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