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 {
  50                 uint8_t type;
  51                 struct ether_addr mac_addr;
  52         } _packed_ client_id;
  53         uint32_t xid;
  54         usec_t start_time;
  55         uint16_t secs;
  56         unsigned int attempt;
  57         usec_t request_sent;
  58         sd_event_source *timeout_t1;
  59         sd_event_source *timeout_t2;
  60         sd_event_source *timeout_expire;
  61         sd_dhcp_client_cb_t cb;
  62         void *userdata;
  63         sd_dhcp_lease *lease;
  64 };
  65
  66 static const uint8_t default_req_opts[] = {
  67         DHCP_OPTION_SUBNET_MASK,
  68         DHCP_OPTION_ROUTER,
  69         DHCP_OPTION_HOST_NAME,
  70         DHCP_OPTION_DOMAIN_NAME,
  71         DHCP_OPTION_DOMAIN_NAME_SERVER,
  72         DHCP_OPTION_NTP_SERVER,
  73 };
  74
  75 static int client_receive_message_raw(sd_event_source *s, int fd,
  76                                       uint32_t revents, void *userdata);
  77 static int client_receive_message_udp(sd_event_source *s, int fd,
  78                                       uint32_t revents, void *userdata);
  79
  80 int sd_dhcp_client_set_callback(sd_dhcp_client *client, sd_dhcp_client_cb_t cb,
  81                                 void *userdata) {
  82         assert_return(client, -EINVAL);
  83
  84         client->cb = cb;
  85         client->userdata = userdata;
  86
  87         return 0;
  88 }
  89
  90 int sd_dhcp_client_set_request_option(sd_dhcp_client *client, uint8_t option) {
  91         size_t i;
  92
  93         assert_return(client, -EINVAL);
  94         assert_return (client->state == DHCP_STATE_INIT, -EBUSY);
  95
  96         switch(option) {
  97         case DHCP_OPTION_PAD:
  98         case DHCP_OPTION_OVERLOAD:
  99         case DHCP_OPTION_MESSAGE_TYPE:
 100         case DHCP_OPTION_PARAMETER_REQUEST_LIST:
 101         case DHCP_OPTION_END:
 102                 return -EINVAL;
 103
 104         default:
 105                 break;
 106         }
 107
 108         for (i = 0; i < client->req_opts_size; i++)
 109                 if (client->req_opts[i] == option)
 110                         return -EEXIST;
 111
 112         if (!GREEDY_REALLOC(client->req_opts, client->req_opts_allocated,
 113                             client->req_opts_size + 1))
 114                 return -ENOMEM;
 115
 116         client->req_opts[client->req_opts_size++] = option;
 117
 118         return 0;
 119 }
 120
 121 int sd_dhcp_client_set_request_address(sd_dhcp_client *client,
 122                                        const struct in_addr *last_addr) {
 123         assert_return(client, -EINVAL);
 124         assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
 125
 126         if (last_addr)
 127                 client->last_addr = last_addr->s_addr;
 128         else
 129                 client->last_addr = INADDR_ANY;
 130
 131         return 0;
 132 }
 133
 134 int sd_dhcp_client_set_index(sd_dhcp_client *client, int interface_index) {
 135         assert_return(client, -EINVAL);
 136         assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
 137         assert_return(interface_index >= -1, -EINVAL);
 138
 139         client->index = interface_index;
 140
 141         return 0;
 142 }
 143
 144 int sd_dhcp_client_set_mac(sd_dhcp_client *client,
 145                            const struct ether_addr *addr) {
 146         assert_return(client, -EINVAL);
 147         assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
 148
 149         log_dhcp_client(client, "set MAC address to "
 150                         "%02hhx:%02hhx:%02hhx:%02hhx:%02hhx:%02hhx",
 151                         addr->ether_addr_octet[0],
 152                         addr->ether_addr_octet[1],
 153                         addr->ether_addr_octet[2],
 154                         addr->ether_addr_octet[3],
 155                         addr->ether_addr_octet[4],
 156                         addr->ether_addr_octet[5]);
 157
 158         memcpy(&client->client_id.mac_addr, addr, ETH_ALEN);
 159         client->client_id.type = 0x01;
 160
 161         return 0;
 162 }
 163
 164 int sd_dhcp_client_get_lease(sd_dhcp_client *client, sd_dhcp_lease **ret) {
 165         assert_return(client, -EINVAL);
 166         assert_return(ret, -EINVAL);
 167
 168         if (client->state != DHCP_STATE_BOUND &&
 169             client->state != DHCP_STATE_RENEWING &&
 170             client->state != DHCP_STATE_REBINDING)
 171                 return -EADDRNOTAVAIL;
 172
 173         *ret = sd_dhcp_lease_ref(client->lease);
 174
 175         return 0;
 176 }
 177
 178 static int client_notify(sd_dhcp_client *client, int event) {
 179         if (client->cb)
 180                 client->cb(client, event, client->userdata);
 181
 182         return 0;
 183 }
 184
 185 static int client_initialize(sd_dhcp_client *client) {
 186         assert_return(client, -EINVAL);
 187
 188         client->receive_message =
 189                 sd_event_source_unref(client->receive_message);
 190
 191         client->fd = safe_close(client->fd);
 192
 193         client->timeout_resend = sd_event_source_unref(client->timeout_resend);
 194
 195         client->timeout_t1 = sd_event_source_unref(client->timeout_t1);
 196         client->timeout_t2 = sd_event_source_unref(client->timeout_t2);
 197         client->timeout_expire = sd_event_source_unref(client->timeout_expire);
 198
 199         client->attempt = 1;
 200
 201         client->state = DHCP_STATE_INIT;
 202         client->xid = 0;
 203
 204         if (client->lease)
 205                 client->lease = sd_dhcp_lease_unref(client->lease);
 206
 207         return 0;
 208 }
 209
 210 static int client_stop(sd_dhcp_client *client, int error) {
 211         assert_return(client, -EINVAL);
 212
 213         client_notify(client, error);
 214
 215         client_initialize(client);
 216
 217         log_dhcp_client(client, "STOPPED");
 218
 219         return 0;
 220 }
 221
 222 static int client_message_init(sd_dhcp_client *client, DHCPMessage *message,
 223                                uint8_t type, uint8_t **opt, size_t *optlen) {
 224         int r;
 225
 226         assert(client);
 227         assert(client->secs);
 228         assert(message);
 229         assert(opt);
 230         assert(optlen);
 231
 232         r = dhcp_message_init(message, BOOTREQUEST, client->xid, type, opt,
 233                               optlen);
 234         if (r < 0)
 235                 return r;
 236
 237         /* Although 'secs' field is a SHOULD in RFC 2131, certain DHCP servers
 238            refuse to issue an DHCP lease if 'secs' is set to zero */
 239         message->secs = htobe16(client->secs);
 240
 241         memcpy(&message->chaddr, &client->client_id.mac_addr, ETH_ALEN);
 242
 243         if (client->state == DHCP_STATE_RENEWING ||
 244             client->state == DHCP_STATE_REBINDING)
 245                 message->ciaddr = client->lease->address;
 246
 247         /* Some DHCP servers will refuse to issue an DHCP lease if the Client
 248            Identifier option is not set */
 249         r = dhcp_option_append(opt, optlen, DHCP_OPTION_CLIENT_IDENTIFIER,
 250                                sizeof(client->client_id), &client->client_id);
 251         if (r < 0)
 252                 return r;
 253
 254         if (type == DHCP_DISCOVER || type == DHCP_REQUEST) {
 255                 be16_t max_size;
 256
 257                 r = dhcp_option_append(opt, optlen,
 258                                        DHCP_OPTION_PARAMETER_REQUEST_LIST,
 259                                        client->req_opts_size,
 260                                        client->req_opts);
 261                 if (r < 0)
 262                         return r;
 263
 264                 /* Some DHCP servers will send bigger DHCP packets than the
 265                    defined default size unless the Maximum Messge Size option
 266                    is explicitely set */
 267                 max_size = htobe16(DHCP_IP_UDP_SIZE + DHCP_MESSAGE_SIZE +
 268                                    DHCP_MIN_OPTIONS_SIZE);
 269                 r = dhcp_option_append(opt, optlen,
 270                                        DHCP_OPTION_MAXIMUM_MESSAGE_SIZE,
 271                                        2, &max_size);
 272                 if (r < 0)
 273                         return r;
 274         }
 275
 276         return 0;
 277 }
 278
 279 static int dhcp_client_send_raw(sd_dhcp_client *client, DHCPPacket *packet,
 280                                 size_t len) {
 281         dhcp_packet_append_ip_headers(packet, INADDR_ANY, DHCP_PORT_CLIENT,
 282                                       INADDR_BROADCAST, DHCP_PORT_SERVER, len);
 283
 284         return dhcp_network_send_raw_socket(client->fd, &client->link,
 285                                             packet, len);
 286 }
 287
 288 static int client_send_discover(sd_dhcp_client *client) {
 289         _cleanup_free_ DHCPPacket *discover;
 290         size_t optlen, len;
 291         uint8_t *opt;
 292         usec_t time_now;
 293         int r;
 294
 295         assert(client);
 296
 297         r = sd_event_get_now_monotonic(client->event, &time_now);
 298         if (r < 0)
 299                 return r;
 300         assert(time_now >= client->start_time);
 301
 302         /* seconds between sending first and last DISCOVER
 303          * must always be strictly positive to deal with broken servers */
 304         client->secs = ((time_now - client->start_time) / USEC_PER_SEC) ? : 1;
 305
 306         optlen = DHCP_MIN_OPTIONS_SIZE;
 307         len = sizeof(DHCPPacket) + optlen;
 308
 309         discover = malloc0(len);
 310         if (!discover)
 311                 return -ENOMEM;
 312
 313         r = client_message_init(client, &discover->dhcp, DHCP_DISCOVER,
 314                                 &opt, &optlen);
 315         if (r < 0)
 316                 return r;
 317
 318         if (client->last_addr != INADDR_ANY) {
 319                 r = dhcp_option_append(&opt, &optlen,
 320                                          DHCP_OPTION_REQUESTED_IP_ADDRESS,
 321                                          4, &client->last_addr);
 322                 if (r < 0)
 323                         return r;
 324         }
 325
 326         r = dhcp_option_append(&opt, &optlen, DHCP_OPTION_END, 0, NULL);
 327         if (r < 0)
 328                 return r;
 329
 330         r = dhcp_client_send_raw(client, discover, len - optlen);
 331         if (r < 0)
 332                 return r;
 333
 334         log_dhcp_client(client, "DISCOVER");
 335
 336         return 0;
 337 }
 338
 339 static int client_send_request(sd_dhcp_client *client) {
 340         _cleanup_free_ DHCPPacket *request;
 341         size_t optlen, len;
 342         uint8_t *opt;
 343         int r;
 344
 345         optlen = DHCP_MIN_OPTIONS_SIZE;
 346         len = sizeof(DHCPPacket) + optlen;
 347
 348         request = malloc0(len);
 349         if (!request)
 350                 return -ENOMEM;
 351
 352         r = client_message_init(client, &request->dhcp, DHCP_REQUEST, &opt,
 353                                 &optlen);
 354         if (r < 0)
 355                 return r;
 356
 357         switch (client->state) {
 358
 359         case DHCP_STATE_INIT_REBOOT:
 360                 r = dhcp_option_append(&opt, &optlen,
 361                                          DHCP_OPTION_REQUESTED_IP_ADDRESS,
 362                                          4, &client->last_addr);
 363                 if (r < 0)
 364                         return r;
 365                 break;
 366
 367         case DHCP_STATE_REQUESTING:
 368                 r = dhcp_option_append(&opt, &optlen,
 369                                        DHCP_OPTION_REQUESTED_IP_ADDRESS,
 370                                        4, &client->lease->address);
 371                 if (r < 0)
 372                         return r;
 373
 374                 r = dhcp_option_append(&opt, &optlen,
 375                                        DHCP_OPTION_SERVER_IDENTIFIER,
 376                                        4, &client->lease->server_address);
 377                 if (r < 0)
 378                         return r;
 379                 break;
 380
 381         case DHCP_STATE_INIT:
 382         case DHCP_STATE_SELECTING:
 383         case DHCP_STATE_REBOOTING:
 384         case DHCP_STATE_BOUND:
 385         case DHCP_STATE_RENEWING:
 386         case DHCP_STATE_REBINDING:
 387
 388                 break;
 389         }
 390
 391         r = dhcp_option_append(&opt, &optlen, DHCP_OPTION_END, 0, NULL);
 392         if (r < 0)
 393                 return r;
 394
 395         if (client->state == DHCP_STATE_RENEWING) {
 396                 r = dhcp_network_send_udp_socket(client->fd,
 397                                                  client->lease->server_address,
 398                                                  DHCP_PORT_SERVER,
 399                                                  &request->dhcp,
 400                                                  len - optlen - DHCP_IP_UDP_SIZE);
 401         } else {
 402                 r = dhcp_client_send_raw(client, request, len - optlen);
 403         }
 404         if (r < 0)
 405                 return r;
 406
 407         log_dhcp_client(client, "REQUEST");
 408
 409         return 0;
 410 }
 411
 412 static int client_timeout_resend(sd_event_source *s, uint64_t usec,
 413                                  void *userdata) {
 414         sd_dhcp_client *client = userdata;
 415         usec_t next_timeout = 0;
 416         uint64_t time_now;
 417         uint32_t time_left;
 418         int r;
 419
 420         assert(s);
 421         assert(client);
 422         assert(client->event);
 423
 424         r = sd_event_get_now_monotonic(client->event, &time_now);
 425         if (r < 0)
 426                 goto error;
 427
 428         switch (client->state) {
 429         case DHCP_STATE_RENEWING:
 430
 431                 time_left = (client->lease->t2 - client->lease->t1) / 2;
 432                 if (time_left < 60)
 433                         time_left = 60;
 434
 435                 next_timeout = time_now + time_left * USEC_PER_SEC;
 436
 437                 break;
 438
 439         case DHCP_STATE_REBINDING:
 440
 441                 time_left = (client->lease->lifetime - client->lease->t2) / 2;
 442                 if (time_left < 60)
 443                         time_left = 60;
 444
 445                 next_timeout = time_now + time_left * USEC_PER_SEC;
 446                 break;
 447
 448         case DHCP_STATE_REBOOTING:
 449                 /* start over as we did not receive a timely ack or nak */
 450                 client->state = DHCP_STATE_INIT;
 451                 client->attempt = 1;
 452                 client->xid = random_u32();
 453
 454                 /* fall through */
 455         case DHCP_STATE_INIT:
 456         case DHCP_STATE_INIT_REBOOT:
 457         case DHCP_STATE_SELECTING:
 458         case DHCP_STATE_REQUESTING:
 459         case DHCP_STATE_BOUND:
 460
 461                 if (client->attempt < 64)
 462                         client->attempt *= 2;
 463
 464                 next_timeout = time_now + (client->attempt - 1) * USEC_PER_SEC;
 465
 466                 break;
 467         }
 468
 469         next_timeout += (random_u32() & 0x1fffff);
 470
 471         client->timeout_resend = sd_event_source_unref(client->timeout_resend);
 472
 473         r = sd_event_add_monotonic(client->event,
 474                                      &client->timeout_resend,
 475                                      next_timeout,
 476                                      10 * USEC_PER_MSEC,
 477                                      client_timeout_resend, client);
 478         if (r < 0)
 479                 goto error;
 480
 481         r = sd_event_source_set_priority(client->timeout_resend,
 482                                          client->event_priority);
 483         if (r < 0)
 484                 goto error;
 485
 486         switch (client->state) {
 487         case DHCP_STATE_INIT:
 488                 r = client_send_discover(client);
 489                 if (r >= 0) {
 490                         client->state = DHCP_STATE_SELECTING;
 491                         client->attempt = 1;
 492                 } else {
 493                         if (client->attempt >= 64)
 494                                 goto error;
 495                 }
 496
 497                 break;
 498
 499         case DHCP_STATE_SELECTING:
 500                 r = client_send_discover(client);
 501                 if (r < 0 && client->attempt >= 64)
 502                         goto error;
 503
 504                 break;
 505
 506         case DHCP_STATE_INIT_REBOOT:
 507         case DHCP_STATE_REQUESTING:
 508         case DHCP_STATE_RENEWING:
 509         case DHCP_STATE_REBINDING:
 510                 r = client_send_request(client);
 511                 if (r < 0 && client->attempt >= 64)
 512                          goto error;
 513
 514                 if (client->state == DHCP_STATE_INIT_REBOOT)
 515                         client->state = DHCP_STATE_REBOOTING;
 516
 517                 client->request_sent = time_now;
 518
 519                 break;
 520
 521         case DHCP_STATE_REBOOTING:
 522         case DHCP_STATE_BOUND:
 523
 524                 break;
 525         }
 526
 527         return 0;
 528
 529 error:
 530         client_stop(client, r);
 531
 532         /* Errors were dealt with when stopping the client, don't spill
 533            errors into the event loop handler */
 534         return 0;
 535 }
 536
 537 static int client_initialize_events(sd_dhcp_client *client,
 538                                     sd_event_io_handler_t io_callback) {
 539         int r;
 540
 541         assert(client);
 542         assert(client->event);
 543
 544         r = sd_event_add_io(client->event, &client->receive_message,
 545                             client->fd, EPOLLIN, io_callback,
 546                             client);
 547         if (r < 0)
 548                 goto error;
 549
 550         r = sd_event_source_set_priority(client->receive_message,
 551                                          client->event_priority);
 552         if (r < 0)
 553                 goto error;
 554
 555         client->timeout_resend = sd_event_source_unref(client->timeout_resend);
 556
 557         r = sd_event_add_monotonic(client->event,
 558                                    &client->timeout_resend, 0, 0,
 559                                    client_timeout_resend, client);
 560         if (r < 0)
 561                 goto error;
 562
 563         r = sd_event_source_set_priority(client->timeout_resend,
 564                                          client->event_priority);
 565
 566 error:
 567         if (r < 0)
 568                 client_stop(client, r);
 569
 570         return 0;
 571
 572 }
 573
 574 static int client_start(sd_dhcp_client *client) {
 575         int r;
 576
 577         assert_return(client, -EINVAL);
 578         assert_return(client->event, -EINVAL);
 579         assert_return(client->index > 0, -EINVAL);
 580         assert_return(client->fd < 0, -EBUSY);
 581         assert_return(client->xid == 0, -EINVAL);
 582         assert_return(client->state == DHCP_STATE_INIT ||
 583                       client->state == DHCP_STATE_INIT_REBOOT, -EBUSY);
 584
 585         client->xid = random_u32();
 586
 587         r = dhcp_network_bind_raw_socket(client->index, &client->link);
 588
 589         if (r < 0) {
 590                 client_stop(client, r);
 591                 return r;
 592         }
 593         client->fd = r;
 594
 595         if (client->state == DHCP_STATE_INIT) {
 596                 client->start_time = now(CLOCK_MONOTONIC);
 597                 client->secs = 0;
 598         }
 599
 600         log_dhcp_client(client, "STARTED");
 601
 602         return client_initialize_events(client, client_receive_message_raw);
 603 }
 604
 605 static int client_timeout_expire(sd_event_source *s, uint64_t usec,
 606                                  void *userdata) {
 607         sd_dhcp_client *client = userdata;
 608
 609         log_dhcp_client(client, "EXPIRED");
 610
 611         client_notify(client, DHCP_EVENT_EXPIRED);
 612
 613         /* start over as the lease was lost */
 614         client_initialize(client);
 615         client_start(client);
 616
 617         return 0;
 618 }
 619
 620 static int client_timeout_t2(sd_event_source *s, uint64_t usec, void *userdata) {
 621         sd_dhcp_client *client = userdata;
 622         int r;
 623
 624         client->receive_message = sd_event_source_unref(client->receive_message);
 625         client->fd = safe_close(client->fd);
 626
 627         client->state = DHCP_STATE_REBINDING;
 628         client->attempt = 1;
 629
 630         r = dhcp_network_bind_raw_socket(client->index, &client->link);
 631         if (r < 0) {
 632                 client_stop(client, r);
 633                 return 0;
 634         }
 635
 636         client->fd = r;
 637
 638         log_dhcp_client(client, "TIMEOUT T2");
 639
 640         return client_initialize_events(client, client_receive_message_raw);
 641 }
 642
 643 static int client_timeout_t1(sd_event_source *s, uint64_t usec,
 644                              void *userdata) {
 645         sd_dhcp_client *client = userdata;
 646         int r;
 647
 648         client->state = DHCP_STATE_RENEWING;
 649         client->attempt = 1;
 650
 651         r = dhcp_network_bind_udp_socket(client->index,
 652                                          client->lease->address,
 653                                          DHCP_PORT_CLIENT);
 654         if (r < 0) {
 655                 client_stop(client, r);
 656                 return 0;
 657         }
 658
 659         client->fd = r;
 660
 661         log_dhcp_client(client, "TIMEOUT T1");
 662
 663         return client_initialize_events(client, client_receive_message_udp);
 664 }
 665
 666 static int client_handle_offer(sd_dhcp_client *client, DHCPMessage *offer,
 667                                size_t len) {
 668         _cleanup_dhcp_lease_unref_ sd_dhcp_lease *lease = NULL;
 669         int r;
 670
 671         r = dhcp_lease_new(&lease);
 672         if (r < 0)
 673                 return r;
 674
 675         r = dhcp_option_parse(offer, len, dhcp_lease_parse_options, lease);
 676         if (r != DHCP_OFFER)
 677                 return -ENOMSG;
 678
 679         lease->next_server = offer->siaddr;
 680
 681         lease->address = offer->yiaddr;
 682
 683         if (lease->address == INADDR_ANY ||
 684             lease->server_address == INADDR_ANY ||
 685             lease->subnet_mask == INADDR_ANY ||
 686             lease->lifetime == 0)
 687                 return -ENOMSG;
 688
 689         client->lease = lease;
 690         lease = NULL;
 691
 692         log_dhcp_client(client, "OFFER");
 693
 694         return 0;
 695 }
 696
 697 static int client_handle_ack(sd_dhcp_client *client, DHCPMessage *ack,
 698                              size_t len) {
 699         _cleanup_dhcp_lease_unref_ sd_dhcp_lease *lease = NULL;
 700         int r;
 701
 702         r = dhcp_lease_new(&lease);
 703         if (r < 0)
 704                 return r;
 705
 706         r = dhcp_option_parse(ack, len, dhcp_lease_parse_options, lease);
 707         if (r == DHCP_NAK) {
 708                 log_dhcp_client(client, "NAK");
 709                 return DHCP_EVENT_NO_LEASE;
 710         }
 711
 712         if (r != DHCP_ACK)
 713                 return -ENOMSG;
 714
 715         lease->next_server = ack->siaddr;
 716
 717         lease->address = ack->yiaddr;
 718
 719         if (lease->address == INADDR_ANY ||
 720             lease->server_address == INADDR_ANY ||
 721             lease->subnet_mask == INADDR_ANY || lease->lifetime == 0)
 722                 return -ENOMSG;
 723
 724         r = DHCP_EVENT_IP_ACQUIRE;
 725         if (client->lease) {
 726                 if (client->lease->address != lease->address ||
 727                     client->lease->subnet_mask != lease->subnet_mask ||
 728                     client->lease->router != lease->router) {
 729                         r = DHCP_EVENT_IP_CHANGE;
 730                 }
 731
 732                 client->lease = sd_dhcp_lease_unref(client->lease);
 733         }
 734
 735         client->lease = lease;
 736         lease = NULL;
 737
 738         log_dhcp_client(client, "ACK");
 739
 740         return r;
 741 }
 742
 743 static uint64_t client_compute_timeout(uint64_t request_sent,
 744                                        uint32_t lifetime) {
 745         return request_sent + (lifetime - 3) * USEC_PER_SEC +
 746                 + (random_u32() & 0x1fffff);
 747 }
 748
 749 static int client_set_lease_timeouts(sd_dhcp_client *client, uint64_t usec) {
 750         uint64_t next_timeout;
 751         int r;
 752
 753         assert(client);
 754         assert(client->event);
 755
 756         /* don't set timers for infinite leases */
 757         if (client->lease->lifetime == 0xffffffff)
 758                 return 0;
 759
 760         if (client->lease->lifetime < 10)
 761                 return -EINVAL;
 762
 763         client->timeout_t1 = sd_event_source_unref(client->timeout_t1);
 764         client->timeout_t2 = sd_event_source_unref(client->timeout_t2);
 765         client->timeout_expire = sd_event_source_unref(client->timeout_expire);
 766
 767         if (!client->lease->t1)
 768                 client->lease->t1 = client->lease->lifetime / 2;
 769
 770         next_timeout = client_compute_timeout(client->request_sent,
 771                                               client->lease->t1);
 772         if (next_timeout < usec)
 773                 return -EINVAL;
 774
 775         r = sd_event_add_monotonic(client->event,
 776                                    &client->timeout_t1,
 777                                    next_timeout,
 778                                    10 * USEC_PER_MSEC,
 779                                    client_timeout_t1, client);
 780         if (r < 0)
 781                 return r;
 782
 783         r = sd_event_source_set_priority(client->timeout_t1,
 784                                          client->event_priority);
 785         if (r < 0)
 786                 return r;
 787
 788         if (!client->lease->t2)
 789                 client->lease->t2 = client->lease->lifetime * 7 / 8;
 790
 791         if (client->lease->t2 < client->lease->t1)
 792                 return -EINVAL;
 793
 794         if (client->lease->lifetime < client->lease->t2)
 795                 return -EINVAL;
 796
 797         next_timeout = client_compute_timeout(client->request_sent,
 798                                               client->lease->t2);
 799         if (next_timeout < usec)
 800                 return -EINVAL;
 801
 802         r = sd_event_add_monotonic(client->event,
 803                                    &client->timeout_t2,
 804                                    next_timeout,
 805                                    10 * USEC_PER_MSEC,
 806                                    client_timeout_t2, client);
 807         if (r < 0)
 808                 return r;
 809
 810         r = sd_event_source_set_priority(client->timeout_t2,
 811                                          client->event_priority);
 812         if (r < 0)
 813                 return r;
 814
 815         next_timeout = client_compute_timeout(client->request_sent,
 816                                               client->lease->lifetime);
 817         if (next_timeout < usec)
 818                 return -EINVAL;
 819
 820         r = sd_event_add_monotonic(client->event,
 821                                    &client->timeout_expire, next_timeout,
 822                                    10 * USEC_PER_MSEC,
 823                                    client_timeout_expire, client);
 824         if (r < 0)
 825                 return r;
 826
 827         r = sd_event_source_set_priority(client->timeout_expire,
 828                                          client->event_priority);
 829         if (r < 0)
 830                 return r;
 831
 832         return 0;
 833 }
 834
 835 static int client_handle_message(sd_dhcp_client *client, DHCPMessage *message,
 836                                  int len, usec_t time_now) {
 837         int r = 0, notify_event = 0;
 838
 839         assert(client);
 840         assert(client->event);
 841         assert(message);
 842
 843         if (len < DHCP_MESSAGE_SIZE) {
 844                 log_dhcp_client(client, "message too small (%d bytes): "
 845                                 "ignoring", len);
 846                 return 0;
 847         }
 848
 849         if (message->op != BOOTREPLY) {
 850                 log_dhcp_client(client, "not a BOOTREPLY message: ignoring");
 851                 return 0;
 852         }
 853
 854         if (be32toh(message->xid) != client->xid) {
 855                 log_dhcp_client(client, "received xid (%u) does not match "
 856                                 "expected (%u): ignoring",
 857                                 be32toh(message->xid), client->xid);
 858                 return 0;
 859         }
 860
 861         if (memcmp(&message->chaddr[0], &client->client_id.mac_addr,
 862                    ETH_ALEN)) {
 863                 log_dhcp_client(client, "received chaddr does not match "
 864                                 "expected: ignoring");
 865                 return 0;
 866         }
 867
 868         switch (client->state) {
 869         case DHCP_STATE_SELECTING:
 870
 871                 r = client_handle_offer(client, message, len);
 872                 if (r >= 0) {
 873
 874                         client->timeout_resend =
 875                                 sd_event_source_unref(client->timeout_resend);
 876
 877                         client->state = DHCP_STATE_REQUESTING;
 878                         client->attempt = 1;
 879
 880                         r = sd_event_add_monotonic(client->event,
 881                                                    &client->timeout_resend, 0,
 882                                                    0, client_timeout_resend,
 883                                                    client);
 884                         if (r < 0)
 885                                 goto error;
 886
 887                         r = sd_event_source_set_priority(client->timeout_resend,
 888                                                          client->event_priority);
 889                         if (r < 0)
 890                                 goto error;
 891                 }
 892
 893                 break;
 894
 895         case DHCP_STATE_REBOOTING:
 896         case DHCP_STATE_REQUESTING:
 897         case DHCP_STATE_RENEWING:
 898         case DHCP_STATE_REBINDING:
 899
 900                 r = client_handle_ack(client, message, len);
 901
 902                 if (r == DHCP_EVENT_NO_LEASE) {
 903
 904                         client->timeout_resend =
 905                                 sd_event_source_unref(client->timeout_resend);
 906
 907                         if (client->state == DHCP_STATE_REBOOTING) {
 908                                 r = client_initialize(client);
 909                                 if (r < 0)
 910                                         goto error;
 911
 912                                 r = client_start(client);
 913                                 if (r < 0)
 914                                         goto error;
 915                         }
 916
 917                         goto error;
 918                 }
 919
 920                 if (r >= 0) {
 921                         client->timeout_resend =
 922                                 sd_event_source_unref(client->timeout_resend);
 923
 924                         if (IN_SET(client->state, DHCP_STATE_REQUESTING,
 925                                    DHCP_STATE_REBOOTING))
 926                                 notify_event = DHCP_EVENT_IP_ACQUIRE;
 927                         else if (r != DHCP_EVENT_IP_ACQUIRE)
 928                                 notify_event = r;
 929
 930                         client->state = DHCP_STATE_BOUND;
 931                         client->attempt = 1;
 932
 933                         client->last_addr = client->lease->address;
 934
 935                         r = client_set_lease_timeouts(client, time_now);
 936                         if (r < 0)
 937                                 goto error;
 938
 939                         if (notify_event)
 940                                 client_notify(client, notify_event);
 941
 942                         client->receive_message =
 943                                 sd_event_source_unref(client->receive_message);
 944                         client->fd = safe_close(client->fd);
 945                 }
 946
 947                 r = 0;
 948
 949                 break;
 950
 951         case DHCP_STATE_INIT:
 952         case DHCP_STATE_INIT_REBOOT:
 953         case DHCP_STATE_BOUND:
 954
 955                 break;
 956         }
 957
 958 error:
 959         if (r < 0 || r == DHCP_EVENT_NO_LEASE)
 960                 return client_stop(client, r);
 961
 962         return 0;
 963 }
 964
 965 static int client_receive_message_udp(sd_event_source *s, int fd,
 966                                       uint32_t revents, void *userdata) {
 967         sd_dhcp_client *client = userdata;
 968         _cleanup_free_ DHCPMessage *message = NULL;
 969         int buflen = 0, len, r;
 970         usec_t time_now;
 971
 972         assert(s);
 973         assert(client);
 974         assert(client->event);
 975
 976         r = ioctl(fd, FIONREAD, &buflen);
 977         if (r < 0 || buflen <= 0)
 978                 buflen = sizeof(DHCPMessage) + DHCP_MIN_OPTIONS_SIZE;
 979
 980         message = malloc0(buflen);
 981         if (!message)
 982                 return -ENOMEM;
 983
 984         len = read(fd, message, buflen);
 985         if (len < 0)
 986                 return 0;
 987
 988         r = sd_event_get_now_monotonic(client->event, &time_now);
 989         if (r < 0)
 990                 return client_stop(client, r);
 991
 992         return client_handle_message(client, message, len,
 993                                      time_now);
 994 }
 995
 996 static int client_receive_message_raw(sd_event_source *s, int fd,
 997                                       uint32_t revents, void *userdata) {
 998         sd_dhcp_client *client = userdata;
 999         _cleanup_free_ DHCPPacket *packet = NULL;
1000         usec_t time_now;
1001         uint8_t cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))];
1002         struct iovec iov = {};
1003         struct msghdr msg = {
1004                 .msg_iov = &iov,
1005                 .msg_iovlen = 1,
1006                 .msg_control = cmsgbuf,
1007                 .msg_controllen = sizeof(cmsgbuf),
1008         };
1009         struct cmsghdr *cmsg;
1010         bool checksum = true;
1011         int buflen = 0, len, r;
1012
1013         assert(s);
1014         assert(client);
1015         assert(client->event);
1016
1017         r = ioctl(fd, FIONREAD, &buflen);
1018         if (r < 0 || buflen <= 0)
1019                 buflen = sizeof(DHCPPacket) + DHCP_MIN_OPTIONS_SIZE;
1020
1021         packet = malloc0(buflen);
1022         if (!packet)
1023                 return -ENOMEM;
1024
1025         iov.iov_base = packet;
1026         iov.iov_len = buflen;
1027
1028         len = recvmsg(fd, &msg, 0);
1029         if (len < 0) {
1030                 log_dhcp_client(client, "could not receive message from raw "
1031                                 "socket: %s", strerror(errno));
1032                 return 0;
1033         }
1034
1035         for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
1036                 if (cmsg->cmsg_level == SOL_PACKET && cmsg->cmsg_type == PACKET_AUXDATA) {
1037                         struct tpacket_auxdata *aux = (void *)CMSG_DATA(cmsg);
1038
1039                         checksum = !(aux->tp_status & TP_STATUS_CSUMNOTREADY);
1040                         break;
1041                 }
1042         }
1043
1044         r = dhcp_packet_verify_headers(packet, len, checksum);
1045         if (r < 0)
1046                 return 0;
1047
1048         len -= DHCP_IP_UDP_SIZE;
1049
1050         r = sd_event_get_now_monotonic(client->event, &time_now);
1051         if (r < 0)
1052                 return client_stop(client, r);
1053
1054         return client_handle_message(client, &packet->dhcp, len, time_now);
1055 }
1056
1057 int sd_dhcp_client_start(sd_dhcp_client *client) {
1058         int r;
1059
1060         assert_return(client, -EINVAL);
1061
1062         r = client_initialize(client);
1063         if (r < 0)
1064                 return r;
1065
1066         if (client->last_addr)
1067                 client->state = DHCP_STATE_INIT_REBOOT;
1068
1069         return client_start(client);
1070 }
1071
1072 int sd_dhcp_client_stop(sd_dhcp_client *client) {
1073         return client_stop(client, DHCP_EVENT_STOP);
1074 }
1075
1076 int sd_dhcp_client_attach_event(sd_dhcp_client *client, sd_event *event,
1077                                 int priority) {
1078         int r;
1079
1080         assert_return(client, -EINVAL);
1081         assert_return(!client->event, -EBUSY);
1082
1083         if (event)
1084                 client->event = sd_event_ref(event);
1085         else {
1086                 r = sd_event_default(&client->event);
1087                 if (r < 0)
1088                         return 0;
1089         }
1090
1091         client->event_priority = priority;
1092
1093         return 0;
1094 }
1095
1096 int sd_dhcp_client_detach_event(sd_dhcp_client *client) {
1097         assert_return(client, -EINVAL);
1098
1099         client->event = sd_event_unref(client->event);
1100
1101         return 0;
1102 }
1103
1104 sd_event *sd_dhcp_client_get_event(sd_dhcp_client *client) {
1105         if (!client)
1106                 return NULL;
1107
1108         return client->event;
1109 }
1110
1111 void sd_dhcp_client_free(sd_dhcp_client *client) {
1112         if (!client)
1113                 return;
1114
1115         sd_dhcp_client_stop(client);
1116         sd_dhcp_client_detach_event(client);
1117
1118         free(client->req_opts);
1119         free(client);
1120 }
1121
1122 DEFINE_TRIVIAL_CLEANUP_FUNC(sd_dhcp_client*, sd_dhcp_client_free);
1123 #define _cleanup_dhcp_client_free_ _cleanup_(sd_dhcp_client_freep)
1124
1125 int sd_dhcp_client_new(sd_dhcp_client **ret) {
1126         _cleanup_dhcp_client_free_ sd_dhcp_client *client = NULL;
1127
1128         assert_return(ret, -EINVAL);
1129
1130         client = new0(sd_dhcp_client, 1);
1131         if (!client)
1132                 return -ENOMEM;
1133
1134         client->state = DHCP_STATE_INIT;
1135         client->index = -1;
1136         client->fd = -1;
1137         client->attempt = 1;
1138
1139         client->req_opts_size = ELEMENTSOF(default_req_opts);
1140
1141         client->req_opts = memdup(default_req_opts, client->req_opts_size);
1142         if (!client->req_opts)
1143                 return -ENOMEM;
1144
1145         *ret = client;
1146         client = NULL;
1147
1148         return 0;
1149 }