src/libcharon/plugins/dhcp/dhcp_socket.c

   1 /*
   2  * Copyright (C) 2010 Martin Willi
   3  * Copyright (C) 2010 revosec AG
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License as published by the
   7  * Free Software Foundation; either version 2 of the License, or (at your
   8  * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  12  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * for more details.
  14  */
  15
  16 #include "dhcp_socket.h"
  17
  18 #include <unistd.h>
  19 #include <errno.h>
  20 #include <string.h>
  21 #include <netinet/in.h>
  22 #include <netinet/ip.h>
  23 #include <netinet/udp.h>
  24 #include <linux/if_arp.h>
  25 #include <linux/if_ether.h>
  26 #include <linux/filter.h>
  27
  28 #include <utils/linked_list.h>
  29 #include <utils/identification.h>
  30 #include <threading/mutex.h>
  31 #include <threading/condvar.h>
  32 #include <threading/thread.h>
  33
  34 #include <hydra.h>
  35 #include <daemon.h>
  36 #include <processing/jobs/callback_job.h>
  37
  38 #define DHCP_SERVER_PORT 67
  39 #define DHCP_CLIENT_PORT 68
  40 #define DHCP_TRIES 5
  41
  42 typedef struct private_dhcp_socket_t private_dhcp_socket_t;
  43
  44 /**
  45  * Private data of an dhcp_socket_t object.
  46  */
  47 struct private_dhcp_socket_t {
  48
  49         /**
  50          * Public dhcp_socket_t interface.
  51          */
  52         dhcp_socket_t public;
  53
  54         /**
  55          * Random number generator
  56          */
  57         rng_t *rng;
  58
  59         /**
  60          * List of transactions in DISCOVER
  61          */
  62         linked_list_t *discover;
  63
  64         /**
  65          * List of transactions in REQUEST
  66          */
  67         linked_list_t *request;
  68
  69         /**
  70          * List of successfully completed transactions
  71          */
  72         linked_list_t *completed;
  73
  74         /**
  75          * Lock for transactions
  76          */
  77         mutex_t *mutex;
  78
  79         /**
  80          * Condvar to wait for transaction completion
  81          */
  82         condvar_t *condvar;
  83
  84         /**
  85          * Threads waiting in condvar
  86          */
  87         int waiting;
  88
  89         /**
  90          * DHCP send socket
  91          */
  92         int send;
  93
  94         /**
  95          * DHCP receive socket
  96          */
  97         int receive;
  98
  99         /**
 100          * Do we use per-identity or random leases (and MAC addresses)
 101          */
 102         bool identity_lease;
 103
 104         /**
 105          * DHCP server address, or broadcast
 106          */
 107         host_t *dst;
 108
 109         /**
 110          * Callback job receiving DHCP responses
 111          */
 112         callback_job_t *job;
 113 };
 114
 115 /**
 116  * DHCP opcode (or BOOTP actually)
 117  */
 118 typedef enum {
 119         BOOTREQUEST = 1,
 120         BOOTREPLY = 2,
 121 } dhcp_opcode_t;
 122
 123 /**
 124  * Some DHCP options used
 125  */
 126 typedef enum {
 127         DHCP_DNS_SERVER = 6,
 128         DHCP_HOST_NAME = 12,
 129         DHCP_NBNS_SERVER = 44,
 130         DHCP_REQUESTED_IP = 50,
 131         DHCP_MESSAGE_TYPE = 53,
 132         DHCP_SERVER_ID = 54,
 133         DHCP_PARAM_REQ_LIST = 55,
 134         DHCP_CLIENT_ID = 61,
 135         DHCP_OPTEND = 255,
 136 } dhcp_option_type_t;
 137
 138 /**
 139  * DHCP messages types in the DHCP_MESSAGE_TYPE option
 140  */
 141 typedef enum {
 142         DHCP_DISCOVER = 1,
 143         DHCP_OFFER = 2,
 144         DHCP_REQUEST = 3,
 145         DHCP_DECLINE = 4,
 146         DHCP_ACK = 5,
 147         DHCP_NAK = 6,
 148         DHCP_RELEASE = 7,
 149         DHCP_INFORM = 8,
 150 } dhcp_message_type_t;
 151 /**
 152  * DHCP option encoding, a TLV
 153  */
 154 typedef struct __attribute__((packed)) {
 155         u_int8_t type;
 156         u_int8_t len;
 157         char data[];
 158 } dhcp_option_t;
 159
 160 /**
 161  * DHCP message format, with a maximum size options buffer
 162  */
 163 typedef struct __attribute__((packed)) {
 164         u_int8_t opcode;
 165         u_int8_t hw_type;
 166         u_int8_t hw_addr_len;
 167         u_int8_t hop_count;
 168         u_int32_t transaction_id;
 169         u_int16_t number_of_seconds;
 170         u_int16_t flags;
 171         u_int32_t client_address;
 172         u_int32_t your_address;
 173         u_int32_t server_address;
 174         u_int32_t gateway_address;
 175         char client_hw_addr[6];
 176         char client_hw_padding[10];
 177         char server_hostname[64];
 178         char boot_filename[128];
 179         u_int32_t magic_cookie;
 180         char options[252];
 181 } dhcp_t;
 182
 183 /**
 184  * Prepare a DHCP message for a given transaction
 185  */
 186 static int prepare_dhcp(private_dhcp_socket_t *this,
 187                                                 dhcp_transaction_t *transaction,
 188                                                 dhcp_message_type_t type, dhcp_t *dhcp)
 189 {
 190         chunk_t chunk, broadcast = chunk_from_chars(0xFF,0xFF,0xFF,0xFF);
 191         identification_t *identity;
 192         dhcp_option_t *option;
 193         int optlen = 0;
 194         host_t *src;
 195         u_int32_t id;
 196
 197         memset(dhcp, 0, sizeof(*dhcp));
 198         dhcp->opcode = BOOTREQUEST;
 199         dhcp->hw_type = ARPHRD_ETHER;
 200         dhcp->hw_addr_len = 6;
 201         dhcp->transaction_id = transaction->get_id(transaction);
 202         if (chunk_equals(broadcast, this->dst->get_address(this->dst)))
 203         {
 204                 /* TODO: send with 0.0.0.0 source address */
 205         }
 206         else
 207         {
 208                 /* act as relay agent */
 209                 src = hydra->kernel_interface->get_source_addr(hydra->kernel_interface,
 210                                                                                                            this->dst, NULL);
 211                 if (src)
 212                 {
 213                         memcpy(&dhcp->gateway_address, src->get_address(src).ptr,
 214                                    sizeof(dhcp->gateway_address));
 215                         src->destroy(src);
 216                 }
 217         }
 218
 219         identity = transaction->get_identity(transaction);
 220         chunk = identity->get_encoding(identity);
 221         /* magic bytes, a locally administered unicast MAC */
 222         dhcp->client_hw_addr[0] = 0x7A;
 223         dhcp->client_hw_addr[1] = 0xA7;
 224         /* with ID specific postfix */
 225         if (this->identity_lease)
 226         {
 227                 id = htonl(chunk_hash(chunk));
 228         }
 229         else
 230         {
 231                 id = transaction->get_id(transaction);
 232         }
 233         memcpy(&dhcp->client_hw_addr[2], &id, sizeof(id));
 234
 235         dhcp->magic_cookie = htonl(0x63825363);
 236
 237         option = (dhcp_option_t*)&dhcp->options[optlen];
 238         option->type = DHCP_MESSAGE_TYPE;
 239         option->len = 1;
 240         option->data[0] = type;
 241         optlen += sizeof(dhcp_option_t) + option->len;
 242
 243         if (identity->get_type(identity) == ID_FQDN)
 244         {
 245                 option = (dhcp_option_t*)&dhcp->options[optlen];
 246                 option->type = DHCP_HOST_NAME;
 247                 option->len = min(chunk.len, 64);
 248                 memcpy(option->data, chunk.ptr, option->len);
 249                 optlen += sizeof(dhcp_option_t) + option->len;
 250         }
 251
 252         option = (dhcp_option_t*)&dhcp->options[optlen];
 253         option->type = DHCP_CLIENT_ID;
 254         option->len = min(chunk.len, 64);
 255         memcpy(option->data, chunk.ptr, option->len);
 256         optlen += sizeof(dhcp_option_t) + option->len;
 257
 258         return optlen;
 259 }
 260
 261 /**
 262  * Send a DHCP message with given options length
 263  */
 264 static bool send_dhcp(private_dhcp_socket_t *this,
 265                                           dhcp_transaction_t *transaction, dhcp_t *dhcp, int optlen)
 266 {
 267         host_t *dst;
 268         ssize_t len;
 269
 270         dst = transaction->get_server(transaction);
 271         if (!dst)
 272         {
 273                 dst = this->dst;
 274         }
 275         len = offsetof(dhcp_t, magic_cookie) + ((optlen + 4) / 64 * 64 + 64);
 276         return sendto(this->send, dhcp, len, 0, dst->get_sockaddr(dst),
 277                                   *dst->get_sockaddr_len(dst)) == len;
 278 }
 279
 280 /**
 281  * Send DHCP discover using a given transaction
 282  */
 283 static bool discover(private_dhcp_socket_t *this,
 284                                          dhcp_transaction_t *transaction)
 285 {
 286         dhcp_option_t *option;
 287         dhcp_t dhcp;
 288         int optlen;
 289
 290         optlen = prepare_dhcp(this, transaction, DHCP_DISCOVER, &dhcp);
 291
 292         DBG1(DBG_CFG, "sending DHCP DISCOVER to %H", this->dst);
 293
 294         option = (dhcp_option_t*)&dhcp.options[optlen];
 295         option->type = DHCP_PARAM_REQ_LIST;
 296         option->len = 2;
 297         option->data[0] = DHCP_DNS_SERVER;
 298         option->data[1] = DHCP_NBNS_SERVER;
 299         optlen += sizeof(dhcp_option_t) + option->len;
 300
 301         dhcp.options[optlen++] = DHCP_OPTEND;
 302
 303         if (!send_dhcp(this, transaction, &dhcp, optlen))
 304         {
 305                 DBG1(DBG_CFG, "sending DHCP DISCOVER failed: %s", strerror(errno));
 306                 return FALSE;
 307         }
 308         return TRUE;
 309 }
 310
 311 /**
 312  * Send DHCP request using a given transaction
 313  */
 314 static bool request(private_dhcp_socket_t *this,
 315                                         dhcp_transaction_t *transaction)
 316 {
 317         dhcp_option_t *option;
 318         dhcp_t dhcp;
 319         host_t *offer, *server;
 320         chunk_t chunk;
 321         int optlen;
 322
 323         optlen = prepare_dhcp(this, transaction, DHCP_REQUEST, &dhcp);
 324
 325         offer = transaction->get_address(transaction);
 326         server = transaction->get_server(transaction);
 327         if (!offer || !server)
 328         {
 329                 return FALSE;
 330         }
 331         DBG1(DBG_CFG, "sending DHCP REQUEST for %H to %H", offer, server);
 332
 333         option = (dhcp_option_t*)&dhcp.options[optlen];
 334         option->type = DHCP_REQUESTED_IP;
 335         option->len = 4;
 336         chunk = offer->get_address(offer);
 337         memcpy(option->data, chunk.ptr, min(chunk.len, option->len));
 338         optlen += sizeof(dhcp_option_t) + option->len;
 339
 340         option = (dhcp_option_t*)&dhcp.options[optlen];
 341         option->type = DHCP_SERVER_ID;
 342         option->len = 4;
 343         chunk = server->get_address(server);
 344         memcpy(option->data, chunk.ptr, min(chunk.len, option->len));
 345         optlen += sizeof(dhcp_option_t) + option->len;
 346
 347         option = (dhcp_option_t*)&dhcp.options[optlen];
 348         option->type = DHCP_PARAM_REQ_LIST;
 349         option->len = 2;
 350         option->data[0] = DHCP_DNS_SERVER;
 351         option->data[1] = DHCP_NBNS_SERVER;
 352         optlen += sizeof(dhcp_option_t) + option->len;
 353
 354         dhcp.options[optlen++] = DHCP_OPTEND;
 355
 356         if (!send_dhcp(this, transaction, &dhcp, optlen))
 357         {
 358                 DBG1(DBG_CFG, "sending DHCP REQUEST failed: %s", strerror(errno));
 359                 return FALSE;
 360         }
 361         return TRUE;
 362 }
 363
 364 METHOD(dhcp_socket_t, enroll, dhcp_transaction_t*,
 365         private_dhcp_socket_t *this, identification_t *identity)
 366 {
 367         dhcp_transaction_t *transaction;
 368         u_int32_t id;
 369         int try;
 370
 371         this->rng->get_bytes(this->rng, sizeof(id), (u_int8_t*)&id);
 372         transaction = dhcp_transaction_create(id, identity);
 373
 374         this->mutex->lock(this->mutex);
 375         this->discover->insert_last(this->discover, transaction);
 376         try = 1;
 377         while (try <= DHCP_TRIES && discover(this, transaction))
 378         {
 379                 if (!this->condvar->timed_wait(this->condvar, this->mutex, 1000 * try) &&
 380                         this->request->find_first(this->request, NULL,
 381                                                                           (void**)&transaction) == SUCCESS)
 382                 {
 383                         break;
 384                 }
 385                 try++;
 386         }
 387         if (this->discover->remove(this->discover, transaction, NULL))
 388         {       /* no OFFER received */
 389                 this->mutex->unlock(this->mutex);
 390                 transaction->destroy(transaction);
 391                 DBG1(DBG_CFG, "DHCP DISCOVER timed out");
 392                 return NULL;
 393         }
 394
 395         try = 1;
 396         while (try <= DHCP_TRIES && request(this, transaction))
 397         {
 398                 if (!this->condvar->timed_wait(this->condvar, this->mutex, 1000 * try) &&
 399                         this->completed->remove(this->completed, transaction, NULL))
 400                 {
 401                         break;
 402                 }
 403                 try++;
 404         }
 405         if (this->request->remove(this->request, transaction, NULL))
 406         {       /* no ACK received */
 407                 this->mutex->unlock(this->mutex);
 408                 transaction->destroy(transaction);
 409                 DBG1(DBG_CFG, "DHCP REQUEST timed out");
 410                 return NULL;
 411         }
 412         this->mutex->unlock(this->mutex);
 413
 414         return transaction;
 415 }
 416
 417 METHOD(dhcp_socket_t, release, void,
 418         private_dhcp_socket_t *this, dhcp_transaction_t *transaction)
 419 {
 420         dhcp_option_t *option;
 421         dhcp_t dhcp;
 422         host_t *release, *server;
 423         chunk_t chunk;
 424         int optlen;
 425
 426         optlen = prepare_dhcp(this, transaction, DHCP_RELEASE, &dhcp);
 427
 428         release = transaction->get_address(transaction);
 429         server = transaction->get_server(transaction);
 430         if (!release || !server)
 431         {
 432                 return;
 433         }
 434         DBG1(DBG_CFG, "sending DHCP RELEASE for %H to %H", release, server);
 435
 436         chunk = release->get_address(release);
 437         memcpy(&dhcp.client_address, chunk.ptr,
 438                    min(chunk.len, sizeof(dhcp.client_address)));
 439
 440         option = (dhcp_option_t*)&dhcp.options[optlen];
 441         option->type = DHCP_SERVER_ID;
 442         option->len = 4;
 443         chunk = server->get_address(server);
 444         memcpy(option->data, chunk.ptr, min(chunk.len, option->len));
 445         optlen += sizeof(dhcp_option_t) + option->len;
 446
 447         dhcp.options[optlen++] = DHCP_OPTEND;
 448
 449         if (!send_dhcp(this, transaction, &dhcp, optlen))
 450         {
 451                 DBG1(DBG_CFG, "sending DHCP RELEASE failed: %s", strerror(errno));
 452         }
 453 }
 454
 455 /**
 456  * Handle a DHCP OFFER
 457  */
 458 static void handle_offer(private_dhcp_socket_t *this, dhcp_t *dhcp, int optlen)
 459 {
 460         dhcp_transaction_t *transaction = NULL;
 461         enumerator_t *enumerator;
 462         host_t *offer, *server;
 463
 464         offer = host_create_from_chunk(AF_INET,
 465                                         chunk_from_thing(dhcp->your_address), 0);
 466
 467         this->mutex->lock(this->mutex);
 468         enumerator = this->discover->create_enumerator(this->discover);
 469         while (enumerator->enumerate(enumerator, &transaction))
 470         {
 471                 if (transaction->get_id(transaction) == dhcp->transaction_id)
 472                 {
 473                         this->discover->remove_at(this->discover, enumerator);
 474                         this->request->insert_last(this->request, transaction);
 475                         break;
 476                 }
 477         }
 478         enumerator->destroy(enumerator);
 479
 480         if (transaction)
 481         {
 482                 int optsize, optpos = 0, pos;
 483                 dhcp_option_t *option;
 484
 485                 while (optlen > sizeof(dhcp_option_t))
 486                 {
 487                         option = (dhcp_option_t*)&dhcp->options[optpos];
 488                         optsize = sizeof(dhcp_option_t) + option->len;
 489                         if (option->type == DHCP_OPTEND || optlen < optsize)
 490                         {
 491                                 break;
 492                         }
 493                         if (option->type == DHCP_DNS_SERVER ||
 494                                 option->type == DHCP_NBNS_SERVER)
 495                         {
 496                                 for (pos = 0; pos + 4 <= option->len; pos += 4)
 497                                 {
 498                                         transaction->add_attribute(transaction, option->type ==
 499                                                 DHCP_DNS_SERVER ? INTERNAL_IP4_DNS : INTERNAL_IP4_NBNS,
 500                                                 chunk_create((char*)&option->data[pos], 4));
 501                                 }
 502                         }
 503                         if (option->type == DHCP_SERVER_ID && option->len == 4)
 504                         {
 505                                 server = host_create_from_chunk(AF_INET,
 506                                                         chunk_create(option->data, 4), DHCP_SERVER_PORT);
 507                         }
 508                         optlen -= optsize;
 509                         optpos += optsize;
 510                 }
 511                 if (!server)
 512                 {
 513                         server = host_create_from_chunk(AF_INET,
 514                                 chunk_from_thing(dhcp->server_address), DHCP_SERVER_PORT);
 515                 }
 516                 DBG1(DBG_CFG, "received DHCP OFFER %H from %H", offer, server);
 517                 transaction->set_address(transaction, offer->clone(offer));
 518                 transaction->set_server(transaction, server->clone(server));
 519         }
 520         this->mutex->unlock(this->mutex);
 521         this->condvar->broadcast(this->condvar);
 522         offer->destroy(offer);
 523         server->destroy(server);
 524 }
 525
 526 /**
 527  * Handle a DHCP ACK
 528  */
 529 static void handle_ack(private_dhcp_socket_t *this, dhcp_t *dhcp, int optlen)
 530 {
 531         dhcp_transaction_t *transaction;
 532         enumerator_t *enumerator;
 533         host_t *offer;
 534
 535         offer = host_create_from_chunk(AF_INET,
 536                                                 chunk_from_thing(dhcp->your_address), 0);
 537
 538         this->mutex->lock(this->mutex);
 539         enumerator = this->request->create_enumerator(this->request);
 540         while (enumerator->enumerate(enumerator, &transaction))
 541         {
 542                 if (transaction->get_id(transaction) == dhcp->transaction_id)
 543                 {
 544                         DBG1(DBG_CFG, "received DHCP ACK for %H", offer);
 545                         this->request->remove_at(this->request, enumerator);
 546                         this->completed->insert_last(this->completed, transaction);
 547                         break;
 548                 }
 549         }
 550         enumerator->destroy(enumerator);
 551         this->mutex->unlock(this->mutex);
 552         this->condvar->broadcast(this->condvar);
 553         offer->destroy(offer);
 554 }
 555
 556 /**
 557  * Receive DHCP responses
 558  */
 559 static job_requeue_t receive_dhcp(private_dhcp_socket_t *this)
 560 {
 561         struct sockaddr_ll addr;
 562         socklen_t addr_len = sizeof(addr);
 563         struct __attribute__((packed)) {
 564                 struct iphdr ip;
 565                 struct udphdr udp;
 566                 dhcp_t dhcp;
 567         } packet;
 568         int oldstate, optlen, origoptlen, optsize, optpos = 0;
 569         ssize_t len;
 570         dhcp_option_t *option;
 571
 572         oldstate = thread_cancelability(TRUE);
 573         len = recvfrom(this->receive, &packet, sizeof(packet), 0,
 574                                         (struct sockaddr*)&addr, &addr_len);
 575         thread_cancelability(oldstate);
 576
 577         if (len >= sizeof(struct iphdr) + sizeof(struct udphdr) +
 578                 offsetof(dhcp_t, options))
 579         {
 580                 origoptlen = optlen = len - sizeof(struct iphdr) +
 581                                          sizeof(struct udphdr) + offsetof(dhcp_t, options);
 582                 while (optlen > sizeof(dhcp_option_t))
 583                 {
 584                         option = (dhcp_option_t*)&packet.dhcp.options[optpos];
 585                         optsize = sizeof(dhcp_option_t) + option->len;
 586                         if (option->type == DHCP_OPTEND || optlen < optsize)
 587                         {
 588                                 break;
 589                         }
 590                         if (option->type == DHCP_MESSAGE_TYPE && option->len == 1)
 591                         {
 592                                 switch (option->data[0])
 593                                 {
 594                                         case DHCP_OFFER:
 595                                                 handle_offer(this, &packet.dhcp, origoptlen);
 596                                                 break;
 597                                         case DHCP_ACK:
 598                                                 handle_ack(this, &packet.dhcp, origoptlen);
 599                                         default:
 600                                                 break;
 601                                 }
 602                                 break;
 603                         }
 604                         optlen -= optsize;
 605                         optpos += optsize;
 606                 }
 607         }
 608         return JOB_REQUEUE_DIRECT;
 609 }
 610
 611 METHOD(dhcp_socket_t, destroy, void,
 612         private_dhcp_socket_t *this)
 613 {
 614         if (this->job)
 615         {
 616                 this->job->cancel(this->job);
 617         }
 618         while (this->waiting)
 619         {
 620                 this->condvar->signal(this->condvar);
 621         }
 622         if (this->send > 0)
 623         {
 624                 close(this->send);
 625         }
 626         if (this->receive > 0)
 627         {
 628                 close(this->receive);
 629         }
 630         this->mutex->destroy(this->mutex);
 631         this->condvar->destroy(this->condvar);
 632         this->discover->destroy_offset(this->discover,
 633                                                                 offsetof(dhcp_transaction_t, destroy));
 634         this->request->destroy_offset(this->request,
 635                                                                 offsetof(dhcp_transaction_t, destroy));
 636         this->completed->destroy_offset(this->completed,
 637                                                                 offsetof(dhcp_transaction_t, destroy));
 638         DESTROY_IF(this->rng);
 639         DESTROY_IF(this->dst);
 640         free(this);
 641 }
 642
 643 /**
 644  * See header
 645  */
 646 dhcp_socket_t *dhcp_socket_create()
 647 {
 648         private_dhcp_socket_t *this;
 649         struct sockaddr_in src;
 650         int on = 1;
 651         struct sock_filter dhcp_filter_code[] = {
 652                 BPF_STMT(BPF_LD+BPF_B+BPF_ABS,
 653                                  offsetof(struct iphdr, protocol)),
 654                 BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, IPPROTO_UDP, 0, 16),
 655                 BPF_STMT(BPF_LD+BPF_H+BPF_ABS, sizeof(struct iphdr) +
 656                                  offsetof(struct udphdr, source)),
 657                 BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, DHCP_SERVER_PORT, 0, 14),
 658                 BPF_STMT(BPF_LD+BPF_H+BPF_ABS, sizeof(struct iphdr) +
 659                                  offsetof(struct udphdr, dest)),
 660                 BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, DHCP_CLIENT_PORT, 0, 2),
 661                 BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, DHCP_SERVER_PORT, 0, 1),
 662                 BPF_JUMP(BPF_JMP+BPF_JA, 0, 0, 10),
 663                 BPF_STMT(BPF_LD+BPF_B+BPF_ABS, sizeof(struct iphdr) +
 664                                  sizeof(struct udphdr) + offsetof(dhcp_t, opcode)),
 665                 BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, BOOTREPLY, 0, 8),
 666                 BPF_STMT(BPF_LD+BPF_B+BPF_ABS, sizeof(struct iphdr) +
 667                                  sizeof(struct udphdr) + offsetof(dhcp_t, hw_type)),
 668                 BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, ARPHRD_ETHER, 0, 6),
 669                 BPF_STMT(BPF_LD+BPF_B+BPF_ABS, sizeof(struct iphdr) +
 670                                  sizeof(struct udphdr) + offsetof(dhcp_t, hw_addr_len)),
 671                 BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, 6, 0, 4),
 672                 BPF_STMT(BPF_LD+BPF_W+BPF_ABS, sizeof(struct iphdr) +
 673                                  sizeof(struct udphdr) + offsetof(dhcp_t, magic_cookie)),
 674                 BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, 0x63825363, 0, 2),
 675                 BPF_STMT(BPF_LD+BPF_W+BPF_LEN, 0),
 676                 BPF_STMT(BPF_RET+BPF_A, 0),
 677                 BPF_STMT(BPF_RET+BPF_K, 0),
 678         };
 679         struct sock_fprog dhcp_filter = {
 680                 sizeof(dhcp_filter_code) / sizeof(struct sock_filter),
 681                 dhcp_filter_code,
 682         };
 683
 684         INIT(this,
 685                 .public = {
 686                         .enroll = _enroll,
 687                         .release = _release,
 688                         .destroy = _destroy,
 689                 },
 690                 .rng = lib->crypto->create_rng(lib->crypto, RNG_WEAK),
 691                 .mutex = mutex_create(MUTEX_TYPE_DEFAULT),
 692                 .condvar = condvar_create(CONDVAR_TYPE_DEFAULT),
 693                 .discover = linked_list_create(),
 694                 .request = linked_list_create(),
 695                 .completed = linked_list_create(),
 696         );
 697
 698         if (!this->rng)
 699         {
 700                 DBG1(DBG_CFG, "unable to create RNG");
 701                 destroy(this);
 702                 return NULL;
 703         }
 704         this->identity_lease = lib->settings->get_bool(lib->settings,
 705                                                         "charon.plugins.dhcp.identity_lease", FALSE);
 706         this->dst = host_create_from_string(lib->settings->get_str(lib->settings,
 707                                                         "charon.plugins.dhcp.server", "255.255.255.255"),
 708                                                         DHCP_SERVER_PORT);
 709         if (!this->dst)
 710         {
 711                 DBG1(DBG_CFG, "configured DHCP server address invalid");
 712                 destroy(this);
 713                 return NULL;
 714         }
 715
 716         this->send = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
 717         if (this->send == -1)
 718         {
 719                 DBG1(DBG_CFG, "unable to create DHCP send socket: %s", strerror(errno));
 720                 destroy(this);
 721                 return NULL;
 722         }
 723         if (setsockopt(this->send, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
 724         {
 725                 DBG1(DBG_CFG, "unable to reuse DHCP socket address: %s", strerror(errno));
 726                 destroy(this);
 727                 return NULL;
 728         }
 729         if (setsockopt(this->send, SOL_SOCKET, SO_BROADCAST, &on, sizeof(on)) == -1)
 730         {
 731                 DBG1(DBG_CFG, "unable to broadcast on DHCP socket: %s", strerror(errno));
 732                 destroy(this);
 733                 return NULL;
 734         }
 735         src.sin_family = AF_INET;
 736         src.sin_port = htons(DHCP_CLIENT_PORT);
 737         src.sin_addr.s_addr = INADDR_ANY;
 738         if (bind(this->send, (struct sockaddr*)&src, sizeof(src)) == -1)
 739         {
 740                 DBG1(DBG_CFG, "unable to bind DHCP send socket: %s", strerror(errno));
 741                 destroy(this);
 742                 return NULL;
 743         }
 744
 745         this->receive = socket(AF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
 746         if (this->receive == -1)
 747         {
 748                 DBG1(DBG_NET, "opening DHCP receive socket failed: %s", strerror(errno));
 749                 destroy(this);
 750                 return NULL;
 751         }
 752         if (setsockopt(this->receive, SOL_SOCKET, SO_ATTACH_FILTER,
 753                                    &dhcp_filter, sizeof(dhcp_filter)) < 0)
 754         {
 755                 DBG1(DBG_CFG, "installing DHCP socket filter failed: %s",
 756                          strerror(errno));
 757                 destroy(this);
 758                 return NULL;
 759         }
 760
 761         this->job = callback_job_create((callback_job_cb_t)receive_dhcp,
 762                                                                         this, NULL, NULL);
 763         lib->processor->queue_job(lib->processor, (job_t*)this->job);
 764
 765         return &this->public;
 766 }
 767