)
{
        struct data_string ds;
        struct option_cache *oc;
        struct dhc6_addr *addr;
        isc_result_t rval = ISC_R_SUCCESS;
        unsigned code;

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

        oc = lookup_option(&dhcpv6_universe, options, D6O_IAADDR);
        for ( ; oc != NULL ; oc = oc->next) {
                addr = dmalloc(sizeof(*addr), MDL);
                if (addr == NULL) {
                        log_error("Out of memory allocating "
                                  "address structure.");
                        return ISC_R_NOMEMORY;
                } else if (evaluate_option_cache(&ds, packet, NULL, NULL,
                                                 options, NULL, &global_scope,
                                                 oc, MDL) &&
                           (ds.len >= 24)) {

                        addr->address.len = 16;
                        memcpy(addr->address.iabuf, ds.data, 16);
                        addr->starts = cur_time;
                        addr->preferred_life = getULong(ds.data + 16);
                        addr->max_life = getULong(ds.data + 20);

                        log_debug("RCV:  | | X-- IAADDR %s",
                                  piaddr(addr->address));
                        log_debug("RCV:  | | | X-- Preferred lifetime %u.",
                                  addr->preferred_life);
                        log_debug("RCV:  | | | X-- Max lifetime %u.",
                                  addr->max_life);

                        /*
                         * RFC 3315 section 22.6 says we must discard
                         * addresses whose pref is later than valid.
                         */
                        if ((addr->preferred_life > addr->max_life)) {
                                log_debug("RCV:  | | | !-- INVALID lifetimes, "
                                          "IAADDR discarded.  Check your "
                                          "server configuration.");
                                dfree(addr, MDL);
                                data_string_forget(&ds, MDL);
                                continue;
                        }

                        /*
                         * Fortunately this is the last recursion in the
                         * protocol.
                         */
                        if (ds.len > 24) {
                                if (!option_state_allocate(&addr->options,
                                                           MDL)) {
                                        log_error("Out of memory allocating "
                                                  "IAADDR option state.");
                                        dfree(addr, MDL);
                                        data_string_forget(&ds, MDL);
                                        return ISC_R_NOMEMORY;
                                }

                                if (!parse_option_buffer(addr->options,
                                                         ds.data + 24,
                                                         ds.len - 24,
                                                         &dhcpv6_universe)) {
                                        log_error("Corrupt IAADDR options.");
                                        option_state_dereference(&addr->options,
                                                                 MDL);
                                        dfree(addr, MDL);
                                        data_string_forget(&ds, MDL);
                                        return DHCP_R_BADPARSE;
                                }
                        }

                        data_string_forget(&ds, MDL);

                        if (addr->options != NULL) {
                                log_debug("RCV:  | | | X-- [Options]");

                                /* Get the status code if the return value
                                 * indicates an error or the status code
                                 * indicates no address toss the address
                                 */
                                code = STATUS_Success;
                                rval = dhc6_check_status(ISC_R_SUCCESS,
                                                         addr->options,
                                                         "IAADDR", &code);
                                if (rval != ISC_R_SUCCESS) {
                                        log_debug("RCV:  | | | X-- Status code"
                                                  " issue, IAADDR discarded.");
                                        option_state_dereference(&addr->options,
                                                                 MDL);
                                        dfree(addr, MDL);
                                        continue;
                                }
                        }

                        *paddr = addr;
                        paddr = &addr->next;
                } else {
                        log_error("Invalid IAADDR option cache.");
                        dfree(addr, MDL);
                        if (ds.len != 0)
                                data_string_forget(&ds, MDL);
                        return ISC_R_UNEXPECTED;
                }
        }
        delete_option(&dhcpv6_universe, options, D6O_IAADDR);

        return ISC_R_SUCCESS;
}

static isc_result_t
dhc6_parse_prefixes(struct dhc6_addr **ppfx, struct packet *packet,
                    struct option_state *options)
{
        struct data_string ds;
        struct option_cache *oc;
        struct dhc6_addr *pfx;
        isc_result_t rval = ISC_R_SUCCESS;
        unsigned code;

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

        oc = lookup_option(&dhcpv6_universe, options, D6O_IAPREFIX);
        for ( ; oc != NULL ; oc = oc->next) {
                pfx = dmalloc(sizeof(*pfx), MDL);
                if (pfx == NULL) {
                        log_error("Out of memory allocating "
                                  "prefix structure.");
                        return ISC_R_NOMEMORY;
                } else if (evaluate_option_cache(&ds, packet, NULL, NULL,
                                                 options, NULL, &global_scope,
                                                 oc, MDL) &&
                           (ds.len >= 25)) {

                        pfx->preferred_life = getULong(ds.data);
                        pfx->max_life = getULong(ds.data + 4);
                        pfx->plen = getUChar(ds.data + 8);
                        pfx->address.len = 16;
                        memcpy(pfx->address.iabuf, ds.data + 9, 16);
                        pfx->starts = cur_time;

                        log_debug("RCV:  | | X-- IAPREFIX %s/%d",
                                  piaddr(pfx->address), (int)pfx->plen);
                        log_debug("RCV:  | | | X-- Preferred lifetime %u.",
                                  pfx->preferred_life);
                        log_debug("RCV:  | | | X-- Max lifetime %u.",
                                  pfx->max_life);

                        /* Sanity check over the prefix length */
                        if ((pfx->plen < 4) || (pfx->plen > 128)) {
                                log_debug("RCV:  | | | !-- INVALID prefix "
                                          "length, IAPREFIX discarded.  "
                                          "Check your server configuration.");
                                dfree(pfx, MDL);
                                data_string_forget(&ds, MDL);
                                continue;
                        }
                        /*
                         * RFC 3633 section 10 says we must discard
                         * prefixes whose pref is later than valid.
                         */
                        if ((pfx->preferred_life > pfx->max_life)) {
                                log_debug("RCV:  | | | !-- INVALID lifetimes, "
                                          "IAPREFIX discarded.  Check your "
                                          "server configuration.");
                                dfree(pfx, MDL);
                                data_string_forget(&ds, MDL);
                                continue;
                        }

                        /*
                         * Fortunately this is the last recursion in the
                         * protocol.
                         */
                        if (ds.len > 25) {
                                if (!option_state_allocate(&pfx->options,
                                                           MDL)) {
                                        log_error("Out of memory allocating "
                                                  "IAPREFIX option state.");
                                        dfree(pfx, MDL);
                                        data_string_forget(&ds, MDL);
                                        return ISC_R_NOMEMORY;
                                }

                                if (!parse_option_buffer(pfx->options,
                                                         ds.data + 25,
                                                         ds.len - 25,
                                                         &dhcpv6_universe)) {
                                        log_error("Corrupt IAPREFIX options.");
                                        option_state_dereference(&pfx->options,
                                                                 MDL);
                                        dfree(pfx, MDL);
                                        data_string_forget(&ds, MDL);
                                        return DHCP_R_BADPARSE;
                                }
                        }

                        data_string_forget(&ds, MDL);

                        if (pfx->options != NULL) {
                                log_debug("RCV:  | | | X-- [Options]");

                                /* Get the status code if the return value
                                 * indicates an error or the status code
                                 * indicates no prefix toss the prefix
                                 */
                                code = STATUS_Success;
                                rval = dhc6_check_status(ISC_R_SUCCESS,
                                                         pfx->options,
                                                         "IAPREFIX", &code);
                                if (rval != ISC_R_SUCCESS) {
                                        log_debug("RCV:  | | | X-- Status code"
                                                  " issue IAPREFIX discarded.");
                                        option_state_dereference(&pfx->options,
                                                                 MDL);
                                        dfree(pfx, MDL);
                                        continue;
                                }
                        }

                        *ppfx = pfx;
                        ppfx = &pfx->next;
                } else {
                        log_error("Invalid IAPREFIX option cache.");
                        dfree(pfx, MDL);
                        if (ds.len != 0)
                                data_string_forget(&ds, MDL);
                        return ISC_R_UNEXPECTED;
                }
        }
        delete_option(&dhcpv6_universe, options, D6O_IAPREFIX);

        return ISC_R_SUCCESS;
}

/* Clean up a lease object, deallocate all its parts, and set it to NULL. */
void
dhc6_lease_destroy(struct dhc6_lease **src, const char *file, int line)
{
        struct dhc6_ia *ia, *nia;
        struct dhc6_lease *lease;

        if (src == NULL || *src == NULL) {
                log_error("Attempt to destroy null lease.");
                return;
        }
        lease = *src;

        if (lease->server_id.len != 0)
                data_string_forget(&lease->server_id, file, line);

        for (ia = lease->bindings ; ia != NULL ; ia = nia) {
                nia = ia->next;

                dhc6_ia_destroy(&ia, file, line);
        }

        if (lease->options != NULL)
                option_state_dereference(&lease->options, file, line);

        dfree(lease, file, line);
        *src = NULL;
}

/*
 * Traverse the addresses list, and destroy their contents, and NULL the
 * list pointer.
 */
static void
dhc6_ia_destroy(struct dhc6_ia **src, const char *file, int line)
{
        struct dhc6_addr *addr, *naddr;
        struct dhc6_ia *ia;

        if (src == NULL || *src == NULL) {
                log_error("Attempt to destroy null IA.");
                return;
        }
        ia = *src;

        for (addr = ia->addrs ; addr != NULL ; addr = naddr) {
                naddr = addr->next;

                if (addr->options != NULL)
                        option_state_dereference(&addr->options, file, line);

                dfree(addr, file, line);
        }

        if (ia->options != NULL)
                option_state_dereference(&ia->options, file, line);

        dfree(ia, file, line);
        *src = NULL;
}

/*
 * For a given lease, insert it into the tail of the lease list.  Upon
 * finding a duplicate by server id, remove it and take over its position.
 */
static void
insert_lease(struct dhc6_lease **head, struct dhc6_lease *new)
{
        while (*head != NULL) {
                if ((*head)->server_id.len == new->server_id.len &&
                    memcmp((*head)->server_id.data, new->server_id.data,
                           new->server_id.len) == 0) {
                        new->next = (*head)->next;
                        dhc6_lease_destroy(head, MDL);
                        break;
                }

                head= &(*head)->next;
        }

        *head = new;
        return;
}

/*!
 *
 * \brief Determine a score for a lease.  We use this to
 * compare and choose leases if we receive multiple candidates.
 *
 * We originally started with scores of 50 for a binding and 100 for
 * an address.  This would select multiple adresses over multiple
 * bindings.  As part of the 7550 work I've changed this to be
 * 10000 for a binding, 100 for an address and 1 for an option.
 * This will cause us to choose a lease with more bindings over
 * a lease with less bindings but more addresses which seems
 * to be the best selection criteria to me.
 * In theory we could end up with a lease with enough addresses
 * or options being better but at 100 to 1 I don't think it's likely.
 *
 * \param client = the state of the entire client
 * \param lease  = the lease to score.
 *
 * \retrun the score of the lease
 */

/* The scores for individual items. */
#ifdef USE_ORIGINAL_CLIENT_LEASE_WEIGHTS
#define SCORE_BINDING  50
#define SCORE_ADDRESS 100
#else
#define SCORE_BINDING 10000
#define SCORE_ADDRESS   100
#endif

#define SCORE_OPTION      1
/* We need a lease with at least 1 binding and 1 address */
#define SCORE_MIN (SCORE_BINDING + SCORE_ADDRESS)

static int
dhc6_score_lease(struct client_state *client, struct dhc6_lease *lease)
{
        struct dhc6_ia *ia;
        struct dhc6_addr *addr;
        struct option **req;
        int i;

        if (lease->score)
                return lease->score;

        lease->score = SCORE_OPTION;

        /* If this lease lacks a required option, dump it. */
        /* XXX: we should be able to cache the failure... */
        req = client->config->required_options;
        if (req != NULL) {
                for (i = 0 ; req[i] != NULL ; i++) {
                        if (lookup_option(&dhcpv6_universe, lease->options,
                                          req[i]->code) == NULL) {
                                lease->score = 0;
                                return lease->score;
                        }
                }
        }

        /* If this lease contains a requested option, improve its score. */
        req = client->config->requested_options;
        if (req != NULL) {
                for (i = 0 ; req[i] != NULL ; i++) {
                        if (lookup_option(&dhcpv6_universe, lease->options,
                                          req[i]->code) != NULL)
                                lease->score += SCORE_OPTION;
                }
        }

        for (ia = lease->bindings ; ia != NULL ; ia = ia->next) {
                lease->score += SCORE_BINDING;

                for (addr = ia->addrs ; addr != NULL ; addr = addr->next) {
                        lease->score += SCORE_ADDRESS;
                }
        }

        return lease->score;
}

/*
 * start_init6() kicks off the process, transmitting a packet and
 * scheduling a retransmission event.
 */
void
start_init6(struct client_state *client)
{
        struct timeval tv;

        log_debug("PRC: Soliciting for leases (INIT).");
        client->state = S_INIT;

        /* Initialize timers, RFC3315 section 17.1.2. */
        client->IRT = SOL_TIMEOUT * 100;
        client->MRT = SOL_MAX_RT * 100;
        client->MRC = 0;
        /* Default is 0 (no max) but -1 changes this. */
        if (!onetry)
                client->MRD = 0;
        else
                client->MRD = client->config->timeout;

        dhc6_retrans_init(client);

        /*
         * RFC3315 section 17.1.2 goes out of its way:
         * Also, the first RT MUST be selected to be strictly greater than IRT
         * by choosing RAND to be strictly greater than 0.
         */
        /* if RAND < 0 then RAND = -RAND */
        if (client->RT <= client->IRT)
                client->RT = client->IRT + (client->IRT - client->RT);
        /* if RAND == 0 then RAND = 1 */
        if (client->RT <= client->IRT)
                client->RT = client->IRT + 1;

        client->v6_handler = init_handler;

        /*
         * RFC3315 section 17.1.2 says we MUST start the first packet
         * between 0 and SOL_MAX_DELAY seconds.  The good news is
         * SOL_MAX_DELAY is 1.
         */
        tv.tv_sec = cur_tv.tv_sec;
        tv.tv_usec = cur_tv.tv_usec;
        tv.tv_usec += (random() % (SOL_MAX_DELAY * 100)) * 10000;
        if (tv.tv_usec >= 1000000) {
                tv.tv_sec += 1;
                tv.tv_usec -= 1000000;
        }
        add_timeout(&tv, do_init6, client, NULL, NULL);

        if (nowait)
                go_daemon();
}

/*
 * start_info_request6() kicks off the process, transmitting an info
 * request packet and scheduling a retransmission event.
 */
void
start_info_request6(struct client_state *client)
{
        struct timeval tv;

        log_debug("PRC: Requesting information (INIT).");
        client->state = S_INIT;

        /* Initialize timers, RFC3315 section 18.1.5. */
        client->IRT = INF_TIMEOUT * 100;
        client->MRT = INF_MAX_RT * 100;
        client->MRC = 0;
        /* Default is 0 (no max) but -1 changes this. */
        if (!onetry)
                client->MRD = 0;
        else
                client->MRD = client->config->timeout;

        dhc6_retrans_init(client);

        client->v6_handler = info_request_handler;

        /*
         * RFC3315 section 18.1.5 says we MUST start the first packet
         * between 0 and INF_MAX_DELAY seconds.  The good news is
         * INF_MAX_DELAY is 1.
         */
        tv.tv_sec = cur_tv.tv_sec;
        tv.tv_usec = cur_tv.tv_usec;
        tv.tv_usec += (random() % (INF_MAX_DELAY * 100)) * 10000;
        if (tv.tv_usec >= 1000000) {
                tv.tv_sec += 1;
                tv.tv_usec -= 1000000;
        }
        add_timeout(&tv, do_info_request6, client, NULL, NULL);

        if (nowait)
                go_daemon();
}

/*
 * start_confirm6() kicks off an "init-reboot" version of the process, at
 * startup to find out if old bindings are 'fair' and at runtime whenever
 * a link cycles state we'll eventually want to do this.
 */
void
start_confirm6(struct client_state *client)
{
        struct timeval tv;

        /* If there is no active lease, there is nothing to check. */
        if ((client->active_lease == NULL) ||
            !active_prefix(client) ||
            client->active_lease->released) {
                start_init6(client);
                return;
        }

        log_debug("PRC: Confirming active lease (INIT-REBOOT).");
        client->state = S_REBOOTING;

        /* Initialize timers, RFC3315 section 17.1.3. */
        client->IRT = CNF_TIMEOUT * 100;
        client->MRT = CNF_MAX_RT * 100;
        client->MRC = 0;
        client->MRD = CNF_MAX_RD;

        dhc6_retrans_init(client);

        client->v6_handler = reply_handler;

        /*
         * RFC3315 section 18.1.2 says we MUST start the first packet
         * between 0 and CNF_MAX_DELAY seconds.  The good news is
         * CNF_MAX_DELAY is 1.
         */
        tv.tv_sec = cur_tv.tv_sec;
        tv.tv_usec = cur_tv.tv_usec;
        tv.tv_usec += (random() % (CNF_MAX_DELAY * 100)) * 10000;
        if (tv.tv_usec >= 1000000) {
                tv.tv_sec += 1;
                tv.tv_usec -= 1000000;
        }

        /* We do a rebind instead of a confirm if the user
         * is requesting PDs or previously requesed PDs or
         * increased the number of NAs or TAs they want
         * Confirms don't tell us if PDs are still on-link and
         * we won't add new IAs on a confirm.
         */

        if ((wanted_ia_pd != 0) ||
            (dhc6_count_ia(client->active_lease, D6O_IA_PD) != 0) ||
            (dhc6_count_ia(client->active_lease, D6O_IA_NA) < wanted_ia_na) ||
            (dhc6_count_ia(client->active_lease, D6O_IA_TA) < wanted_ia_ta)) {
                client->state = S_REBINDING;
                client->refresh_type = DHCPV6_REBIND;
                add_timeout(&tv, do_refresh6, client, NULL, NULL);
        } else
                add_timeout(&tv, do_confirm6, client, NULL, NULL);
}

/*
 * check_timing6() check on the timing for sending a v6 message
 * and then do the basic initialization for a v6 message.
 */
#define CHK_TIM_SUCCESS         0
#define CHK_TIM_MRC_EXCEEDED    1
#define CHK_TIM_MRD_EXCEEDED    2
#define CHK_TIM_ALLOC_FAILURE   3

int
check_timing6 (struct client_state *client, u_int8_t msg_type,
               char *msg_str, struct dhc6_lease *lease,
               struct data_string *ds)
{
        struct timeval elapsed;

        /*
         * Start_time starts at the first transmission.
         */
        if (client->txcount == 0) {
                client->start_time.tv_sec = cur_tv.tv_sec;
                client->start_time.tv_usec = cur_tv.tv_usec;
        } else if ((client->MRC != 0) && (client->txcount > client->MRC)) {
                log_info("Max retransmission count exceeded.");
                return(CHK_TIM_MRC_EXCEEDED);
        }

        /* elapsed = cur - start */
        elapsed.tv_sec = cur_tv.tv_sec - client->start_time.tv_sec;
        elapsed.tv_usec = cur_tv.tv_usec - client->start_time.tv_usec;
        if (elapsed.tv_usec < 0) {
                elapsed.tv_sec -= 1;
                elapsed.tv_usec += 1000000;
        }

        /* Check if finished (-1 argument). */
        if ((client->MRD != 0) && (elapsed.tv_sec >= client->MRD)) {
                log_info("Max retransmission duration exceeded.");
                return(CHK_TIM_MRD_EXCEEDED);
        }

        memset(ds, 0, sizeof(*ds));
        if (!buffer_allocate(&(ds->buffer), 4, MDL)) {
                log_error("Unable to allocate memory for %s.", msg_str);
                return(CHK_TIM_ALLOC_FAILURE);
        }
        ds->data = ds->buffer->data;
        ds->len = 4;

        ds->buffer->data[0] = msg_type;
        memcpy(ds->buffer->data + 1, client->dhcpv6_transaction_id, 3);

        /* Form an elapsed option. */
        /* Maximum value is 65535 1/100s coded as 0xffff. */
        if ((elapsed.tv_sec < 0) || (elapsed.tv_sec > 655) ||
            ((elapsed.tv_sec == 655) && (elapsed.tv_usec > 350000))) {
                client->elapsed = 0xffff;
        } else {
                client->elapsed = elapsed.tv_sec * 100;
                client->elapsed += elapsed.tv_usec / 10000;
        }

        if (client->elapsed == 0)
                log_debug("XMT: Forming %s, 0 ms elapsed.", msg_str);
        else
                log_debug("XMT: Forming %s, %u0 ms elapsed.", msg_str,
                          (unsigned)client->elapsed);

        client->elapsed = htons(client->elapsed);

        make_client6_options(client, &client->sent_options, lease, msg_type);

        return(CHK_TIM_SUCCESS);
}

/*!
 *
 * \brief Create an iaid from information from the client.
 *
 * \param client = the state of the entire client
 * \param ia     = the ia to fill in
 * \param idx    = index of the ia in case we are doing multiples
 * \param len    = length of the base IA (4 for TA, 12 for NA & PD)
 *
 * \return ISC_R_SUCCESS - all is well continue, any other return indicates
 *                         an error and the packet should be tossed
 */

static isc_result_t
dhc6_create_iaid(struct client_state *client,
                 struct data_string *ia,
                 int idx,
                 unsigned len)
{
        int start_idx, copy_len;

        memset(ia, 0, sizeof(*ia));
        if (!buffer_allocate(&ia->buffer, 12, MDL)) {
                return (ISC_R_NOMEMORY);
        }
        ia->data = ia->buffer->data;
        ia->len = len;

        /*
         * A simple IAID is the last 4 bytes
         * of the hardware address.
         */
        if (client->interface->hw_address.hlen > 4) {
                start_idx = client->interface->hw_address.hlen - 4;
                copy_len = 4;
        } else {
                start_idx = 0;
                copy_len = client->interface->hw_address.hlen;
        }
        memcpy(ia->buffer->data,
               client->interface->hw_address.hbuf + start_idx,
               copy_len);
        if (idx)
                ia->buffer->data[3] += idx;

        return (ISC_R_SUCCESS);
}

/*!
 *
 * \brief Add bare IA_NAs, IA_TAs or IA_PDs to the packet we are building.
 *
 * Attempt to add the number of bare IAs indicated by wanted to
 * the packet.  As we have already added a number of IAs based
 * on what is in the current lease after we create an IAID we check
 * it against the current lease and skip any that are already in use.
 *
 * \param client = the state of the entire client
 * \param packet = the packet we are building and where we
 *                 shall append the IA_NA, IA_TA  or IA_PDs we create
 * \param wanted = the number of IA_NA, IA_TA or IA_PDs we want to create
 * \param ia_type = the type of the IAs we want to create: NA, TA or PD.
 *
 * \return ISC_R_SUCCESS - all is well continue, any other return indicates
 *                         an error and the packet should be tossed
 */
static isc_result_t
dhc6_bare_ia_xx(struct client_state *client,
                struct data_string *packet,
                int wanted,
                u_int16_t ia_type)
{
        struct dhc6_ia *old_ia;
        struct data_string ia;
        u_int32_t t1, t2;
        int i, len;
        isc_result_t rval;
        char *type_string;
        struct option *type_option;

        /* figure out what type of option we are working with */
        switch (ia_type) {
              case D6O_IA_NA:
                type_string = "IA_NA";
                type_option = ia_na_option;
                len = 12;
                break;
              case D6O_IA_TA:
                type_string = "IA_TA";
                type_option = ia_ta_option;
                len = 4;
                break;
              case D6O_IA_PD:
                type_string = "IA_PD";
                type_option = ia_pd_option;
                len = 12;
                break;
              default:
                return (ISC_R_FAILURE);
        }

        for (i = 0; wanted != 0; i++) {
                rval = dhc6_create_iaid(client, &ia, i, len);
                if (rval != ISC_R_SUCCESS) {
                        log_error("Unable to allocate memory for %s.",
                                  type_string);
                        return (rval);
                }

                /* If we are already using this IAID, skip it and try again */
                if ((client->active_lease != NULL) &&
                    ((old_ia = find_ia(client->active_lease->bindings,
                                       ia_type,
                                       (char *)ia.buffer->data)) != NULL)) {
                        data_string_forget(&ia, MDL);
                        continue;
                }

                /* We have a good IAID, log it */
                log_debug("XMT:  X-- %s %s",
                          type_string, print_hex_1(4, ia.buffer->data, 55));

                /* If we are requesting an NA or a PD we also want to add
                 * the renew and rebind times we are requesting.
                 */
                if (len == 12) {
                        t1 = client->config->requested_lease / 2;
                        t2 = t1 + (t1 / 2);
                        putULong(ia.buffer->data + 4, t1);
                        putULong(ia.buffer->data + 8, t2);

                        log_debug("XMT:  | X-- Request renew in  +%u",
                                  (unsigned)t1);
                        log_debug("XMT:  | X-- Request rebind in +%u",
                                  (unsigned)t2);
                }

                /* and append it to the packet */
                append_option(packet, &dhcpv6_universe, type_option, &ia);
                data_string_forget(&ia, MDL);

                /* decrement the number of IAs we want */
                wanted--;
        }

        return (ISC_R_SUCCESS);
}

/*
 * do_init6() marshals and transmits a solicit.
 */
void
do_init6(void *input)
{
        struct client_state *client;
        struct dhc6_ia *old_ia;
        struct dhc6_addr *old_addr;
        struct data_string ds;
        struct data_string ia;
        struct data_string addr;
        struct timeval tv;
        u_int32_t t1, t2;
        int i, send_ret;

        client = input;

        /*
         * In RFC3315 section 17.1.2, the retransmission timer is
         * used as the selecting timer.
         */
        if (client->advertised_leases != NULL) {
                start_selecting6(client);
                return;
        }

        switch(check_timing6(client, DHCPV6_SOLICIT, "Solicit", NULL, &ds)) {
              case CHK_TIM_MRC_EXCEEDED:
              case CHK_TIM_ALLOC_FAILURE:
                return;
              case CHK_TIM_MRD_EXCEEDED:
                client->state = S_STOPPED;
                if (client->active_lease != NULL) {
                        dhc6_lease_destroy(&client->active_lease, MDL);
                        client->active_lease = NULL;
                }
                /* Stop if and only if this is the last client. */
                if (stopping_finished())
                        exit(2);
                return;
        }

        /*
         * Fetch any configured 'sent' options (includes DUID) in wire format.
         */
        dhcpv6_universe.encapsulate(&ds, NULL, NULL, client,
                                    NULL, client->sent_options, &global_scope,
                                    &dhcpv6_universe);

        /* Use a specific handler with rapid-commit. */
        if (lookup_option(&dhcpv6_universe, client->sent_options,
                          D6O_RAPID_COMMIT) != NULL) {
                client->v6_handler = rapid_commit_handler;
        }

        /* Append IA_NA. */
        for (i = 0; i < wanted_ia_na; i++) {
                /*
                 * XXX: maybe the IA_NA('s) should be put into the sent_options
                 * cache.  They'd have to be pulled down as they also contain
                 * different option caches in the same universe...
                 */
                if (dhc6_create_iaid(client, &ia, i, 12) != ISC_R_SUCCESS) {
                        log_error("Unable to allocate memory for IA_NA.");
                        data_string_forget(&ds, MDL);
                        return;
                }

                t1 = client->config->requested_lease / 2;
                t2 = t1 + (t1 / 2);
                putULong(ia.buffer->data + 4, t1);
                putULong(ia.buffer->data + 8, t2);

                log_debug("XMT:  X-- IA_NA %s",
                          print_hex_1(4, ia.buffer->data, 55));
                log_debug("XMT:  | X-- Request renew in  +%u", (unsigned)t1);
                log_debug("XMT:  | X-- Request rebind in +%u", (unsigned)t2);

                if ((client->active_lease != NULL) &&
                    ((old_ia = find_ia(client->active_lease->bindings,
                                       D6O_IA_NA,
                                       (char *)ia.buffer->data)) != NULL)) {
                        /*
                         * For each address in the old IA_NA,
                         * request a binding.
                         */
                        memset(&addr, 0, sizeof(addr));
                        for (old_addr = old_ia->addrs ; old_addr != NULL ;
                             old_addr = old_addr->next) {
                                if (old_addr->address.len != 16) {
                                        log_error("Invalid IPv6 address "
                                                  "length %d.  "
                                                  "Ignoring.  (%s:%d)",
                                                  old_addr->address.len,
                                                  MDL);
                                        continue;
                                }

                                if (!buffer_allocate(&addr.buffer, 24, MDL)) {
                                        log_error("Unable to allocate memory "
                                                  "for IAADDR.");
                                        data_string_forget(&ia, MDL);
                                        data_string_forget(&ds, MDL);
                                        return;
                                }
                                addr.data = addr.buffer->data;
                                addr.len = 24;

                                memcpy(addr.buffer->data,
                                       old_addr->address.iabuf,
                                       16);

                                t1 = client->config->requested_lease;
                                t2 = t1 + (t1 / 2);
                                putULong(addr.buffer->data + 16, t1);
                                putULong(addr.buffer->data + 20, t2);

                                log_debug("XMT:  | X-- Request address %s.",
                                          piaddr(old_addr->address));
                                log_debug("XMT:  | | X-- Request "
                                          "preferred in +%u",
                                          (unsigned)t1);
                                log_debug("XMT:  | | X-- Request valid "
                                          "in     +%u",
                                          (unsigned)t2);

                                append_option(&ia, &dhcpv6_universe,
                                              iaaddr_option,
                                              &addr);

                                data_string_forget(&addr, MDL);
                        }
                }

                append_option(&ds, &dhcpv6_universe, ia_na_option, &ia);
                data_string_forget(&ia, MDL);
        }

        /* Append IA_TA. */
        for (i = 0; i < wanted_ia_ta; i++) {
                /*
                 * XXX: maybe the IA_TA('s) should be put into the sent_options
                 * cache.  They'd have to be pulled down as they also contain
                 * different option caches in the same universe...
                 */
                if (dhc6_create_iaid(client, &ia, i, 4) != ISC_R_SUCCESS) {
                        log_error("Unable to allocate memory for IA_TA.");
                        data_string_forget(&ds, MDL);
                        return;
                }

                log_debug("XMT:  X-- IA_TA %s",
                          print_hex_1(4, ia.buffer->data, 55));

                if ((client->active_lease != NULL) &&
                    ((old_ia = find_ia(client->active_lease->bindings,
                                       D6O_IA_TA,
                                       (char *)ia.buffer->data)) != NULL)) {
                        /*
                         * For each address in the old IA_TA,
                         * request a binding.
                         */
                        memset(&addr, 0, sizeof(addr));
                        for (old_addr = old_ia->addrs ; old_addr != NULL ;
                             old_addr = old_addr->next) {
                                if (old_addr->address.len != 16) {
                                        log_error("Invalid IPv6 address "
                                                  "length %d.  "
                                                  "Ignoring.  (%s:%d)",
                                                  old_addr->address.len,
                                                  MDL);
                                        continue;
                                }

                                if (!buffer_allocate(&addr.buffer, 24, MDL)) {
                                        log_error("Unable to allocate memory "
                                                  "for IAADDR.");
                                        data_string_forget(&ia, MDL);
                                        data_string_forget(&ds, MDL);
                                        return;
                                }
                                addr.data = addr.buffer->data;
                                addr.len = 24;

                                memcpy(addr.buffer->data,
                                       old_addr->address.iabuf,
                                       16);

                                t1 = client->config->requested_lease;
                                t2 = t1 + (t1 / 2);
                                putULong(addr.buffer->data + 16, t1);
                                putULong(addr.buffer->data + 20, t2);

                                log_debug("XMT:  | X-- Request address %s.",
                                          piaddr(old_addr->address));
                                log_debug("XMT:  | | X-- Request "
                                          "preferred in +%u",
                                          (unsigned)t1);
                                log_debug("XMT:  | | X-- Request valid "
                                          "in     +%u",
                                          (unsigned)t2);

                                append_option(&ia, &dhcpv6_universe,
                                              iaaddr_option,
                                              &addr);

                                data_string_forget(&addr, MDL);
                        }
                }

                append_option(&ds, &dhcpv6_universe, ia_ta_option, &ia);
                data_string_forget(&ia, MDL);
        }

        /* Append IA_PD. */
        for (i = 0; i < wanted_ia_pd; i++) {
                /*
                 * XXX: maybe the IA_PD('s) should be put into the sent_options
                 * cache.  They'd have to be pulled down as they also contain
                 * different option caches in the same universe...
                 */
                memset(&ia, 0, sizeof(ia));
                if (dhc6_create_iaid(client, &ia, i, 12) != ISC_R_SUCCESS) {
                        log_error("Unable to allocate memory for IA_PD.");
                        data_string_forget(&ds, MDL);
                        return;
                }

                t1 = client->config->requested_lease / 2;
                t2 = t1 + (t1 / 2);
                putULong(ia.buffer->data + 4, t1);
                putULong(ia.buffer->data + 8, t2);

                log_debug("XMT:  X-- IA_PD %s",
                          print_hex_1(4, ia.buffer->data, 55));
                log_debug("XMT:  | X-- Request renew in  +%u", (unsigned)t1);
                log_debug("XMT:  | X-- Request rebind in +%u", (unsigned)t2);

                if ((client->active_lease != NULL) &&
                    ((old_ia = find_ia(client->active_lease->bindings,
                                       D6O_IA_PD,
                                       (char *)ia.buffer->data)) != NULL)) {
                        /*
                         * For each prefix in the old IA_PD,
                         * request a binding.
                         */
                        memset(&addr, 0, sizeof(addr));
                        for (old_addr = old_ia->addrs ; old_addr != NULL ;
                             old_addr = old_addr->next) {
                                if (old_addr->address.len != 16) {
                                        log_error("Invalid IPv6 prefix, "
                                                  "Ignoring.  (%s:%d)",
                                                  MDL);
                                        continue;
                                }

                                if (!buffer_allocate(&addr.buffer, 25, MDL)) {
                                        log_error("Unable to allocate memory "
                                                  "for IAPREFIX.");
                                        data_string_forget(&ia, MDL);
                                        data_string_forget(&ds, MDL);
                                        return;
                                }
                                addr.data = addr.buffer->data;
                                addr.len = 25;

                                t1 = client->config->requested_lease;
                                t2 = t1 + (t1 / 2);
                                putULong(addr.buffer->data, t1);
                                putULong(addr.buffer->data + 4, t2);

                                putUChar(addr.buffer->data + 8,
                                         old_addr->plen);
                                memcpy(addr.buffer->data + 9,
                                       old_addr->address.iabuf,
                                       16);

                                log_debug("XMT:  | X-- Request prefix %s/%u.",
                                          piaddr(old_addr->address),
                                          (unsigned) old_addr->plen);
                                log_debug("XMT:  | | X-- Request "
                                          "preferred in +%u",
                                          (unsigned)t1);
                                log_debug("XMT:  | | X-- Request valid "
                                          "in     +%u",
                                          (unsigned)t2);

                                append_option(&ia, &dhcpv6_universe,
                                              iaprefix_option,
                                              &addr);

                                data_string_forget(&addr, MDL);
                        }
                }

                append_option(&ds, &dhcpv6_universe, ia_pd_option, &ia);
                data_string_forget(&ia, MDL);
        }

        /* Transmit and wait. */

        log_info("XMT: Solicit on %s, interval %ld0ms.",
                 client->name ? client->name : client->interface->name,
                 (long int)client->RT);

        send_ret = send_packet6(client->interface,
                                ds.data, ds.len, &DHCPv6DestAddr);
        if (send_ret != ds.len) {
                log_error("dhc6: send_packet6() sent %d of %d bytes",
                          send_ret, ds.len);
        }

        data_string_forget(&ds, MDL);

        /* Wait RT */
        tv.tv_sec = cur_tv.tv_sec + client->RT / 100;
        tv.tv_usec = cur_tv.tv_usec + (client->RT % 100) * 10000;
        if (tv.tv_usec >= 1000000) {
                tv.tv_sec += 1;
                tv.tv_usec -= 1000000;
        }
        add_timeout(&tv, do_init6, client, NULL, NULL);

        dhc6_retrans_advance(client);
}

/* do_info_request6() marshals and transmits an information-request. */
void
do_info_request6(void *input)
{
        struct client_state *client;
        struct data_string ds;
        struct timeval tv;
        int send_ret;

        client = input;

        switch(check_timing6(client, DHCPV6_INFORMATION_REQUEST,
                             "Info-Request", NULL, &ds)) {
              case CHK_TIM_MRC_EXCEEDED:
              case CHK_TIM_ALLOC_FAILURE:
                return;
              case CHK_TIM_MRD_EXCEEDED:
                exit(2);
              case CHK_TIM_SUCCESS:
                break;
        }

        /* Fetch any configured 'sent' options (includes DUID) in wire format.
         */
        dhcpv6_universe.encapsulate(&ds, NULL, NULL, client,
                                    NULL, client->sent_options, &global_scope,
                                    &dhcpv6_universe);

        /* Transmit and wait. */

        log_info("XMT: Info-Request on %s, interval %ld0ms.",
                 client->name ? client->name : client->interface->name,
                 (long int)client->RT);

        send_ret = send_packet6(client->interface,
                                ds.data, ds.len, &DHCPv6DestAddr);
        if (send_ret != ds.len) {
                log_error("dhc6: send_packet6() sent %d of %d bytes",
                          send_ret, ds.len);
        }

        data_string_forget(&ds, MDL);

        /* Wait RT */
        tv.tv_sec = cur_tv.tv_sec + client->RT / 100;
        tv.tv_usec = cur_tv.tv_usec + (client->RT % 100) * 10000;
        if (tv.tv_usec >= 1000000) {
                tv.tv_sec += 1;
                tv.tv_usec -= 1000000;
        }
        add_timeout(&tv, do_info_request6, client, NULL, NULL);

        dhc6_retrans_advance(client);
}

/* do_confirm6() creates a Confirm packet and transmits it.  This function
 * is called on every timeout to (re)transmit.
 */
void
do_confirm6(void *input)
{
        struct client_state *client;
        struct data_string ds;
        int send_ret, added;
        struct timeval tv;

        client = input;

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

        /* In section 17.1.3, it is said:
         *
         *   If the client receives no responses before the message
         *   transmission process terminates, as described in section 14,
         *   the client SHOULD continue to use any IP addresses, using the
         *   last known lifetimes for those addresses, and SHOULD continue
         *   to use any other previously obtained configuration parameters.
         *
         * So if confirm times out, we go active.
         *
         * XXX: Should we reduce all IA's t1 to 0, so that we renew and
         * stick there until we get a reply?
         */

        switch(check_timing6(client, DHCPV6_CONFIRM, "Confirm",
                             client->active_lease, &ds)) {
              case CHK_TIM_MRC_EXCEEDED:
              case CHK_TIM_MRD_EXCEEDED:
                start_bound(client);
                return;
              case CHK_TIM_ALLOC_FAILURE:
                return;
              case CHK_TIM_SUCCESS:
                break;
        }

        /* Fetch any configured 'sent' options (includes DUID') in wire format.
         */
        dhcpv6_universe.encapsulate(&ds, NULL, NULL, client, NULL,
                                    client->sent_options, &global_scope,
                                    &dhcpv6_universe);

        /* Append IA's. */
        if (wanted_ia_na &&
            dhc6_add_ia_na(client, &ds, client->active_lease,
                           DHCPV6_CONFIRM, 0, &added) != ISC_R_SUCCESS) {
                data_string_forget(&ds, MDL);
                return;
        }
        if (wanted_ia_ta &&
            dhc6_add_ia_ta(client, &ds, client->active_lease,
                           DHCPV6_CONFIRM, 0, &added) != ISC_R_SUCCESS) {
                data_string_forget(&ds, MDL);
                return;
        }

        /* Transmit and wait. */

        log_info("XMT: Confirm on %s, interval %ld0ms.",
                 client->name ? client->name : client->interface->name,
                 (long int)client->RT);

        send_ret = send_packet6(client->interface, ds.data, ds.len,
                                &DHCPv6DestAddr);
        if (send_ret != ds.len) {
                log_error("dhc6: sendpacket6() sent %d of %d bytes",
                          send_ret, ds.len);
        }

        data_string_forget(&ds, MDL);

        /* Wait RT */
        tv.tv_sec = cur_tv.tv_sec + client->RT / 100;
        tv.tv_usec = cur_tv.tv_usec + (client->RT % 100) * 10000;
        if (tv.tv_usec >= 1000000) {
                tv.tv_sec += 1;
                tv.tv_usec -= 1000000;
        }
        add_timeout(&tv, do_confirm6, client, NULL, NULL);

        dhc6_retrans_advance(client);
}

/*
 * Release addresses.
 */
void
start_release6(struct client_state *client)
{
        /* Cancel any pending transmissions */
        cancel_timeout(do_confirm6, client);
        cancel_timeout(do_select6, client);
        cancel_timeout(do_refresh6, client);
        cancel_timeout(do_release6, client);
        client->state = S_STOPPED;

        /*
         * It is written:  "The client MUST NOT use any of the addresses it
         * is releasing as the source address in the Release message or in
         * any subsequently transmitted message."  So unconfigure now.
         */
        unconfigure6(client, "RELEASE6");

        /* Note this in the lease file. */
        if (client->active_lease == NULL)
                return;
        client->active_lease->released = ISC_TRUE;
        write_client6_lease(client, client->active_lease, 0, 1);

        /* Set timers per RFC3315 section 18.1.6. */
        client->IRT = REL_TIMEOUT * 100;
        client->MRT = 0;
        client->MRC = REL_MAX_RC;
        client->MRD = 0;

        dhc6_retrans_init(client);
        client->v6_handler = reply_handler;

        do_release6(client);
}
/*
 * do_release6() creates a Release packet and transmits it.
 */
static void
do_release6(void *input)
{
        struct client_state *client;
        struct data_string ds;
        int send_ret, added;
        struct timeval tv;

        client = input;

        if ((client->active_lease == NULL) || !active_prefix(client))
                return;

        switch(check_timing6(client, DHCPV6_RELEASE, "Release",
                             client->active_lease, &ds)) {
              case CHK_TIM_MRC_EXCEEDED:
              case CHK_TIM_ALLOC_FAILURE:
              case CHK_TIM_MRD_EXCEEDED:
                goto release_done;
              case CHK_TIM_SUCCESS:
                break;
        }

        /*
         * Don't use unicast as we don't know if we still have an
         * available address with enough scope.
         */

        dhcpv6_universe.encapsulate(&ds, NULL, NULL, client, NULL,
                                    client->sent_options, &global_scope,
                                    &dhcpv6_universe);

        /* Append IA's (but don't release temporary addresses). */
        if (wanted_ia_na &&
            dhc6_add_ia_na(client, &ds, client->active_lease,
                           DHCPV6_RELEASE, 0, &added) != ISC_R_SUCCESS) {
                data_string_forget(&ds, MDL);
                goto release_done;
        }
        if (wanted_ia_pd &&
            dhc6_add_ia_pd(client, &ds, client->active_lease,
                           DHCPV6_RELEASE, 0, &added) != ISC_R_SUCCESS) {
                data_string_forget(&ds, MDL);
                goto release_done;
        }

        /* Transmit and wait. */
        log_info("XMT: Release on %s, interval %ld0ms.",
                 client->name ? client->name : client->interface->name,
                 (long int)client->RT);

        send_ret = send_packet6(client->interface, ds.data, ds.len,
                                &DHCPv6DestAddr);
        if (send_ret != ds.len) {
                log_error("dhc6: sendpacket6() sent %d of %d bytes",
                          send_ret, ds.len);
        }

        data_string_forget(&ds, MDL);

        /* Wait RT */
        tv.tv_sec = cur_tv.tv_sec + client->RT / 100;
        tv.tv_usec = cur_tv.tv_usec + (client->RT % 100) * 10000;
        if (tv.tv_usec >= 1000000) {
                tv.tv_sec += 1;
                tv.tv_usec -= 1000000;
        }
        add_timeout(&tv, do_release6, client, NULL, NULL);
        dhc6_retrans_advance(client);
        return;

      release_done:
        dhc6_lease_destroy(&client->active_lease, MDL);
        client->active_lease = NULL;
        if (stopping_finished())
                exit(0);
}

/* status_log() just puts a status code into displayable form and logs it
 * to info level.
 */
static void
status_log(int code, const char *scope, const char *additional, int len)
{
        const char *msg = NULL;

        switch(code) {
              case STATUS_Success:
                msg = "Success";
                break;

              case STATUS_UnspecFail:
                msg = "UnspecFail";
                break;

              case STATUS_NoAddrsAvail:
                msg = "NoAddrsAvail";
                break;

              case STATUS_NoBinding:
                msg = "NoBinding";
                break;

              case STATUS_NotOnLink:
                msg = "NotOnLink";
                break;

              case STATUS_UseMulticast:
                msg = "UseMulticast";
                break;

              case STATUS_NoPrefixAvail:
                msg = "NoPrefixAvail";
                break;

              default:
                msg = "UNKNOWN";
                break;
        }

        if (len > 0)
                log_info("%s status code %s: %s", scope, msg,
                         print_hex_1(len,
                                     (const unsigned char *)additional, 50));
        else
                log_info("%s status code %s.", scope, msg);
}

/* Acquire a status code.
 */
static isc_result_t
dhc6_get_status_code(struct option_state *options, unsigned *code,
                     struct data_string *msg)
{
        struct option_cache *oc;
        struct data_string ds;
        isc_result_t rval = ISC_R_SUCCESS;

        if ((options == NULL) || (code == NULL))
                return DHCP_R_INVALIDARG;

        if ((msg != NULL) && (msg->len != 0))
                return DHCP_R_INVALIDARG;

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

        /* Assume success if there is no option. */
        *code = STATUS_Success;

        oc = lookup_option(&dhcpv6_universe, options, D6O_STATUS_CODE);
        if ((oc != NULL) &&
            evaluate_option_cache(&ds, NULL, NULL, NULL, options,
                                  NULL, &global_scope, oc, MDL)) {
                if (ds.len < 2) {
                        log_error("Invalid status code length %d.", ds.len);
                        rval = DHCP_R_FORMERR;
                } else
                        *code = getUShort(ds.data);

                if ((msg != NULL) && (ds.len > 2)) {
                        data_string_copy(msg, &ds, MDL);
                        msg->data += 2;
                        msg->len -= 2;
                }

                data_string_forget(&ds, MDL);
                return rval;
        }

        return ISC_R_NOTFOUND;
}

/* Look at status codes in an advertise, and reform the return value.
 */
static isc_result_t
dhc6_check_status(isc_result_t rval, struct option_state *options,
                  const char *scope, unsigned *code)
{
        struct data_string msg;
        isc_result_t status;

        if ((scope == NULL) || (code == NULL))
                return DHCP_R_INVALIDARG;

        /* If we don't find a code, we assume success. */
        *code = STATUS_Success;

        /* If there is no options cache, then there is no code. */
        if (options != NULL) {
                memset(&msg, 0, sizeof(msg));
                status = dhc6_get_status_code(options, code, &msg);

                if (status == ISC_R_SUCCESS) {
                        status_log(*code, scope, (char *)msg.data, msg.len);
                        data_string_forget(&msg, MDL);

                        if (*code != STATUS_Success)
                                rval = ISC_R_FAILURE;

                } else if (status != ISC_R_NOTFOUND)
                        rval = status;
        }

        return rval;
}

/* Determine if this packet could provide usable information.
 * We check the status codes at the top level and at the IA level,
 * IAADDRS have already been checked in the leaseify step and any with
 * a bad format or status code that wasn't success have been dropped.
 *
 * leaseify has also already removed any IAs for which the top level status
 * code or the IA status code indicated no addresses or prefixes were
 * available.
 */
static isc_result_t
dhc6_check_advertise(struct dhc6_lease *lease)
{
        struct dhc6_ia *ia;
        isc_result_t rval = ISC_R_SUCCESS;
        int have_addrs = ISC_FALSE;
        unsigned code;
        const char *scope;
        int got_na = 0, got_ta = 0, got_pd = 0;

        rval = dhc6_check_status(rval, lease->options, "message", &code);

        for (ia = lease->bindings ; ia != NULL ; ia = ia->next) {
                switch (ia->ia_type) {
                        case D6O_IA_NA:
                                scope = "IA_NA";
                                got_na++;
                                break;
                        case D6O_IA_TA:
                                scope = "IA_TA";
                                got_ta++;
                                break;
                        case D6O_IA_PD:
                                scope = "IA_PD";
                                got_pd++;
                                break;
                        default:
                                log_error("dhc6_check_advertise: no type.");
                                return ISC_R_FAILURE;
                }
                /* Currently we toss packets if we have an error getting a
                 * status code or if the status code isn't success, so
                 * no need to loop through the addresses */
                rval = dhc6_check_status(rval, ia->options, scope, &code);
                if (rval != ISC_R_SUCCESS)
                        continue;

                /* We don't need to check status on IAADDRS here as we already
                 * did it as part of the leaseify step and tossed bad IAADDRS.
                 * We are just checking to see if we have any addrs.
                 * Should we check the addr itself for usability?
                 */
                if (ia->addrs != NULL) {
                        have_addrs = ISC_TRUE;
                }
        }

        /* If we didn't get some addrs or the user required us to
         * get all of the requested IAs and we didn't return an error
         */
        if ((have_addrs != ISC_TRUE) ||
            ((require_all_ias != 0) &&
             ((got_na < wanted_ia_na) ||
              (got_ta < wanted_ia_ta) ||
              (got_pd < wanted_ia_pd))))
                rval = ISC_R_ADDRNOTAVAIL;

        return rval;
}

/* status code <-> action matrix for the client in INIT state
 * (rapid/commit).  Returns always false as no action is defined.
 */
static isc_boolean_t
dhc6_init_action(struct client_state *client, isc_result_t *rvalp,
                 unsigned code)
{
        if (rvalp == NULL)
                log_fatal("Impossible condition at %s:%d.", MDL);

        if (client == NULL) {
                *rvalp = DHCP_R_INVALIDARG;
                return ISC_FALSE;
        }

        if (*rvalp == ISC_R_SUCCESS)
                return ISC_FALSE;

        /* No possible action in any case... */
        return ISC_FALSE;
}

/* status code <-> action matrix for the client in SELECT state
 * (request/reply).  Returns true if action was taken (and the
 * packet should be ignored), or false if no action was taken.
 */
static isc_boolean_t
dhc6_select_action(struct client_state *client, isc_result_t *rvalp,
                   unsigned code)
{
        struct dhc6_lease *lease;
        isc_result_t rval;

        if (rvalp == NULL)
                log_fatal("Impossible condition at %s:%d.", MDL);

        if (client == NULL) {
                *rvalp = DHCP_R_INVALIDARG;
                return ISC_FALSE;
        }
        rval = *rvalp;

        if (rval == ISC_R_SUCCESS)
                return ISC_FALSE;

        switch (code) {
                /* We may have an earlier failure status code (so no
                 * success rval), and a success code now.  This
                 * doesn't upgrade the rval to success, but it does
                 * mean we take no action here.
                 */
              case STATUS_Success:
                /* Gimpy server, or possibly an attacker. */
              case STATUS_NoBinding:
              case STATUS_UseMulticast:
                /* Take no action. */
                return ISC_FALSE;

                /* If the server can't deal with us, either try the
                 * next advertised server, or continue retrying if there
                 * weren't any.
                 */
              default:
              case STATUS_UnspecFail:
                if (client->advertised_leases != NULL) {
                        dhc6_lease_destroy(&client->selected_lease, MDL);
                        client->selected_lease = NULL;

                        start_selecting6(client);

                        break;
                } else /* Take no action - continue to retry. */
                        return ISC_FALSE;

                /* If the server has no addresses, try other servers if
                 * we got some, otherwise go to INIT to hope for more
                 * servers.
                 */
              case STATUS_NoAddrsAvail:
              case STATUS_NoPrefixAvail:
                if (client->state == S_REBOOTING)
                        return ISC_FALSE;

                if (client->selected_lease == NULL)
                        log_fatal("Impossible case at %s:%d.", MDL);

                dhc6_lease_destroy(&client->selected_lease, MDL);
                client->selected_lease = NULL;

                if (client->advertised_leases != NULL)
                        start_selecting6(client);
                else
                        start_init6(client);

                break;

                /* If we got a NotOnLink from a Confirm, then we're not
                 * on link.  Kill the old-active binding and start over.
                 *
                 * If we got a NotOnLink from our Request, something weird
                 * happened.  Start over from scratch anyway.
                 */
              case STATUS_NotOnLink:
                if (client->state == S_REBOOTING) {
                        if (client->active_lease == NULL)
                                log_fatal("Impossible case at %s:%d.", MDL);

                        dhc6_lease_destroy(&client->active_lease, MDL);
                } else {
                        if (client->selected_lease == NULL)
                                log_fatal("Impossible case at %s:%d.", MDL);

                        dhc6_lease_destroy(&client->selected_lease, MDL);
                        client->selected_lease = NULL;

                        while (client->advertised_leases != NULL) {
                                lease = client->advertised_leases;
                                client->advertised_leases = lease->next;

                                dhc6_lease_destroy(&lease, MDL);
                        }
                }

                start_init6(client);
                break;
        }

        return ISC_TRUE;
}

static void
dhc6_withdraw_lease(struct client_state *client)
{
        struct dhc6_ia *ia;
        struct dhc6_addr *addr;

        if ((client == NULL) || (client->active_lease == NULL))
                return;

        for (ia = client->active_lease->bindings ; ia != NULL ;
             ia = ia->next) {
                for (addr = ia->addrs ; addr != NULL ; addr = addr->next) {
                        addr->max_life = addr->preferred_life = 0;
                }
        }

        /* Perform expiry. */
        do_expire(client);
}

/* status code <-> action matrix for the client in BOUND state
 * (request/reply).  Returns true if action was taken (and the
 * packet should be ignored), or false if no action was taken.
 */
static isc_boolean_t
dhc6_reply_action(struct client_state *client, isc_result_t *rvalp,
                  unsigned code)
{
        isc_result_t rval;

        if (rvalp == NULL)
                log_fatal("Impossible condition at %s:%d.", MDL);

        if (client == NULL) {
                *rvalp = DHCP_R_INVALIDARG;
                return ISC_FALSE;
        }
        rval = *rvalp;

        if (rval == ISC_R_SUCCESS)
                return ISC_FALSE;

        switch (code) {
                /* It's possible an earlier status code set rval to a failure
                 * code, and we've encountered a later success.
                 */
              case STATUS_Success:
                /* In "refreshes" (where we get replies), we probably
                 * still have a valid lease.  So "take no action" and
                 * the upper levels will keep retrying until the lease
                 * expires (or we rebind).
                 */
              case STATUS_UnspecFail:
                /* For unknown codes...it's a soft (retryable) error. */
              default:
                return ISC_FALSE;

                /* The server is telling us to use a multicast address, so
                 * we have to delete the unicast option from the active
                 * lease, then allow retransmission to occur normally.
                 * (XXX: It might be preferable in this case to retransmit
                 * sooner than the current interval, but for now we don't.)
                 */
              case STATUS_UseMulticast:
                if (client->active_lease != NULL)
                        delete_option(&dhcp_universe,
                                      client->active_lease->options,
                                      D6O_UNICAST);
                return ISC_FALSE;

                /* "When the client receives a NotOnLink status from the
                 *  server in response to a Request, the client can either
                 *  re-issue the Request without specifying any addresses
                 *  or restart the DHCP server discovery process."
                 *
                 * This is strange.  If competing server evaluation is
                 * useful (and therefore in the protocol), then why would
                 * a client's first reaction be to request from the same
                 * server on a different link?  Surely you'd want to
                 * re-evaluate your server selection.
                 *
                 * Well, I guess that's the answer.
                 */
              case STATUS_NotOnLink:
                /* In this case, we need to rescind all current active
                 * bindings (just 'expire' them all normally, if early).
                 * They're no use to us on the wrong link.  Then head back
                 * to init, redo server selection and get new addresses.
                 */
                dhc6_withdraw_lease(client);
                break;

                /* "If the status code is NoAddrsAvail, the client has
                 *  received no usable addresses in the IA and may choose
                 *  to try obtaining addresses for the IA from another
                 *  server."
                 */
              case STATUS_NoAddrsAvail:
              case STATUS_NoPrefixAvail:
                /* Head back to init, keeping any active bindings (!). */
                start_init6(client);
                break;

                /* -  sends a Request message if the IA contained a Status
                 *    Code option with the NoBinding status (and does not
                 *    send any additional Renew/Rebind messages)
                 */
              case STATUS_NoBinding:
                if (client->advertised_leases != NULL)
                        log_fatal("Impossible condition at %s:%d.", MDL);

                client->advertised_leases =
                                dhc6_dup_lease(client->active_lease, MDL);
                start_selecting6(client);
                break;
        }

        return ISC_TRUE;
}

/* status code <-> action matrix for the client in STOPPED state
 * (release/decline).  Returns true if action was taken (and the
 * packet should be ignored), or false if no action was taken.
 * NoBinding is translated into Success.
 */
static isc_boolean_t
dhc6_stop_action(struct client_state *client, isc_result_t *rvalp,
                  unsigned code)
{
        isc_result_t rval;

        if (rvalp == NULL)
                log_fatal("Impossible condition at %s:%d.", MDL);

        if (client == NULL) {
                *rvalp = DHCP_R_INVALIDARG;
                return ISC_FALSE;
        }
        rval = *rvalp;

        if (rval == ISC_R_SUCCESS)
                return ISC_FALSE;

        switch (code) {
                /* It's possible an earlier status code set rval to a failure
                 * code, and we've encountered a later success.
                 */
              case STATUS_Success:
                /* For unknown codes...it's a soft (retryable) error. */
              case STATUS_UnspecFail:
              default:
                return ISC_FALSE;

                /* NoBinding is not an error */
              case STATUS_NoBinding:
                if (rval == ISC_R_FAILURE)
                        *rvalp = ISC_R_SUCCESS;
                return ISC_FALSE;

                /* Should not happen */
              case STATUS_NoAddrsAvail:
              case STATUS_NoPrefixAvail:
                break;

                /* Give up on it */
              case STATUS_NotOnLink:
                break;

                /* The server is telling us to use a multicast address, so
                 * we have to delete the unicast option from the active
                 * lease, then allow retransmission to occur normally.
                 * (XXX: It might be preferable in this case to retransmit
                 * sooner than the current interval, but for now we don't.)
                 */
              case STATUS_UseMulticast:
                if (client->active_lease != NULL)
                        delete_option(&dhcp_universe,
                                      client->active_lease->options,
                                      D6O_UNICAST);
                return ISC_FALSE;
        }

        return ISC_TRUE;
}

/* Look at a new and old lease, and make sure the new information is not
 * losing us any state.
 */
static isc_result_t
dhc6_check_reply(struct client_state *client, struct dhc6_lease *new)
{
        isc_boolean_t (*action)(struct client_state *,
                                isc_result_t *, unsigned);
        struct dhc6_ia *ia;
        isc_result_t rval = ISC_R_SUCCESS;
        unsigned code;
        const char *scope;
        int nscore, sscore;
        int have_addrs = ISC_FALSE;
        int got_na = 0, got_ta = 0, got_pd = 0;

        if ((client == NULL) || (new == NULL))
                return DHCP_R_INVALIDARG;

        switch (client->state) {
              case S_INIT:
                action = dhc6_init_action;
                break;

              case S_SELECTING:
              case S_REBOOTING:
                action = dhc6_select_action;
                break;

              case S_RENEWING:
              case S_REBINDING:
                action = dhc6_reply_action;
                break;

              case S_STOPPED:
                action = dhc6_stop_action;
                break;

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

        /* If there is a code to extract, and if there is some
         * action to take based on that code, then take the action
         * and do not continue.
         */
        rval = dhc6_check_status(rval, new->options, "message", &code);
        if (action(client, &rval, code))
                return ISC_R_CANCELED;

        for (ia = new->bindings ; ia != NULL ; ia = ia->next) {
                switch (ia->ia_type) {
                        case D6O_IA_NA:
                                scope = "IA_NA";
                                got_na++;
                                break;
                        case D6O_IA_TA:
                                scope = "IA_TA";
                                got_ta++;
                                break;
                        case D6O_IA_PD:
                                scope = "IA_PD";
                                got_pd++;
                                break;
                        default:
                                log_error("dhc6_check_reply: no type.");
                                return DHCP_R_INVALIDARG;
                }
                rval = dhc6_check_status(rval, ia->options, scope, &code);

                if (action(client, &rval, code))
                        return ISC_R_CANCELED;

                if (ia->addrs != NULL) {
                        have_addrs = ISC_TRUE;
                }
        }

        /* A Confirm->Reply is unsuitable for comparison to the old lease. */
        if (client->state == S_REBOOTING)
                return rval;

        /* We expect the lease to have at least one address and if
         * required all of the requested IAs if not flag it as
         * NoAddrs and call the action routine to try again.
         *
         * Currently we don't completely handle TAs in all cases
         * so we don't check them for requires.  I've left the
         * check in and commented it as I eventually do want
         * us to check for TAs as well.  SAR
         */
        if ((have_addrs != ISC_TRUE) ||
            ((require_all_ias != 0) &&
             ((got_na < wanted_ia_na) ||
              /*(got_ta < wanted_ia_ta) ||*/
              (got_pd < wanted_ia_pd)))) {
                rval = ISC_R_FAILURE;
                if (action(client, &rval, STATUS_NoAddrsAvail) == ISC_TRUE) {
                        return ISC_R_CANCELED;
                }
        }

        /* No old lease in rapid-commit. */
        if (client->state == S_INIT)
                return rval;

        switch (client->state) {
              case S_SELECTING:
                /* Compare the new lease with the selected lease to make
                 * sure there is no risky business.
                 */
                nscore = dhc6_score_lease(client, new);
                sscore = dhc6_score_lease(client, client->selected_lease);
                if ((client->advertised_leases != NULL) &&
                    (nscore < (sscore / 2))) {
                        /* XXX: An attacker might reply this way to make
                         * XXX: sure we latch onto their configuration.
                         * XXX: We might want to ignore the packet and
                         * XXX: schedule re-selection at the next timeout?
                         */
                        log_error("PRC: BAIT AND SWITCH detected.  Score of "
                                  "supplied lease (%d) is substantially "
                                  "smaller than the advertised score (%d).  "
                                  "Trying other servers.",
                                  nscore, sscore);

                        dhc6_lease_destroy(&client->selected_lease, MDL);
                        client->selected_lease = NULL;

                        start_selecting6(client);

                        return ISC_R_CANCELED;
                }
                break;

              case S_RENEWING:
              case S_REBINDING:
                /* This leaves one RFC3315 status check unimplemented:
                 *
                 * -  sends a Renew/Rebind if the IA is not in the Reply
                 *    message
                 *
                 * We rely on the scheduling system to note that the IA has
                 * not left Renewal/Rebinding/whatever since it still carries
                 * old times from the last successful binding.  So this is
                 * implemented actually, just not explicitly.
                 */
                break;

              case S_STOPPED:
                /* Nothing critical to do at this stage. */
                break;

              default:
                log_fatal("REALLY impossible condition at %s:%d.", MDL);
                return ISC_R_CANCELED;
        }

        return rval;
}

/* While in init state, we only collect advertisements.  If there happens
 * to be an advertisement with a preference option of 255, that's an
 * automatic exit.  Otherwise, we collect advertisements until our timeout
 * expires (client->RT).
 */
void
init_handler(struct packet *packet, struct client_state *client)
{
        struct dhc6_lease *lease;

        /* In INIT state, we send solicits, we only expect to get
         * advertises (rapid commit has its own handler).
         */
        if (packet->dhcpv6_msg_type != DHCPV6_ADVERTISE)
                return;

        /* RFC3315 section 15.3 validation (same as 15.10 since we
         * always include a client id).
         */
        if (!valid_reply(packet, client)) {
                log_error("Invalid Advertise - rejecting.");
                return;
        }

        lease = dhc6_leaseify(packet, client);

        /* Out of memory or corrupt packet condition...hopefully a temporary
         * problem.  Returning now makes us try to retransmit later.
         */
        if (lease == NULL)
                return;

        if (dhc6_check_advertise(lease) != ISC_R_SUCCESS) {
                log_debug("PRC: Lease failed to satisfy.");
                dhc6_lease_destroy(&lease, MDL);
                return;
        }

        insert_lease(&client->advertised_leases, lease);

        /* According to RFC3315 section 17.1.2, the client MUST wait for
         * the first RT before selecting a lease.  But on the 400th RT,
         * we dont' want to wait the full timeout if we finally get an
         * advertise.  We could probably wait a second, but ohwell,
         * RFC3315 doesn't say so.
         *
         * If the lease is highest possible preference, 255, RFC3315 claims
         * we should continue immediately even on the first RT.  We probably
         * should not if the advertise contains less than one IA and address.
         */
        if ((client->txcount > 1) ||
            ((lease->pref == 255) &&
             (dhc6_score_lease(client, lease) > SCORE_MIN))) {
                log_debug("RCV:  Advertisement immediately selected.");
                cancel_timeout(do_init6, client);
                start_selecting6(client);
        } else
                log_debug("RCV:  Advertisement recorded.");
}

/* info_request_handler() accepts a Reply to an Info-request.
 */
void
info_request_handler(struct packet *packet, struct client_state *client)
{
        isc_result_t check_status;
        unsigned code;

        if (packet->dhcpv6_msg_type != DHCPV6_REPLY)
                return;

        /* RFC3315 section 15.10 validation (same as 15.3 since we
         * always include a client id).
         */
        if (!valid_reply(packet, client)) {
                log_error("Invalid Reply - rejecting.");
                return;
        }

        check_status = dhc6_check_status(ISC_R_SUCCESS, packet->options,
                                         "message", &code);

        if (check_status != ISC_R_SUCCESS) {
                /* If no action was taken, but there is an error, then
                 * we wait for a retransmission.
                 */
                if (check_status != ISC_R_CANCELED)
                        return;
        }

        /* We're done retransmitting at this point. */
        cancel_timeout(do_info_request6, client);

        /* Action was taken, so now that we've torn down our scheduled
         * retransmissions, return.
         */
        if (check_status == ISC_R_CANCELED)
                return;

        /* Cleanup if a previous attempt to go bound failed. */
        if (client->old_lease != NULL) {
                dhc6_lease_destroy(&client->old_lease, MDL);
                client->old_lease = NULL;
        }

        /* Cache options in the active_lease. */
        if (client->active_lease != NULL)
                client->old_lease = client->active_lease;
        client->active_lease = dmalloc(sizeof(struct dhc6_lease), MDL);
        if (client->active_lease == NULL)
                log_fatal("Out of memory for v6 lease structure.");
        option_state_reference(&client->active_lease->options,
                               packet->options, MDL);

        execute_statements_in_scope(NULL, (struct packet *)packet, NULL, client,
                                    client->active_lease->options,
                                    client->active_lease->options,
                                    &global_scope, client->config->on_receipt,
                                    NULL, NULL);

        start_informed(client);
}

/* Specific version of init_handler() for rapid-commit.
 */
void
rapid_commit_handler(struct packet *packet, struct client_state *client)
{
        struct dhc6_lease *lease;
        isc_result_t check_status;

        /* On ADVERTISE just fall back to the init_handler().
         */
        if (packet->dhcpv6_msg_type == DHCPV6_ADVERTISE) {
                init_handler(packet, client);
                return;
        } else if (packet->dhcpv6_msg_type != DHCPV6_REPLY)
                return;

        /* RFC3315 section 15.10 validation (same as 15.3 since we
         * always include a client id).
         */
        if (!valid_reply(packet, client)) {
                log_error("Invalid Reply - rejecting.");
                return;
        }

        /* A rapid-commit option MUST be here. */
        if (lookup_option(&dhcpv6_universe, packet->options,
                          D6O_RAPID_COMMIT) == 0) {
                log_error("Reply without Rapid-Commit - rejecting.");
                return;
        }

        lease = dhc6_leaseify(packet, client);

        /* Out of memory or corrupt packet condition...hopefully a temporary
         * problem.  Returning now makes us try to retransmit later.
         */
        if (lease == NULL)
                return;

        check_status = dhc6_check_reply(client, lease);
        if (check_status != ISC_R_SUCCESS) {
                dhc6_lease_destroy(&lease, MDL);
                return;
        }

        /* Jump to the selecting state. */
        cancel_timeout(do_init6, client);
        client->state = S_SELECTING;

        /* Merge any bindings in the active lease (if there is one) into
         * the new active lease.
         */
        dhc6_merge_lease(client->active_lease, lease);

        /* Cleanup if a previous attempt to go bound failed. */
        if (client->old_lease != NULL) {
                dhc6_lease_destroy(&client->old_lease, MDL);
                client->old_lease = NULL;
        }

        /* Make this lease active and BIND to it. */
        if (client->active_lease != NULL)
                client->old_lease = client->active_lease;
        client->active_lease = lease;

        /* We're done with the ADVERTISEd leases, if any. */
        while(client->advertised_leases != NULL) {
                lease = client->advertised_leases;
                client->advertised_leases = lease->next;

                dhc6_lease_destroy(&lease, MDL);
        }

        start_bound(client);
}

/* Find the 'best' lease in the cache of advertised leases (usually).  From
 * RFC3315 Section 17.1.3:
 *
 *   Upon receipt of one or more valid Advertise messages, the client
 *   selects one or more Advertise messages based upon the following
 *   criteria.
 *
 *   -  Those Advertise messages with the highest server preference value
 *      are preferred over all other Advertise messages.
 *
 *   -  Within a group of Advertise messages with the same server
 *      preference value, a client MAY select those servers whose
 *      Advertise messages advertise information of interest to the
 *      client.  For example, the client may choose a server that returned
 *      an advertisement with configuration options of interest to the
 *      client.
 *
 *   -  The client MAY choose a less-preferred server if that server has a
 *      better set of advertised parameters, such as the available
 *      addresses advertised in IAs.
 *
 * Note that the first and third contradict each other.  The third should
 * probably be taken to mean that the client should prefer answers that
 * offer bindings, even if that violates the preference rule.
 *
 * The above also isn't deterministic where there are ties.  So the final
 * tiebreaker we add, if all other values are equal, is to compare the
 * server identifiers and to select the numerically lower one.
 */
static struct dhc6_lease *
dhc6_best_lease(struct client_state *client, struct dhc6_lease **head)
{
        struct dhc6_lease **rpos, *rval, **candp, *cand;
        int cscore, rscore;

        if (head == NULL || *head == NULL)
                return NULL;

        rpos = head;
        rval = *rpos;
        rscore = dhc6_score_lease(client, rval);
        candp = &rval->next;
        cand = *candp;

        log_debug("PRC: Considering best lease.");
        log_debug("PRC:  X-- Initial candidate %s (s: %d, p: %u).",
                  print_hex_1(rval->server_id.len,
                              rval->server_id.data, 48),
                  rscore, (unsigned)rval->pref);

        for (; cand != NULL ; candp = &cand->next, cand = *candp) {
                cscore = dhc6_score_lease(client, cand);

                log_debug("PRC:  X-- Candidate %s (s: %d, p: %u).",
                          print_hex_1(cand->server_id.len,
                                      cand->server_id.data, 48),
                          cscore, (unsigned)cand->pref);

                /* Above you'll find quoted RFC3315 Section 17.1.3.
                 *
                 * The third clause tells us to give up on leases that
                 * have no bindings even if their preference is better.
                 * So where our 'selected' lease's score is less than
                 * SCORE_MIN (1 ia + 1 addr), choose any candidate >= SCORE_MIN.
                 *
                 * The first clause tells us to make preference the primary
                 * deciding factor.  So if it's lower, reject, if it's
                 * higher, select.
                 *
                 * The second clause tells us where the preference is
                 * equal, we should use 'our judgement' of what we like
                 * to see in an advertisement primarily.
                 *
                 * But there can still be a tie.  To make this deterministic,
                 * we compare the server identifiers and select the binary
                 * lowest.
                 *
                 * Since server id's are unique in this list, there is
                 * no further tie to break.
                 */
                if ((rscore < SCORE_MIN) && (cscore >= SCORE_MIN)) {
                        log_debug("PRC:  | X-- Selected, has bindings.");
                } else if (cand->pref < rval->pref) {
                        log_debug("PRC:  | X-- Rejected, lower preference.");
                        continue;
                } else if (cand->pref > rval->pref) {
                        log_debug("PRC:  | X-- Selected, higher preference.");
                } else if (cscore > rscore) {
                        log_debug("PRC:  | X-- Selected, equal preference, "
                                  "higher score.");
                } else if (cscore < rscore) {
                        log_debug("PRC:  | X-- Rejected, equal preference, "
                                  "lower score.");
                        continue;
                } else if ((cand->server_id.len < rval->server_id.len) ||
                           ((cand->server_id.len == rval->server_id.len) &&
                            (memcmp(cand->server_id.data,
                                    rval->server_id.data,
                                    cand->server_id.len) < 0))) {
                        log_debug("PRC:  | X-- Selected, equal preference, "
                                  "equal score, binary lesser server ID.");
                } else {
                        log_debug("PRC:  | X-- Rejected, equal preference, "
                                  "equal score, binary greater server ID.");
                        continue;
                }

                rpos = candp;
                rval = cand;
                rscore = cscore;
        }

        /* Remove the selected lease from the chain. */
        *rpos = rval->next;

        return rval;
}

/* Select a lease out of the advertised leases and setup state to try and
 * acquire that lease.
 */
void
start_selecting6(struct client_state *client)
{
        struct dhc6_lease *lease;

        if (client->advertised_leases == NULL) {
                log_error("Can not enter DHCPv6 SELECTING state with no "
                          "leases to select from!");
                return;
        }

        log_debug("PRC: Selecting best advertised lease.");
        client->state = S_SELECTING;

        lease = dhc6_best_lease(client, &client->advertised_leases);

        if (lease == NULL)
                log_fatal("Impossible error at %s:%d.", MDL);

        client->selected_lease = lease;

        /* Set timers per RFC3315 section 18.1.1. */
        client->IRT = REQ_TIMEOUT * 100;
        client->MRT = REQ_MAX_RT * 100;
        client->MRC = REQ_MAX_RC;
        client->MRD = 0;

        dhc6_retrans_init(client);

        client->v6_handler = reply_handler;

        /* ("re")transmit the first packet. */
        do_select6(client);
}

/* Transmit a Request to select a lease offered in Advertisements.  In
 * the event of failure, either move on to the next-best advertised lease,
 * or head back to INIT state if there are none.
 */
void
do_select6(void *input)
{
        struct client_state *client;
        struct dhc6_lease *lease;
        struct data_string ds;
        struct timeval tv;
        int send_ret, added;

        client = input;

        /* 'lease' is fewer characters to type. */
        lease = client->selected_lease;
        if (lease == NULL || lease->bindings == NULL) {
                log_error("Illegal to attempt selection without selecting "
                          "a lease.");
                return;
        }

        switch(check_timing6(client, DHCPV6_REQUEST, "Request", lease, &ds)) {
              case CHK_TIM_MRC_EXCEEDED:
              case CHK_TIM_MRD_EXCEEDED:
                log_debug("PRC: Lease %s failed.",
                          print_hex_1(lease->server_id.len,
                                      lease->server_id.data, 56));

                /* Get rid of the lease that timed/counted out. */
                dhc6_lease_destroy(&lease, MDL);
                client->selected_lease = NULL;

                /* If there are more leases great.  If not, get more. */
                if (client->advertised_leases != NULL)
                        start_selecting6(client);
                else
                        start_init6(client);
                return;
              case CHK_TIM_ALLOC_FAILURE:
                return;
              case CHK_TIM_SUCCESS:
                break;
        }

        /* Now make a packet that looks suspiciously like the one we
         * got from the server.  But different.
         *
         * XXX: I guess IAID is supposed to be something the client
         * indicates and uses as a key to its internal state.  It is
         * kind of odd to ask the server for IA's whose IAID the client
         * did not manufacture.  We first need a formal dhclient.conf
         * construct for the iaid, then we can delve into this matter
         * more properly.  In the time being, this will work.
         */

        /* Fetch any configured 'sent' options (includes DUID) in wire format.
         */
        dhcpv6_universe.encapsulate(&ds, NULL, NULL, client,
                                    NULL, client->sent_options, &global_scope,
                                    &dhcpv6_universe);

        /* Now append any IA's, and within them any IAADDR/IAPREFIXs.
         * For each type of IA (na, ta, pd) we start with the ones for
         * which we already have addresses (dhc6_add_ia_xx) and then
         * if we still want more we add aditional IAs (dhc6_bare_ia_xx)
         */
        if (wanted_ia_na &&
            ((dhc6_add_ia_na(client, &ds, lease, DHCPV6_REQUEST,
                             wanted_ia_na, &added) != ISC_R_SUCCESS) ||
             (dhc6_bare_ia_xx(client, &ds, wanted_ia_na - added,
                              D6O_IA_NA) != ISC_R_SUCCESS))) {
                data_string_forget(&ds, MDL);
                return;
        }
        if (wanted_ia_ta &&
            ((dhc6_add_ia_ta(client, &ds, lease, DHCPV6_REQUEST,
                             wanted_ia_ta, &added) != ISC_R_SUCCESS) ||
             (dhc6_bare_ia_xx(client, &ds, wanted_ia_ta - added,
                              D6O_IA_TA) != ISC_R_SUCCESS))) {
                data_string_forget(&ds, MDL);
                return;
        }
        if (wanted_ia_pd &&
            ((dhc6_add_ia_pd(client, &ds, lease, DHCPV6_REQUEST,
                             wanted_ia_pd, &added) != ISC_R_SUCCESS) ||
             (dhc6_bare_ia_xx(client, &ds, wanted_ia_pd - added,
                              D6O_IA_PD) != ISC_R_SUCCESS))) {
                data_string_forget(&ds, MDL);
                return;
        }

        log_info("XMT: Request on %s, interval %ld0ms.",
                 client->name ? client->name : client->interface->name,
                 (long int)client->RT);

        send_ret = send_packet6(client->interface,
                                ds.data, ds.len, &DHCPv6DestAddr);
        if (send_ret != ds.len) {
                log_error("dhc6: send_packet6() sent %d of %d bytes",
                          send_ret, ds.len);
        }

        data_string_forget(&ds, MDL);

        /* Wait RT */
        tv.tv_sec = cur_tv.tv_sec + client->RT / 100;
        tv.tv_usec = cur_tv.tv_usec + (client->RT % 100) * 10000;
        if (tv.tv_usec >= 1000000) {
                tv.tv_sec += 1;
                tv.tv_usec -= 1000000;
        }
        add_timeout(&tv, do_select6, client, NULL, NULL);

        dhc6_retrans_advance(client);
}

/*!
 *
 * \brief Count the number of IAs in the bindings
 *
 * \param lease  the lease to count
 * \param ia_type the type of the IA we wish to count
 *
 * \return The number of IAs of the specified type we found
 */
static int
dhc6_count_ia(struct dhc6_lease *lease, u_int16_t ia_type)
{
        struct dhc6_ia *ia;
        int i = 0;

        for (ia = lease->bindings; ia != NULL; ia = ia->next) {
                if (ia->ia_type == ia_type)
                        /* bump the counter for the correct types */
                        i++;
        }

        return (i);
}

/*!
 *
 * \brief Add IA_NA information from the lease to the packet
 * we are building.
 *
 * Walk through the lease and for each IA_NA in the lease
 * and for each address in the IA_NA append that information
 * onto the packet-so-far.  If wanted is 0 include all IA_NAs
 * in the lease if wanted is non-zero include only that many
 * IA_NAs (this may occur if sommebody restarts a client with
 * arugments for a smaller number of NAs than before).
 *
 * \param client = the state of the entire client
 * \param packet = the packet we are building and where we
 *                 shall append the IA_NAs we create
 * \param lease  = the current lease
 * \param message = the type of the packet
 * \param wanted  = the number of IA_NAs to include in the packet
 *                  0 means include all
 * \param added   = the number of IA_NAs that were added to the packet
 *
 * \return ISC_R_SUCCESS - all is well continue, any other return
 *                         indicates an error (most likely memory issues)
 *                         and the packet should be tossed.
 */
static isc_result_t
dhc6_add_ia_na(struct client_state *client, struct data_string *packet,
               struct dhc6_lease *lease, u_int8_t message,
               int wanted, int *added)
{
        struct data_string iads;
        struct data_string addrds;
        struct dhc6_addr *addr;
        struct dhc6_ia *ia;
        isc_result_t rval = ISC_R_SUCCESS;
        TIME t1, t2;
        int i;

        *added = 0;
        memset(&iads, 0, sizeof(iads));
        memset(&addrds, 0, sizeof(addrds));
        for (ia = lease->bindings, i = 0;
             ia != NULL && rval == ISC_R_SUCCESS && (wanted == 0 || i < wanted);
             ia = ia->next) {
                if (ia->ia_type != D6O_IA_NA)
                        continue;

                /* Now that we know this is an NA bump the counter */
                i++;

                if (!buffer_allocate(&iads.buffer, 12, MDL)) {
                        log_error("Unable to allocate memory for IA_NA.");
                        rval = ISC_R_NOMEMORY;
                        break;
                }

                /* Copy the IAID into the packet buffer. */
                memcpy(iads.buffer->data, ia->iaid, 4);
                iads.data = iads.buffer->data;
                iads.len = 12;

                switch (message) {
                      case DHCPV6_REQUEST:
                      case DHCPV6_RENEW:
                      case DHCPV6_REBIND:

                        t1 = client->config->requested_lease / 2;
                        t2 = t1 + (t1 / 2);
#if MAX_TIME > 0xffffffff
                        if (t1 > 0xffffffff)
                                t1 = 0xffffffff;
                        if (t2 > 0xffffffff)
                                t2 = 0xffffffff;
#endif
                        putULong(iads.buffer->data + 4, t1);
                        putULong(iads.buffer->data + 8, t2);

                        log_debug("XMT:  X-- IA_NA %s",
                                  print_hex_1(4, iads.data, 59));
                        log_debug("XMT:  | X-- Requested renew  +%u",
                                  (unsigned) t1);
                        log_debug("XMT:  | X-- Requested rebind +%u",
                                  (unsigned) t2);
                        break;

                      case DHCPV6_CONFIRM:
                      case DHCPV6_RELEASE:
                      case DHCPV6_DECLINE:
                        /* Set t1 and t2 to zero; server will ignore them */
                        memset(iads.buffer->data + 4, 0, 8);
                        log_debug("XMT:  X-- IA_NA %s",
                                  print_hex_1(4, iads.buffer->data, 55));

                        break;

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

                for (addr = ia->addrs ; addr != NULL ; addr = addr->next) {
                        /*
                         * Do not confirm expired addresses, do not request
                         * expired addresses (but we keep them around for
                         * solicit).
                         */
                        if (addr->flags & DHC6_ADDR_EXPIRED)
                                continue;

                        if (addr->address.len != 16) {
                                log_error("Illegal IPv6 address length (%d), "
                                          "ignoring.  (%s:%d)",
                                          addr->address.len, MDL);
                                continue;
                        }

                        if (!buffer_allocate(&addrds.buffer, 24, MDL)) {
                                log_error("Unable to allocate memory for "
                                          "IAADDR.");
                                rval = ISC_R_NOMEMORY;
                                break;
                        }

                        addrds.data = addrds.buffer->data;
                        addrds.len = 24;

                        /* Copy the address into the packet buffer. */
                        memcpy(addrds.buffer->data, addr->address.iabuf, 16);

                        /* Copy in additional information as appropriate */
                        switch (message) {
                              case DHCPV6_REQUEST:
                              case DHCPV6_RENEW:
                              case DHCPV6_REBIND:
                                t1 = client->config->requested_lease;
                                t2 = t1 + 300;
                                putULong(addrds.buffer->data + 16, t1);
                                putULong(addrds.buffer->data + 20, t2);

                                log_debug("XMT:  | | X-- IAADDR %s",
                                          piaddr(addr->address));
                                log_debug("XMT:  | | | X-- Preferred "
                                          "lifetime +%u", (unsigned)t1);
                                log_debug("XMT:  | | | X-- Max lifetime +%u",
                                          (unsigned)t2);

                                break;

                              case DHCPV6_CONFIRM:
                                /*
                                 * Set preferred and max life to zero,
                                 * per 17.1.3.
                                 */
                                memset(addrds.buffer->data + 16, 0, 8);
                                log_debug("XMT:  | X-- Confirm Address %s",
                                          piaddr(addr->address));
                                break;

                              case DHCPV6_RELEASE:
                                /* Preferred and max life are irrelevant */
                                memset(addrds.buffer->data + 16, 0, 8);
                                log_debug("XMT:  | X-- Release Address %s",
                                          piaddr(addr->address));
                                break;

                              case DHCPV6_DECLINE:
                                /* Preferred and max life are irrelevant */
                                memset(addrds.buffer->data + 16, 0, 8);
                                log_debug("XMT:  | X-- Decline Address %s",
                                          piaddr(addr->address));
                                break;

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

                        append_option(&iads, &dhcpv6_universe, iaaddr_option,
                                      &addrds);
                        data_string_forget(&addrds, MDL);
                }

                /*
                 * It doesn't make sense to make a request without an
                 * address.
                 */
                if (ia->addrs == NULL) {
                        log_debug("!!!:  V IA_NA has no IAADDRs - removed.");
                        rval = ISC_R_FAILURE;
                } else if (rval == ISC_R_SUCCESS) {
                        log_debug("XMT:  V IA_NA appended.");
                        append_option(packet, &dhcpv6_universe, ia_na_option,
                                      &iads);
                }

                data_string_forget(&iads, MDL);
        }

        if (rval == ISC_R_SUCCESS)
                *added = i;

        return (rval);
}

/*!
 *
 * \brief Add IA_TA information from the lease to the packet
 * we are building.
 *
 * Walk through the lease and for each IA_TA in the lease
 * and for each address in the IA_TA append that information
 * onto the packet-so-far.  If wanted is 0 include all IA_TAs
 * in the lease if wanted is non-zero include only that many
 * IA_TAs (this may occur if sommebody restarts a client with
 * arugments for a smaller number of TAs than before).
 *
 * \param client = the state of the entire client
 * \param packet = the packet we are building and where we
 *                 shall append the IA_TAs we create
 * \param lease  = the current lease
 * \param message = the type of the packet
 * \param wanted  = the number of IA_TAs to include in the packet
 *                  0 means include all
 * \param added   = the number of IA_TAs that were added to the packet
 *
 * \return ISC_R_SUCCESS - all is well continue, any other return
 *                         indicates an error (most likely memory issues)
 *                         and the packet should be tossed.
 */
static isc_result_t
dhc6_add_ia_ta(struct client_state *client, struct data_string *packet,
               struct dhc6_lease *lease, u_int8_t message,
               int wanted, int *added)
{
        struct data_string iads;
        struct data_string addrds;
        struct dhc6_addr *addr;
        struct dhc6_ia *ia;
        isc_result_t rval = ISC_R_SUCCESS;
        TIME t1, t2;
        int i;

        *added = 0;
        memset(&iads, 0, sizeof(iads));
        memset(&addrds, 0, sizeof(addrds));
        for (ia = lease->bindings, i = 0;
             ia != NULL && rval == ISC_R_SUCCESS && (wanted == 0 || i < wanted);
             ia = ia->next) {
                if (ia->ia_type != D6O_IA_TA)
                        continue;

                /* Now that we know this is an TA bump the counter */
                i++;

                if (!buffer_allocate(&iads.buffer, 4, MDL)) {
                        log_error("Unable to allocate memory for IA_TA.");
                        rval = ISC_R_NOMEMORY;
                        break;
                }

                /* Copy the IAID into the packet buffer. */
                memcpy(iads.buffer->data, ia->iaid, 4);
                iads.data = iads.buffer->data;
                iads.len = 4;

                log_debug("XMT:  X-- IA_TA %s",
                          print_hex_1(4, iads.buffer->data, 55));

                for (addr = ia->addrs ; addr != NULL ; addr = addr->next) {
                        /*
                         * Do not confirm expired addresses, do not request
                         * expired addresses (but we keep them around for
                         * solicit).
                         */
                        if (addr->flags & DHC6_ADDR_EXPIRED)
                                continue;

                        if (addr->address.len != 16) {
                                log_error("Illegal IPv6 address length (%d), "
                                          "ignoring.  (%s:%d)",
                                          addr->address.len, MDL);
                                continue;
                        }

                        if (!buffer_allocate(&addrds.buffer, 24, MDL)) {
                                log_error("Unable to allocate memory for "
                                          "IAADDR.");
                                rval = ISC_R_NOMEMORY;
                                break;
                        }

                        addrds.data = addrds.buffer->data;
                        addrds.len = 24;

                        /* Copy the address into the packet buffer. */
                        memcpy(addrds.buffer->data, addr->address.iabuf, 16);

                        /* Copy in additional information as appropriate */
                        switch (message) {
                              case DHCPV6_REQUEST:
                              case DHCPV6_RENEW:
                              case DHCPV6_REBIND:
                                t1 = client->config->requested_lease;
                                t2 = t1 + 300;
                                putULong(addrds.buffer->data + 16, t1);
                                putULong(addrds.buffer->data + 20, t2);

                                log_debug("XMT:  | | X-- IAADDR %s",
                                          piaddr(addr->address));
                                log_debug("XMT:  | | | X-- Preferred "
                                          "lifetime +%u", (unsigned)t1);
                                log_debug("XMT:  | | | X-- Max lifetime +%u",
                                          (unsigned)t2);

                                break;

                              case DHCPV6_CONFIRM:
                                /*
                                 * Set preferred and max life to zero,
                                 * per 17.1.3.
                                 */
                                memset(addrds.buffer->data + 16, 0, 8);
                                log_debug("XMT:  | X-- Confirm Address %s",
                                          piaddr(addr->address));
                                break;

                              case DHCPV6_RELEASE:
                                /* Preferred and max life are irrelevant */
                                memset(addrds.buffer->data + 16, 0, 8);
                                log_debug("XMT:  | X-- Release Address %s",
                                          piaddr(addr->address));
                                break;

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

                        append_option(&iads, &dhcpv6_universe, iaaddr_option,
                                      &addrds);
                        data_string_forget(&addrds, MDL);
                }

                /*
                 * It doesn't make sense to make a request without an
                 * address.
                 */
                if (ia->addrs == NULL) {
                        log_debug("!!!:  V IA_TA has no IAADDRs - removed.");
                        rval = ISC_R_FAILURE;
                } else if (rval == ISC_R_SUCCESS) {
                        log_debug("XMT:  V IA_TA appended.");
                        append_option(packet, &dhcpv6_universe, ia_ta_option,
                                      &iads);
                }

                data_string_forget(&iads, MDL);
        }

        if (rval == ISC_R_SUCCESS)
                *added = i;

        return (rval);
}

/*!
 *
 * \brief Add IA_PD information from the lease to the packet
 * we are building.
 *
 * Walk through the lease and for each IA_PD in the lease
 * and for each address in the IA_PD append that information
 * onto the packet-so-far.  If wanted is 0 include all IA_PDs
 * in the lease if wanted is non-zero include only that many
 * IA_PDs (this may occur if sommebody restarts a client with
 * arugments for a smaller number of PDs than before).
 *
 * \param client = the state of the entire client
 * \param packet = the packet we are building and where we
 *                 shall append the IA_PDs we create
 * \param lease  = the current lease
 * \param message = the type of the packet
 * \param wanted  = the number of IA_PDs to include in the packet
 *                  0 means include all
 * \param added   = the number of IA_PDs that were added to the packet
 *
 * \return ISC_R_SUCCESS - all is well continue, any other return
 *                         indicates an error (most likely memory issues)
 *                         and the packet should be tossed.
 */
static isc_result_t
dhc6_add_ia_pd(struct client_state *client, struct data_string *packet,
               struct dhc6_lease *lease, u_int8_t message,
               int wanted, int *added)
{
        struct data_string iads;
        struct data_string prefds;
        struct dhc6_addr *pref;
        struct dhc6_ia *ia;
        isc_result_t rval = ISC_R_SUCCESS;
        TIME t1, t2;
        int i;

        *added = 0;
        memset(&iads, 0, sizeof(iads));
        memset(&prefds, 0, sizeof(prefds));
        for (ia = lease->bindings, i = 0;
             ia != NULL && rval == ISC_R_SUCCESS && (wanted == 0 || i < wanted);
             ia = ia->next) {
                if (ia->ia_type != D6O_IA_PD)
                        continue;

                /* Now that we know this is an PD bump the counter */
                i++;

                if (!buffer_allocate(&iads.buffer, 12, MDL)) {
                        log_error("Unable to allocate memory for IA_PD.");
                        rval = ISC_R_NOMEMORY;
                        break;
                }

                /* Copy the IAID into the packet buffer. */
                memcpy(iads.buffer->data, ia->iaid, 4);
                iads.data = iads.buffer->data;
                iads.len = 12;

                switch (message) {
                      case DHCPV6_REQUEST:
                      case DHCPV6_RENEW:
                      case DHCPV6_REBIND:

                        t1 = client->config->requested_lease / 2;
                        t2 = t1 + (t1 / 2);
#if MAX_TIME > 0xffffffff
                        if (t1 > 0xffffffff)
                                t1 = 0xffffffff;
                        if (t2 > 0xffffffff)
                                t2 = 0xffffffff;
#endif
                        putULong(iads.buffer->data + 4, t1);
                        putULong(iads.buffer->data + 8, t2);

                        log_debug("XMT:  X-- IA_PD %s",
                                  print_hex_1(4, iads.data, 59));
                        log_debug("XMT:  | X-- Requested renew  +%u",
                                  (unsigned) t1);
                        log_debug("XMT:  | X-- Requested rebind +%u",
                                  (unsigned) t2);
                        break;

                      case DHCPV6_RELEASE:
                        /* Set t1 and t2 to zero; server will ignore them */
                        memset(iads.buffer->data + 4, 0, 8);
                        log_debug("XMT:  X-- IA_PD %s",
                                  print_hex_1(4, iads.buffer->data, 55));

                        break;

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

                for (pref = ia->addrs ; pref != NULL ; pref = pref->next) {
                        /*
                         * Do not confirm expired prefixes, do not request
                         * expired prefixes (but we keep them around for
                         * solicit).
                         */
                        if (pref->flags & DHC6_ADDR_EXPIRED)
                                continue;

                        if (pref->address.len != 16) {
                                log_error("Illegal IPv6 prefix "
                                          "ignoring.  (%s:%d)",
                                          MDL);
                                continue;
                        }

                        if (pref->plen == 0) {
                                log_info("Null IPv6 prefix, "
                                         "ignoring. (%s:%d)",
                                         MDL);
                        }

                        if (!buffer_allocate(&prefds.buffer, 25, MDL)) {
                                log_error("Unable to allocate memory for "
                                          "IAPREFIX.");
                                rval = ISC_R_NOMEMORY;
                                break;
                        }

                        prefds.data = prefds.buffer->data;
                        prefds.len = 25;

                        /* Copy the prefix into the packet buffer. */
                        putUChar(prefds.buffer->data + 8, pref->plen);
                        memcpy(prefds.buffer->data + 9,
                               pref->address.iabuf,
                               16);

                        /* Copy in additional information as appropriate */
                        switch (message) {
                              case DHCPV6_REQUEST:
                              case DHCPV6_RENEW:
                              case DHCPV6_REBIND:
                                t1 = client->config->requested_lease;
                                t2 = t1 + 300;
                                putULong(prefds.buffer->data, t1);
                                putULong(prefds.buffer->data + 4, t2);

                                log_debug("XMT:  | | X-- IAPREFIX %s/%u",
                                          piaddr(pref->address),
                                          (unsigned) pref->plen);
                                log_debug("XMT:  | | | X-- Preferred "
                                          "lifetime +%u", (unsigned)t1);
                                log_debug("XMT:  | | | X-- Max lifetime +%u",
                                          (unsigned)t2);

                                break;

                              case DHCPV6_RELEASE:
                                /* Preferred and max life are irrelevant */
                                memset(prefds.buffer->data, 0, 8);
                                log_debug("XMT:  | X-- Release Prefix %s/%u",
                                          piaddr(pref->address),
                                          (unsigned) pref->plen);
                                break;

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

                        append_option(&iads, &dhcpv6_universe,
                                      iaprefix_option, &prefds);
                        data_string_forget(&prefds, MDL);
                }

                /*
                 * It doesn't make sense to make a request without an
                 * address.
                 */
                if (ia->addrs == NULL) {
                        log_debug("!!!:  V IA_PD has no IAPREFIXs - removed.");
                        rval = ISC_R_FAILURE;
                } else if (rval == ISC_R_SUCCESS) {
                        log_debug("XMT:  V IA_PD appended.");
                        append_option(packet, &dhcpv6_universe,
                                      ia_pd_option, &iads);
                }

                data_string_forget(&iads, MDL);
        }

        if (rval == ISC_R_SUCCESS)
                *added = i;

        return (rval);
}

/* stopping_finished() checks if there is a remaining work to do.
 */
static isc_boolean_t
stopping_finished(void)
{
        struct interface_info *ip;
        struct client_state *client;

        for (ip = interfaces; ip; ip = ip -> next) {
                for (client = ip -> client; client; client = client -> next) {
                        if (client->state != S_STOPPED)
                                return ISC_FALSE;
                        if (client->active_lease != NULL)
                                return ISC_FALSE;
                }
        }
        return ISC_TRUE;
}

/* reply_handler() accepts a Reply while we're attempting Select or Renew or
 * Rebind.  Basically any Reply packet.
 */
void
reply_handler(struct packet *packet, struct client_state *client)
{
        struct dhc6_lease *lease;
        isc_result_t check_status;

        if (packet->dhcpv6_msg_type != DHCPV6_REPLY)
                return;

        /* RFC3315 section 15.10 validation (same as 15.3 since we
         * always include a client id).
         */
        if (!valid_reply(packet, client)) {
                log_error("Invalid Reply - rejecting.");
                return;
        }

        lease = dhc6_leaseify(packet, client);

        /* Out of memory or corrupt packet condition...hopefully a temporary
         * problem.  Returning now makes us try to retransmit later.
         */
        if (lease == NULL)
                return;

        check_status = dhc6_check_reply(client, lease);
        if (check_status != ISC_R_SUCCESS) {
                dhc6_lease_destroy(&lease, MDL);

                /* If no action was taken, but there is an error, then
                 * we wait for a retransmission.
                 */
                if (check_status != ISC_R_CANCELED)
                        return;
        }

        /* We're done retransmitting at this point. */
        cancel_timeout(do_confirm6, client);
        cancel_timeout(do_select6, client);
        cancel_timeout(do_refresh6, client);
        cancel_timeout(do_release6, client);

        /* If this is in response to a Release/Decline, clean up and return. */
        if (client->state == S_STOPPED) {
                if (client->active_lease == NULL)
                        return;

                dhc6_lease_destroy(&client->active_lease, MDL);
                client->active_lease = NULL;
                /* We should never wait for nothing!? */
                if (stopping_finished())
                        exit(0);
                return;
        }

        /* Action was taken, so now that we've torn down our scheduled
         * retransmissions, return.
         */
        if (check_status == ISC_R_CANCELED)
                return;

        if (client->selected_lease != NULL) {
                dhc6_lease_destroy(&client->selected_lease, MDL);
                client->selected_lease = NULL;
        }

        /* If this is in response to a confirm, we use the lease we've
         * already got, not the reply we were sent.
         */
        if (client->state == S_REBOOTING) {
                if (client->active_lease == NULL)
                        log_fatal("Impossible condition at %s:%d.", MDL);

                dhc6_lease_destroy(&lease, MDL);
                start_bound(client);
                return;
        }

        /* Merge any bindings in the active lease (if there is one) into
         * the new active lease.
         */
        dhc6_merge_lease(client->active_lease, lease);

        /* Cleanup if a previous attempt to go bound failed. */
        if (client->old_lease != NULL) {
                dhc6_lease_destroy(&client->old_lease, MDL);
                client->old_lease = NULL;
        }

        /* Make this lease active and BIND to it. */
        if (client->active_lease != NULL)
                client->old_lease = client->active_lease;
        client->active_lease = lease;

        /* We're done with the ADVERTISEd leases, if any. */
        while(client->advertised_leases != NULL) {
                lease = client->advertised_leases;
                client->advertised_leases = lease->next;

                dhc6_lease_destroy(&lease, MDL);
        }

        start_bound(client);
}

/* DHCPv6 packets are a little sillier than they needed to be - the root
 * packet contains options, then IA's which contain options, then within
 * that IAADDR's which contain options.
 *
 * To sort this out at dhclient-script time (which fetches config parameters
 * in environment variables), start_bound() iterates over each IAADDR, and
 * calls this function to marshall an environment variable set that includes
 * the most-specific option values related to that IAADDR in particular.
 *
 * To achieve this, we load environment variables for the root options space,
 * then the IA, then the IAADDR.  Any duplicate option names will be
 * over-written by the later versions.
 */
static void
dhc6_marshall_values(const char *prefix, struct client_state *client,
                     struct dhc6_lease *lease, struct dhc6_ia *ia,
                     struct dhc6_addr *addr)
{
        /* Option cache contents, in descending order of
         * scope.
         */
        if ((lease != NULL) && (lease->options != NULL))
                script_write_params6(client, prefix, lease->options);
        if ((ia != NULL) && (ia->options != NULL))
                script_write_params6(client, prefix, ia->options);
        if ((addr != NULL) && (addr->options != NULL))
                script_write_params6(client, prefix, addr->options);

        /* addr fields. */
        if (addr != NULL) {
                if ((ia != NULL) && (ia->ia_type == D6O_IA_PD)) {
                        client_envadd(client, prefix,
                                      "ip6_prefix", "%s/%u",
                                      piaddr(addr->address),
                                      (unsigned) addr->plen);
                } else {
                        client_envadd(client, prefix, "ip6_prefixlen",
                                      "%d", DHCLIENT_DEFAULT_PREFIX_LEN);
                        client_envadd(client, prefix, "ip6_address",
                                      "%s", piaddr(addr->address));
                }
                if ((ia != NULL) && (ia->ia_type == D6O_IA_TA)) {
                        client_envadd(client, prefix,
                                      "ip6_type", "temporary");
                }
                client_envadd(client, prefix, "life_starts", "%d",
                              (int)(addr->starts));
                client_envadd(client, prefix, "preferred_life", "%u",
                              addr->preferred_life);
                client_envadd(client, prefix, "max_life", "%u",
                              addr->max_life);
        }

        /* ia fields. */
        if (ia != NULL) {
                client_envadd(client, prefix, "iaid", "%s",
                              print_hex_1(4, ia->iaid, 12));
                client_envadd(client, prefix, "starts", "%d",
                              (int)(ia->starts));
                client_envadd(client, prefix, "renew", "%u", ia->renew);
                client_envadd(client, prefix, "rebind", "%u", ia->rebind);
        }
}

/* Look at where the client's active lease is sitting.  If it's looking to
 * time out on renew, rebind, depref, or expiration, do those things.
 */
static void
dhc6_check_times(struct client_state *client)
{
        struct dhc6_lease *lease;
        struct dhc6_ia *ia;
        struct dhc6_addr *addr;
        TIME renew=MAX_TIME, rebind=MAX_TIME, depref=MAX_TIME,
             lo_expire=MAX_TIME, hi_expire=0, max_ia_starts = 0, tmp;
        int has_addrs = ISC_FALSE;
        struct timeval tv;

        lease = client->active_lease;

        /* Bit spammy.  We should probably keep record of scheduled
         * events instead.
         */
        cancel_timeout(start_renew6, client);
        cancel_timeout(start_rebind6, client);
        cancel_timeout(do_depref, client);
        cancel_timeout(do_expire, client);

        for(ia = lease->bindings ; ia != NULL ; ia = ia->next) {
                TIME this_ia_lo_expire, this_ia_hi_expire, use_expire;

                this_ia_lo_expire = MAX_TIME;
                this_ia_hi_expire = 0;

                for (addr = ia->addrs ; addr != NULL ; addr = addr->next) {
                        if(!(addr->flags & DHC6_ADDR_DEPREFFED)) {
                                if (addr->preferred_life == 0xffffffff)
                                        tmp = MAX_TIME;
                                else
                                        tmp = addr->starts +
                                              addr->preferred_life;

                                if (tmp < depref)
                                        depref = tmp;
                        }

                        if (!(addr->flags & DHC6_ADDR_EXPIRED)) {
                                /* Find EPOCH-relative expiration. */
                                if (addr->max_life == 0xffffffff)
                                        tmp = MAX_TIME;
                                else
                                        tmp = addr->starts + addr->max_life;

                                /* Make the times ia->starts relative. */
                                tmp -= ia->starts;

                                if (tmp > this_ia_hi_expire)
                                        this_ia_hi_expire = tmp;
                                if (tmp < this_ia_lo_expire)
                                        this_ia_lo_expire = tmp;

                                has_addrs = ISC_TRUE;
                        }
                }

                /* These times are ia->starts relative. */
                if (this_ia_lo_expire <= (this_ia_hi_expire / 2))
                        use_expire = this_ia_hi_expire;
                else
                        use_expire = this_ia_lo_expire;

                /*
                 * If the auto-selected expiration time is "infinite", or
                 * zero, assert a reasonable default.
                 */
                if ((use_expire == MAX_TIME) || (use_expire <= 1))
                        use_expire = client->config->requested_lease / 2;
                else
                        use_expire /= 2;

                /* Don't renew/rebind temporary addresses. */
                /* For NA and PD we find the most recent IA and the smallest
                 * values for the renew and rebind then base the timer on
                 * the sum of the them.
                 * Normally all the IAs will have the same time as they
                 * are requested and served as a group but in some cases the
                 * client isn't asking for all of the IAs (for example
                 * restarted with a different set of arguments) or the server
                 * isn't updating the client on all of them (probably a
                 * broken server).
                 */
                if (ia->ia_type != D6O_IA_TA) {
                        if (ia->starts > max_ia_starts)
                                max_ia_starts = ia->starts;

                        if (ia->renew == 0) {
                                tmp = use_expire;
                        } else if (ia->renew == 0xffffffff)
                                tmp = MAX_TIME;
                        else
                                tmp = ia->renew;

                        if (tmp < renew)
                                renew = tmp;

                        if (ia->rebind == 0) {
                                /* Set rebind to 3/4 expiration interval. */
                                tmp = use_expire + (use_expire / 2);
                        } else if (ia->rebind == 0xffffffff)
                                tmp = MAX_TIME;
                        else
                                tmp = ia->rebind;

                        if (tmp < rebind)
                                rebind = tmp;
                }

                /*
                 * Return expiration ranges to EPOCH relative for event
                 * scheduling (add_timeout()).
                 */
                this_ia_hi_expire += ia->starts;
                this_ia_lo_expire += ia->starts;

                if (this_ia_hi_expire > hi_expire)
                        hi_expire = this_ia_hi_expire;
                if (this_ia_lo_expire < lo_expire)
                        lo_expire = this_ia_lo_expire;
        }

        /* If there are no addresses, give up, go to INIT.
         * Note that if an address is unexpired with a date in the past,
         * we're scheduling an expiration event to ocurr in the past.  We
         * could probably optimize this to expire now (but then there's
         * recursion).
         *
         * In the future, we may decide that we're done here, or to
         * schedule a future request (using 4-pkt info-request model).
         */
        if (has_addrs == ISC_FALSE) {
                dhc6_lease_destroy(&client->active_lease, MDL);
                client->active_lease = NULL;

                /* Go back to the beginning. */
                start_init6(client);
                return;
        }

        /* Second part of calculating the renew and rebind times.
         * We have the start time and the desired periods for renew
         * and rebind, just add them to get the desired end time.
         */
        if (renew != MAX_TIME)
                renew += max_ia_starts;
        if (rebind != MAX_TIME)
                rebind += max_ia_starts;

        switch(client->state) {
              case S_BOUND:
                /* We'd like to hit renewing, but if rebinding has already
                 * passed (time warp), head straight there.
                 */
                if ((rebind > cur_time) && (renew < rebind)) {
                        log_debug("PRC: Renewal event scheduled in %d seconds, "
                                  "to run for %u seconds.",
                                  (int)(renew - cur_time),
                                  (unsigned)(rebind - renew));
                        client->next_MRD = rebind;
                        tv.tv_sec = renew;
                        tv.tv_usec = 0;
                        add_timeout(&tv, start_renew6, client, NULL, NULL);

                        break;
                }
                /* FALL THROUGH */
              case S_RENEWING:
                /* While actively renewing, MRD is bounded by the time
                 * we stop renewing and start rebinding.  This helps us
                 * process the state change on time.
                 */
                client->MRD = rebind - cur_time;
                if (rebind != MAX_TIME) {
                        log_debug("PRC: Rebind event scheduled in %d seconds, "
                                  "to run for %d seconds.",
                                  (int)(rebind - cur_time),
                                  (int)(hi_expire - rebind));
                        client->next_MRD = hi_expire;
                        tv.tv_sec = rebind;
                        tv.tv_usec = 0;
                        add_timeout(&tv, start_rebind6, client, NULL, NULL);
                }
                break;

              case S_REBINDING:
                /* For now, we rebind up until the last lease expires.  In
                 * the future, we might want to start SOLICITing when we've
                 * depreffed an address.
                 */
                client->MRD = hi_expire - cur_time;
                break;

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

        /* Separately, set a time at which we will depref and expire
         * leases.  This might happen with multiple addresses while we
         * keep trying to refresh.
         */
        if (depref != MAX_TIME) {
                log_debug("PRC: Depreference scheduled in %d seconds.",
                          (int)(depref - cur_time));
                tv.tv_sec = depref;
                tv.tv_usec = 0;
                add_timeout(&tv, do_depref, client, NULL, NULL);
        }
        if (lo_expire != MAX_TIME) {
                log_debug("PRC: Expiration scheduled in %d seconds.",
                          (int)(lo_expire - cur_time));
                tv.tv_sec = lo_expire;
                tv.tv_usec = 0;
                add_timeout(&tv, do_expire, client, NULL, NULL);
        }
}

/* In a given IA chain, find the IA with the same type and 'iaid'. */
static struct dhc6_ia *
find_ia(struct dhc6_ia *head, u_int16_t type, const char *id)
{
        struct dhc6_ia *ia;

        for (ia = head ; ia != NULL ; ia = ia->next) {
                if (ia->ia_type != type)
                        continue;
                if (memcmp(ia->iaid, id, 4) == 0)
                        return ia;
        }

        return NULL;
}

/* In a given address chain, find a matching address. */
static struct dhc6_addr *
find_addr(struct dhc6_addr *head, struct iaddr *address)
{
        struct dhc6_addr *addr;

        for (addr = head ; addr != NULL ; addr = addr->next) {
                if ((addr->address.len == address->len) &&
                    (memcmp(addr->address.iabuf, address->iabuf,
                            address->len) == 0))
                        return addr;
        }

        return NULL;
}

/* In a given prefix chain, find a matching prefix. */
static struct dhc6_addr *
find_pref(struct dhc6_addr *head, struct iaddr *prefix, u_int8_t plen)
{
        struct dhc6_addr *pref;

        for (pref = head ; pref != NULL ; pref = pref->next) {
                if ((pref->address.len == prefix->len) &&
                    (pref->plen == plen) &&
                    (memcmp(pref->address.iabuf, prefix->iabuf,
                            prefix->len) == 0))
                        return pref;
        }

        return NULL;
}

/*
 *
 * \brief  Merge the bindings from the source lease into the destination
 * lease structure, where they are missing.
 *
 * This is used to merge any extra information we have in the current
 * (older, src) lease into the lease we have just received.  For example
 * the src lease might include a binding for an NA that is still usable
 * but that we didn't request or that the server is no longer serving.
 * We want to keep that information until we toss the binding (expire,
 * release) so we move it to the new lease.
 *
 * We have to copy the stateful objects rather than move them over,
 * because later code needs to be able to compare new versus old if
 * they contain any bindings.
 *
 * \param src The older lease to copy the objects from
 * \param dst The newer lease to copy the objects to
 */
static void
dhc6_merge_lease(struct dhc6_lease *src, struct dhc6_lease *dst)
{
        struct dhc6_ia *sia, *dia, *tia, **eia;
        struct dhc6_addr *saddr, *daddr, *taddr;
        int changes = 0;

        if ((dst == NULL) || (src == NULL))
                return;

        for (sia = src->bindings ; sia != NULL ; sia = sia->next) {
                dia = find_ia(dst->bindings, sia->ia_type, (char *)sia->iaid);

                if (dia == NULL) {
                        tia = dhc6_dup_ia(sia, MDL);

                        if (tia == NULL)
                                log_fatal("Out of memory merging lease - "
                                          "Unable to continue without losing "
                                          "state! (%s:%d)", MDL);

                        /* Put any bindings that aren't in the new lease at the
                         * end of the list.  If the user or server reduces the
                         * number of IAs the ones in use will be at the front
                         * and will be used when building the next requests
                         * We could be more efficient by finding the end
                         * of the list once but we don't expect to do this
                         * often.
                         */
                        for (eia = &dst->bindings;
                             *eia != NULL;
                             eia = &(*eia)->next) {
                                ; /* no work just find the end */
                        }
                        *eia = tia;
                        changes = 1;
                } else {
                        for (saddr = sia->addrs ; saddr != NULL ;
                             saddr = saddr->next) {
                                if (sia->ia_type != D6O_IA_PD)
                                        daddr = find_addr(dia->addrs,
                                                          &saddr->address);
                                else
                                        daddr = find_pref(dia->addrs,
                                                          &saddr->address,
                                                          saddr->plen);

                                if (daddr == NULL) {
                                        taddr = dhc6_dup_addr(saddr, MDL);

                                        if (taddr == NULL)
                                                log_fatal("Out of memory "
                                                          "merging lease - "
                                                          "Unable to continue "
                                                          "without losing "
                                                          "state! (%s:%d)",
                                                          MDL);

                                        /* XXX: consider sorting? */
                                        taddr->next = dia->addrs;
                                        dia->addrs = taddr;
                                        changes = 1;
                                }
                        }
                }
        }

        /* If we made changes, reset the score to 0 so it is recalculated. */
        if (changes)
                dst->score = 0;
}

/* We've either finished selecting or succeeded in Renew or Rebinding our
 * lease.  In all cases we got a Reply.  Give dhclient-script a tickle
 * to inform it about the new values, and then lay in wait for the next
 * event.
 */
static void
start_bound(struct client_state *client)
{
        struct dhc6_ia *ia, *oldia;
        struct dhc6_addr *addr, *oldaddr;
        struct dhc6_lease *lease, *old;
        const char *reason;
#if defined (NSUPDATE)
        TIME dns_update_offset = 1;
#endif

        lease = client->active_lease;
        if (lease == NULL) {
                log_error("Cannot enter bound state unless an active lease "
                          "is selected.");
                return;
        }
        lease->released = ISC_FALSE;
        old = client->old_lease;

        client->v6_handler = bound_handler;

        switch (client->state) {
              case S_SELECTING:
              case S_REBOOTING: /* Pretend we got bound. */
                reason = "BOUND6";
                break;

              case S_RENEWING:
                reason = "RENEW6";
                break;

              case S_REBINDING:
                reason = "REBIND6";
                break;

              default:
                log_fatal("Impossible condition at %s:%d.", MDL);
                /* Silence compiler warnings. */
                return;
        }

        log_debug("PRC: Bound to lease %s.",
                  print_hex_1(client->active_lease->server_id.len,
                              client->active_lease->server_id.data, 55));
        client->state = S_BOUND;

        write_client6_lease(client, lease, 0, 1);

        oldia = NULL;
        for (ia = lease->bindings ; ia != NULL ; ia = ia->next) {
                if (old != NULL)
                        oldia = find_ia(old->bindings,
                                        ia->ia_type,
                                        (char *)ia->iaid);
                else
                        oldia = NULL;

                for (addr = ia->addrs ; addr != NULL ; addr = addr->next) {
                        /* Don't try to use the address if it's already expired */
                        if (addr->flags & DHC6_ADDR_EXPIRED)
                                continue;

                        if (oldia != NULL) {
                                if (ia->ia_type != D6O_IA_PD)
                                        oldaddr = find_addr(oldia->addrs,
                                                            &addr->address);
                                else
                                        oldaddr = find_pref(oldia->addrs,
                                                            &addr->address,
                                                            addr->plen);
                        } else
                                oldaddr = NULL;

#if defined (NSUPDATE)
                        if ((oldaddr == NULL) && (ia->ia_type == D6O_IA_NA))
                                dhclient_schedule_updates(client,
                                                          &addr->address,
                                                          dns_update_offset++);
#endif

                        /* Shell out to setup the new binding. */
                        script_init(client, reason, NULL);

                        if (old != NULL)
                                dhc6_marshall_values("old_", client, old,
                                                     oldia, oldaddr);
                        dhc6_marshall_values("new_", client, lease, ia, addr);
                        script_write_requested6(client);

                        script_go(client);
                }

                /* XXX: maybe we should loop on the old values instead? */
                if (ia->addrs == NULL) {
                        script_init(client, reason, NULL);

                        if (old != NULL)
                                dhc6_marshall_values("old_", client, old,
                                                     oldia,
                                                     oldia != NULL ?
                                                         oldia->addrs : NULL);

                        dhc6_marshall_values("new_", client, lease, ia,
                                             NULL);
                        script_write_requested6(client);

                        script_go(client);
                }
        }

        /* XXX: maybe we should loop on the old values instead? */
        if (lease->bindings == NULL) {
                script_init(client, reason, NULL);

                if (old != NULL)
                        dhc6_marshall_values("old_", client, old,
                                             old->bindings,
                                             (old->bindings != NULL) ?
                                                old->bindings->addrs : NULL);

                dhc6_marshall_values("new_", client, lease, NULL, NULL);
                script_write_requested6(client);

                script_go(client);
        }

#ifdef DHCP4o6
        if (dhcpv4_over_dhcpv6)
                dhcp4o6_start();
#endif

        go_daemon();

        if (client->old_lease != NULL) {
                dhc6_lease_destroy(&client->old_lease, MDL);
                client->old_lease = NULL;
        }

        /* Schedule events. */
        dhc6_check_times(client);
}

/* While bound, ignore packets.  In the future we'll want to answer
 * Reconfigure-Request messages and the like.
 */
void
bound_handler(struct packet *packet, struct client_state *client)
{
        log_debug("RCV: Input packets are ignored once bound.");
}

/* start_renew6() gets us all ready to go to start transmitting Renew packets.
 * Note that client->next_MRD must be set before entering this function -
 * it must be set to the time at which the client should start Rebinding.
 */
void
start_renew6(void *input)
{
        struct client_state *client;

        client = (struct client_state *)input;

        log_info("PRC: Renewing lease on %s.",
                 client->name ? client->name : client->interface->name);
        client->state = S_RENEWING;

        client->v6_handler = reply_handler;

        /* Times per RFC3315 section 18.1.3. */
        client->IRT = REN_TIMEOUT * 100;
        client->MRT = REN_MAX_RT * 100;
        client->MRC = 0;
        /* MRD is special in renew - we need to set it by checking timer
         * state.
         */
        client->MRD = client->next_MRD - cur_time;

        dhc6_retrans_init(client);

        client->refresh_type = DHCPV6_RENEW;
        do_refresh6(client);
}

/* do_refresh6() transmits one DHCPv6 packet, be it a Renew or Rebind, and
 * gives the retransmission state a bump for the next time.  Note that
 * client->refresh_type must be set before entering this function.
 */
void
do_refresh6(void *input)
{
        struct option_cache *oc;
        struct sockaddr_in6 unicast, *dest_addr = &DHCPv6DestAddr;
        struct data_string ds;
        struct client_state *client;
        struct dhc6_lease *lease;
        struct timeval elapsed, tv;
        int send_ret, added;

        client = (struct client_state *)input;
        memset(&ds, 0, sizeof(ds));

        lease = client->active_lease;
        if (lease == NULL) {
                log_error("Cannot renew without an active binding.");
                return;
        }

        /* Ensure we're emitting a valid message type. */
        switch (client->refresh_type) {
              case DHCPV6_RENEW:
              case DHCPV6_REBIND:
                break;

              default:
                log_fatal("Internal inconsistency (%d) at %s:%d.",
                          client->refresh_type, MDL);
        }

        /*
         * Start_time starts at the first transmission.
         */
        if (client->txcount == 0) {
                client->start_time.tv_sec = cur_tv.tv_sec;
                client->start_time.tv_usec = cur_tv.tv_usec;
        }

        /* elapsed = cur - start */
        elapsed.tv_sec = cur_tv.tv_sec - client->start_time.tv_sec;
        elapsed.tv_usec = cur_tv.tv_usec - client->start_time.tv_usec;
        if (elapsed.tv_usec < 0) {
                elapsed.tv_sec -= 1;
                elapsed.tv_usec += 1000000;
        }
        if (((client->MRC != 0) && (client->txcount > client->MRC)) ||
            ((client->MRD != 0) && (elapsed.tv_sec >= client->MRD))) {
                /* We're done.  Move on to the next phase, if any. */
                dhc6_check_times(client);
                return;
        }

        /*
         * Check whether the server has sent a unicast option; if so, we can
         * use the address it specified for RENEWs.
         */
        oc = lookup_option(&dhcpv6_universe, lease->options, D6O_UNICAST);
        if (oc && evaluate_option_cache(&ds, NULL, NULL, NULL,
                                        lease->options, NULL, &global_scope,
                                        oc, MDL)) {
                if (ds.len < 16) {
                        log_error("Invalid unicast option length %d.", ds.len);
                } else {
                        memset(&unicast, 0, sizeof(DHCPv6DestAddr));
                        unicast.sin6_family = AF_INET6;
                        unicast.sin6_port = remote_port;
                        memcpy(&unicast.sin6_addr, ds.data, 16);
                        if (client->refresh_type == DHCPV6_RENEW) {
                                dest_addr = &unicast;
                        }
                }

                data_string_forget(&ds, MDL);
        }

        /* Commence forming a renew packet. */
        memset(&ds, 0, sizeof(ds));
        if (!buffer_allocate(&ds.buffer, 4, MDL)) {
                log_error("Unable to allocate memory for packet.");
                return;
        }
        ds.data = ds.buffer->data;
        ds.len = 4;

        ds.buffer->data[0] = client->refresh_type;
        memcpy(ds.buffer->data + 1, client->dhcpv6_transaction_id, 3);

        /* Form an elapsed option. */
        /* Maximum value is 65535 1/100s coded as 0xffff. */
        if ((elapsed.tv_sec < 0) || (elapsed.tv_sec > 655) ||
            ((elapsed.tv_sec == 655) && (elapsed.tv_usec > 350000))) {
                client->elapsed = 0xffff;
        } else {
                client->elapsed = elapsed.tv_sec * 100;
                client->elapsed += elapsed.tv_usec / 10000;
        }

        if (client->elapsed == 0)
                log_debug("XMT: Forming %s, 0 ms elapsed.",
                          dhcpv6_type_names[client->refresh_type]);
        else
                log_debug("XMT: Forming %s, %u0 ms elapsed.",
                          dhcpv6_type_names[client->refresh_type],
                          (unsigned)client->elapsed);

        client->elapsed = htons(client->elapsed);

        make_client6_options(client, &client->sent_options, lease,
                             client->refresh_type);

        /* Put in any options from the sent cache. */
        dhcpv6_universe.encapsulate(&ds, NULL, NULL, client, NULL,
                                    client->sent_options, &global_scope,
                                    &dhcpv6_universe);

        /* Now append any IA's, and within them any IAADDR/IAPREFIXs.
         * For each type of IA (na, ta, pd) we start with the ones for
         * which we already have addresses (dhc6_add_ia_xx) and then
         * if we still want more we add aditional IAs (dhc6_bare_ia_xx)
         */
        if (wanted_ia_na &&
            ((dhc6_add_ia_na(client, &ds, lease, client->refresh_type,
                             wanted_ia_na, &added) != ISC_R_SUCCESS) ||
             (dhc6_bare_ia_xx(client, &ds, wanted_ia_na - added,
                              D6O_IA_NA) != ISC_R_SUCCESS))) {
                data_string_forget(&ds, MDL);
                return;
        }
        if (wanted_ia_pd &&
            ((dhc6_add_ia_pd(client, &ds, lease, client->refresh_type,
                             wanted_ia_pd, &added) != ISC_R_SUCCESS) ||
             (dhc6_bare_ia_xx(client, &ds, wanted_ia_pd - added,
                              D6O_IA_PD) != ISC_R_SUCCESS))) {
                data_string_forget(&ds, MDL);
                return;
        }

        log_info("XMT: %s on %s, interval %ld0ms.",
                 dhcpv6_type_names[client->refresh_type],
                 client->name ? client->name : client->interface->name,
                 (long int)client->RT);

        send_ret = send_packet6(client->interface, ds.data, ds.len, dest_addr);

        if (send_ret != ds.len) {
                log_error("dhc6: send_packet6() sent %d of %d bytes",
                          send_ret, ds.len);
        }

        data_string_forget(&ds, MDL);

        /* Wait RT */
        tv.tv_sec = cur_tv.tv_sec + client->RT / 100;
        tv.tv_usec = cur_tv.tv_usec + (client->RT % 100) * 10000;
        if (tv.tv_usec >= 1000000) {
                tv.tv_sec += 1;
                tv.tv_usec -= 1000000;
        }
        add_timeout(&tv, do_refresh6, client, NULL, NULL);

        dhc6_retrans_advance(client);
}

/* start_rebind6() gets us all set up to go and rebind a lease.  Note that
 * client->next_MRD must be set before entering this function.  In this case,
 * MRD must be set to the maximum time any address in the packet will
 * expire.
 */
void
start_rebind6(void *input)
{
        struct client_state *client;

        client = (struct client_state *)input;

        log_info("PRC: Rebinding lease on %s.",
                 client->name ? client->name : client->interface->name);
        client->state = S_REBINDING;

        client->v6_handler = reply_handler;

        /* Times per RFC3315 section 18.1.4. */
        client->IRT = REB_TIMEOUT * 100;
        client->MRT = REB_MAX_RT * 100;
        client->MRC = 0;
        /* MRD is special in rebind - it's determined by the timer
         * state.
         */
        client->MRD = client->next_MRD - cur_time;

        dhc6_retrans_init(client);

        client->refresh_type = DHCPV6_REBIND;
        do_refresh6(client);
}

/* do_depref() runs through a given lease's addresses, for each that has
 * not yet been depreffed, shells out to the dhclient-script to inform it
 * of the status change.  The dhclient-script should then do...something...
 * to encourage applications to move off the address and onto one of the
 * remaining 'preferred' addresses.
 */
void
do_depref(void *input)
{
        struct client_state *client;
        struct dhc6_lease *lease;
        struct dhc6_ia *ia;
        struct dhc6_addr *addr;

        client = (struct client_state *)input;

        lease = client->active_lease;
        if (lease == NULL)
                return;

        for (ia = lease->bindings ; ia != NULL ; ia = ia->next) {
                for (addr = ia->addrs ; addr != NULL ; addr = addr->next) {
                        if (addr->flags & DHC6_ADDR_DEPREFFED)
                                continue;

                        if (addr->starts + addr->preferred_life <= cur_time) {
                                script_init(client, "DEPREF6", NULL);
                                dhc6_marshall_values("cur_", client, lease,
                                                     ia, addr);
                                script_write_requested6(client);
                                script_go(client);

                                addr->flags |= DHC6_ADDR_DEPREFFED;

                                if (ia->ia_type != D6O_IA_PD)
                                    log_info("PRC: Address %s depreferred.",
                                             piaddr(addr->address));
                                else
                                    log_info("PRC: Prefix %s/%u depreferred.",
                                             piaddr(addr->address),
                                             (unsigned) addr->plen);

#if defined (NSUPDATE)
                                /* Remove DDNS bindings at depref time. */
                                if ((ia->ia_type == D6O_IA_NA) &&
                                    client->config->do_forward_update)
                                        client_dns_remove(client,
                                                          &addr->address);
#endif
                        }
                }
        }

        dhc6_check_times(client);
}

/* do_expire() searches through all the addresses on a given lease, and
 * expires/removes any addresses that are no longer valid.
 */
void
do_expire(void *input)
{
        struct client_state *client;
        struct dhc6_lease *lease;
        struct dhc6_ia *ia, **tia;
        struct dhc6_addr *addr;
        int has_addrs = ISC_FALSE;
        int ia_has_addrs = ISC_FALSE;

        client = (struct client_state *)input;

        lease = client->active_lease;
        if (lease == NULL)
                return;

        for (ia = lease->bindings, tia = &lease->bindings; ia != NULL ; ) {
                ia_has_addrs = ISC_FALSE;
                for (addr = ia->addrs ; addr != NULL ; addr = addr->next) {
                        if (addr->flags & DHC6_ADDR_EXPIRED)
                                continue;

                        if (addr->starts + addr->max_life <= cur_time) {
                                script_init(client, "EXPIRE6", NULL);
                                dhc6_marshall_values("old_", client, lease,
                                                     ia, addr);
                                script_write_requested6(client);
                                script_go(client);

                                addr->flags |= DHC6_ADDR_EXPIRED;

                                if (ia->ia_type != D6O_IA_PD)
                                    log_info("PRC: Address %s expired.",
                                             piaddr(addr->address));
                                else
                                    log_info("PRC: Prefix %s/%u expired.",
                                             piaddr(addr->address),
                                             (unsigned) addr->plen);

#if defined (NSUPDATE)
                                /* We remove DNS records at depref time, but
                                 * it is possible that we might get here
                                 * without depreffing.
                                 */
                                if ((ia->ia_type == D6O_IA_NA) &&
                                    client->config->do_forward_update &&
                                    !(addr->flags & DHC6_ADDR_DEPREFFED))
                                        client_dns_remove(client,
                                                          &addr->address);
#endif

                                continue;
                        }

                        ia_has_addrs = ISC_TRUE;
                        has_addrs = ISC_TRUE;
                }

                /* Update to the next ia and git rid of this ia
                 * if it doesn't have any leases.
                 */
                if (ia_has_addrs == ISC_TRUE) {
                        /* leases, just advance the list pointer */
                        tia = &(*tia)->next;
                } else {
                        /* no leases, update the list pointer
                         * and free the ia
                         */
                        *tia = ia->next;
                        dhc6_ia_destroy(&ia, MDL);
                }
                /* lastly update the ia pointer to our new ia */
                ia = *tia;
        }

        /* Clean up empty leases. */
        if (has_addrs == ISC_FALSE) {
                log_info("PRC: Bound lease is devoid of active addresses."
                         "  Re-initializing.");

                dhc6_lease_destroy(&lease, MDL);
                client->active_lease = NULL;

                start_init6(client);
                return;
        }

        /* Schedule the next run through. */
        dhc6_check_times(client);
}

/*
 * Run client script to unconfigure interface.
 * Called with reason STOP6 when dhclient -x is run, or with reason
 * RELEASE6 when server has replied to a Release message.
 * Stateless is a special case.
 */
void
unconfigure6(struct client_state *client, const char *reason)
{
        struct dhc6_ia *ia;
        struct dhc6_addr *addr;

        if (stateless) {
                script_init(client, reason, NULL);
                if (client->active_lease != NULL)
                        script_write_params6(client, "old_",
                                             client->active_lease->options);
                script_write_requested6(client);
                script_go(client);
                return;
        }

        if (client->active_lease == NULL)
                return;

        for (ia = client->active_lease->bindings ; ia != NULL ; ia = ia->next) {
                if (ia->ia_type == D6O_IA_TA)
                        continue;

                for (addr = ia->addrs ; addr != NULL ; addr = addr->next) {
                        script_init(client, reason, NULL);
                        dhc6_marshall_values("old_", client,
                                             client->active_lease, ia, addr);
                        script_write_requested6(client);
                        script_go(client);

#if defined (NSUPDATE)
                        if ((ia->ia_type == D6O_IA_NA) &&
                            client->config->do_forward_update)
                                client_dns_remove(client, &addr->address);
#endif
                }
        }
}

void
refresh_info_request6(void *input)
{
        struct client_state *client;

        client = (struct client_state *)input;
        start_info_request6(client);
}

/* Timeout for Information-Request (using the IRT option).
 */
static void
dhc6_check_irt(struct client_state *client)
{
        struct option **req;
        struct option_cache *oc;
        TIME expire = MAX_TIME;
        struct timeval tv;
        int i;
        isc_boolean_t found = ISC_FALSE;

        cancel_timeout(refresh_info_request6, client);

        req = client->config->requested_options;
        for (i = 0; req[i] != NULL; i++) {
                if (req[i] == irt_option) {
                        found = ISC_TRUE;
                        break;
                }
        }
        /* Simply return gives a endless loop waiting for nothing. */
        if (!found) {
#ifdef DHCP4o6
                if (!dhcpv4_over_dhcpv6)
#endif
                exit(0);
        }

        oc = lookup_option(&dhcpv6_universe, client->active_lease->options,
                           D6O_INFORMATION_REFRESH_TIME);
        if (oc != NULL) {
                struct data_string irt;

                memset(&irt, 0, sizeof(irt));
                if (!evaluate_option_cache(&irt, NULL, NULL, client,
                                           client->active_lease->options,
                                           NULL, &global_scope, oc, MDL) ||
                    (irt.len < 4)) {
                        log_error("Can't evaluate IRT.");
                } else {
                        expire = getULong(irt.data);
                        if (expire < IRT_MINIMUM)
                                expire = IRT_MINIMUM;
                        if (expire == 0xffffffff)
                                expire = MAX_TIME;
                }
                data_string_forget(&irt, MDL);
        } else
                expire = IRT_DEFAULT;

        if (expire != MAX_TIME) {
                log_debug("PRC: Refresh event scheduled in %u seconds.",
                          (unsigned) expire);
                tv.tv_sec = cur_time + expire;
                tv.tv_usec = 0;
                add_timeout(&tv, refresh_info_request6, client, NULL, NULL);
        }
}

/* We got a Reply. Give dhclient-script a tickle to inform it about
 * the new values, and then lay in wait for the next event.
 */
static void
start_informed(struct client_state *client)
{
        client->v6_handler = informed_handler;

        log_debug("PRC: Done.");

        client->state = S_BOUND;

        script_init(client, "RENEW6", NULL);
        if (client->old_lease != NULL)
                script_write_params6(client, "old_",
                                     client->old_lease->options);
        script_write_params6(client, "new_", client->active_lease->options);
        script_write_requested6(client);
        script_go(client);

#ifdef DHCP4o6
        if (dhcpv4_over_dhcpv6)
                dhcp4o6_start();
#endif

        go_daemon();

        if (client->old_lease != NULL) {
                dhc6_lease_destroy(&client->old_lease, MDL);
                client->old_lease = NULL;
        }

        /* Schedule events. */
        dhc6_check_irt(client);
}

/* While informed, ignore packets.
 */
void
informed_handler(struct packet *packet, struct client_state *client)
{
        log_debug("RCV: Input packets are ignored once bound.");
}

/* make_client6_options() fetches option caches relevant to the client's
 * scope and places them into the sent_options cache.  This cache is later
 * used to populate DHCPv6 output packets with options.
 */
static void
make_client6_options(struct client_state *client, struct option_state **op,
                     struct dhc6_lease *lease, u_int8_t message)
{
        struct option_cache *oc;
        struct option **req;
        struct buffer *buffer;
        int buflen, i, oro_len;

        if ((op == NULL) || (client == NULL))
                return;

        if (*op)
                option_state_dereference(op, MDL);

        /* Create a cache to carry options to transmission. */
        option_state_allocate(op, MDL);

        /* Create and store an 'elapsed time' option in the cache. */
        oc = NULL;
        if (option_cache_allocate(&oc, MDL)) {
                const unsigned char *cdata;

                cdata = (unsigned char *)&client->elapsed;

                if (make_const_data(&oc->expression, cdata, 2, 0, 0, MDL)) {
                        option_reference(&oc->option, elapsed_option, MDL);
                        save_option(&dhcpv6_universe, *op, oc);
                }

                option_cache_dereference(&oc, MDL);
        }

        /* Bring in any configured options to send. */
        if (client->config->on_transmission)
                execute_statements_in_scope(NULL, NULL, NULL, client,
                                            lease ? lease->options : NULL,
                                            *op, &global_scope,
                                            client->config->on_transmission,
                                            NULL, NULL);

        /* Rapid-commit is only for SOLICITs. */
        if (message != DHCPV6_SOLICIT)
                delete_option(&dhcpv6_universe, *op, D6O_RAPID_COMMIT);

        /* See if the user configured a DUID in a relevant scope.  If not,
         * introduce our default manufactured id.
         */
        if ((oc = lookup_option(&dhcpv6_universe, *op,
                                D6O_CLIENTID)) == NULL) {
                if (!option_cache(&oc, &default_duid, NULL, clientid_option,
                                  MDL))
                        log_fatal("Failure assembling a DUID.");

                save_option(&dhcpv6_universe, *op, oc);
                option_cache_dereference(&oc, MDL);
        }

        /* In cases where we're responding to a single server, put the
         * server's id in the response.
         *
         * Note that lease is NULL for SOLICIT or INFO request messages,
         * and otherwise MUST be present.
         */
        if (lease == NULL) {
                if ((message != DHCPV6_SOLICIT) &&
                    (message != DHCPV6_INFORMATION_REQUEST))
                        log_fatal("Impossible condition at %s:%d.", MDL);
        } else if ((message != DHCPV6_REBIND) &&
                   (message != DHCPV6_CONFIRM)) {
                oc = lookup_option(&dhcpv6_universe, lease->options,
                                   D6O_SERVERID);
                if (oc != NULL)
                        save_option(&dhcpv6_universe, *op, oc);
        }

        /* 'send dhcp6.oro foo;' syntax we used in 4.0.0a1/a2 has been
         * deprecated by adjustments to the 'request' syntax also used for
         * DHCPv4.
         */
        if (lookup_option(&dhcpv6_universe, *op, D6O_ORO) != NULL)
                log_error("'send dhcp6.oro' syntax is deprecated, please "
                          "use the 'request' syntax (\"man dhclient.conf\").");

        /* Construct and store an ORO (Option Request Option).  It is a
         * fatal error to fail to send an ORO (of at least zero length).
         *
         * Discussion:  RFC3315 appears to be inconsistent in its statements
         * of whether or not the ORO is mandatory.  In section 18.1.1
         * ("Creation and Transmission of Request Messages"):
         *
         *    The client MUST include an Option Request option (see section
         *    22.7) to indicate the options the client is interested in
         *    receiving.  The client MAY include options with data values as
         *    hints to the server about parameter values the client would like
         *    to have returned.
         *
         * This MUST is missing from the creation/transmission of other
         * messages (such as Renew and Rebind), and the section 22.7 ("Option
         * Request Option" format and definition):
         *
         *    A client MAY include an Option Request option in a Solicit,
         *    Request, Renew, Rebind, Confirm or Information-request message to
         *    inform the server about options the client wants the server to
         *    send to the client.  A server MAY include an Option Request
         *    option in a Reconfigure option to indicate which options the
         *    client should request from the server.
         *
         * seems to relax the requirement from MUST to MAY (and still other
         * language in RFC3315 supports this).
         *
         * In lieu of a clarification of RFC3315, we will conform with the
         * MUST.  Instead of an absent ORO, we will if there are no options
         * to request supply an empty ORO.  Theoretically, an absent ORO is
         * difficult to interpret (does the client want all options or no
         * options?).  A zero-length ORO is intuitively clear: requesting
         * nothing.
         */
        buffer = NULL;
        oro_len = 0;
        buflen = 32;
        if (!buffer_allocate(&buffer, buflen, MDL))
                log_fatal("Out of memory constructing DHCPv6 ORO.");
        req = client->config->requested_options;
        if (req != NULL) {
                for (i = 0 ; req[i] != NULL ; i++) {
                        if (buflen == oro_len) {
                                struct buffer *tmpbuf = NULL;

                                buflen += 32;

                                /* Shell game. */
                                buffer_reference(&tmpbuf, buffer, MDL);
                                buffer_dereference(&buffer, MDL);

                                if (!buffer_allocate(&buffer, buflen, MDL))
                                        log_fatal("Out of memory resizing "
                                                  "DHCPv6 ORO buffer.");

                                memcpy(buffer->data, tmpbuf->data, oro_len);

                                buffer_dereference(&tmpbuf, MDL);
                        }

                        if (req[i]->universe == &dhcpv6_universe) {
                                /* Append the code to the ORO. */
                                putUShort(buffer->data + oro_len,
                                          req[i]->code);
                                oro_len += 2;
                        }
                }
        }

        oc = NULL;
        if (make_const_option_cache(&oc, &buffer, NULL, oro_len,
                                    oro_option, MDL)) {
                save_option(&dhcpv6_universe, *op, oc);
        } else {
                log_fatal("Unable to create ORO option cache.");
        }

        /*
         * Note: make_const_option_cache() consumes the buffer, we do not
         * need to dereference it (XXX).
         */
        option_cache_dereference(&oc, MDL);
}

/* A clone of the DHCPv4 script_write_params() minus the DHCPv4-specific
 * filename, server-name, etc specifics.
 *
 * Simply, store all values present in all universes of the option state
 * (probably derived from a DHCPv6 packet) into environment variables
 * named after the option names (and universe names) but with the 'prefix'
 * prepended.
 *
 * Later, dhclient-script may compare for example "new_time_servers" and
 * "old_time_servers" for differences, and only upon detecting a change
 * bother to rewrite ntp.conf and restart it.  Or something along those
 * generic lines.
 */
static void
script_write_params6(struct client_state *client, const char *prefix,
                     struct option_state *options)
{
        struct envadd_state es;
        int i;

        if (options == NULL)
                return;

        es.client = client;
        es.prefix = prefix;

        for (i = 0 ; i < options->universe_count ; i++) {
                option_space_foreach(NULL, NULL, client, NULL, options,
                                     &global_scope, universes[i], &es,
                                     client_option_envadd);
        }
}

/*
 * A clone of the DHCPv4 routine.
 * Write out the environment variables for the objects that the
 * client requested.  If the object was requested the variable will be:
 * requested_<option_name>=1
 * If it wasn't requested there won't be a variable.
 */
static void script_write_requested6(client)
        struct client_state *client;
{
        int i;
        struct option **req;
        char name[256];
        req = client->config->requested_options;

        if (req == NULL)
                return;

        for (i = 0 ; req[i] != NULL ; i++) {
                if ((req[i]->universe == &dhcpv6_universe) &&
                    dhcp_option_ev_name (name, sizeof(name), req[i])) {
                        client_envadd(client, "requested_", name, "%d", 1);
                }
        }
}

/*
 * Check if there is something not fully defined in the active lease.
 */
static isc_boolean_t
active_prefix(struct client_state *client)
{
        struct dhc6_lease *lease;
        struct dhc6_ia *ia;
        struct dhc6_addr *pref;
        char zeros[16];

        lease = client->active_lease;
        if (lease == NULL)
                return ISC_FALSE;
        memset(zeros, 0, 16);
        for (ia = lease->bindings; ia != NULL; ia = ia->next) {
                if (ia->ia_type != D6O_IA_PD)
                        continue;
                for (pref = ia->addrs; pref != NULL; pref = pref->next) {
                        if (pref->plen == 0)
                                return ISC_FALSE;
                        if (pref->address.len != 16)
                                return ISC_FALSE;
                        if (memcmp(pref->address.iabuf, zeros, 16) == 0)
                                return ISC_FALSE;
                }
        }
        return ISC_TRUE;
}
#endif /* DHCPv6 */