server/bootp.c

   1 /* bootp.c
   2
   3    BOOTP Protocol support. */
   4
   5 /*
   6  * Copyright (c) 2004-2005 by Internet Systems Consortium, Inc. ("ISC")
   7  * Copyright (c) 1995-2003 by Internet Software Consortium
   8  *
   9  * Permission to use, copy, modify, and distribute this software for any
  10  * purpose with or without fee is hereby granted, provided that the above
  11  * copyright notice and this permission notice appear in all copies.
  12  *
  13  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
  14  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  15  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
  16  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  17  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  18  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
  19  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  20  *
  21  *   Internet Systems Consortium, Inc.
  22  *   950 Charter Street
  23  *   Redwood City, CA 94063
  24  *   <info@isc.org>
  25  *   http://www.isc.org/
  26  *
  27  * This software has been written for Internet Systems Consortium
  28  * by Ted Lemon in cooperation with Vixie Enterprises and Nominum, Inc.
  29  * To learn more about Internet Systems Consortium, see
  30  * ``http://www.isc.org/''.  To learn more about Vixie Enterprises,
  31  * see ``http://www.vix.com''.   To learn more about Nominum, Inc., see
  32  * ``http://www.nominum.com''.
  33  */
  34
  35 #ifndef lint
  36 static char copyright[] =
  37 "$Id: bootp.c,v 1.77 2007/05/08 23:05:21 dhankins Exp $ Copyright (c) 2004-2005 Internet Systems Consortium.  All rights reserved.\n";
  38 #endif /* not lint */
  39
  40 #include "dhcpd.h"
  41
  42 #if defined (TRACING)
  43 # define send_packet trace_packet_send
  44 #endif
  45
  46 void bootp (packet)
  47         struct packet *packet;
  48 {
  49         int result;
  50         struct host_decl *hp = (struct host_decl *)0;
  51         struct host_decl *host = (struct host_decl *)0;
  52         struct packet outgoing;
  53         struct dhcp_packet raw;
  54         struct sockaddr_in to;
  55         struct in_addr from;
  56         struct hardware hto;
  57         struct option_state *options = (struct option_state *)0;
  58         struct lease *lease = (struct lease *)0;
  59         unsigned i;
  60         struct data_string d1;
  61         struct option_cache *oc;
  62         char msgbuf [1024];
  63         int ignorep;
  64         int peer_has_leases = 0;
  65
  66         if (packet -> raw -> op != BOOTREQUEST)
  67                 return;
  68
  69         /* %Audit% This is log output. %2004.06.17,Safe%
  70          * If we truncate we hope the user can get a hint from the log.
  71          */
  72         snprintf (msgbuf, sizeof msgbuf, "BOOTREQUEST from %s via %s",
  73                  print_hw_addr (packet -> raw -> htype,
  74                                 packet -> raw -> hlen,
  75                                 packet -> raw -> chaddr),
  76                  packet -> raw -> giaddr.s_addr
  77                  ? inet_ntoa (packet -> raw -> giaddr)
  78                  : packet -> interface -> name);
  79
  80         if (!locate_network (packet)) {
  81                 log_info ("%s: network unknown", msgbuf);
  82                 return;
  83         }
  84
  85         find_lease (&lease, packet, packet -> shared_network,
  86                     0, 0, (struct lease *)0, MDL);
  87
  88         if (lease && lease->host)
  89                 host_reference(&hp, lease->host, MDL);
  90
  91         if (!lease || ((lease->flags & STATIC_LEASE) == 0)) {
  92                 struct host_decl *h;
  93                 /* We didn't find an applicable fixed-address host
  94                    declaration.  Just in case we may be able to dynamically
  95                    assign an address, see if there's a host declaration
  96                    that doesn't have an ip address associated with it. */
  97
  98                 if (!hp)
  99                         find_hosts_by_haddr(&hp, packet->raw->htype,
 100                                             packet->raw->chaddr,
 101                                             packet->raw->hlen, MDL);
 102
 103                 for (h = hp; h; h = h -> n_ipaddr) {
 104                         if (!h -> fixed_addr) {
 105                                 host_reference(&host, h, MDL);
 106                                 break;
 107                         }
 108                 }
 109
 110                 if (hp)
 111                         host_dereference(&hp, MDL);
 112
 113                 if (host) {
 114                         host_reference(&hp, host, MDL);
 115                         host_dereference(&host, MDL);
 116                 }
 117
 118                 /* Allocate a lease if we have not yet found one. */
 119                 if (!lease)
 120                         allocate_lease (&lease, packet,
 121                                         packet -> shared_network -> pools,
 122                                         &peer_has_leases);
 123
 124                 if (lease)
 125                         ack_lease (packet, lease, 0, 0, msgbuf, 0, hp);
 126                 else
 127                         log_info ("%s: BOOTP from dynamic client and no "
 128                                   "dynamic leases", msgbuf);
 129
 130                 goto out;
 131         }
 132
 133         /* Run the executable statements to compute the client and server
 134            options. */
 135         option_state_allocate (&options, MDL);
 136
 137         /* Execute the subnet statements. */
 138         execute_statements_in_scope ((struct binding_value **)0,
 139                                      packet, lease, (struct client_state *)0,
 140                                      packet -> options, options,
 141                                      &lease -> scope, lease -> subnet -> group,
 142                                      (struct group *)0);
 143
 144         /* Execute statements from class scopes. */
 145         for (i = packet -> class_count; i > 0; i--) {
 146                 execute_statements_in_scope
 147                         ((struct binding_value **)0,
 148                          packet, lease, (struct client_state *)0,
 149                          packet -> options, options,
 150                          &lease -> scope, packet -> classes [i - 1] -> group,
 151                          lease -> subnet -> group);
 152         }
 153
 154         /* Execute the host statements. */
 155         execute_statements_in_scope ((struct binding_value **)0,
 156                                      packet, lease, (struct client_state *)0,
 157                                      packet -> options, options,
 158                                      &lease -> scope,
 159                                      hp -> group, lease -> subnet -> group);
 160
 161         /* Drop the request if it's not allowed for this client. */
 162         if ((oc = lookup_option (&server_universe, options, SV_ALLOW_BOOTP)) &&
 163             !evaluate_boolean_option_cache (&ignorep, packet, lease,
 164                                             (struct client_state *)0,
 165                                             packet -> options, options,
 166                                             &lease -> scope, oc, MDL)) {
 167                 if (!ignorep)
 168                         log_info ("%s: bootp disallowed", msgbuf);
 169                 goto out;
 170         }
 171
 172         if ((oc = lookup_option (&server_universe,
 173                                  options, SV_ALLOW_BOOTING)) &&
 174             !evaluate_boolean_option_cache (&ignorep, packet, lease,
 175                                             (struct client_state *)0,
 176                                             packet -> options, options,
 177                                             &lease -> scope, oc, MDL)) {
 178                 if (!ignorep)
 179                         log_info ("%s: booting disallowed", msgbuf);
 180                 goto out;
 181         }
 182
 183         /* Set up the outgoing packet... */
 184         memset (&outgoing, 0, sizeof outgoing);
 185         memset (&raw, 0, sizeof raw);
 186         outgoing.raw = &raw;
 187
 188         /* If we didn't get a known vendor magic number on the way in,
 189            just copy the input options to the output. */
 190         if (!packet -> options_valid &&
 191             !(evaluate_boolean_option_cache
 192               (&ignorep, packet, lease, (struct client_state *)0,
 193                packet -> options, options, &lease -> scope,
 194                lookup_option (&server_universe, options,
 195                               SV_ALWAYS_REPLY_RFC1048), MDL))) {
 196                 memcpy (outgoing.raw -> options,
 197                         packet -> raw -> options, DHCP_OPTION_LEN);
 198                 outgoing.packet_length = BOOTP_MIN_LEN;
 199         } else {
 200
 201                 /* Use the subnet mask from the subnet declaration if no other
 202                    mask has been provided. */
 203
 204                 oc = (struct option_cache *)0;
 205                 i = DHO_SUBNET_MASK;
 206                 if (!lookup_option (&dhcp_universe, options, i)) {
 207                         if (option_cache_allocate (&oc, MDL)) {
 208                                 if (make_const_data
 209                                     (&oc -> expression,
 210                                      lease -> subnet -> netmask.iabuf,
 211                                      lease -> subnet -> netmask.len,
 212                                      0, 0, MDL)) {
 213                                         option_code_hash_lookup(&oc->option,
 214                                                         dhcp_universe.code_hash,
 215                                                                 &i, 0, MDL);
 216                                         save_option (&dhcp_universe,
 217                                                      options, oc);
 218                                 }
 219                                 option_cache_dereference (&oc, MDL);
 220                         }
 221                 }
 222
 223                 /* Pack the options into the buffer.  Unlike DHCP, we
 224                    can't pack options into the filename and server
 225                    name buffers. */
 226
 227                 outgoing.packet_length =
 228                         cons_options (packet, outgoing.raw, lease,
 229                                       (struct client_state *)0, 0,
 230                                       packet -> options, options,
 231                                       &lease -> scope,
 232                                       0, 0, 1, (struct data_string *)0,
 233                                       (const char *)0);
 234                 if (outgoing.packet_length < BOOTP_MIN_LEN)
 235                         outgoing.packet_length = BOOTP_MIN_LEN;
 236         }
 237
 238         /* Take the fields that we care about... */
 239         raw.op = BOOTREPLY;
 240         raw.htype = packet -> raw -> htype;
 241         raw.hlen = packet -> raw -> hlen;
 242         memcpy (raw.chaddr, packet -> raw -> chaddr, sizeof raw.chaddr);
 243         raw.hops = packet -> raw -> hops;
 244         raw.xid = packet -> raw -> xid;
 245         raw.secs = packet -> raw -> secs;
 246         raw.flags = packet -> raw -> flags;
 247         raw.ciaddr = packet -> raw -> ciaddr;
 248
 249         /* yiaddr is an ipv4 address, it must be 4 octets. */
 250         memcpy (&raw.yiaddr, lease->ip_addr.iabuf, 4);
 251
 252         /* If we're always supposed to broadcast to this client, set
 253            the broadcast bit in the bootp flags field. */
 254         if ((oc = lookup_option (&server_universe,
 255                                 options, SV_ALWAYS_BROADCAST)) &&
 256             evaluate_boolean_option_cache (&ignorep, packet, lease,
 257                                            (struct client_state *)0,
 258                                            packet -> options, options,
 259                                            &lease -> scope, oc, MDL))
 260                 raw.flags |= htons (BOOTP_BROADCAST);
 261
 262         /* Figure out the address of the next server. */
 263         memset (&d1, 0, sizeof d1);
 264         oc = lookup_option (&server_universe, options, SV_NEXT_SERVER);
 265         if (oc &&
 266             evaluate_option_cache (&d1, packet, lease,
 267                                    (struct client_state *)0,
 268                                    packet -> options, options,
 269                                    &lease -> scope, oc, MDL)) {
 270                 /* If there was more than one answer, take the first. */
 271                 if (d1.len >= 4 && d1.data)
 272                         memcpy (&raw.siaddr, d1.data, 4);
 273                 data_string_forget (&d1, MDL);
 274         } else {
 275                 if ((lease->subnet->shared_network->interface != NULL) &&
 276                     lease->subnet->shared_network->interface->address_count)
 277                     raw.siaddr =
 278                         lease->subnet->shared_network->interface->addresses[0];
 279                 else if (packet->interface->address_count)
 280                         raw.siaddr = packet->interface->addresses[0];
 281         }
 282
 283         raw.giaddr = packet -> raw -> giaddr;
 284
 285         /* Figure out the filename. */
 286         oc = lookup_option (&server_universe, options, SV_FILENAME);
 287         if (oc &&
 288             evaluate_option_cache (&d1, packet, lease,
 289                                    (struct client_state *)0,
 290                                    packet -> options, options,
 291                                    &lease -> scope, oc, MDL)) {
 292                 memcpy (raw.file, d1.data,
 293                         d1.len > sizeof raw.file ? sizeof raw.file : d1.len);
 294                 if (sizeof raw.file > d1.len)
 295                         memset (&raw.file [d1.len],
 296                                 0, (sizeof raw.file) - d1.len);
 297                 data_string_forget (&d1, MDL);
 298         } else
 299                 memcpy (raw.file, packet -> raw -> file, sizeof raw.file);
 300
 301         /* Choose a server name as above. */
 302         oc = lookup_option (&server_universe, options, SV_SERVER_NAME);
 303         if (oc &&
 304             evaluate_option_cache (&d1, packet, lease,
 305                                    (struct client_state *)0,
 306                                    packet -> options, options,
 307                                    &lease -> scope, oc, MDL)) {
 308                 memcpy (raw.sname, d1.data,
 309                         d1.len > sizeof raw.sname ? sizeof raw.sname : d1.len);
 310                 if (sizeof raw.sname > d1.len)
 311                         memset (&raw.sname [d1.len],
 312                                 0, (sizeof raw.sname) - d1.len);
 313                 data_string_forget (&d1, MDL);
 314         }
 315
 316         /* Execute the commit statements, if there are any. */
 317         execute_statements ((struct binding_value **)0,
 318                             packet, lease, (struct client_state *)0,
 319                             packet -> options,
 320                             options, &lease -> scope, lease -> on_commit);
 321
 322         /* We're done with the option state. */
 323         option_state_dereference (&options, MDL);
 324
 325         /* Set up the hardware destination address... */
 326         hto.hbuf [0] = packet -> raw -> htype;
 327         hto.hlen = packet -> raw -> hlen + 1;
 328         memcpy (&hto.hbuf [1], packet -> raw -> chaddr, packet -> raw -> hlen);
 329
 330         if (packet->interface->address_count)
 331                 from = packet->interface->addresses[0];
 332
 333         /* Report what we're doing... */
 334         log_info ("%s", msgbuf);
 335         log_info ("BOOTREPLY for %s to %s (%s) via %s",
 336               piaddr (lease->ip_addr), hp -> name,
 337               print_hw_addr (packet -> raw -> htype,
 338                              packet -> raw -> hlen,
 339                              packet -> raw -> chaddr),
 340               packet -> raw -> giaddr.s_addr
 341               ? inet_ntoa (packet -> raw -> giaddr)
 342               : packet -> interface -> name);
 343
 344         /* Set up the parts of the address that are in common. */
 345         to.sin_family = AF_INET;
 346 #ifdef HAVE_SA_LEN
 347         to.sin_len = sizeof to;
 348 #endif
 349         memset (to.sin_zero, 0, sizeof to.sin_zero);
 350
 351         /* If this was gatewayed, send it back to the gateway... */
 352         if (raw.giaddr.s_addr) {
 353                 to.sin_addr = raw.giaddr;
 354                 to.sin_port = local_port;
 355
 356                 if (fallback_interface) {
 357                         result = send_packet (fallback_interface,
 358                                               (struct packet *)0,
 359                                               &raw, outgoing.packet_length,
 360                                               from, &to, &hto);
 361                         goto out;
 362                 }
 363
 364         /* If it comes from a client that already knows its address
 365            and is not requesting a broadcast response, and we can
 366            unicast to a client without using the ARP protocol, sent it
 367            directly to that client. */
 368         } else if (!(raw.flags & htons (BOOTP_BROADCAST)) &&
 369                    can_unicast_without_arp (packet -> interface)) {
 370                 to.sin_addr = raw.yiaddr;
 371                 to.sin_port = remote_port;
 372
 373         /* Otherwise, broadcast it on the local network. */
 374         } else {
 375                 to.sin_addr = limited_broadcast;
 376                 to.sin_port = remote_port; /* XXX */
 377         }
 378
 379         errno = 0;
 380         result = send_packet (packet -> interface,
 381                               packet, &raw, outgoing.packet_length,
 382                               from, &to, &hto);
 383       out:
 384         if (options)
 385                 option_state_dereference (&options, MDL);
 386         if (lease)
 387                 lease_dereference (&lease, MDL);
 388         if (hp)
 389                 host_dereference (&hp, MDL);
 390         if (host)
 391                 host_dereference (&host, MDL);
 392 }