src/libsystemd-network/sd-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 #include <sys/ioctl.h>
  27
  28 #include "util.h"
  29 #include "list.h"
  30
  31 #include "dhcp-protocol.h"
  32 #include "dhcp-internal.h"
  33 #include "dhcp-lease-internal.h"
  34 #include "sd-dhcp-client.h"
  35
  36 struct sd_dhcp_client {
  37         DHCPState state;
  38         sd_event *event;
  39         int event_priority;
  40         sd_event_source *timeout_resend;
  41         int index;
  42         int fd;
  43         union sockaddr_union link;
  44         sd_event_source *receive_message;
  45         uint8_t *req_opts;
  46         size_t req_opts_allocated;
  47         size_t req_opts_size;
  48         be32_t last_addr;
  49         struct ether_addr mac_addr;
  50         uint32_t xid;
  51         usec_t start_time;
  52         uint16_t secs;
  53         unsigned int attempt;
  54         usec_t request_sent;
  55         sd_event_source *timeout_t1;
  56         sd_event_source *timeout_t2;
  57         sd_event_source *timeout_expire;
  58         sd_dhcp_client_cb_t cb;
  59         void *userdata;
  60         sd_dhcp_lease *lease;
  61 };
  62
  63 static const uint8_t default_req_opts[] = {
  64         DHCP_OPTION_SUBNET_MASK,
  65         DHCP_OPTION_ROUTER,
  66         DHCP_OPTION_HOST_NAME,
  67         DHCP_OPTION_DOMAIN_NAME,
  68         DHCP_OPTION_DOMAIN_NAME_SERVER,
  69         DHCP_OPTION_NTP_SERVER,
  70 };
  71
  72 static int client_receive_message_raw(sd_event_source *s, int fd,
  73                                       uint32_t revents, void *userdata);
  74 static int client_receive_message_udp(sd_event_source *s, int fd,
  75                                       uint32_t revents, void *userdata);
  76
  77 int sd_dhcp_client_set_callback(sd_dhcp_client *client, sd_dhcp_client_cb_t cb,
  78                                 void *userdata) {
  79         assert_return(client, -EINVAL);
  80
  81         client->cb = cb;
  82         client->userdata = userdata;
  83
  84         return 0;
  85 }
  86
  87 int sd_dhcp_client_set_request_option(sd_dhcp_client *client, uint8_t option) {
  88         size_t i;
  89
  90         assert_return(client, -EINVAL);
  91         assert_return (client->state == DHCP_STATE_INIT, -EBUSY);
  92
  93         switch(option) {
  94         case DHCP_OPTION_PAD:
  95         case DHCP_OPTION_OVERLOAD:
  96         case DHCP_OPTION_MESSAGE_TYPE:
  97         case DHCP_OPTION_PARAMETER_REQUEST_LIST:
  98         case DHCP_OPTION_END:
  99                 return -EINVAL;
 100
 101         default:
 102                 break;
 103         }
 104
 105         for (i = 0; i < client->req_opts_size; i++)
 106                 if (client->req_opts[i] == option)
 107                         return -EEXIST;
 108
 109         if (!GREEDY_REALLOC(client->req_opts, client->req_opts_allocated,
 110                             client->req_opts_size + 1))
 111                 return -ENOMEM;
 112
 113         client->req_opts[client->req_opts_size++] = option;
 114
 115         return 0;
 116 }
 117
 118 int sd_dhcp_client_set_request_address(sd_dhcp_client *client,
 119                                        const struct in_addr *last_addr) {
 120         assert_return(client, -EINVAL);
 121         assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
 122
 123         if (last_addr)
 124                 client->last_addr = last_addr->s_addr;
 125         else
 126                 client->last_addr = INADDR_ANY;
 127
 128         return 0;
 129 }
 130
 131 int sd_dhcp_client_set_index(sd_dhcp_client *client, int interface_index) {
 132         assert_return(client, -EINVAL);
 133         assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
 134         assert_return(interface_index >= -1, -EINVAL);
 135
 136         client->index = interface_index;
 137
 138         return 0;
 139 }
 140
 141 int sd_dhcp_client_set_mac(sd_dhcp_client *client,
 142                            const struct ether_addr *addr) {
 143         assert_return(client, -EINVAL);
 144         assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
 145
 146         log_dhcp_client(client, "set MAC address to "
 147                         "%02hhx:%02hhx:%02hhx:%02hhx:%02hhx:%02hhx",
 148                         addr->ether_addr_octet[0],
 149                         addr->ether_addr_octet[1],
 150                         addr->ether_addr_octet[2],
 151                         addr->ether_addr_octet[3],
 152                         addr->ether_addr_octet[4],
 153                         addr->ether_addr_octet[5]);
 154
 155         memcpy(&client->mac_addr, addr, ETH_ALEN);
 156
 157         return 0;
 158 }
 159
 160 int sd_dhcp_client_get_lease(sd_dhcp_client *client, sd_dhcp_lease **ret) {
 161         assert_return(client, -EINVAL);
 162         assert_return(ret, -EINVAL);
 163
 164         if (client->state != DHCP_STATE_BOUND &&
 165             client->state != DHCP_STATE_RENEWING &&
 166             client->state != DHCP_STATE_REBINDING)
 167                 return -EADDRNOTAVAIL;
 168
 169         *ret = sd_dhcp_lease_ref(client->lease);
 170
 171         return 0;
 172 }
 173
 174 static int client_notify(sd_dhcp_client *client, int event) {
 175         if (client->cb)
 176                 client->cb(client, event, client->userdata);
 177
 178         return 0;
 179 }
 180
 181 static int client_initialize(sd_dhcp_client *client) {
 182         assert_return(client, -EINVAL);
 183
 184         client->receive_message =
 185                 sd_event_source_unref(client->receive_message);
 186
 187         client->fd = safe_close(client->fd);
 188
 189         client->timeout_resend = sd_event_source_unref(client->timeout_resend);
 190
 191         client->timeout_t1 = sd_event_source_unref(client->timeout_t1);
 192         client->timeout_t2 = sd_event_source_unref(client->timeout_t2);
 193         client->timeout_expire = sd_event_source_unref(client->timeout_expire);
 194
 195         client->attempt = 1;
 196
 197         client->start_time = 0;
 198         client->secs = 0;
 199         client->state = DHCP_STATE_INIT;
 200         client->xid = 0;
 201
 202         if (client->lease)
 203                 client->lease = sd_dhcp_lease_unref(client->lease);
 204
 205         return 0;
 206 }
 207
 208 static int client_stop(sd_dhcp_client *client, int error) {
 209         assert_return(client, -EINVAL);
 210
 211         client_notify(client, error);
 212
 213         client_initialize(client);
 214
 215         log_dhcp_client(client, "STOPPED");
 216
 217         return 0;
 218 }
 219
 220 static int client_message_init(sd_dhcp_client *client, DHCPMessage *message,
 221                                uint8_t type, uint16_t secs, uint8_t **opt,
 222                                size_t *optlen) {
 223         int r;
 224
 225         assert(secs);
 226
 227         r = dhcp_message_init(message, BOOTREQUEST, client->xid, type, opt,
 228                               optlen);
 229         if (r < 0)
 230                 return r;
 231
 232         /* Although 'secs' field is a SHOULD in RFC 2131, certain DHCP servers
 233            refuse to issue an DHCP lease if 'secs' is set to zero */
 234         message->secs = htobe16(secs);
 235
 236         memcpy(&message->chaddr, &client->mac_addr, ETH_ALEN);
 237
 238         if (client->state == DHCP_STATE_RENEWING ||
 239             client->state == DHCP_STATE_REBINDING)
 240                 message->ciaddr = client->lease->address;
 241
 242         /* Some DHCP servers will refuse to issue an DHCP lease if the Client
 243            Identifier option is not set */
 244         r = dhcp_option_append(opt, optlen, DHCP_OPTION_CLIENT_IDENTIFIER,
 245                                ETH_ALEN, &client->mac_addr);
 246         if (r < 0)
 247                 return r;
 248
 249         if (type == DHCP_DISCOVER || type == DHCP_REQUEST) {
 250                 be16_t max_size;
 251
 252                 r = dhcp_option_append(opt, optlen,
 253                                        DHCP_OPTION_PARAMETER_REQUEST_LIST,
 254                                        client->req_opts_size,
 255                                        client->req_opts);
 256                 if (r < 0)
 257                         return r;
 258
 259                 /* Some DHCP servers will send bigger DHCP packets than the
 260                    defined default size unless the Maximum Messge Size option
 261                    is explicitely set */
 262                 max_size = htobe16(DHCP_IP_UDP_SIZE + DHCP_MESSAGE_SIZE +
 263                                    DHCP_MIN_OPTIONS_SIZE);
 264                 r = dhcp_option_append(opt, optlen,
 265                                        DHCP_OPTION_MAXIMUM_MESSAGE_SIZE,
 266                                        2, &max_size);
 267                 if (r < 0)
 268                         return r;
 269         }
 270
 271         return 0;
 272 }
 273
 274 static int dhcp_client_send_raw(sd_dhcp_client *client, DHCPPacket *packet,
 275                                 size_t len) {
 276         dhcp_packet_append_ip_headers(packet, INADDR_ANY, DHCP_PORT_CLIENT,
 277                                       INADDR_BROADCAST, DHCP_PORT_SERVER, len);
 278
 279         return dhcp_network_send_raw_socket(client->fd, &client->link,
 280                                             packet, len);
 281 }
 282
 283 static int client_send_discover(sd_dhcp_client *client, uint16_t secs) {
 284         int err = 0;
 285         _cleanup_free_ DHCPPacket *discover;
 286         size_t optlen, len;
 287         uint8_t *opt;
 288
 289         optlen = DHCP_MIN_OPTIONS_SIZE;
 290         len = sizeof(DHCPPacket) + optlen;
 291
 292         discover = malloc0(len);
 293
 294         if (!discover)
 295                 return -ENOMEM;
 296
 297         err = client_message_init(client, &discover->dhcp, DHCP_DISCOVER,
 298                                   secs, &opt, &optlen);
 299         if (err < 0)
 300                 return err;
 301
 302         if (client->last_addr != INADDR_ANY) {
 303                 err = dhcp_option_append(&opt, &optlen,
 304                                          DHCP_OPTION_REQUESTED_IP_ADDRESS,
 305                                          4, &client->last_addr);
 306                 if (err < 0)
 307                         return err;
 308         }
 309
 310         err = dhcp_option_append(&opt, &optlen, DHCP_OPTION_END, 0, NULL);
 311         if (err < 0)
 312                 return err;
 313
 314         err = dhcp_client_send_raw(client, discover, len);
 315         if (err < 0)
 316                 return err;
 317
 318         log_dhcp_client(client, "DISCOVER");
 319
 320         return 0;
 321 }
 322
 323 static int client_send_request(sd_dhcp_client *client, uint16_t secs) {
 324         _cleanup_free_ DHCPPacket *request;
 325         size_t optlen, len;
 326         int err;
 327         uint8_t *opt;
 328
 329         optlen = DHCP_MIN_OPTIONS_SIZE;
 330         len = sizeof(DHCPPacket) + optlen;
 331
 332         request = malloc0(len);
 333         if (!request)
 334                 return -ENOMEM;
 335
 336         err = client_message_init(client, &request->dhcp, DHCP_REQUEST, secs,
 337                                   &opt, &optlen);
 338         if (err < 0)
 339                 return err;
 340
 341         switch (client->state) {
 342
 343         case DHCP_STATE_INIT_REBOOT:
 344                 err = dhcp_option_append(&opt, &optlen,
 345                                          DHCP_OPTION_REQUESTED_IP_ADDRESS,
 346                                          4, &client->last_addr);
 347                 if (err < 0)
 348                         return err;
 349                 break;
 350
 351         case DHCP_STATE_REQUESTING:
 352                 err = dhcp_option_append(&opt, &optlen,
 353                                          DHCP_OPTION_REQUESTED_IP_ADDRESS,
 354                                          4, &client->lease->address);
 355                 if (err < 0)
 356                         return err;
 357
 358                 err = dhcp_option_append(&opt, &optlen,
 359                                          DHCP_OPTION_SERVER_IDENTIFIER,
 360                                          4, &client->lease->server_address);
 361                 if (err < 0)
 362                         return err;
 363                 break;
 364
 365         case DHCP_STATE_INIT:
 366         case DHCP_STATE_SELECTING:
 367         case DHCP_STATE_REBOOTING:
 368         case DHCP_STATE_BOUND:
 369         case DHCP_STATE_RENEWING:
 370         case DHCP_STATE_REBINDING:
 371
 372                 break;
 373         }
 374
 375         err = dhcp_option_append(&opt, &optlen, DHCP_OPTION_END, 0, NULL);
 376         if (err < 0)
 377                 return err;
 378
 379         if (client->state == DHCP_STATE_RENEWING) {
 380                 err = dhcp_network_send_udp_socket(client->fd,
 381                                                    client->lease->server_address,
 382                                                    DHCP_PORT_SERVER,
 383                                                    &request->dhcp,
 384                                                    len - DHCP_IP_UDP_SIZE);
 385         } else {
 386                 err = dhcp_client_send_raw(client, request, len);
 387         }
 388         if (err < 0)
 389                 return err;
 390
 391         log_dhcp_client(client, "REQUEST");
 392
 393         return 0;
 394 }
 395
 396 static uint16_t client_update_secs(sd_dhcp_client *client, usec_t time_now)
 397 {
 398         client->secs = ((time_now - client->start_time) / USEC_PER_SEC) ? : 1;
 399
 400         return client->secs;
 401 }
 402
 403 static int client_timeout_resend(sd_event_source *s, uint64_t usec,
 404                                  void *userdata) {
 405         sd_dhcp_client *client = userdata;
 406         usec_t next_timeout = 0;
 407         uint64_t time_now;
 408         uint32_t time_left;
 409         int r;
 410
 411         assert(s);
 412         assert(client);
 413         assert(client->event);
 414
 415         r = sd_event_get_now_monotonic(client->event, &time_now);
 416         if (r < 0)
 417                 goto error;
 418
 419         switch (client->state) {
 420         case DHCP_STATE_RENEWING:
 421
 422                 time_left = (client->lease->t2 - client->lease->t1) / 2;
 423                 if (time_left < 60)
 424                         time_left = 60;
 425
 426                 next_timeout = time_now + time_left * USEC_PER_SEC;
 427
 428                 break;
 429
 430         case DHCP_STATE_REBINDING:
 431
 432                 time_left = (client->lease->lifetime - client->lease->t2) / 2;
 433                 if (time_left < 60)
 434                         time_left = 60;
 435
 436                 next_timeout = time_now + time_left * USEC_PER_SEC;
 437                 break;
 438
 439         case DHCP_STATE_REBOOTING:
 440                 /* start over as we did not receive a timely ack or nak */
 441                 client->state = DHCP_STATE_INIT;
 442                 client->attempt = 1;
 443                 client->xid = random_u32();
 444
 445                 /* fall through */
 446         case DHCP_STATE_INIT:
 447         case DHCP_STATE_INIT_REBOOT:
 448         case DHCP_STATE_SELECTING:
 449         case DHCP_STATE_REQUESTING:
 450         case DHCP_STATE_BOUND:
 451
 452                 if (client->attempt < 64)
 453                         client->attempt *= 2;
 454
 455                 next_timeout = time_now + (client->attempt - 1) * USEC_PER_SEC;
 456
 457                 break;
 458         }
 459
 460         next_timeout += (random_u32() & 0x1fffff);
 461
 462         client->timeout_resend = sd_event_source_unref(client->timeout_resend);
 463
 464         r = sd_event_add_monotonic(client->event,
 465                                      &client->timeout_resend,
 466                                      next_timeout,
 467                                      10 * USEC_PER_MSEC,
 468                                      client_timeout_resend, client);
 469         if (r < 0)
 470                 goto error;
 471
 472         r = sd_event_source_set_priority(client->timeout_resend,
 473                                          client->event_priority);
 474         if (r < 0)
 475                 goto error;
 476
 477         switch (client->state) {
 478         case DHCP_STATE_INIT:
 479
 480                 client_update_secs(client, time_now);
 481
 482                 r = client_send_discover(client, client->secs);
 483                 if (r >= 0) {
 484                         client->state = DHCP_STATE_SELECTING;
 485                         client->attempt = 1;
 486                 } else {
 487                         if (client->attempt >= 64)
 488                                 goto error;
 489                 }
 490
 491                 break;
 492
 493         case DHCP_STATE_SELECTING:
 494                 client_update_secs(client, time_now);
 495
 496                 r = client_send_discover(client, client->secs);
 497                 if (r < 0 && client->attempt >= 64)
 498                         goto error;
 499
 500                 break;
 501
 502         case DHCP_STATE_INIT_REBOOT:
 503         case DHCP_STATE_REQUESTING:
 504         case DHCP_STATE_RENEWING:
 505         case DHCP_STATE_REBINDING:
 506                 r = client_send_request(client, client->secs);
 507                 if (r < 0 && client->attempt >= 64)
 508                          goto error;
 509
 510                 if (client->state == DHCP_STATE_INIT_REBOOT)
 511                         client->state = DHCP_STATE_REBOOTING;
 512
 513                 client->request_sent = time_now;
 514
 515                 break;
 516
 517         case DHCP_STATE_REBOOTING:
 518         case DHCP_STATE_BOUND:
 519
 520                 break;
 521         }
 522
 523         return 0;
 524
 525 error:
 526         client_stop(client, r);
 527
 528         /* Errors were dealt with when stopping the client, don't spill
 529            errors into the event loop handler */
 530         return 0;
 531 }
 532
 533 static int client_initialize_events(sd_dhcp_client *client,
 534                                     sd_event_io_handler_t io_callback) {
 535         int r;
 536
 537         assert(client);
 538         assert(client->event);
 539
 540         r = sd_event_add_io(client->event, &client->receive_message,
 541                             client->fd, EPOLLIN, io_callback,
 542                             client);
 543         if (r < 0)
 544                 goto error;
 545
 546         r = sd_event_source_set_priority(client->receive_message,
 547                                          client->event_priority);
 548         if (r < 0)
 549                 goto error;
 550
 551         client->timeout_resend = sd_event_source_unref(client->timeout_resend);
 552
 553         r = sd_event_add_monotonic(client->event,
 554                                    &client->timeout_resend, 0, 0,
 555                                    client_timeout_resend, client);
 556         if (r < 0)
 557                 goto error;
 558
 559         r = sd_event_source_set_priority(client->timeout_resend,
 560                                          client->event_priority);
 561
 562 error:
 563         if (r < 0)
 564                 client_stop(client, r);
 565
 566         return 0;
 567
 568 }
 569
 570 static int client_start(sd_dhcp_client *client) {
 571         int r;
 572
 573         assert_return(client, -EINVAL);
 574         assert_return(client->event, -EINVAL);
 575         assert_return(client->index > 0, -EINVAL);
 576         assert_return(client->fd < 0, -EBUSY);
 577         assert_return(client->xid == 0, -EINVAL);
 578         assert_return(client->state == DHCP_STATE_INIT ||
 579                       client->state == DHCP_STATE_INIT_REBOOT, -EBUSY);
 580
 581         client->xid = random_u32();
 582
 583         r = dhcp_network_bind_raw_socket(client->index, &client->link);
 584
 585         if (r < 0) {
 586                 client_stop(client, r);
 587                 return r;
 588         }
 589
 590         client->fd = r;
 591         client->start_time = now(CLOCK_MONOTONIC);
 592         client->secs = 0;
 593
 594         log_dhcp_client(client, "STARTED");
 595
 596         return client_initialize_events(client, client_receive_message_raw);
 597 }
 598
 599 static int client_timeout_expire(sd_event_source *s, uint64_t usec,
 600                                  void *userdata) {
 601         sd_dhcp_client *client = userdata;
 602
 603         log_dhcp_client(client, "EXPIRED");
 604
 605         client_notify(client, DHCP_EVENT_EXPIRED);
 606
 607         /* start over as the lease was lost */
 608         client_initialize(client);
 609         client_start(client);
 610
 611         return 0;
 612 }
 613
 614 static int client_timeout_t2(sd_event_source *s, uint64_t usec, void *userdata) {
 615         sd_dhcp_client *client = userdata;
 616         int r;
 617
 618         client->receive_message = sd_event_source_unref(client->receive_message);
 619         client->fd = safe_close(client->fd);
 620
 621         client->state = DHCP_STATE_REBINDING;
 622         client->attempt = 1;
 623
 624         r = dhcp_network_bind_raw_socket(client->index, &client->link);
 625         if (r < 0) {
 626                 client_stop(client, r);
 627                 return 0;
 628         }
 629
 630         client->fd = r;
 631
 632         log_dhcp_client(client, "TIMEOUT T2");
 633
 634         return client_initialize_events(client, client_receive_message_raw);
 635 }
 636
 637 static int client_timeout_t1(sd_event_source *s, uint64_t usec,
 638                              void *userdata) {
 639         sd_dhcp_client *client = userdata;
 640         int r;
 641
 642         client->state = DHCP_STATE_RENEWING;
 643         client->attempt = 1;
 644
 645         r = dhcp_network_bind_udp_socket(client->index,
 646                                          client->lease->address,
 647                                          DHCP_PORT_CLIENT);
 648         if (r < 0) {
 649                 client_stop(client, r);
 650                 return 0;
 651         }
 652
 653         client->fd = r;
 654
 655         log_dhcp_client(client, "TIMEOUT T1");
 656
 657         return client_initialize_events(client, client_receive_message_udp);
 658 }
 659
 660 static int client_handle_offer(sd_dhcp_client *client, DHCPMessage *offer,
 661                                size_t len) {
 662         _cleanup_dhcp_lease_unref_ sd_dhcp_lease *lease = NULL;
 663         int r;
 664
 665         r = dhcp_lease_new(&lease);
 666         if (r < 0)
 667                 return r;
 668
 669         r = dhcp_option_parse(offer, len, dhcp_lease_parse_options, lease);
 670         if (r != DHCP_OFFER)
 671                 return -ENOMSG;
 672
 673         lease->next_server = offer->siaddr;
 674
 675         lease->address = offer->yiaddr;
 676
 677         if (lease->address == INADDR_ANY ||
 678             lease->server_address == INADDR_ANY ||
 679             lease->subnet_mask == INADDR_ANY ||
 680             lease->lifetime == 0)
 681                 return -ENOMSG;
 682
 683         client->lease = lease;
 684         lease = NULL;
 685
 686         log_dhcp_client(client, "OFFER");
 687
 688         return 0;
 689 }
 690
 691 static int client_handle_ack(sd_dhcp_client *client, DHCPMessage *ack,
 692                              size_t len) {
 693         _cleanup_dhcp_lease_unref_ sd_dhcp_lease *lease = NULL;
 694         int r;
 695
 696         r = dhcp_lease_new(&lease);
 697         if (r < 0)
 698                 return r;
 699
 700         r = dhcp_option_parse(ack, len, dhcp_lease_parse_options, lease);
 701         if (r == DHCP_NAK) {
 702                 log_dhcp_client(client, "NAK");
 703                 return DHCP_EVENT_NO_LEASE;
 704         }
 705
 706         if (r != DHCP_ACK)
 707                 return -ENOMSG;
 708
 709         lease->next_server = ack->siaddr;
 710
 711         lease->address = ack->yiaddr;
 712
 713         if (lease->address == INADDR_ANY ||
 714             lease->server_address == INADDR_ANY ||
 715             lease->subnet_mask == INADDR_ANY || lease->lifetime == 0)
 716                 return -ENOMSG;
 717
 718         r = DHCP_EVENT_IP_ACQUIRE;
 719         if (client->lease) {
 720                 if (client->lease->address != lease->address ||
 721                     client->lease->subnet_mask != lease->subnet_mask ||
 722                     client->lease->router != lease->router) {
 723                         r = DHCP_EVENT_IP_CHANGE;
 724                 }
 725
 726                 client->lease = sd_dhcp_lease_unref(client->lease);
 727         }
 728
 729         client->lease = lease;
 730         lease = NULL;
 731
 732         log_dhcp_client(client, "ACK");
 733
 734         return r;
 735 }
 736
 737 static uint64_t client_compute_timeout(uint64_t request_sent,
 738                                        uint32_t lifetime) {
 739         return request_sent + (lifetime - 3) * USEC_PER_SEC +
 740                 + (random_u32() & 0x1fffff);
 741 }
 742
 743 static int client_set_lease_timeouts(sd_dhcp_client *client, uint64_t usec) {
 744         uint64_t next_timeout;
 745         int r;
 746
 747         assert(client);
 748         assert(client->event);
 749
 750         if (client->lease->lifetime < 10)
 751                 return -EINVAL;
 752
 753         client->timeout_t1 = sd_event_source_unref(client->timeout_t1);
 754         client->timeout_t2 = sd_event_source_unref(client->timeout_t2);
 755         client->timeout_expire = sd_event_source_unref(client->timeout_expire);
 756
 757         if (!client->lease->t1)
 758                 client->lease->t1 = client->lease->lifetime / 2;
 759
 760         next_timeout = client_compute_timeout(client->request_sent,
 761                                               client->lease->t1);
 762         if (next_timeout < usec)
 763                 return -EINVAL;
 764
 765         r = sd_event_add_monotonic(client->event,
 766                                    &client->timeout_t1,
 767                                    next_timeout,
 768                                    10 * USEC_PER_MSEC,
 769                                    client_timeout_t1, client);
 770         if (r < 0)
 771                 return r;
 772
 773         r = sd_event_source_set_priority(client->timeout_t1,
 774                                          client->event_priority);
 775         if (r < 0)
 776                 return r;
 777
 778         if (!client->lease->t2)
 779                 client->lease->t2 = client->lease->lifetime * 7 / 8;
 780
 781         if (client->lease->t2 < client->lease->t1)
 782                 return -EINVAL;
 783
 784         if (client->lease->lifetime < client->lease->t2)
 785                 return -EINVAL;
 786
 787         next_timeout = client_compute_timeout(client->request_sent,
 788                                               client->lease->t2);
 789         if (next_timeout < usec)
 790                 return -EINVAL;
 791
 792         r = sd_event_add_monotonic(client->event,
 793                                    &client->timeout_t2,
 794                                    next_timeout,
 795                                    10 * USEC_PER_MSEC,
 796                                    client_timeout_t2, client);
 797         if (r < 0)
 798                 return r;
 799
 800         r = sd_event_source_set_priority(client->timeout_t2,
 801                                          client->event_priority);
 802         if (r < 0)
 803                 return r;
 804
 805         next_timeout = client_compute_timeout(client->request_sent,
 806                                               client->lease->lifetime);
 807         if (next_timeout < usec)
 808                 return -EINVAL;
 809
 810         r = sd_event_add_monotonic(client->event,
 811                                    &client->timeout_expire, next_timeout,
 812                                    10 * USEC_PER_MSEC,
 813                                    client_timeout_expire, client);
 814         if (r < 0)
 815                 return r;
 816
 817         r = sd_event_source_set_priority(client->timeout_expire,
 818                                          client->event_priority);
 819         if (r < 0)
 820                 return r;
 821
 822         return 0;
 823 }
 824
 825 static int client_handle_message(sd_dhcp_client *client, DHCPMessage *message,
 826                                  int len, usec_t time_now) {
 827         int r = 0, notify_event = 0;
 828
 829         assert(client);
 830         assert(client->event);
 831         assert(message);
 832
 833         if (len < DHCP_MESSAGE_SIZE) {
 834                 log_dhcp_client(client, "message too small (%d bytes): "
 835                                 "ignoring", len);
 836                 return 0;
 837         }
 838
 839         if (message->op != BOOTREPLY) {
 840                 log_dhcp_client(client, "not a BOOTREPLY message: ignoring");
 841                 return 0;
 842         }
 843
 844         if (be32toh(message->xid) != client->xid) {
 845                 log_dhcp_client(client, "received xid (%u) does not match "
 846                                 "expected (%u): ignoring",
 847                                 be32toh(message->xid), client->xid);
 848                 return 0;
 849         }
 850
 851         if (memcmp(&message->chaddr[0], &client->mac_addr.ether_addr_octet,
 852                    ETHER_ADDR_LEN)) {
 853                 log_dhcp_client(client, "received chaddr does not match "
 854                                 "expected: ignoring");
 855                 return 0;
 856         }
 857
 858         switch (client->state) {
 859         case DHCP_STATE_SELECTING:
 860
 861                 r = client_handle_offer(client, message, len);
 862                 if (r >= 0) {
 863
 864                         client->timeout_resend =
 865                                 sd_event_source_unref(client->timeout_resend);
 866
 867                         client->state = DHCP_STATE_REQUESTING;
 868                         client->attempt = 1;
 869
 870                         r = sd_event_add_monotonic(client->event,
 871                                                    &client->timeout_resend, 0,
 872                                                    0, client_timeout_resend,
 873                                                    client);
 874                         if (r < 0)
 875                                 goto error;
 876
 877                         r = sd_event_source_set_priority(client->timeout_resend,
 878                                                          client->event_priority);
 879                         if (r < 0)
 880                                 goto error;
 881                 }
 882
 883                 break;
 884
 885         case DHCP_STATE_REBOOTING:
 886         case DHCP_STATE_REQUESTING:
 887         case DHCP_STATE_RENEWING:
 888         case DHCP_STATE_REBINDING:
 889
 890                 r = client_handle_ack(client, message, len);
 891
 892                 if (r == DHCP_EVENT_NO_LEASE) {
 893
 894                         client->timeout_resend =
 895                                 sd_event_source_unref(client->timeout_resend);
 896
 897                         if (client->state == DHCP_STATE_REBOOTING) {
 898                                 r = client_initialize(client);
 899                                 if (r < 0)
 900                                         goto error;
 901
 902                                 r = client_start(client);
 903                                 if (r < 0)
 904                                         goto error;
 905                         }
 906
 907                         goto error;
 908                 }
 909
 910                 if (r >= 0) {
 911                         client->timeout_resend =
 912                                 sd_event_source_unref(client->timeout_resend);
 913
 914                         if (IN_SET(client->state, DHCP_STATE_REQUESTING,
 915                                    DHCP_STATE_REBOOTING))
 916                                 notify_event = DHCP_EVENT_IP_ACQUIRE;
 917                         else if (r != DHCP_EVENT_IP_ACQUIRE)
 918                                 notify_event = r;
 919
 920                         client->state = DHCP_STATE_BOUND;
 921                         client->attempt = 1;
 922
 923                         client->last_addr = client->lease->address;
 924
 925                         r = client_set_lease_timeouts(client, time_now);
 926                         if (r < 0)
 927                                 goto error;
 928
 929                         if (notify_event)
 930                                 client_notify(client, notify_event);
 931
 932                         client->receive_message =
 933                                 sd_event_source_unref(client->receive_message);
 934                         client->fd = safe_close(client->fd);
 935                 }
 936
 937                 r = 0;
 938
 939                 break;
 940
 941         case DHCP_STATE_INIT:
 942         case DHCP_STATE_INIT_REBOOT:
 943         case DHCP_STATE_BOUND:
 944
 945                 break;
 946         }
 947
 948 error:
 949         if (r < 0 || r == DHCP_EVENT_NO_LEASE)
 950                 return client_stop(client, r);
 951
 952         return 0;
 953 }
 954
 955 static int client_receive_message_udp(sd_event_source *s, int fd,
 956                                       uint32_t revents, void *userdata) {
 957         sd_dhcp_client *client = userdata;
 958         _cleanup_free_ DHCPMessage *message = NULL;
 959         int buflen = 0, len, r;
 960         usec_t time_now;
 961
 962         assert(s);
 963         assert(client);
 964         assert(client->event);
 965
 966         r = ioctl(fd, FIONREAD, &buflen);
 967         if (r < 0 || buflen <= 0)
 968                 buflen = sizeof(DHCPMessage) + DHCP_MIN_OPTIONS_SIZE;
 969
 970         message = malloc0(buflen);
 971         if (!message)
 972                 return -ENOMEM;
 973
 974         len = read(fd, message, buflen);
 975         if (len < 0)
 976                 return 0;
 977
 978         r = sd_event_get_now_monotonic(client->event, &time_now);
 979         if (r < 0)
 980                 return client_stop(client, r);
 981
 982         return client_handle_message(client, message, len,
 983                                      time_now);
 984 }
 985
 986 static int client_receive_message_raw(sd_event_source *s, int fd,
 987                                       uint32_t revents, void *userdata) {
 988         sd_dhcp_client *client = userdata;
 989         _cleanup_free_ DHCPPacket *packet = NULL;
 990         usec_t time_now;
 991         uint8_t cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))];
 992         struct iovec iov = {};
 993         struct msghdr msg = {
 994                 .msg_iov = &iov,
 995                 .msg_iovlen = 1,
 996                 .msg_control = cmsgbuf,
 997                 .msg_controllen = sizeof(cmsgbuf),
 998         };
 999         struct cmsghdr *cmsg;
1000         bool checksum = true;
1001         int buflen = 0, len, r;
1002
1003         assert(s);
1004         assert(client);
1005         assert(client->event);
1006
1007         r = ioctl(fd, FIONREAD, &buflen);
1008         if (r < 0 || buflen <= 0)
1009                 buflen = sizeof(DHCPPacket) + DHCP_MIN_OPTIONS_SIZE;
1010
1011         packet = malloc0(buflen);
1012         if (!packet)
1013                 return -ENOMEM;
1014
1015         iov.iov_base = packet;
1016         iov.iov_len = buflen;
1017
1018         len = recvmsg(fd, &msg, 0);
1019         if (len < 0) {
1020                 log_dhcp_client(client, "could not receive message from raw "
1021                                 "socket: %s", strerror(errno));
1022                 return 0;
1023         }
1024
1025         for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
1026                 if (cmsg->cmsg_level == SOL_PACKET && cmsg->cmsg_type == PACKET_AUXDATA) {
1027                         struct tpacket_auxdata *aux = (void *)CMSG_DATA(cmsg);
1028
1029                         checksum = !(aux->tp_status & TP_STATUS_CSUMNOTREADY);
1030                         break;
1031                 }
1032         }
1033
1034         r = dhcp_packet_verify_headers(packet, len, checksum);
1035         if (r < 0)
1036                 return 0;
1037
1038         len -= DHCP_IP_UDP_SIZE;
1039
1040         r = sd_event_get_now_monotonic(client->event, &time_now);
1041         if (r < 0)
1042                 return client_stop(client, r);
1043
1044         return client_handle_message(client, &packet->dhcp, len, time_now);
1045 }
1046
1047 int sd_dhcp_client_start(sd_dhcp_client *client) {
1048         int r;
1049
1050         assert_return(client, -EINVAL);
1051
1052         r = client_initialize(client);
1053         if (r < 0)
1054                 return r;
1055
1056         if (client->last_addr)
1057                 client->state = DHCP_STATE_INIT_REBOOT;
1058
1059         return client_start(client);
1060 }
1061
1062 int sd_dhcp_client_stop(sd_dhcp_client *client) {
1063         return client_stop(client, DHCP_EVENT_STOP);
1064 }
1065
1066 int sd_dhcp_client_attach_event(sd_dhcp_client *client, sd_event *event,
1067                                 int priority) {
1068         int r;
1069
1070         assert_return(client, -EINVAL);
1071         assert_return(!client->event, -EBUSY);
1072
1073         if (event)
1074                 client->event = sd_event_ref(event);
1075         else {
1076                 r = sd_event_default(&client->event);
1077                 if (r < 0)
1078                         return 0;
1079         }
1080
1081         client->event_priority = priority;
1082
1083         return 0;
1084 }
1085
1086 int sd_dhcp_client_detach_event(sd_dhcp_client *client) {
1087         assert_return(client, -EINVAL);
1088
1089         client->event = sd_event_unref(client->event);
1090
1091         return 0;
1092 }
1093
1094 sd_event *sd_dhcp_client_get_event(sd_dhcp_client *client) {
1095         if (!client)
1096                 return NULL;
1097
1098         return client->event;
1099 }
1100
1101 void sd_dhcp_client_free(sd_dhcp_client *client) {
1102         if (!client)
1103                 return;
1104
1105         sd_dhcp_client_stop(client);
1106         sd_dhcp_client_detach_event(client);
1107
1108         free(client->req_opts);
1109         free(client);
1110 }
1111
1112 DEFINE_TRIVIAL_CLEANUP_FUNC(sd_dhcp_client*, sd_dhcp_client_free);
1113 #define _cleanup_dhcp_client_free_ _cleanup_(sd_dhcp_client_freep)
1114
1115 int sd_dhcp_client_new(sd_dhcp_client **ret) {
1116         _cleanup_dhcp_client_free_ sd_dhcp_client *client = NULL;
1117
1118         assert_return(ret, -EINVAL);
1119
1120         client = new0(sd_dhcp_client, 1);
1121         if (!client)
1122                 return -ENOMEM;
1123
1124         client->state = DHCP_STATE_INIT;
1125         client->index = -1;
1126         client->fd = -1;
1127         client->attempt = 1;
1128
1129         client->req_opts_size = ELEMENTSOF(default_req_opts);
1130
1131         client->req_opts = memdup(default_req_opts, client->req_opts_size);
1132         if (!client->req_opts)
1133                 return -ENOMEM;
1134
1135         *ret = client;
1136         client = NULL;
1137
1138         return 0;
1139 }