src/libsystemd-dhcp/dhcp-client.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright (C) 2013 Intel Corporation. All rights reserved.
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <stdlib.h>
  21 #include <errno.h>
  22 #include <string.h>
  23 #include <stdio.h>
  24 #include <net/ethernet.h>
  25 #include <sys/param.h>
  26
  27 #include "util.h"
  28 #include "list.h"
  29
  30 #include "dhcp-protocol.h"
  31 #include "dhcp-internal.h"
  32 #include "sd-dhcp-client.h"
  33
  34 #define DHCP_CLIENT_MIN_OPTIONS_SIZE            312
  35
  36 struct DHCPLease {
  37         uint32_t t1;
  38         uint32_t t2;
  39         uint32_t lifetime;
  40         be32_t address;
  41         be32_t server_address;
  42         be32_t subnet_mask;
  43         be32_t router;
  44 };
  45
  46 typedef struct DHCPLease DHCPLease;
  47
  48 struct sd_dhcp_client {
  49         DHCPState state;
  50         sd_event *event;
  51         sd_event_source *timeout_resend;
  52         int index;
  53         int fd;
  54         union sockaddr_union link;
  55         sd_event_source *receive_message;
  56         uint8_t *req_opts;
  57         size_t req_opts_allocated;
  58         size_t req_opts_size;
  59         be32_t last_addr;
  60         struct ether_addr mac_addr;
  61         uint32_t xid;
  62         usec_t start_time;
  63         unsigned int attempt;
  64         usec_t request_sent;
  65         sd_event_source *timeout_t1;
  66         sd_event_source *timeout_t2;
  67         sd_event_source *timeout_expire;
  68         sd_dhcp_client_cb_t cb;
  69         void *userdata;
  70         DHCPLease *lease;
  71 };
  72
  73 static const uint8_t default_req_opts[] = {
  74         DHCP_OPTION_SUBNET_MASK,
  75         DHCP_OPTION_ROUTER,
  76         DHCP_OPTION_HOST_NAME,
  77         DHCP_OPTION_DOMAIN_NAME,
  78         DHCP_OPTION_DOMAIN_NAME_SERVER,
  79         DHCP_OPTION_NTP_SERVER,
  80 };
  81
  82 static int client_receive_message(sd_event_source *s, int fd,
  83                                   uint32_t revents, void *userdata);
  84
  85 int sd_dhcp_client_set_callback(sd_dhcp_client *client, sd_dhcp_client_cb_t cb,
  86                                 void *userdata)
  87 {
  88         assert_return(client, -EINVAL);
  89
  90         client->cb = cb;
  91         client->userdata = userdata;
  92
  93         return 0;
  94 }
  95
  96 int sd_dhcp_client_set_request_option(sd_dhcp_client *client, uint8_t option)
  97 {
  98         size_t i;
  99
 100         assert_return(client, -EINVAL);
 101         assert_return (client->state == DHCP_STATE_INIT, -EBUSY);
 102
 103         switch(option) {
 104         case DHCP_OPTION_PAD:
 105         case DHCP_OPTION_OVERLOAD:
 106         case DHCP_OPTION_MESSAGE_TYPE:
 107         case DHCP_OPTION_PARAMETER_REQUEST_LIST:
 108         case DHCP_OPTION_END:
 109                 return -EINVAL;
 110
 111         default:
 112                 break;
 113         }
 114
 115         for (i = 0; i < client->req_opts_size; i++)
 116                 if (client->req_opts[i] == option)
 117                         return -EEXIST;
 118
 119         if (!GREEDY_REALLOC(client->req_opts, client->req_opts_allocated,
 120                             client->req_opts_size + 1))
 121                 return -ENOMEM;
 122
 123         client->req_opts[client->req_opts_size++] = option;
 124
 125         return 0;
 126 }
 127
 128 int sd_dhcp_client_set_request_address(sd_dhcp_client *client,
 129                                        const struct in_addr *last_addr)
 130 {
 131         assert_return(client, -EINVAL);
 132         assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
 133
 134         if (last_addr)
 135                 client->last_addr = last_addr->s_addr;
 136         else
 137                 client->last_addr = INADDR_ANY;
 138
 139         return 0;
 140 }
 141
 142 int sd_dhcp_client_set_index(sd_dhcp_client *client, int interface_index)
 143 {
 144         assert_return(client, -EINVAL);
 145         assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
 146         assert_return(interface_index >= -1, -EINVAL);
 147
 148         client->index = interface_index;
 149
 150         return 0;
 151 }
 152
 153 int sd_dhcp_client_set_mac(sd_dhcp_client *client,
 154                            const struct ether_addr *addr)
 155 {
 156         assert_return(client, -EINVAL);
 157         assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
 158
 159         memcpy(&client->mac_addr, addr, ETH_ALEN);
 160
 161         return 0;
 162 }
 163
 164 int sd_dhcp_client_get_address(sd_dhcp_client *client, struct in_addr *addr)
 165 {
 166         assert_return(client, -EINVAL);
 167         assert_return(addr, -EINVAL);
 168
 169         switch (client->state) {
 170         case DHCP_STATE_INIT:
 171         case DHCP_STATE_SELECTING:
 172         case DHCP_STATE_INIT_REBOOT:
 173         case DHCP_STATE_REBOOTING:
 174         case DHCP_STATE_REQUESTING:
 175                 return -EADDRNOTAVAIL;
 176
 177         case DHCP_STATE_BOUND:
 178         case DHCP_STATE_RENEWING:
 179         case DHCP_STATE_REBINDING:
 180                 addr->s_addr = client->lease->address;
 181
 182                 break;
 183         }
 184
 185         return 0;
 186 }
 187
 188 int sd_dhcp_client_get_netmask(sd_dhcp_client *client, struct in_addr *addr)
 189 {
 190         assert_return(client, -EINVAL);
 191         assert_return(addr, -EINVAL);
 192
 193         switch (client->state) {
 194         case DHCP_STATE_INIT:
 195         case DHCP_STATE_SELECTING:
 196         case DHCP_STATE_INIT_REBOOT:
 197         case DHCP_STATE_REBOOTING:
 198         case DHCP_STATE_REQUESTING:
 199                 return -EADDRNOTAVAIL;
 200
 201         case DHCP_STATE_BOUND:
 202         case DHCP_STATE_RENEWING:
 203         case DHCP_STATE_REBINDING:
 204                 addr->s_addr = client->lease->subnet_mask;
 205
 206                 break;
 207         }
 208
 209         return 0;
 210 }
 211
 212 int sd_dhcp_client_prefixlen(const struct in_addr *addr)
 213 {
 214         int len = 0;
 215         uint32_t mask;
 216
 217         assert_return(addr, -EADDRNOTAVAIL);
 218
 219         mask = be32toh(addr->s_addr);
 220         while (mask) {
 221                 len++;
 222                 mask = mask << 1;
 223         }
 224
 225         return len;
 226 }
 227
 228 int sd_dhcp_client_get_router(sd_dhcp_client *client, struct in_addr *addr)
 229 {
 230         assert_return(client, -EINVAL);
 231         assert_return(addr, -EINVAL);
 232
 233         switch (client->state) {
 234         case DHCP_STATE_INIT:
 235         case DHCP_STATE_SELECTING:
 236         case DHCP_STATE_INIT_REBOOT:
 237         case DHCP_STATE_REBOOTING:
 238         case DHCP_STATE_REQUESTING:
 239                 return -EADDRNOTAVAIL;
 240
 241         case DHCP_STATE_BOUND:
 242         case DHCP_STATE_RENEWING:
 243         case DHCP_STATE_REBINDING:
 244                 addr->s_addr = client->lease->router;
 245
 246                 break;
 247         }
 248
 249         return 0;
 250 }
 251
 252 static int client_notify(sd_dhcp_client *client, int event)
 253 {
 254         if (client->cb)
 255                 client->cb(client, event, client->userdata);
 256
 257         return 0;
 258 }
 259
 260 static int client_stop(sd_dhcp_client *client, int error)
 261 {
 262         assert_return(client, -EINVAL);
 263
 264         client->receive_message =
 265                 sd_event_source_unref(client->receive_message);
 266
 267         if (client->fd >= 0)
 268                 close(client->fd);
 269         client->fd = -1;
 270
 271         client->timeout_resend = sd_event_source_unref(client->timeout_resend);
 272
 273         client->timeout_t1 = sd_event_source_unref(client->timeout_t1);
 274         client->timeout_t2 = sd_event_source_unref(client->timeout_t2);
 275         client->timeout_expire = sd_event_source_unref(client->timeout_expire);
 276
 277         client->attempt = 1;
 278
 279         client_notify(client, error);
 280
 281         switch (client->state) {
 282
 283         case DHCP_STATE_INIT:
 284         case DHCP_STATE_SELECTING:
 285         case DHCP_STATE_REQUESTING:
 286         case DHCP_STATE_BOUND:
 287
 288                 client->start_time = 0;
 289                 client->state = DHCP_STATE_INIT;
 290                 break;
 291
 292         case DHCP_STATE_INIT_REBOOT:
 293         case DHCP_STATE_REBOOTING:
 294         case DHCP_STATE_RENEWING:
 295         case DHCP_STATE_REBINDING:
 296
 297                 break;
 298         }
 299
 300         if (client->lease) {
 301                 free(client->lease);
 302                 client->lease = NULL;
 303         }
 304
 305         return 0;
 306 }
 307
 308 static int client_packet_init(sd_dhcp_client *client, uint8_t type,
 309                               DHCPMessage *message, uint16_t secs,
 310                               uint8_t **opt, size_t *optlen)
 311 {
 312         int err;
 313         be16_t max_size;
 314
 315         *opt = (uint8_t *)(message + 1);
 316
 317         if (*optlen < 4)
 318                 return -ENOBUFS;
 319         *optlen -= 4;
 320
 321         message->op = BOOTREQUEST;
 322         message->htype = 1;
 323         message->hlen = ETHER_ADDR_LEN;
 324         message->xid = htobe32(client->xid);
 325
 326         /* Although 'secs' field is a SHOULD in RFC 2131, certain DHCP servers
 327            refuse to issue an DHCP lease if 'secs' is set to zero */
 328         message->secs = htobe16(secs);
 329
 330         if (client->state == DHCP_STATE_RENEWING ||
 331             client->state == DHCP_STATE_REBINDING)
 332                 message->ciaddr = client->lease->address;
 333
 334         memcpy(&message->chaddr, &client->mac_addr, ETH_ALEN);
 335         (*opt)[0] = 0x63;
 336         (*opt)[1] = 0x82;
 337         (*opt)[2] = 0x53;
 338         (*opt)[3] = 0x63;
 339
 340         *opt += 4;
 341
 342         err = dhcp_option_append(opt, optlen, DHCP_OPTION_MESSAGE_TYPE, 1,
 343                                  &type);
 344         if (err < 0)
 345                 return err;
 346
 347         /* Some DHCP servers will refuse to issue an DHCP lease if the Cliient
 348            Identifier option is not set */
 349         err = dhcp_option_append(opt, optlen, DHCP_OPTION_CLIENT_IDENTIFIER,
 350                                  ETH_ALEN, &client->mac_addr);
 351         if (err < 0)
 352                 return err;
 353
 354         if (type == DHCP_DISCOVER || type == DHCP_REQUEST) {
 355                 err = dhcp_option_append(opt, optlen,
 356                                          DHCP_OPTION_PARAMETER_REQUEST_LIST,
 357                                          client->req_opts_size,
 358                                          client->req_opts);
 359                 if (err < 0)
 360                         return err;
 361
 362                 /* Some DHCP servers will send bigger DHCP packets than the
 363                    defined default size unless the Maximum Messge Size option
 364                    is explicitely set */
 365                 max_size = htobe16(DHCP_IP_UDP_SIZE + DHCP_MESSAGE_SIZE +
 366                                    DHCP_CLIENT_MIN_OPTIONS_SIZE);
 367                 err = dhcp_option_append(opt, optlen,
 368                                          DHCP_OPTION_MAXIMUM_MESSAGE_SIZE,
 369                                          2, &max_size);
 370                 if (err < 0)
 371                         return err;
 372         }
 373
 374         return 0;
 375 }
 376
 377 static uint16_t client_checksum(void *buf, int len)
 378 {
 379         uint32_t sum;
 380         uint16_t *check;
 381         int i;
 382         uint8_t *odd;
 383
 384         sum = 0;
 385         check = buf;
 386
 387         for (i = 0; i < len / 2 ; i++)
 388                 sum += check[i];
 389
 390         if (len & 0x01) {
 391                 odd = buf;
 392                 sum += odd[len - 1];
 393         }
 394
 395         while (sum >> 16)
 396                 sum = (sum & 0xffff) + (sum >> 16);
 397
 398         return ~sum;
 399 }
 400
 401 static void client_append_ip_headers(DHCPPacket *packet, uint16_t len)
 402 {
 403         packet->ip.version = IPVERSION;
 404         packet->ip.ihl = DHCP_IP_SIZE / 4;
 405         packet->ip.tot_len = htobe16(len);
 406
 407         packet->ip.protocol = IPPROTO_UDP;
 408         packet->ip.saddr = INADDR_ANY;
 409         packet->ip.daddr = INADDR_BROADCAST;
 410
 411         packet->udp.source = htobe16(DHCP_PORT_CLIENT);
 412         packet->udp.dest = htobe16(DHCP_PORT_SERVER);
 413         packet->udp.len = htobe16(len - DHCP_IP_SIZE);
 414
 415         packet->ip.check = packet->udp.len;
 416         packet->udp.check = client_checksum(&packet->ip.ttl, len - 8);
 417
 418         packet->ip.ttl = IPDEFTTL;
 419         packet->ip.check = 0;
 420         packet->ip.check = client_checksum(&packet->ip, DHCP_IP_SIZE);
 421 }
 422
 423 static int client_send_discover(sd_dhcp_client *client, uint16_t secs)
 424 {
 425         int err = 0;
 426         _cleanup_free_ DHCPPacket *discover;
 427         size_t optlen, len;
 428         uint8_t *opt;
 429
 430         optlen = DHCP_CLIENT_MIN_OPTIONS_SIZE;
 431         len = sizeof(DHCPPacket) + optlen;
 432
 433         discover = malloc0(len);
 434
 435         if (!discover)
 436                 return -ENOMEM;
 437
 438         err = client_packet_init(client, DHCP_DISCOVER, &discover->dhcp,
 439                                  secs, &opt, &optlen);
 440         if (err < 0)
 441                 return err;
 442
 443         if (client->last_addr != INADDR_ANY) {
 444                 err = dhcp_option_append(&opt, &optlen,
 445                                          DHCP_OPTION_REQUESTED_IP_ADDRESS,
 446                                          4, &client->last_addr);
 447                 if (err < 0)
 448                         return err;
 449         }
 450
 451         err = dhcp_option_append(&opt, &optlen, DHCP_OPTION_END, 0, NULL);
 452         if (err < 0)
 453                 return err;
 454
 455         client_append_ip_headers(discover, len);
 456
 457         err = dhcp_network_send_raw_socket(client->fd, &client->link,
 458                                            discover, len);
 459
 460         return err;
 461 }
 462
 463 static int client_send_request(sd_dhcp_client *client, uint16_t secs)
 464 {
 465         _cleanup_free_ DHCPPacket *request;
 466         size_t optlen, len;
 467         int err;
 468         uint8_t *opt;
 469
 470         optlen = DHCP_CLIENT_MIN_OPTIONS_SIZE;
 471         len = DHCP_MESSAGE_SIZE + optlen;
 472
 473         request = malloc0(len);
 474         if (!request)
 475                 return -ENOMEM;
 476
 477         err = client_packet_init(client, DHCP_REQUEST, &request->dhcp, secs,
 478                                  &opt, &optlen);
 479         if (err < 0)
 480                 return err;
 481
 482         if (client->state == DHCP_STATE_REQUESTING) {
 483                 err = dhcp_option_append(&opt, &optlen,
 484                                          DHCP_OPTION_REQUESTED_IP_ADDRESS,
 485                                          4, &client->lease->address);
 486                 if (err < 0)
 487                         return err;
 488
 489                 err = dhcp_option_append(&opt, &optlen,
 490                                          DHCP_OPTION_SERVER_IDENTIFIER,
 491                                          4, &client->lease->server_address);
 492                 if (err < 0)
 493                         return err;
 494         }
 495
 496         err = dhcp_option_append(&opt, &optlen, DHCP_OPTION_END, 0, NULL);
 497         if (err < 0)
 498                 return err;
 499
 500         if (client->state == DHCP_STATE_RENEWING) {
 501                 err = dhcp_network_send_udp_socket(client->fd,
 502                                                    client->lease->server_address,
 503                                                    &request->dhcp,
 504                                                    len - DHCP_IP_UDP_SIZE);
 505         } else {
 506                 client_append_ip_headers(request, len);
 507
 508                 err = dhcp_network_send_raw_socket(client->fd, &client->link,
 509                                                    request, len);
 510         }
 511
 512         return err;
 513 }
 514
 515 static int client_timeout_resend(sd_event_source *s, uint64_t usec,
 516                                  void *userdata)
 517 {
 518         sd_dhcp_client *client = userdata;
 519         usec_t next_timeout = 0;
 520         uint32_t time_left;
 521         uint16_t secs;
 522         int err = 0;
 523
 524         switch (client->state) {
 525         case DHCP_STATE_RENEWING:
 526
 527                 time_left = (client->lease->t2 - client->lease->t1)/2;
 528                 if (time_left < 60)
 529                         time_left = 60;
 530
 531                 next_timeout = usec + time_left * USEC_PER_SEC;
 532
 533                 break;
 534
 535         case DHCP_STATE_REBINDING:
 536
 537                 time_left = (client->lease->lifetime - client->lease->t2)/2;
 538                 if (time_left < 60)
 539                         time_left = 60;
 540
 541                 next_timeout = usec + time_left * USEC_PER_SEC;
 542                 break;
 543
 544         case DHCP_STATE_INIT:
 545         case DHCP_STATE_INIT_REBOOT:
 546         case DHCP_STATE_REBOOTING:
 547         case DHCP_STATE_SELECTING:
 548         case DHCP_STATE_REQUESTING:
 549         case DHCP_STATE_BOUND:
 550
 551                 if (client->attempt < 64)
 552                         client->attempt *= 2;
 553
 554                 next_timeout = usec + (client->attempt - 1) * USEC_PER_SEC;
 555
 556                 break;
 557         }
 558
 559         next_timeout += (random_u32() & 0x1fffff);
 560
 561         err = sd_event_add_monotonic(client->event, next_timeout,
 562                                      10 * USEC_PER_MSEC,
 563                                      client_timeout_resend, client,
 564                                      &client->timeout_resend);
 565         if (err < 0)
 566                 goto error;
 567
 568         secs = (usec - client->start_time) / USEC_PER_SEC;
 569
 570         switch (client->state) {
 571         case DHCP_STATE_INIT:
 572                 err = client_send_discover(client, secs);
 573                 if (err >= 0) {
 574                         client->state = DHCP_STATE_SELECTING;
 575                         client->attempt = 1;
 576                 } else {
 577                         if (client->attempt >= 64)
 578                                 goto error;
 579                 }
 580
 581                 break;
 582
 583         case DHCP_STATE_SELECTING:
 584                 err = client_send_discover(client, secs);
 585                 if (err < 0 && client->attempt >= 64)
 586                         goto error;
 587
 588                 break;
 589
 590         case DHCP_STATE_REQUESTING:
 591         case DHCP_STATE_RENEWING:
 592         case DHCP_STATE_REBINDING:
 593                 err = client_send_request(client, secs);
 594                 if (err < 0 && client->attempt >= 64)
 595                          goto error;
 596
 597                 client->request_sent = usec;
 598
 599                 break;
 600
 601         case DHCP_STATE_INIT_REBOOT:
 602         case DHCP_STATE_REBOOTING:
 603         case DHCP_STATE_BOUND:
 604
 605                 break;
 606         }
 607
 608         return 0;
 609
 610 error:
 611         client_stop(client, err);
 612
 613         /* Errors were dealt with when stopping the client, don't spill
 614            errors into the event loop handler */
 615         return 0;
 616 }
 617
 618 static int client_initialize_events(sd_dhcp_client *client, usec_t usec)
 619 {
 620         int r;
 621
 622         r = sd_event_add_io(client->event, client->fd, EPOLLIN,
 623                             client_receive_message, client,
 624                             &client->receive_message);
 625         if (r < 0)
 626                 goto error;
 627
 628         r = sd_event_add_monotonic(client->event, usec, 0,
 629                                    client_timeout_resend, client,
 630                                    &client->timeout_resend);
 631
 632 error:
 633         if (r < 0)
 634                 client_stop(client, r);
 635
 636         return 0;
 637
 638 }
 639
 640 static int client_timeout_expire(sd_event_source *s, uint64_t usec,
 641                                  void *userdata)
 642 {
 643         sd_dhcp_client *client = userdata;
 644
 645         client_stop(client, DHCP_EVENT_EXPIRED);
 646
 647         return 0;
 648 }
 649
 650 static int client_timeout_t2(sd_event_source *s, uint64_t usec, void *userdata)
 651 {
 652         sd_dhcp_client *client = userdata;
 653         int r;
 654
 655         if (client->fd >= 0) {
 656                 client->receive_message =
 657                         sd_event_source_unref(client->receive_message);
 658                 close(client->fd);
 659                 client->fd = -1;
 660         }
 661
 662         client->state = DHCP_STATE_REBINDING;
 663         client->attempt = 1;
 664
 665         r = dhcp_network_bind_raw_socket(client->index, &client->link);
 666         if (r < 0) {
 667                 client_stop(client, r);
 668                 return 0;
 669         }
 670
 671         client->fd = r;
 672
 673         return client_initialize_events(client, usec);
 674 }
 675
 676 static int client_timeout_t1(sd_event_source *s, uint64_t usec, void *userdata)
 677 {
 678         sd_dhcp_client *client = userdata;
 679         int r;
 680
 681         client->state = DHCP_STATE_RENEWING;
 682         client->attempt = 1;
 683
 684         r = dhcp_network_bind_udp_socket(client->index,
 685                                          client->lease->address);
 686         if (r < 0) {
 687                 client_stop(client, r);
 688                 return 0;
 689         }
 690
 691         client->fd = r;
 692
 693         return client_initialize_events(client, usec);
 694 }
 695
 696 static int client_parse_offer(uint8_t code, uint8_t len, const uint8_t *option,
 697                               void *user_data)
 698 {
 699         DHCPLease *lease = user_data;
 700         be32_t val;
 701
 702         switch(code) {
 703
 704         case DHCP_OPTION_IP_ADDRESS_LEASE_TIME:
 705                 if (len == 4) {
 706                         memcpy(&val, option, 4);
 707                         lease->lifetime = be32toh(val);
 708                 }
 709
 710                 break;
 711
 712         case DHCP_OPTION_SERVER_IDENTIFIER:
 713                 if (len >= 4)
 714                         memcpy(&lease->server_address, option, 4);
 715
 716                 break;
 717
 718         case DHCP_OPTION_SUBNET_MASK:
 719                 if (len >= 4)
 720                         memcpy(&lease->subnet_mask, option, 4);
 721
 722                 break;
 723
 724         case DHCP_OPTION_ROUTER:
 725                 if (len >= 4)
 726                         memcpy(&lease->router, option, 4);
 727
 728                 break;
 729
 730         case DHCP_OPTION_RENEWAL_T1_TIME:
 731                 if (len == 4) {
 732                         memcpy(&val, option, 4);
 733                         lease->t1 = be32toh(val);
 734                 }
 735
 736                 break;
 737
 738         case DHCP_OPTION_REBINDING_T2_TIME:
 739                 if (len == 4) {
 740                         memcpy(&val, option, 4);
 741                         lease->t2 = be32toh(val);
 742                 }
 743
 744                 break;
 745         }
 746
 747         return 0;
 748 }
 749
 750 static int client_verify_headers(sd_dhcp_client *client, DHCPPacket *message,
 751                                  size_t len)
 752 {
 753         size_t hdrlen;
 754
 755         if (len < (DHCP_IP_UDP_SIZE + DHCP_MESSAGE_SIZE))
 756                 return -EINVAL;
 757
 758         hdrlen = message->ip.ihl * 4;
 759         if (hdrlen < 20 || hdrlen > len || client_checksum(&message->ip,
 760                                                            hdrlen))
 761                 return -EINVAL;
 762
 763         message->ip.check = message->udp.len;
 764         message->ip.ttl = 0;
 765
 766         if (hdrlen + be16toh(message->udp.len) > len ||
 767             client_checksum(&message->ip.ttl, be16toh(message->udp.len) + 12))
 768                 return -EINVAL;
 769
 770         if (be16toh(message->udp.source) != DHCP_PORT_SERVER ||
 771             be16toh(message->udp.dest) != DHCP_PORT_CLIENT)
 772                 return -EINVAL;
 773
 774         if (message->dhcp.op != BOOTREPLY)
 775                 return -EINVAL;
 776
 777         if (be32toh(message->dhcp.xid) != client->xid)
 778                 return -EINVAL;
 779
 780         if (memcmp(&message->dhcp.chaddr[0], &client->mac_addr.ether_addr_octet,
 781                     ETHER_ADDR_LEN))
 782                 return -EINVAL;
 783
 784         return 0;
 785 }
 786
 787 static int client_receive_offer(sd_dhcp_client *client, DHCPPacket *offer,
 788                                 size_t len)
 789 {
 790         int err;
 791         DHCPLease *lease;
 792
 793         err = client_verify_headers(client, offer, len);
 794         if (err < 0)
 795                 return err;
 796
 797         lease = new0(DHCPLease, 1);
 798         if (!lease)
 799                 return -ENOMEM;
 800
 801         len = len - DHCP_IP_UDP_SIZE;
 802         if (dhcp_option_parse(&offer->dhcp, len, client_parse_offer,
 803                               lease) != DHCP_OFFER)
 804                 goto error;
 805
 806         lease->address = offer->dhcp.yiaddr;
 807
 808         if (lease->address == INADDR_ANY ||
 809             lease->server_address == INADDR_ANY ||
 810             lease->subnet_mask == INADDR_ANY ||
 811             lease->lifetime == 0)
 812                 goto error;
 813
 814         client->lease = lease;
 815
 816         return 0;
 817
 818 error:
 819         free(lease);
 820
 821         return -ENOMSG;
 822 }
 823
 824 static int client_receive_ack(sd_dhcp_client *client, const uint8_t *buf,
 825                               size_t len)
 826 {
 827         int r;
 828         DHCPPacket *ack;
 829         DHCPMessage *dhcp;
 830         DHCPLease *lease;
 831
 832         if (client->state == DHCP_STATE_RENEWING) {
 833                 dhcp = (DHCPMessage *)buf;
 834         } else {
 835                 ack = (DHCPPacket *)buf;
 836
 837                 r = client_verify_headers(client, ack, len);
 838                 if (r < 0)
 839                         return r;
 840
 841                 dhcp = &ack->dhcp;
 842                 len -= DHCP_IP_UDP_SIZE;
 843         }
 844
 845         lease = new0(DHCPLease, 1);
 846         if (!lease)
 847                 return -ENOMEM;
 848
 849         r = dhcp_option_parse(dhcp, len, client_parse_offer, lease);
 850
 851         if (r == DHCP_NAK) {
 852                 r = DHCP_EVENT_NO_LEASE;
 853                 goto error;
 854         }
 855
 856         if (r != DHCP_ACK) {
 857                 r = -ENOMSG;
 858                 goto error;
 859         }
 860
 861         lease->address = dhcp->yiaddr;
 862
 863         if (lease->address == INADDR_ANY ||
 864             lease->server_address == INADDR_ANY ||
 865             lease->subnet_mask == INADDR_ANY || lease->lifetime == 0) {
 866                 r = -ENOMSG;
 867                 goto error;
 868         }
 869
 870         r = DHCP_EVENT_IP_ACQUIRE;
 871         if (client->lease) {
 872                 if (client->lease->address != lease->address ||
 873                     client->lease->subnet_mask != lease->subnet_mask ||
 874                     client->lease->router != lease->router) {
 875                         r = DHCP_EVENT_IP_CHANGE;
 876                 }
 877
 878                 free(client->lease);
 879         }
 880
 881         client->lease = lease;
 882
 883         return r;
 884
 885 error:
 886         free(lease);
 887
 888         return r;
 889 }
 890
 891 static uint64_t client_compute_timeout(uint64_t request_sent,
 892                                        uint32_t lifetime)
 893 {
 894         return request_sent + (lifetime - 3) * USEC_PER_SEC +
 895                 + (random_u32() & 0x1fffff);
 896 }
 897
 898 static int client_set_lease_timeouts(sd_dhcp_client *client, uint64_t usec)
 899 {
 900         int err;
 901         uint64_t next_timeout;
 902
 903         if (client->lease->lifetime < 10)
 904                 return -EINVAL;
 905
 906         client->timeout_t1 = sd_event_source_unref(client->timeout_t1);
 907         client->timeout_t2 = sd_event_source_unref(client->timeout_t2);
 908         client->timeout_expire = sd_event_source_unref(client->timeout_expire);
 909
 910         if (!client->lease->t1)
 911                 client->lease->t1 = client->lease->lifetime / 2;
 912
 913         next_timeout = client_compute_timeout(client->request_sent,
 914                                               client->lease->t1);
 915         if (next_timeout < usec)
 916                 return -EINVAL;
 917
 918         err = sd_event_add_monotonic(client->event, next_timeout,
 919                                      10 * USEC_PER_MSEC,
 920                                      client_timeout_t1, client,
 921                                      &client->timeout_t1);
 922         if (err < 0)
 923                 return err;
 924
 925         if (!client->lease->t2)
 926                 client->lease->t2 = client->lease->lifetime * 7 / 8;
 927
 928         if (client->lease->t2 < client->lease->t1)
 929                 return -EINVAL;
 930
 931         if (client->lease->lifetime < client->lease->t2)
 932                 return -EINVAL;
 933
 934         next_timeout = client_compute_timeout(client->request_sent,
 935                                               client->lease->t2);
 936         if (next_timeout < usec)
 937                 return -EINVAL;
 938
 939         err = sd_event_add_monotonic(client->event, next_timeout,
 940                                      10 * USEC_PER_MSEC,
 941                                      client_timeout_t2, client,
 942                                      &client->timeout_t2);
 943         if (err < 0)
 944                 return err;
 945
 946         next_timeout = client_compute_timeout(client->request_sent,
 947                                               client->lease->lifetime);
 948         if (next_timeout < usec)
 949                 return -EINVAL;
 950
 951         err = sd_event_add_monotonic(client->event, next_timeout,
 952                                      10 * USEC_PER_MSEC,
 953                                      client_timeout_expire, client,
 954                                      &client->timeout_expire);
 955         if (err < 0)
 956                 return err;
 957
 958         return 0;
 959 }
 960
 961 static int client_receive_message(sd_event_source *s, int fd,
 962                                   uint32_t revents, void *userdata)
 963 {
 964         sd_dhcp_client *client = userdata;
 965         uint8_t buf[sizeof(DHCPPacket) + DHCP_CLIENT_MIN_OPTIONS_SIZE];
 966         int buflen = sizeof(buf);
 967         int len, r = 0, notify_event = 0;
 968         DHCPPacket *message;
 969         usec_t time_now;
 970
 971         len = read(fd, &buf, buflen);
 972         if (len < 0)
 973                 return 0;
 974
 975         r = sd_event_get_now_monotonic(client->event, &time_now);
 976         if (r < 0)
 977                 goto error;
 978
 979         switch (client->state) {
 980         case DHCP_STATE_SELECTING:
 981
 982                 message = (DHCPPacket *)&buf;
 983
 984                 if (client_receive_offer(client, message, len) >= 0) {
 985
 986                         client->timeout_resend =
 987                                 sd_event_source_unref(client->timeout_resend);
 988
 989                         client->state = DHCP_STATE_REQUESTING;
 990                         client->attempt = 1;
 991
 992                         r = sd_event_add_monotonic(client->event, time_now, 0,
 993                                                    client_timeout_resend,
 994                                                    client,
 995                                                    &client->timeout_resend);
 996                         if (r < 0)
 997                                 goto error;
 998                 }
 999
1000                 break;
1001
1002         case DHCP_STATE_REQUESTING:
1003         case DHCP_STATE_RENEWING:
1004         case DHCP_STATE_REBINDING:
1005
1006                 r = client_receive_ack(client, buf, len);
1007
1008                 if (r == DHCP_EVENT_NO_LEASE)
1009                         goto error;
1010
1011                 if (r >= 0) {
1012                         client->timeout_resend =
1013                                 sd_event_source_unref(client->timeout_resend);
1014
1015                         if (client->state == DHCP_STATE_REQUESTING)
1016                                 notify_event = DHCP_EVENT_IP_ACQUIRE;
1017                         else if (r != DHCP_EVENT_IP_ACQUIRE)
1018                                 notify_event = r;
1019
1020                         client->state = DHCP_STATE_BOUND;
1021                         client->attempt = 1;
1022
1023                         client->last_addr = client->lease->address;
1024
1025                         r = client_set_lease_timeouts(client, time_now);
1026                         if (r < 0)
1027                                 goto error;
1028
1029                         if (notify_event)
1030                                 client_notify(client, notify_event);
1031
1032                         client->receive_message =
1033                                 sd_event_source_unref(client->receive_message);
1034                         close(client->fd);
1035                         client->fd = -1;
1036                 }
1037
1038                 r = 0;
1039
1040                 break;
1041
1042         case DHCP_STATE_INIT:
1043         case DHCP_STATE_INIT_REBOOT:
1044         case DHCP_STATE_REBOOTING:
1045         case DHCP_STATE_BOUND:
1046
1047                 break;
1048         }
1049
1050 error:
1051         if (r < 0 || r == DHCP_EVENT_NO_LEASE)
1052                 return client_stop(client, r);
1053
1054         return 0;
1055 }
1056
1057 int sd_dhcp_client_start(sd_dhcp_client *client)
1058 {
1059         int r;
1060
1061         assert_return(client, -EINVAL);
1062         assert_return(client->index > 0, -EINVAL);
1063         assert_return(client->state == DHCP_STATE_INIT ||
1064                       client->state == DHCP_STATE_INIT_REBOOT, -EBUSY);
1065
1066         client->xid = random_u32();
1067
1068         r = dhcp_network_bind_raw_socket(client->index, &client->link);
1069
1070         if (r < 0) {
1071                 client_stop(client, r);
1072                 return r;
1073         }
1074
1075         client->fd = r;
1076         client->start_time = now(CLOCK_MONOTONIC);
1077
1078         return client_initialize_events(client, client->start_time);
1079 }
1080
1081 int sd_dhcp_client_stop(sd_dhcp_client *client)
1082 {
1083         return client_stop(client, DHCP_EVENT_STOP);
1084 }
1085
1086 sd_dhcp_client *sd_dhcp_client_free(sd_dhcp_client *client)
1087 {
1088         assert_return(client, NULL);
1089
1090         sd_dhcp_client_stop(client);
1091
1092         sd_event_unref(client->event);
1093         free(client->req_opts);
1094         free(client);
1095
1096         return NULL;
1097 }
1098
1099 sd_dhcp_client *sd_dhcp_client_new(sd_event *event)
1100 {
1101         sd_dhcp_client *client;
1102
1103         assert_return(event, NULL);
1104
1105         client = new0(sd_dhcp_client, 1);
1106         if (!client)
1107                 return NULL;
1108
1109         client->event = sd_event_ref(event);
1110         client->state = DHCP_STATE_INIT;
1111         client->index = -1;
1112         client->fd = -1;
1113         client->attempt = 1;
1114
1115         client->req_opts_size = ELEMENTSOF(default_req_opts);
1116
1117         client->req_opts = memdup(default_req_opts, client->req_opts_size);
1118         if (!client->req_opts) {
1119                 free(client);
1120                 return NULL;
1121         }
1122
1123         return client;
1124 }