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 <net/if_arp.h>
  26 #include <sys/param.h>
  27 #include <sys/ioctl.h>
  28
  29 #include "util.h"
  30 #include "list.h"
  31
  32 #include "dhcp-protocol.h"
  33 #include "dhcp-internal.h"
  34 #include "dhcp-lease-internal.h"
  35 #include "sd-dhcp-client.h"
  36
  37 struct sd_dhcp_client {
  38         DHCPState state;
  39         sd_event *event;
  40         int event_priority;
  41         sd_event_source *timeout_resend;
  42         int index;
  43         int fd;
  44         union sockaddr_union link;
  45         sd_event_source *receive_message;
  46         uint8_t *req_opts;
  47         size_t req_opts_allocated;
  48         size_t req_opts_size;
  49         be32_t last_addr;
  50         struct {
  51                 uint8_t type;
  52                 struct ether_addr mac_addr;
  53         } _packed_ client_id;
  54         uint32_t xid;
  55         usec_t start_time;
  56         uint16_t secs;
  57         unsigned int attempt;
  58         usec_t request_sent;
  59         sd_event_source *timeout_t1;
  60         sd_event_source *timeout_t2;
  61         sd_event_source *timeout_expire;
  62         sd_dhcp_client_cb_t cb;
  63         void *userdata;
  64         sd_dhcp_lease *lease;
  65 };
  66
  67 static const uint8_t default_req_opts[] = {
  68         DHCP_OPTION_SUBNET_MASK,
  69         DHCP_OPTION_ROUTER,
  70         DHCP_OPTION_HOST_NAME,
  71         DHCP_OPTION_DOMAIN_NAME,
  72         DHCP_OPTION_DOMAIN_NAME_SERVER,
  73         DHCP_OPTION_NTP_SERVER,
  74 };
  75
  76 static int client_receive_message_raw(sd_event_source *s, int fd,
  77                                       uint32_t revents, void *userdata);
  78 static int client_receive_message_udp(sd_event_source *s, int fd,
  79                                       uint32_t revents, void *userdata);
  80
  81 int sd_dhcp_client_set_callback(sd_dhcp_client *client, sd_dhcp_client_cb_t cb,
  82                                 void *userdata) {
  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         size_t i;
  93
  94         assert_return(client, -EINVAL);
  95         assert_return (client->state == DHCP_STATE_INIT, -EBUSY);
  96
  97         switch(option) {
  98         case DHCP_OPTION_PAD:
  99         case DHCP_OPTION_OVERLOAD:
 100         case DHCP_OPTION_MESSAGE_TYPE:
 101         case DHCP_OPTION_PARAMETER_REQUEST_LIST:
 102         case DHCP_OPTION_END:
 103                 return -EINVAL;
 104
 105         default:
 106                 break;
 107         }
 108
 109         for (i = 0; i < client->req_opts_size; i++)
 110                 if (client->req_opts[i] == option)
 111                         return -EEXIST;
 112
 113         if (!GREEDY_REALLOC(client->req_opts, client->req_opts_allocated,
 114                             client->req_opts_size + 1))
 115                 return -ENOMEM;
 116
 117         client->req_opts[client->req_opts_size++] = option;
 118
 119         return 0;
 120 }
 121
 122 int sd_dhcp_client_set_request_address(sd_dhcp_client *client,
 123                                        const struct in_addr *last_addr) {
 124         assert_return(client, -EINVAL);
 125         assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
 126
 127         if (last_addr)
 128                 client->last_addr = last_addr->s_addr;
 129         else
 130                 client->last_addr = INADDR_ANY;
 131
 132         return 0;
 133 }
 134
 135 int sd_dhcp_client_set_index(sd_dhcp_client *client, int interface_index) {
 136         assert_return(client, -EINVAL);
 137         assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
 138         assert_return(interface_index >= -1, -EINVAL);
 139
 140         client->index = interface_index;
 141
 142         return 0;
 143 }
 144
 145 int sd_dhcp_client_set_mac(sd_dhcp_client *client,
 146                            const struct ether_addr *addr) {
 147         bool need_restart = false;
 148
 149         assert_return(client, -EINVAL);
 150         assert_return(addr, -EINVAL);
 151
 152         if (memcmp(&client->client_id.mac_addr, addr, ETH_ALEN) == 0)
 153                 return 0;
 154
 155         if (client->state != DHCP_STATE_INIT) {
 156                 log_dhcp_client(client, "Changing MAC address on running DHCP "
 157                                 "client, restarting");
 158                 sd_dhcp_client_stop(client);
 159                 need_restart = true;
 160         }
 161
 162         memcpy(&client->client_id.mac_addr, addr, ETH_ALEN);
 163         client->client_id.type = 0x01;
 164
 165         if (need_restart)
 166                 sd_dhcp_client_start(client);
 167
 168         return 0;
 169 }
 170
 171 int sd_dhcp_client_get_lease(sd_dhcp_client *client, sd_dhcp_lease **ret) {
 172         assert_return(client, -EINVAL);
 173         assert_return(ret, -EINVAL);
 174
 175         if (client->state != DHCP_STATE_BOUND &&
 176             client->state != DHCP_STATE_RENEWING &&
 177             client->state != DHCP_STATE_REBINDING)
 178                 return -EADDRNOTAVAIL;
 179
 180         *ret = sd_dhcp_lease_ref(client->lease);
 181
 182         return 0;
 183 }
 184
 185 static int client_notify(sd_dhcp_client *client, int event) {
 186         if (client->cb)
 187                 client->cb(client, event, client->userdata);
 188
 189         return 0;
 190 }
 191
 192 static int client_initialize(sd_dhcp_client *client) {
 193         assert_return(client, -EINVAL);
 194
 195         client->receive_message =
 196                 sd_event_source_unref(client->receive_message);
 197
 198         client->fd = safe_close(client->fd);
 199
 200         client->timeout_resend = sd_event_source_unref(client->timeout_resend);
 201
 202         client->timeout_t1 = sd_event_source_unref(client->timeout_t1);
 203         client->timeout_t2 = sd_event_source_unref(client->timeout_t2);
 204         client->timeout_expire = sd_event_source_unref(client->timeout_expire);
 205
 206         client->attempt = 1;
 207
 208         client->state = DHCP_STATE_INIT;
 209         client->xid = 0;
 210
 211         if (client->lease)
 212                 client->lease = sd_dhcp_lease_unref(client->lease);
 213
 214         return 0;
 215 }
 216
 217 static int client_stop(sd_dhcp_client *client, int error) {
 218         assert_return(client, -EINVAL);
 219
 220         client_notify(client, error);
 221
 222         client_initialize(client);
 223
 224         log_dhcp_client(client, "STOPPED");
 225
 226         return 0;
 227 }
 228
 229 static int client_message_init(sd_dhcp_client *client, DHCPMessage *message,
 230                                uint8_t type, uint8_t **opt, size_t *optlen) {
 231         int r;
 232
 233         assert(client);
 234         assert(client->secs);
 235         assert(message);
 236         assert(opt);
 237         assert(optlen);
 238
 239         r = dhcp_message_init(message, BOOTREQUEST, client->xid, type, opt,
 240                               optlen);
 241         if (r < 0)
 242                 return r;
 243
 244         /* Although 'secs' field is a SHOULD in RFC 2131, certain DHCP servers
 245            refuse to issue an DHCP lease if 'secs' is set to zero */
 246         message->secs = htobe16(client->secs);
 247
 248         memcpy(&message->chaddr, &client->client_id.mac_addr, ETH_ALEN);
 249
 250         if (client->state == DHCP_STATE_RENEWING ||
 251             client->state == DHCP_STATE_REBINDING)
 252                 message->ciaddr = client->lease->address;
 253
 254         /* Some DHCP servers will refuse to issue an DHCP lease if the Client
 255            Identifier option is not set */
 256         r = dhcp_option_append(opt, optlen, DHCP_OPTION_CLIENT_IDENTIFIER,
 257                                sizeof(client->client_id), &client->client_id);
 258         if (r < 0)
 259                 return r;
 260
 261         if (type == DHCP_DISCOVER || type == DHCP_REQUEST) {
 262                 be16_t max_size;
 263
 264                 r = dhcp_option_append(opt, optlen,
 265                                        DHCP_OPTION_PARAMETER_REQUEST_LIST,
 266                                        client->req_opts_size,
 267                                        client->req_opts);
 268                 if (r < 0)
 269                         return r;
 270
 271                 /* Some DHCP servers will send bigger DHCP packets than the
 272                    defined default size unless the Maximum Messge Size option
 273                    is explicitely set */
 274                 max_size = htobe16(DHCP_IP_UDP_SIZE + DHCP_MESSAGE_SIZE +
 275                                    DHCP_MIN_OPTIONS_SIZE);
 276                 r = dhcp_option_append(opt, optlen,
 277                                        DHCP_OPTION_MAXIMUM_MESSAGE_SIZE,
 278                                        2, &max_size);
 279                 if (r < 0)
 280                         return r;
 281         }
 282
 283         return 0;
 284 }
 285
 286 static int dhcp_client_send_raw(sd_dhcp_client *client, DHCPPacket *packet,
 287                                 size_t len) {
 288         dhcp_packet_append_ip_headers(packet, INADDR_ANY, DHCP_PORT_CLIENT,
 289                                       INADDR_BROADCAST, DHCP_PORT_SERVER, len);
 290
 291         return dhcp_network_send_raw_socket(client->fd, &client->link,
 292                                             packet, len);
 293 }
 294
 295 static int client_send_discover(sd_dhcp_client *client) {
 296         _cleanup_free_ DHCPPacket *discover = NULL;
 297         size_t optlen, len;
 298         uint8_t *opt;
 299         usec_t time_now;
 300         int r;
 301
 302         assert(client);
 303
 304         r = sd_event_now(client->event, CLOCK_MONOTONIC, &time_now);
 305         if (r < 0)
 306                 return r;
 307         assert(time_now >= client->start_time);
 308
 309         /* seconds between sending first and last DISCOVER
 310          * must always be strictly positive to deal with broken servers */
 311         client->secs = ((time_now - client->start_time) / USEC_PER_SEC) ? : 1;
 312
 313         optlen = DHCP_MIN_OPTIONS_SIZE;
 314         len = sizeof(DHCPPacket) + optlen;
 315
 316         discover = malloc0(len);
 317         if (!discover)
 318                 return -ENOMEM;
 319
 320         r = client_message_init(client, &discover->dhcp, DHCP_DISCOVER,
 321                                 &opt, &optlen);
 322         if (r < 0)
 323                 return r;
 324
 325         if (client->last_addr != INADDR_ANY) {
 326                 r = dhcp_option_append(&opt, &optlen,
 327                                          DHCP_OPTION_REQUESTED_IP_ADDRESS,
 328                                          4, &client->last_addr);
 329                 if (r < 0)
 330                         return r;
 331         }
 332
 333         r = dhcp_option_append(&opt, &optlen, DHCP_OPTION_END, 0, NULL);
 334         if (r < 0)
 335                 return r;
 336
 337         r = dhcp_client_send_raw(client, discover, len - optlen);
 338         if (r < 0)
 339                 return r;
 340
 341         log_dhcp_client(client, "DISCOVER");
 342
 343         return 0;
 344 }
 345
 346 static int client_send_request(sd_dhcp_client *client) {
 347         _cleanup_free_ DHCPPacket *request;
 348         size_t optlen, len;
 349         uint8_t *opt;
 350         int r;
 351
 352         optlen = DHCP_MIN_OPTIONS_SIZE;
 353         len = sizeof(DHCPPacket) + optlen;
 354
 355         request = malloc0(len);
 356         if (!request)
 357                 return -ENOMEM;
 358
 359         r = client_message_init(client, &request->dhcp, DHCP_REQUEST, &opt,
 360                                 &optlen);
 361         if (r < 0)
 362                 return r;
 363
 364         switch (client->state) {
 365
 366         case DHCP_STATE_INIT_REBOOT:
 367                 r = dhcp_option_append(&opt, &optlen,
 368                                          DHCP_OPTION_REQUESTED_IP_ADDRESS,
 369                                          4, &client->last_addr);
 370                 if (r < 0)
 371                         return r;
 372                 break;
 373
 374         case DHCP_STATE_REQUESTING:
 375                 r = dhcp_option_append(&opt, &optlen,
 376                                        DHCP_OPTION_REQUESTED_IP_ADDRESS,
 377                                        4, &client->lease->address);
 378                 if (r < 0)
 379                         return r;
 380
 381                 r = dhcp_option_append(&opt, &optlen,
 382                                        DHCP_OPTION_SERVER_IDENTIFIER,
 383                                        4, &client->lease->server_address);
 384                 if (r < 0)
 385                         return r;
 386                 break;
 387
 388         case DHCP_STATE_INIT:
 389         case DHCP_STATE_SELECTING:
 390         case DHCP_STATE_REBOOTING:
 391         case DHCP_STATE_BOUND:
 392         case DHCP_STATE_RENEWING:
 393         case DHCP_STATE_REBINDING:
 394
 395                 break;
 396         }
 397
 398         r = dhcp_option_append(&opt, &optlen, DHCP_OPTION_END, 0, NULL);
 399         if (r < 0)
 400                 return r;
 401
 402         if (client->state == DHCP_STATE_RENEWING) {
 403                 r = dhcp_network_send_udp_socket(client->fd,
 404                                                  client->lease->server_address,
 405                                                  DHCP_PORT_SERVER,
 406                                                  &request->dhcp,
 407                                                  len - optlen - DHCP_IP_UDP_SIZE);
 408         } else {
 409                 r = dhcp_client_send_raw(client, request, len - optlen);
 410         }
 411         if (r < 0)
 412                 return r;
 413
 414         log_dhcp_client(client, "REQUEST");
 415
 416         return 0;
 417 }
 418
 419 static int client_timeout_resend(sd_event_source *s, uint64_t usec,
 420                                  void *userdata) {
 421         sd_dhcp_client *client = userdata;
 422         usec_t next_timeout = 0;
 423         uint64_t time_now;
 424         uint32_t time_left;
 425         int r;
 426
 427         assert(s);
 428         assert(client);
 429         assert(client->event);
 430
 431         r = sd_event_now(client->event, CLOCK_MONOTONIC, &time_now);
 432         if (r < 0)
 433                 goto error;
 434
 435         switch (client->state) {
 436         case DHCP_STATE_RENEWING:
 437
 438                 time_left = (client->lease->t2 - client->lease->t1) / 2;
 439                 if (time_left < 60)
 440                         time_left = 60;
 441
 442                 next_timeout = time_now + time_left * USEC_PER_SEC;
 443
 444                 break;
 445
 446         case DHCP_STATE_REBINDING:
 447
 448                 time_left = (client->lease->lifetime - client->lease->t2) / 2;
 449                 if (time_left < 60)
 450                         time_left = 60;
 451
 452                 next_timeout = time_now + time_left * USEC_PER_SEC;
 453                 break;
 454
 455         case DHCP_STATE_REBOOTING:
 456                 /* start over as we did not receive a timely ack or nak */
 457                 client->state = DHCP_STATE_INIT;
 458                 client->attempt = 1;
 459                 client->xid = random_u32();
 460
 461                 /* fall through */
 462         case DHCP_STATE_INIT:
 463         case DHCP_STATE_INIT_REBOOT:
 464         case DHCP_STATE_SELECTING:
 465         case DHCP_STATE_REQUESTING:
 466         case DHCP_STATE_BOUND:
 467
 468                 if (client->attempt < 64)
 469                         client->attempt *= 2;
 470
 471                 next_timeout = time_now + (client->attempt - 1) * USEC_PER_SEC;
 472
 473                 break;
 474         }
 475
 476         next_timeout += (random_u32() & 0x1fffff);
 477
 478         client->timeout_resend = sd_event_source_unref(client->timeout_resend);
 479
 480         r = sd_event_add_time(client->event,
 481                               &client->timeout_resend,
 482                               CLOCK_MONOTONIC,
 483                               next_timeout, 10 * USEC_PER_MSEC,
 484                               client_timeout_resend, client);
 485         if (r < 0)
 486                 goto error;
 487
 488         r = sd_event_source_set_priority(client->timeout_resend,
 489                                          client->event_priority);
 490         if (r < 0)
 491                 goto error;
 492
 493         switch (client->state) {
 494         case DHCP_STATE_INIT:
 495                 r = client_send_discover(client);
 496                 if (r >= 0) {
 497                         client->state = DHCP_STATE_SELECTING;
 498                         client->attempt = 1;
 499                 } else {
 500                         if (client->attempt >= 64)
 501                                 goto error;
 502                 }
 503
 504                 break;
 505
 506         case DHCP_STATE_SELECTING:
 507                 r = client_send_discover(client);
 508                 if (r < 0 && client->attempt >= 64)
 509                         goto error;
 510
 511                 break;
 512
 513         case DHCP_STATE_INIT_REBOOT:
 514         case DHCP_STATE_REQUESTING:
 515         case DHCP_STATE_RENEWING:
 516         case DHCP_STATE_REBINDING:
 517                 r = client_send_request(client);
 518                 if (r < 0 && client->attempt >= 64)
 519                          goto error;
 520
 521                 if (client->state == DHCP_STATE_INIT_REBOOT)
 522                         client->state = DHCP_STATE_REBOOTING;
 523
 524                 client->request_sent = time_now;
 525
 526                 break;
 527
 528         case DHCP_STATE_REBOOTING:
 529         case DHCP_STATE_BOUND:
 530
 531                 break;
 532         }
 533
 534         return 0;
 535
 536 error:
 537         client_stop(client, r);
 538
 539         /* Errors were dealt with when stopping the client, don't spill
 540            errors into the event loop handler */
 541         return 0;
 542 }
 543
 544 static int client_initialize_events(sd_dhcp_client *client,
 545                                     sd_event_io_handler_t io_callback) {
 546         int r;
 547
 548         assert(client);
 549         assert(client->event);
 550
 551         r = sd_event_add_io(client->event, &client->receive_message,
 552                             client->fd, EPOLLIN, io_callback,
 553                             client);
 554         if (r < 0)
 555                 goto error;
 556
 557         r = sd_event_source_set_priority(client->receive_message,
 558                                          client->event_priority);
 559         if (r < 0)
 560                 goto error;
 561
 562         client->timeout_resend = sd_event_source_unref(client->timeout_resend);
 563
 564         r = sd_event_add_time(client->event,
 565                               &client->timeout_resend,
 566                               CLOCK_MONOTONIC,
 567                               0, 0,
 568                               client_timeout_resend, client);
 569         if (r < 0)
 570                 goto error;
 571
 572         r = sd_event_source_set_priority(client->timeout_resend,
 573                                          client->event_priority);
 574
 575 error:
 576         if (r < 0)
 577                 client_stop(client, r);
 578
 579         return 0;
 580
 581 }
 582
 583 static int client_start(sd_dhcp_client *client) {
 584         int r;
 585
 586         assert_return(client, -EINVAL);
 587         assert_return(client->event, -EINVAL);
 588         assert_return(client->index > 0, -EINVAL);
 589         assert_return(client->fd < 0, -EBUSY);
 590         assert_return(client->xid == 0, -EINVAL);
 591         assert_return(client->state == DHCP_STATE_INIT ||
 592                       client->state == DHCP_STATE_INIT_REBOOT, -EBUSY);
 593
 594         client->xid = random_u32();
 595
 596         r = dhcp_network_bind_raw_socket(client->index, &client->link);
 597
 598         if (r < 0) {
 599                 client_stop(client, r);
 600                 return r;
 601         }
 602         client->fd = r;
 603
 604         if (client->state == DHCP_STATE_INIT) {
 605                 client->start_time = now(CLOCK_MONOTONIC);
 606                 client->secs = 0;
 607         }
 608
 609         log_dhcp_client(client, "STARTED");
 610
 611         return client_initialize_events(client, client_receive_message_raw);
 612 }
 613
 614 static int client_timeout_expire(sd_event_source *s, uint64_t usec,
 615                                  void *userdata) {
 616         sd_dhcp_client *client = userdata;
 617
 618         log_dhcp_client(client, "EXPIRED");
 619
 620         client_notify(client, DHCP_EVENT_EXPIRED);
 621
 622         /* start over as the lease was lost */
 623         client_initialize(client);
 624         client_start(client);
 625
 626         return 0;
 627 }
 628
 629 static int client_timeout_t2(sd_event_source *s, uint64_t usec, void *userdata) {
 630         sd_dhcp_client *client = userdata;
 631         int r;
 632
 633         client->receive_message = sd_event_source_unref(client->receive_message);
 634         client->fd = safe_close(client->fd);
 635
 636         client->state = DHCP_STATE_REBINDING;
 637         client->attempt = 1;
 638
 639         r = dhcp_network_bind_raw_socket(client->index, &client->link);
 640         if (r < 0) {
 641                 client_stop(client, r);
 642                 return 0;
 643         }
 644
 645         client->fd = r;
 646
 647         log_dhcp_client(client, "TIMEOUT T2");
 648
 649         return client_initialize_events(client, client_receive_message_raw);
 650 }
 651
 652 static int client_timeout_t1(sd_event_source *s, uint64_t usec,
 653                              void *userdata) {
 654         sd_dhcp_client *client = userdata;
 655         int r;
 656
 657         client->state = DHCP_STATE_RENEWING;
 658         client->attempt = 1;
 659
 660         r = dhcp_network_bind_udp_socket(client->index,
 661                                          client->lease->address,
 662                                          DHCP_PORT_CLIENT);
 663         if (r < 0) {
 664                 client_stop(client, r);
 665                 return 0;
 666         }
 667
 668         client->fd = r;
 669
 670         log_dhcp_client(client, "TIMEOUT T1");
 671
 672         return client_initialize_events(client, client_receive_message_udp);
 673 }
 674
 675 static int client_handle_offer(sd_dhcp_client *client, DHCPMessage *offer,
 676                                size_t len) {
 677         _cleanup_dhcp_lease_unref_ sd_dhcp_lease *lease = NULL;
 678         int r;
 679
 680         r = dhcp_lease_new(&lease);
 681         if (r < 0)
 682                 return r;
 683
 684         r = dhcp_option_parse(offer, len, dhcp_lease_parse_options, lease);
 685         if (r != DHCP_OFFER) {
 686                 log_dhcp_client(client, "receieved message was not an OFFER, ignoring");
 687                 return -ENOMSG;
 688         }
 689
 690         lease->next_server = offer->siaddr;
 691
 692         lease->address = offer->yiaddr;
 693
 694         if (lease->address == INADDR_ANY ||
 695             lease->server_address == INADDR_ANY ||
 696             lease->lifetime == 0) {
 697                 log_dhcp_client(client, "receieved lease lacks address, server "
 698                                 "address or lease lifetime, ignoring");
 699                 return -ENOMSG;
 700         }
 701
 702         if (lease->subnet_mask == INADDR_ANY) {
 703                 r = dhcp_lease_set_default_subnet_mask(lease);
 704                 if (r < 0) {
 705                         log_dhcp_client(client, "receieved lease lacks subnet "
 706                                         "mask, and a fallback one can not be "
 707                                         "generated, ignoring");
 708                         return -ENOMSG;
 709                 }
 710         }
 711
 712         client->lease = lease;
 713         lease = NULL;
 714
 715         log_dhcp_client(client, "OFFER");
 716
 717         return 0;
 718 }
 719
 720 static int client_handle_ack(sd_dhcp_client *client, DHCPMessage *ack,
 721                              size_t len) {
 722         _cleanup_dhcp_lease_unref_ sd_dhcp_lease *lease = NULL;
 723         int r;
 724
 725         r = dhcp_lease_new(&lease);
 726         if (r < 0)
 727                 return r;
 728
 729         r = dhcp_option_parse(ack, len, dhcp_lease_parse_options, lease);
 730         if (r == DHCP_NAK) {
 731                 log_dhcp_client(client, "NAK");
 732                 return DHCP_EVENT_NO_LEASE;
 733         }
 734
 735         if (r != DHCP_ACK) {
 736                 log_dhcp_client(client, "receieved message was not an ACK, ignoring");
 737                 return -ENOMSG;
 738         }
 739
 740         lease->next_server = ack->siaddr;
 741
 742         lease->address = ack->yiaddr;
 743
 744         if (lease->address == INADDR_ANY ||
 745             lease->server_address == INADDR_ANY ||
 746             lease->lifetime == 0) {
 747                 log_dhcp_client(client, "receieved lease lacks address, server "
 748                                 "address or lease lifetime, ignoring");
 749                 return -ENOMSG;
 750         }
 751
 752         if (lease->subnet_mask == INADDR_ANY) {
 753                 r = dhcp_lease_set_default_subnet_mask(lease);
 754                 if (r < 0) {
 755                         log_dhcp_client(client, "receieved lease lacks subnet "
 756                                         "mask, and a fallback one can not be "
 757                                         "generated, ignoring");
 758                         return -ENOMSG;
 759                 }
 760         }
 761
 762         r = DHCP_EVENT_IP_ACQUIRE;
 763         if (client->lease) {
 764                 if (client->lease->address != lease->address ||
 765                     client->lease->subnet_mask != lease->subnet_mask ||
 766                     client->lease->router != lease->router) {
 767                         r = DHCP_EVENT_IP_CHANGE;
 768                 }
 769
 770                 client->lease = sd_dhcp_lease_unref(client->lease);
 771         }
 772
 773         client->lease = lease;
 774         lease = NULL;
 775
 776         log_dhcp_client(client, "ACK");
 777
 778         return r;
 779 }
 780
 781 static uint64_t client_compute_timeout(sd_dhcp_client *client,
 782                                        uint32_t lifetime, double factor) {
 783         assert(client);
 784         assert(client->request_sent);
 785         assert(lifetime);
 786
 787         return client->request_sent + ((lifetime - 3) * USEC_PER_SEC * factor) +
 788                 + (random_u32() & 0x1fffff);
 789 }
 790
 791 static int client_set_lease_timeouts(sd_dhcp_client *client) {
 792         usec_t time_now;
 793         uint64_t lifetime_timeout;
 794         uint64_t t2_timeout;
 795         uint64_t t1_timeout;
 796         char time_string[FORMAT_TIMESPAN_MAX];
 797         int r;
 798
 799         assert(client);
 800         assert(client->event);
 801         assert(client->lease);
 802         assert(client->lease->lifetime);
 803
 804         client->timeout_t1 = sd_event_source_unref(client->timeout_t1);
 805         client->timeout_t2 = sd_event_source_unref(client->timeout_t2);
 806         client->timeout_expire = sd_event_source_unref(client->timeout_expire);
 807
 808         /* don't set timers for infinite leases */
 809         if (client->lease->lifetime == 0xffffffff)
 810                 return 0;
 811
 812         r = sd_event_now(client->event, CLOCK_MONOTONIC, &time_now);
 813         if (r < 0)
 814                 return r;
 815         assert(client->request_sent <= time_now);
 816
 817         /* convert the various timeouts from relative (secs) to absolute (usecs) */
 818         lifetime_timeout = client_compute_timeout(client, client->lease->lifetime, 1);
 819         if (client->lease->t1 && client->lease->t2) {
 820                 /* both T1 and T2 are given */
 821                 if (client->lease->t1 < client->lease->t2 &&
 822                     client->lease->t2 < client->lease->lifetime) {
 823                         /* they are both valid */
 824                         t2_timeout = client_compute_timeout(client, client->lease->t2, 1);
 825                         t1_timeout = client_compute_timeout(client, client->lease->t1, 1);
 826                 } else {
 827                         /* discard both */
 828                         t2_timeout = client_compute_timeout(client, client->lease->lifetime, 7.0 / 8.0);
 829                         client->lease->t2 = (client->lease->lifetime * 7) / 8;
 830                         t1_timeout = client_compute_timeout(client, client->lease->lifetime, 0.5);
 831                         client->lease->t1 = client->lease->lifetime / 2;
 832                 }
 833         } else if (client->lease->t2 && client->lease->t2 < client->lease->lifetime) {
 834                 /* only T2 is given, and it is valid */
 835                 t2_timeout = client_compute_timeout(client, client->lease->t2, 1);
 836                 t1_timeout = client_compute_timeout(client, client->lease->lifetime, 0.5);
 837                 client->lease->t1 = client->lease->lifetime / 2;
 838                 if (t2_timeout <= t1_timeout) {
 839                         /* the computed T1 would be invalid, so discard T2 */
 840                         t2_timeout = client_compute_timeout(client, client->lease->lifetime, 7.0 / 8.0);
 841                         client->lease->t2 = (client->lease->lifetime * 7) / 8;
 842                 }
 843         } else if (client->lease->t1 && client->lease->t1 < client->lease->lifetime) {
 844                 /* only T1 is given, and it is valid */
 845                 t1_timeout = client_compute_timeout(client, client->lease->t1, 1);
 846                 t2_timeout = client_compute_timeout(client, client->lease->lifetime, 7.0 / 8.0);
 847                 client->lease->t2 = (client->lease->lifetime * 7) / 8;
 848                 if (t2_timeout <= t1_timeout) {
 849                         /* the computed T2 would be invalid, so discard T1 */
 850                         t2_timeout = client_compute_timeout(client, client->lease->lifetime, 0.5);
 851                         client->lease->t2 = client->lease->lifetime / 2;
 852                 }
 853         } else {
 854                 /* fall back to the default timeouts */
 855                 t1_timeout = client_compute_timeout(client, client->lease->lifetime, 0.5);
 856                 client->lease->t1 = client->lease->lifetime / 2;
 857                 t2_timeout = client_compute_timeout(client, client->lease->lifetime, 7.0 / 8.0);
 858                 client->lease->t2 = (client->lease->lifetime * 7) / 8;
 859         }
 860
 861         /* arm lifetime timeout */
 862         r = sd_event_add_time(client->event, &client->timeout_expire,
 863                               CLOCK_MONOTONIC,
 864                               lifetime_timeout, 10 * USEC_PER_MSEC,
 865                               client_timeout_expire, client);
 866         if (r < 0)
 867                 return r;
 868
 869         r = sd_event_source_set_priority(client->timeout_expire,
 870                                          client->event_priority);
 871         if (r < 0)
 872                 return r;
 873
 874         log_dhcp_client(client, "lease expires in %s",
 875                         format_timespan(time_string, FORMAT_TIMESPAN_MAX,
 876                         lifetime_timeout - time_now, 0));
 877
 878         /* don't arm earlier timeouts if this has already expired */
 879         if (lifetime_timeout <= time_now)
 880                 return 0;
 881
 882         /* arm T2 timeout */
 883         r = sd_event_add_time(client->event,
 884                               &client->timeout_t2,
 885                               CLOCK_MONOTONIC,
 886                               t2_timeout,
 887                               10 * USEC_PER_MSEC,
 888                               client_timeout_t2, client);
 889         if (r < 0)
 890                 return r;
 891
 892         r = sd_event_source_set_priority(client->timeout_t2,
 893                                          client->event_priority);
 894         if (r < 0)
 895                 return r;
 896
 897         log_dhcp_client(client, "T2 expires in %s",
 898                         format_timespan(time_string, FORMAT_TIMESPAN_MAX,
 899                         t2_timeout - time_now, 0));
 900
 901         /* don't arm earlier timeout if this has already expired */
 902         if (t2_timeout <= time_now)
 903                 return 0;
 904
 905         /* arm T1 timeout */
 906         r = sd_event_add_time(client->event,
 907                               &client->timeout_t1,
 908                               CLOCK_MONOTONIC,
 909                               t1_timeout, 10 * USEC_PER_MSEC,
 910                               client_timeout_t1, client);
 911         if (r < 0)
 912                 return r;
 913
 914         r = sd_event_source_set_priority(client->timeout_t1,
 915                                          client->event_priority);
 916         if (r < 0)
 917                 return r;
 918
 919         log_dhcp_client(client, "T1 expires in %s",
 920                         format_timespan(time_string, FORMAT_TIMESPAN_MAX,
 921                         t1_timeout - time_now, 0));
 922
 923         return 0;
 924 }
 925
 926 static int client_handle_message(sd_dhcp_client *client, DHCPMessage *message,
 927                                  int len) {
 928         int r = 0, notify_event = 0;
 929
 930         assert(client);
 931         assert(client->event);
 932         assert(message);
 933
 934         if (len < DHCP_MESSAGE_SIZE) {
 935                 log_dhcp_client(client, "message too small (%d bytes): "
 936                                 "ignoring", len);
 937                 return 0;
 938         }
 939
 940         if (be32toh(message->magic) != DHCP_MAGIC_COOKIE) {
 941                 log_dhcp_client(client, "not a DHCP message: ignoring");
 942                 return 0;
 943         }
 944
 945         if (message->op != BOOTREPLY) {
 946                 log_dhcp_client(client, "not a BOOTREPLY message: ignoring");
 947                 return 0;
 948         }
 949
 950         if (be32toh(message->xid) != client->xid) {
 951                 log_dhcp_client(client, "received xid (%u) does not match "
 952                                 "expected (%u): ignoring",
 953                                 be32toh(message->xid), client->xid);
 954                 return 0;
 955         }
 956
 957         if (message->htype != ARPHRD_ETHER || message->hlen != ETHER_ADDR_LEN) {
 958                 log_dhcp_client(client, "not an ethernet packet");
 959                 return 0;
 960         }
 961
 962         if (memcmp(&message->chaddr[0], &client->client_id.mac_addr,
 963                    ETH_ALEN)) {
 964                 log_dhcp_client(client, "received chaddr does not match "
 965                                 "expected: ignoring");
 966                 return 0;
 967         }
 968
 969         switch (client->state) {
 970         case DHCP_STATE_SELECTING:
 971
 972                 r = client_handle_offer(client, message, len);
 973                 if (r >= 0) {
 974
 975                         client->timeout_resend =
 976                                 sd_event_source_unref(client->timeout_resend);
 977
 978                         client->state = DHCP_STATE_REQUESTING;
 979                         client->attempt = 1;
 980
 981                         r = sd_event_add_time(client->event,
 982                                               &client->timeout_resend,
 983                                               CLOCK_MONOTONIC,
 984                                               0, 0,
 985                                               client_timeout_resend, client);
 986                         if (r < 0)
 987                                 goto error;
 988
 989                         r = sd_event_source_set_priority(client->timeout_resend,
 990                                                          client->event_priority);
 991                         if (r < 0)
 992                                 goto error;
 993                 } else if (r == -ENOMSG)
 994                         /* invalid message, let's ignore it */
 995                         return 0;
 996
 997                 break;
 998
 999         case DHCP_STATE_REBOOTING:
1000         case DHCP_STATE_REQUESTING:
1001         case DHCP_STATE_RENEWING:
1002         case DHCP_STATE_REBINDING:
1003
1004                 r = client_handle_ack(client, message, len);
1005                 if (r == DHCP_EVENT_NO_LEASE) {
1006
1007                         client->timeout_resend =
1008                                 sd_event_source_unref(client->timeout_resend);
1009
1010                         if (client->state == DHCP_STATE_REBOOTING) {
1011                                 r = client_initialize(client);
1012                                 if (r < 0)
1013                                         goto error;
1014
1015                                 r = client_start(client);
1016                                 if (r < 0)
1017                                         goto error;
1018                         }
1019
1020                         goto error;
1021                 } else if (r >= 0) {
1022                         client->timeout_resend =
1023                                 sd_event_source_unref(client->timeout_resend);
1024
1025                         if (IN_SET(client->state, DHCP_STATE_REQUESTING,
1026                                    DHCP_STATE_REBOOTING))
1027                                 notify_event = DHCP_EVENT_IP_ACQUIRE;
1028                         else if (r != DHCP_EVENT_IP_ACQUIRE)
1029                                 notify_event = r;
1030
1031                         client->state = DHCP_STATE_BOUND;
1032                         client->attempt = 1;
1033
1034                         client->last_addr = client->lease->address;
1035
1036                         r = client_set_lease_timeouts(client);
1037                         if (r < 0)
1038                                 goto error;
1039
1040                         if (notify_event)
1041                                 client_notify(client, notify_event);
1042
1043                         client->receive_message =
1044                                 sd_event_source_unref(client->receive_message);
1045                         client->fd = safe_close(client->fd);
1046                 } else if (r == -ENOMSG)
1047                         /* invalid message, let's ignore it */
1048                         return 0;
1049
1050                 break;
1051
1052         case DHCP_STATE_INIT:
1053         case DHCP_STATE_INIT_REBOOT:
1054         case DHCP_STATE_BOUND:
1055
1056                 break;
1057         }
1058
1059 error:
1060         if (r < 0 || r == DHCP_EVENT_NO_LEASE)
1061                 return client_stop(client, r);
1062
1063         return 0;
1064 }
1065
1066 static int client_receive_message_udp(sd_event_source *s, int fd,
1067                                       uint32_t revents, void *userdata) {
1068         sd_dhcp_client *client = userdata;
1069         _cleanup_free_ DHCPMessage *message = NULL;
1070         int buflen = 0, len, r;
1071
1072         assert(s);
1073         assert(client);
1074
1075         r = ioctl(fd, FIONREAD, &buflen);
1076         if (r < 0 || buflen <= 0)
1077                 buflen = sizeof(DHCPMessage) + DHCP_MIN_OPTIONS_SIZE;
1078
1079         message = malloc0(buflen);
1080         if (!message)
1081                 return -ENOMEM;
1082
1083         len = read(fd, message, buflen);
1084         if (len < 0)
1085                 return 0;
1086
1087         return client_handle_message(client, message, len);
1088 }
1089
1090 static int client_receive_message_raw(sd_event_source *s, int fd,
1091                                       uint32_t revents, void *userdata) {
1092         sd_dhcp_client *client = userdata;
1093         _cleanup_free_ DHCPPacket *packet = NULL;
1094         uint8_t cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))];
1095         struct iovec iov = {};
1096         struct msghdr msg = {
1097                 .msg_iov = &iov,
1098                 .msg_iovlen = 1,
1099                 .msg_control = cmsgbuf,
1100                 .msg_controllen = sizeof(cmsgbuf),
1101         };
1102         struct cmsghdr *cmsg;
1103         bool checksum = true;
1104         int buflen = 0, len, r;
1105
1106         assert(s);
1107         assert(client);
1108
1109         r = ioctl(fd, FIONREAD, &buflen);
1110         if (r < 0 || buflen <= 0)
1111                 buflen = sizeof(DHCPPacket) + DHCP_MIN_OPTIONS_SIZE;
1112
1113         packet = malloc0(buflen);
1114         if (!packet)
1115                 return -ENOMEM;
1116
1117         iov.iov_base = packet;
1118         iov.iov_len = buflen;
1119
1120         len = recvmsg(fd, &msg, 0);
1121         if (len < 0) {
1122                 log_dhcp_client(client, "could not receive message from raw "
1123                                 "socket: %s", strerror(errno));
1124                 return 0;
1125         }
1126
1127         for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
1128                 if (cmsg->cmsg_level == SOL_PACKET && cmsg->cmsg_type == PACKET_AUXDATA) {
1129                         struct tpacket_auxdata *aux = (void *)CMSG_DATA(cmsg);
1130
1131                         checksum = !(aux->tp_status & TP_STATUS_CSUMNOTREADY);
1132                         break;
1133                 }
1134         }
1135
1136         r = dhcp_packet_verify_headers(packet, len, checksum);
1137         if (r < 0)
1138                 return 0;
1139
1140         len -= DHCP_IP_UDP_SIZE;
1141
1142         return client_handle_message(client, &packet->dhcp, len);
1143 }
1144
1145 int sd_dhcp_client_start(sd_dhcp_client *client) {
1146         int r;
1147
1148         assert_return(client, -EINVAL);
1149
1150         r = client_initialize(client);
1151         if (r < 0)
1152                 return r;
1153
1154         if (client->last_addr)
1155                 client->state = DHCP_STATE_INIT_REBOOT;
1156
1157         return client_start(client);
1158 }
1159
1160 int sd_dhcp_client_stop(sd_dhcp_client *client) {
1161         return client_stop(client, DHCP_EVENT_STOP);
1162 }
1163
1164 int sd_dhcp_client_attach_event(sd_dhcp_client *client, sd_event *event,
1165                                 int priority) {
1166         int r;
1167
1168         assert_return(client, -EINVAL);
1169         assert_return(!client->event, -EBUSY);
1170
1171         if (event)
1172                 client->event = sd_event_ref(event);
1173         else {
1174                 r = sd_event_default(&client->event);
1175                 if (r < 0)
1176                         return 0;
1177         }
1178
1179         client->event_priority = priority;
1180
1181         return 0;
1182 }
1183
1184 int sd_dhcp_client_detach_event(sd_dhcp_client *client) {
1185         assert_return(client, -EINVAL);
1186
1187         client->event = sd_event_unref(client->event);
1188
1189         return 0;
1190 }
1191
1192 sd_event *sd_dhcp_client_get_event(sd_dhcp_client *client) {
1193         if (!client)
1194                 return NULL;
1195
1196         return client->event;
1197 }
1198
1199 void sd_dhcp_client_free(sd_dhcp_client *client) {
1200         if (!client)
1201                 return;
1202
1203         sd_dhcp_client_stop(client);
1204         sd_dhcp_client_detach_event(client);
1205
1206         free(client->req_opts);
1207         free(client);
1208 }
1209
1210 DEFINE_TRIVIAL_CLEANUP_FUNC(sd_dhcp_client*, sd_dhcp_client_free);
1211 #define _cleanup_dhcp_client_free_ _cleanup_(sd_dhcp_client_freep)
1212
1213 int sd_dhcp_client_new(sd_dhcp_client **ret) {
1214         _cleanup_dhcp_client_free_ sd_dhcp_client *client = NULL;
1215
1216         assert_return(ret, -EINVAL);
1217
1218         client = new0(sd_dhcp_client, 1);
1219         if (!client)
1220                 return -ENOMEM;
1221
1222         client->state = DHCP_STATE_INIT;
1223         client->index = -1;
1224         client->fd = -1;
1225         client->attempt = 1;
1226
1227         client->req_opts_size = ELEMENTSOF(default_req_opts);
1228
1229         client->req_opts = memdup(default_req_opts, client->req_opts_size);
1230         if (!client->req_opts)
1231                 return -ENOMEM;
1232
1233         *ret = client;
1234         client = NULL;
1235
1236         return 0;
1237 }