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