src/libsystemd/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
  27 #include "util.h"
  28 #include "list.h"
  29
  30 #include "dhcp-protocol.h"
  31 #include "dhcp-internal.h"
  32 #include "sd-dhcp-client.h"
  33
  34 #define DHCP_CLIENT_MIN_OPTIONS_SIZE            312
  35
  36 struct DHCPLease {
  37         uint32_t t1;
  38         uint32_t t2;
  39         uint32_t lifetime;
  40         be32_t address;
  41         be32_t server_address;
  42         be32_t subnet_mask;
  43         be32_t router;
  44         struct in_addr *dns;
  45         size_t dns_size;
  46         uint16_t mtu;
  47         char *hostname;
  48 };
  49
  50 typedef struct DHCPLease DHCPLease;
  51
  52 struct sd_dhcp_client {
  53         DHCPState state;
  54         sd_event *event;
  55         sd_event_source *timeout_resend;
  56         int index;
  57         int fd;
  58         union sockaddr_union link;
  59         sd_event_source *receive_message;
  60         uint8_t *req_opts;
  61         size_t req_opts_allocated;
  62         size_t req_opts_size;
  63         be32_t last_addr;
  64         struct ether_addr mac_addr;
  65         uint32_t xid;
  66         usec_t start_time;
  67         unsigned int attempt;
  68         usec_t request_sent;
  69         sd_event_source *timeout_t1;
  70         sd_event_source *timeout_t2;
  71         sd_event_source *timeout_expire;
  72         sd_dhcp_client_cb_t cb;
  73         void *userdata;
  74         DHCPLease *lease;
  75 };
  76
  77 static const uint8_t default_req_opts[] = {
  78         DHCP_OPTION_SUBNET_MASK,
  79         DHCP_OPTION_ROUTER,
  80         DHCP_OPTION_HOST_NAME,
  81         DHCP_OPTION_DOMAIN_NAME,
  82         DHCP_OPTION_DOMAIN_NAME_SERVER,
  83         DHCP_OPTION_NTP_SERVER,
  84 };
  85
  86 static int client_receive_message(sd_event_source *s, int fd,
  87                                   uint32_t revents, void *userdata);
  88
  89 int sd_dhcp_client_set_callback(sd_dhcp_client *client, sd_dhcp_client_cb_t cb,
  90                                 void *userdata) {
  91         assert_return(client, -EINVAL);
  92
  93         client->cb = cb;
  94         client->userdata = userdata;
  95
  96         return 0;
  97 }
  98
  99 int sd_dhcp_client_set_request_option(sd_dhcp_client *client, uint8_t option) {
 100         size_t i;
 101
 102         assert_return(client, -EINVAL);
 103         assert_return (client->state == DHCP_STATE_INIT, -EBUSY);
 104
 105         switch(option) {
 106         case DHCP_OPTION_PAD:
 107         case DHCP_OPTION_OVERLOAD:
 108         case DHCP_OPTION_MESSAGE_TYPE:
 109         case DHCP_OPTION_PARAMETER_REQUEST_LIST:
 110         case DHCP_OPTION_END:
 111                 return -EINVAL;
 112
 113         default:
 114                 break;
 115         }
 116
 117         for (i = 0; i < client->req_opts_size; i++)
 118                 if (client->req_opts[i] == option)
 119                         return -EEXIST;
 120
 121         if (!GREEDY_REALLOC(client->req_opts, client->req_opts_allocated,
 122                             client->req_opts_size + 1))
 123                 return -ENOMEM;
 124
 125         client->req_opts[client->req_opts_size++] = option;
 126
 127         return 0;
 128 }
 129
 130 int sd_dhcp_client_set_request_address(sd_dhcp_client *client,
 131                                        const struct in_addr *last_addr) {
 132         assert_return(client, -EINVAL);
 133         assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
 134
 135         if (last_addr)
 136                 client->last_addr = last_addr->s_addr;
 137         else
 138                 client->last_addr = INADDR_ANY;
 139
 140         return 0;
 141 }
 142
 143 int sd_dhcp_client_set_index(sd_dhcp_client *client, int interface_index) {
 144         assert_return(client, -EINVAL);
 145         assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
 146         assert_return(interface_index >= -1, -EINVAL);
 147
 148         client->index = interface_index;
 149
 150         return 0;
 151 }
 152
 153 int sd_dhcp_client_set_mac(sd_dhcp_client *client,
 154                            const struct ether_addr *addr) {
 155         assert_return(client, -EINVAL);
 156         assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
 157
 158         memcpy(&client->mac_addr, addr, ETH_ALEN);
 159
 160         return 0;
 161 }
 162
 163 int sd_dhcp_client_get_address(sd_dhcp_client *client, struct in_addr *addr) {
 164         assert_return(client, -EINVAL);
 165         assert_return(addr, -EINVAL);
 166
 167         switch (client->state) {
 168         case DHCP_STATE_INIT:
 169         case DHCP_STATE_SELECTING:
 170         case DHCP_STATE_INIT_REBOOT:
 171         case DHCP_STATE_REBOOTING:
 172         case DHCP_STATE_REQUESTING:
 173                 return -EADDRNOTAVAIL;
 174
 175         case DHCP_STATE_BOUND:
 176         case DHCP_STATE_RENEWING:
 177         case DHCP_STATE_REBINDING:
 178                 addr->s_addr = client->lease->address;
 179
 180                 break;
 181         }
 182
 183         return 0;
 184 }
 185
 186 int sd_dhcp_client_get_mtu(sd_dhcp_client *client, uint16_t *mtu) {
 187         assert_return(client, -EINVAL);
 188         assert_return(mtu, -EINVAL);
 189
 190         switch (client->state) {
 191         case DHCP_STATE_INIT:
 192         case DHCP_STATE_SELECTING:
 193         case DHCP_STATE_INIT_REBOOT:
 194         case DHCP_STATE_REBOOTING:
 195         case DHCP_STATE_REQUESTING:
 196                 return -EADDRNOTAVAIL;
 197
 198         case DHCP_STATE_BOUND:
 199         case DHCP_STATE_RENEWING:
 200         case DHCP_STATE_REBINDING:
 201                 if (client->lease->mtu)
 202                         *mtu = client->lease->mtu;
 203                 else
 204                         return -ENOENT;
 205
 206                 break;
 207         }
 208
 209         return 0;
 210 }
 211
 212 int sd_dhcp_client_get_dns(sd_dhcp_client *client, struct in_addr **addr, size_t *addr_size) {
 213         assert_return(client, -EINVAL);
 214         assert_return(addr, -EINVAL);
 215         assert_return(addr_size, -EINVAL);
 216
 217         switch (client->state) {
 218         case DHCP_STATE_INIT:
 219         case DHCP_STATE_SELECTING:
 220         case DHCP_STATE_INIT_REBOOT:
 221         case DHCP_STATE_REBOOTING:
 222         case DHCP_STATE_REQUESTING:
 223                 return -EADDRNOTAVAIL;
 224
 225         case DHCP_STATE_BOUND:
 226         case DHCP_STATE_RENEWING:
 227         case DHCP_STATE_REBINDING:
 228                 if (client->lease->dns_size) {
 229                         *addr_size = client->lease->dns_size;
 230                         *addr = client->lease->dns;
 231                 } else
 232                         return -ENOENT;
 233
 234                 break;
 235         }
 236
 237         return 0;
 238 }
 239
 240 int sd_dhcp_client_get_hostname(sd_dhcp_client *client, const char **hostname) {
 241         assert_return(client, -EINVAL);
 242         assert_return(hostname, -EINVAL);
 243
 244         switch (client->state) {
 245         case DHCP_STATE_INIT:
 246         case DHCP_STATE_SELECTING:
 247         case DHCP_STATE_INIT_REBOOT:
 248         case DHCP_STATE_REBOOTING:
 249         case DHCP_STATE_REQUESTING:
 250                 return -EADDRNOTAVAIL;
 251
 252         case DHCP_STATE_BOUND:
 253         case DHCP_STATE_RENEWING:
 254         case DHCP_STATE_REBINDING:
 255                 if (client->lease->hostname)
 256                         *hostname = client->lease->hostname;
 257                 else
 258                         return -ENOENT;
 259
 260                 break;
 261         }
 262
 263         return 0;
 264 }
 265
 266 int sd_dhcp_client_prefixlen(const struct in_addr *addr) {
 267         int len = 0;
 268         uint32_t mask;
 269
 270         assert_return(addr, -EADDRNOTAVAIL);
 271
 272         mask = be32toh(addr->s_addr);
 273         while (mask) {
 274                 len++;
 275                 mask = mask << 1;
 276         }
 277
 278         return len;
 279 }
 280
 281 int sd_dhcp_client_get_router(sd_dhcp_client *client, struct in_addr *addr) {
 282         assert_return(client, -EINVAL);
 283         assert_return(addr, -EINVAL);
 284
 285         switch (client->state) {
 286         case DHCP_STATE_INIT:
 287         case DHCP_STATE_SELECTING:
 288         case DHCP_STATE_INIT_REBOOT:
 289         case DHCP_STATE_REBOOTING:
 290         case DHCP_STATE_REQUESTING:
 291                 return -EADDRNOTAVAIL;
 292
 293         case DHCP_STATE_BOUND:
 294         case DHCP_STATE_RENEWING:
 295         case DHCP_STATE_REBINDING:
 296                 addr->s_addr = client->lease->router;
 297
 298                 break;
 299         }
 300
 301         return 0;
 302 }
 303
 304 int sd_dhcp_client_get_netmask(sd_dhcp_client *client, struct in_addr *addr) {
 305         assert_return(client, -EINVAL);
 306         assert_return(addr, -EINVAL);
 307
 308         switch (client->state) {
 309         case DHCP_STATE_INIT:
 310         case DHCP_STATE_SELECTING:
 311         case DHCP_STATE_INIT_REBOOT:
 312         case DHCP_STATE_REBOOTING:
 313         case DHCP_STATE_REQUESTING:
 314                 return -EADDRNOTAVAIL;
 315
 316         case DHCP_STATE_BOUND:
 317         case DHCP_STATE_RENEWING:
 318         case DHCP_STATE_REBINDING:
 319                 addr->s_addr = client->lease->subnet_mask;
 320
 321                 break;
 322         }
 323
 324         return 0;
 325 }
 326
 327 static int client_notify(sd_dhcp_client *client, int event) {
 328         if (client->cb)
 329                 client->cb(client, event, client->userdata);
 330
 331         return 0;
 332 }
 333
 334 static void lease_free(DHCPLease *lease) {
 335         if (!lease)
 336                 return;
 337
 338         free(lease->hostname);
 339         free(lease->dns);
 340         free(lease);
 341 }
 342
 343 DEFINE_TRIVIAL_CLEANUP_FUNC(DHCPLease*, lease_free);
 344 #define _cleanup_lease_free_ _cleanup_(lease_freep)
 345
 346 static int client_stop(sd_dhcp_client *client, int error) {
 347         assert_return(client, -EINVAL);
 348
 349         client->receive_message =
 350                 sd_event_source_unref(client->receive_message);
 351
 352         if (client->fd >= 0)
 353                 close(client->fd);
 354         client->fd = -1;
 355
 356         client->timeout_resend = sd_event_source_unref(client->timeout_resend);
 357
 358         client->timeout_t1 = sd_event_source_unref(client->timeout_t1);
 359         client->timeout_t2 = sd_event_source_unref(client->timeout_t2);
 360         client->timeout_expire = sd_event_source_unref(client->timeout_expire);
 361
 362         client->attempt = 1;
 363
 364         client_notify(client, error);
 365
 366         switch (client->state) {
 367
 368         case DHCP_STATE_INIT:
 369         case DHCP_STATE_SELECTING:
 370         case DHCP_STATE_REQUESTING:
 371         case DHCP_STATE_BOUND:
 372
 373                 client->start_time = 0;
 374                 client->state = DHCP_STATE_INIT;
 375                 break;
 376
 377         case DHCP_STATE_INIT_REBOOT:
 378         case DHCP_STATE_REBOOTING:
 379         case DHCP_STATE_RENEWING:
 380         case DHCP_STATE_REBINDING:
 381
 382                 break;
 383         }
 384
 385         if (client->lease) {
 386                 lease_free(client->lease);
 387                 client->lease = NULL;
 388         }
 389
 390         return 0;
 391 }
 392
 393 static int client_packet_init(sd_dhcp_client *client, uint8_t type,
 394                               DHCPMessage *message, uint16_t secs,
 395                               uint8_t **opt, size_t *optlen) {
 396         int err;
 397         be16_t max_size;
 398
 399         *opt = (uint8_t *)(message + 1);
 400
 401         if (*optlen < 4)
 402                 return -ENOBUFS;
 403         *optlen -= 4;
 404
 405         message->op = BOOTREQUEST;
 406         message->htype = 1;
 407         message->hlen = ETHER_ADDR_LEN;
 408         message->xid = htobe32(client->xid);
 409
 410         /* Although 'secs' field is a SHOULD in RFC 2131, certain DHCP servers
 411            refuse to issue an DHCP lease if 'secs' is set to zero */
 412         message->secs = htobe16(secs);
 413
 414         if (client->state == DHCP_STATE_RENEWING ||
 415             client->state == DHCP_STATE_REBINDING)
 416                 message->ciaddr = client->lease->address;
 417
 418         memcpy(&message->chaddr, &client->mac_addr, ETH_ALEN);
 419         (*opt)[0] = 0x63;
 420         (*opt)[1] = 0x82;
 421         (*opt)[2] = 0x53;
 422         (*opt)[3] = 0x63;
 423
 424         *opt += 4;
 425
 426         err = dhcp_option_append(opt, optlen, DHCP_OPTION_MESSAGE_TYPE, 1,
 427                                  &type);
 428         if (err < 0)
 429                 return err;
 430
 431         /* Some DHCP servers will refuse to issue an DHCP lease if the Cliient
 432            Identifier option is not set */
 433         err = dhcp_option_append(opt, optlen, DHCP_OPTION_CLIENT_IDENTIFIER,
 434                                  ETH_ALEN, &client->mac_addr);
 435         if (err < 0)
 436                 return err;
 437
 438         if (type == DHCP_DISCOVER || type == DHCP_REQUEST) {
 439                 err = dhcp_option_append(opt, optlen,
 440                                          DHCP_OPTION_PARAMETER_REQUEST_LIST,
 441                                          client->req_opts_size,
 442                                          client->req_opts);
 443                 if (err < 0)
 444                         return err;
 445
 446                 /* Some DHCP servers will send bigger DHCP packets than the
 447                    defined default size unless the Maximum Messge Size option
 448                    is explicitely set */
 449                 max_size = htobe16(DHCP_IP_UDP_SIZE + DHCP_MESSAGE_SIZE +
 450                                    DHCP_CLIENT_MIN_OPTIONS_SIZE);
 451                 err = dhcp_option_append(opt, optlen,
 452                                          DHCP_OPTION_MAXIMUM_MESSAGE_SIZE,
 453                                          2, &max_size);
 454                 if (err < 0)
 455                         return err;
 456         }
 457
 458         return 0;
 459 }
 460
 461 static uint16_t client_checksum(void *buf, int len) {
 462         uint32_t sum;
 463         uint16_t *check;
 464         int i;
 465         uint8_t *odd;
 466
 467         sum = 0;
 468         check = buf;
 469
 470         for (i = 0; i < len / 2 ; i++)
 471                 sum += check[i];
 472
 473         if (len & 0x01) {
 474                 odd = buf;
 475                 sum += odd[len - 1];
 476         }
 477
 478         while (sum >> 16)
 479                 sum = (sum & 0xffff) + (sum >> 16);
 480
 481         return ~sum;
 482 }
 483
 484 static void client_append_ip_headers(DHCPPacket *packet, uint16_t len) {
 485         packet->ip.version = IPVERSION;
 486         packet->ip.ihl = DHCP_IP_SIZE / 4;
 487         packet->ip.tot_len = htobe16(len);
 488
 489         packet->ip.protocol = IPPROTO_UDP;
 490         packet->ip.saddr = INADDR_ANY;
 491         packet->ip.daddr = INADDR_BROADCAST;
 492
 493         packet->udp.source = htobe16(DHCP_PORT_CLIENT);
 494         packet->udp.dest = htobe16(DHCP_PORT_SERVER);
 495         packet->udp.len = htobe16(len - DHCP_IP_SIZE);
 496
 497         packet->ip.check = packet->udp.len;
 498         packet->udp.check = client_checksum(&packet->ip.ttl, len - 8);
 499
 500         packet->ip.ttl = IPDEFTTL;
 501         packet->ip.check = 0;
 502         packet->ip.check = client_checksum(&packet->ip, DHCP_IP_SIZE);
 503 }
 504
 505 static int client_send_discover(sd_dhcp_client *client, uint16_t secs) {
 506         int err = 0;
 507         _cleanup_free_ DHCPPacket *discover;
 508         size_t optlen, len;
 509         uint8_t *opt;
 510
 511         optlen = DHCP_CLIENT_MIN_OPTIONS_SIZE;
 512         len = sizeof(DHCPPacket) + optlen;
 513
 514         discover = malloc0(len);
 515
 516         if (!discover)
 517                 return -ENOMEM;
 518
 519         err = client_packet_init(client, DHCP_DISCOVER, &discover->dhcp,
 520                                  secs, &opt, &optlen);
 521         if (err < 0)
 522                 return err;
 523
 524         if (client->last_addr != INADDR_ANY) {
 525                 err = dhcp_option_append(&opt, &optlen,
 526                                          DHCP_OPTION_REQUESTED_IP_ADDRESS,
 527                                          4, &client->last_addr);
 528                 if (err < 0)
 529                         return err;
 530         }
 531
 532         err = dhcp_option_append(&opt, &optlen, DHCP_OPTION_END, 0, NULL);
 533         if (err < 0)
 534                 return err;
 535
 536         client_append_ip_headers(discover, len);
 537
 538         err = dhcp_network_send_raw_socket(client->fd, &client->link,
 539                                            discover, len);
 540
 541         return err;
 542 }
 543
 544 static int client_send_request(sd_dhcp_client *client, uint16_t secs) {
 545         _cleanup_free_ DHCPPacket *request;
 546         size_t optlen, len;
 547         int err;
 548         uint8_t *opt;
 549
 550         optlen = DHCP_CLIENT_MIN_OPTIONS_SIZE;
 551         len = DHCP_MESSAGE_SIZE + optlen;
 552
 553         request = malloc0(len);
 554         if (!request)
 555                 return -ENOMEM;
 556
 557         err = client_packet_init(client, DHCP_REQUEST, &request->dhcp, secs,
 558                                  &opt, &optlen);
 559         if (err < 0)
 560                 return err;
 561
 562         if (client->state == DHCP_STATE_REQUESTING) {
 563                 err = dhcp_option_append(&opt, &optlen,
 564                                          DHCP_OPTION_REQUESTED_IP_ADDRESS,
 565                                          4, &client->lease->address);
 566                 if (err < 0)
 567                         return err;
 568
 569                 err = dhcp_option_append(&opt, &optlen,
 570                                          DHCP_OPTION_SERVER_IDENTIFIER,
 571                                          4, &client->lease->server_address);
 572                 if (err < 0)
 573                         return err;
 574         }
 575
 576         err = dhcp_option_append(&opt, &optlen, DHCP_OPTION_END, 0, NULL);
 577         if (err < 0)
 578                 return err;
 579
 580         if (client->state == DHCP_STATE_RENEWING) {
 581                 err = dhcp_network_send_udp_socket(client->fd,
 582                                                    client->lease->server_address,
 583                                                    &request->dhcp,
 584                                                    len - DHCP_IP_UDP_SIZE);
 585         } else {
 586                 client_append_ip_headers(request, len);
 587
 588                 err = dhcp_network_send_raw_socket(client->fd, &client->link,
 589                                                    request, len);
 590         }
 591
 592         return err;
 593 }
 594
 595 static int client_timeout_resend(sd_event_source *s, uint64_t usec,
 596                                  void *userdata) {
 597         sd_dhcp_client *client = userdata;
 598         usec_t next_timeout = 0;
 599         uint32_t time_left;
 600         uint16_t secs;
 601         int err = 0;
 602
 603         switch (client->state) {
 604         case DHCP_STATE_RENEWING:
 605
 606                 time_left = (client->lease->t2 - client->lease->t1)/2;
 607                 if (time_left < 60)
 608                         time_left = 60;
 609
 610                 next_timeout = usec + time_left * USEC_PER_SEC;
 611
 612                 break;
 613
 614         case DHCP_STATE_REBINDING:
 615
 616                 time_left = (client->lease->lifetime - client->lease->t2)/2;
 617                 if (time_left < 60)
 618                         time_left = 60;
 619
 620                 next_timeout = usec + time_left * USEC_PER_SEC;
 621                 break;
 622
 623         case DHCP_STATE_INIT:
 624         case DHCP_STATE_INIT_REBOOT:
 625         case DHCP_STATE_REBOOTING:
 626         case DHCP_STATE_SELECTING:
 627         case DHCP_STATE_REQUESTING:
 628         case DHCP_STATE_BOUND:
 629
 630                 if (client->attempt < 64)
 631                         client->attempt *= 2;
 632
 633                 next_timeout = usec + (client->attempt - 1) * USEC_PER_SEC;
 634
 635                 break;
 636         }
 637
 638         next_timeout += (random_u32() & 0x1fffff);
 639
 640         err = sd_event_add_monotonic(client->event, next_timeout,
 641                                      10 * USEC_PER_MSEC,
 642                                      client_timeout_resend, client,
 643                                      &client->timeout_resend);
 644         if (err < 0)
 645                 goto error;
 646
 647         secs = (usec - client->start_time) / USEC_PER_SEC;
 648
 649         switch (client->state) {
 650         case DHCP_STATE_INIT:
 651                 err = client_send_discover(client, secs);
 652                 if (err >= 0) {
 653                         client->state = DHCP_STATE_SELECTING;
 654                         client->attempt = 1;
 655                 } else {
 656                         if (client->attempt >= 64)
 657                                 goto error;
 658                 }
 659
 660                 break;
 661
 662         case DHCP_STATE_SELECTING:
 663                 err = client_send_discover(client, secs);
 664                 if (err < 0 && client->attempt >= 64)
 665                         goto error;
 666
 667                 break;
 668
 669         case DHCP_STATE_REQUESTING:
 670         case DHCP_STATE_RENEWING:
 671         case DHCP_STATE_REBINDING:
 672                 err = client_send_request(client, secs);
 673                 if (err < 0 && client->attempt >= 64)
 674                          goto error;
 675
 676                 client->request_sent = usec;
 677
 678                 break;
 679
 680         case DHCP_STATE_INIT_REBOOT:
 681         case DHCP_STATE_REBOOTING:
 682         case DHCP_STATE_BOUND:
 683
 684                 break;
 685         }
 686
 687         return 0;
 688
 689 error:
 690         client_stop(client, err);
 691
 692         /* Errors were dealt with when stopping the client, don't spill
 693            errors into the event loop handler */
 694         return 0;
 695 }
 696
 697 static int client_initialize_events(sd_dhcp_client *client, usec_t usec) {
 698         int r;
 699
 700         r = sd_event_add_io(client->event, client->fd, EPOLLIN,
 701                             client_receive_message, client,
 702                             &client->receive_message);
 703         if (r < 0)
 704                 goto error;
 705
 706         r = sd_event_add_monotonic(client->event, usec, 0,
 707                                    client_timeout_resend, client,
 708                                    &client->timeout_resend);
 709
 710 error:
 711         if (r < 0)
 712                 client_stop(client, r);
 713
 714         return 0;
 715
 716 }
 717
 718 static int client_timeout_expire(sd_event_source *s, uint64_t usec,
 719                                  void *userdata) {
 720         sd_dhcp_client *client = userdata;
 721
 722         client_stop(client, DHCP_EVENT_EXPIRED);
 723
 724         return 0;
 725 }
 726
 727 static int client_timeout_t2(sd_event_source *s, uint64_t usec, void *userdata) {
 728         sd_dhcp_client *client = userdata;
 729         int r;
 730
 731         if (client->fd >= 0) {
 732                 client->receive_message =
 733                         sd_event_source_unref(client->receive_message);
 734                 close(client->fd);
 735                 client->fd = -1;
 736         }
 737
 738         client->state = DHCP_STATE_REBINDING;
 739         client->attempt = 1;
 740
 741         r = dhcp_network_bind_raw_socket(client->index, &client->link);
 742         if (r < 0) {
 743                 client_stop(client, r);
 744                 return 0;
 745         }
 746
 747         client->fd = r;
 748
 749         return client_initialize_events(client, usec);
 750 }
 751
 752 static int client_timeout_t1(sd_event_source *s, uint64_t usec, void *userdata) {
 753         sd_dhcp_client *client = userdata;
 754         int r;
 755
 756         client->state = DHCP_STATE_RENEWING;
 757         client->attempt = 1;
 758
 759         r = dhcp_network_bind_udp_socket(client->index,
 760                                          client->lease->address);
 761         if (r < 0) {
 762                 client_stop(client, r);
 763                 return 0;
 764         }
 765
 766         client->fd = r;
 767
 768         return client_initialize_events(client, usec);
 769 }
 770
 771 static int client_parse_offer(uint8_t code, uint8_t len, const uint8_t *option,
 772                               void *user_data) {
 773         DHCPLease *lease = user_data;
 774         be32_t val;
 775
 776         switch(code) {
 777
 778         case DHCP_OPTION_IP_ADDRESS_LEASE_TIME:
 779                 if (len == 4) {
 780                         memcpy(&val, option, 4);
 781                         lease->lifetime = be32toh(val);
 782                 }
 783
 784                 break;
 785
 786         case DHCP_OPTION_SERVER_IDENTIFIER:
 787                 if (len >= 4)
 788                         memcpy(&lease->server_address, option, 4);
 789
 790                 break;
 791
 792         case DHCP_OPTION_SUBNET_MASK:
 793                 if (len >= 4)
 794                         memcpy(&lease->subnet_mask, option, 4);
 795
 796                 break;
 797
 798         case DHCP_OPTION_ROUTER:
 799                 if (len >= 4)
 800                         memcpy(&lease->router, option, 4);
 801
 802                 break;
 803
 804         case DHCP_OPTION_DOMAIN_NAME_SERVER:
 805                 if (len >= 4) {
 806                         unsigned i;
 807
 808                         lease->dns_size = len / 4;
 809
 810                         free(lease->dns);
 811                         lease->dns = new0(struct in_addr, lease->dns_size);
 812                         if (!lease->dns)
 813                                 return -ENOMEM;
 814
 815                         for (i = 0; i < lease->dns_size; i++) {
 816                                 memcpy(&lease->dns[i].s_addr, option + 4 * i, 4);
 817                         }
 818                 }
 819
 820                 break;
 821
 822         case DHCP_OPTION_INTERFACE_MTU:
 823                 if (len >= 2) {
 824                         be16_t mtu;
 825
 826                         memcpy(&mtu, option, 2);
 827                         lease->mtu = be16toh(mtu);
 828
 829                         if (lease->mtu < 68)
 830                                 lease->mtu = 0;
 831                 }
 832
 833                 break;
 834
 835         case DHCP_OPTION_HOST_NAME:
 836                 if (len >= 1) {
 837                         free(lease->hostname);
 838                         lease->hostname = strndup((const char *)option, len);
 839                 }
 840
 841                 break;
 842
 843         case DHCP_OPTION_RENEWAL_T1_TIME:
 844                 if (len == 4) {
 845                         memcpy(&val, option, 4);
 846                         lease->t1 = be32toh(val);
 847                 }
 848
 849                 break;
 850
 851         case DHCP_OPTION_REBINDING_T2_TIME:
 852                 if (len == 4) {
 853                         memcpy(&val, option, 4);
 854                         lease->t2 = be32toh(val);
 855                 }
 856
 857                 break;
 858         }
 859
 860         return 0;
 861 }
 862
 863 static int client_verify_headers(sd_dhcp_client *client, DHCPPacket *message,
 864                                  size_t len) {
 865         size_t hdrlen;
 866
 867         if (len < (DHCP_IP_UDP_SIZE + DHCP_MESSAGE_SIZE))
 868                 return -EINVAL;
 869
 870         hdrlen = message->ip.ihl * 4;
 871         if (hdrlen < 20 || hdrlen > len || client_checksum(&message->ip,
 872                                                            hdrlen))
 873                 return -EINVAL;
 874
 875         message->ip.check = message->udp.len;
 876         message->ip.ttl = 0;
 877
 878         if (hdrlen + be16toh(message->udp.len) > len ||
 879             client_checksum(&message->ip.ttl, be16toh(message->udp.len) + 12))
 880                 return -EINVAL;
 881
 882         if (be16toh(message->udp.source) != DHCP_PORT_SERVER ||
 883             be16toh(message->udp.dest) != DHCP_PORT_CLIENT)
 884                 return -EINVAL;
 885
 886         if (message->dhcp.op != BOOTREPLY)
 887                 return -EINVAL;
 888
 889         if (be32toh(message->dhcp.xid) != client->xid)
 890                 return -EINVAL;
 891
 892         if (memcmp(&message->dhcp.chaddr[0], &client->mac_addr.ether_addr_octet,
 893                     ETHER_ADDR_LEN))
 894                 return -EINVAL;
 895
 896         return 0;
 897 }
 898
 899 static int client_receive_offer(sd_dhcp_client *client, DHCPPacket *offer,
 900                                 size_t len) {
 901         _cleanup_lease_free_ DHCPLease *lease = NULL;
 902         int r;
 903
 904         r = client_verify_headers(client, offer, len);
 905         if (r < 0)
 906                 return r;
 907
 908         lease = new0(DHCPLease, 1);
 909         if (!lease)
 910                 return -ENOMEM;
 911
 912         len = len - DHCP_IP_UDP_SIZE;
 913         r = dhcp_option_parse(&offer->dhcp, len, client_parse_offer,
 914                               lease);
 915         if (r != DHCP_OFFER)
 916                 return -ENOMSG;
 917
 918         lease->address = offer->dhcp.yiaddr;
 919
 920         if (lease->address == INADDR_ANY ||
 921             lease->server_address == INADDR_ANY ||
 922             lease->subnet_mask == INADDR_ANY ||
 923             lease->lifetime == 0)
 924                 return -ENOMSG;
 925
 926         client->lease = lease;
 927         lease = NULL;
 928
 929         return 0;
 930 }
 931
 932 static int client_receive_ack(sd_dhcp_client *client, const uint8_t *buf,
 933                               size_t len) {
 934         DHCPPacket *ack;
 935         DHCPMessage *dhcp;
 936         _cleanup_lease_free_ DHCPLease *lease = NULL;
 937         int r;
 938
 939         if (client->state == DHCP_STATE_RENEWING) {
 940                 dhcp = (DHCPMessage *)buf;
 941         } else {
 942                 ack = (DHCPPacket *)buf;
 943
 944                 r = client_verify_headers(client, ack, len);
 945                 if (r < 0)
 946                         return r;
 947
 948                 dhcp = &ack->dhcp;
 949                 len -= DHCP_IP_UDP_SIZE;
 950         }
 951
 952         lease = new0(DHCPLease, 1);
 953         if (!lease)
 954                 return -ENOMEM;
 955
 956         r = dhcp_option_parse(dhcp, len, client_parse_offer, lease);
 957         if (r == DHCP_NAK)
 958                 return DHCP_EVENT_NO_LEASE;
 959
 960         if (r != DHCP_ACK)
 961                 return -ENOMSG;
 962
 963         lease->address = dhcp->yiaddr;
 964
 965         if (lease->address == INADDR_ANY ||
 966             lease->server_address == INADDR_ANY ||
 967             lease->subnet_mask == INADDR_ANY || lease->lifetime == 0)
 968                 return -ENOMSG;
 969
 970         r = DHCP_EVENT_IP_ACQUIRE;
 971         if (client->lease) {
 972                 if (client->lease->address != lease->address ||
 973                     client->lease->subnet_mask != lease->subnet_mask ||
 974                     client->lease->router != lease->router) {
 975                         r = DHCP_EVENT_IP_CHANGE;
 976                 }
 977
 978                 lease_free(client->lease);
 979         }
 980
 981         client->lease = lease;
 982         lease = NULL;
 983
 984         return r;
 985 }
 986
 987 static uint64_t client_compute_timeout(uint64_t request_sent,
 988                                        uint32_t lifetime) {
 989         return request_sent + (lifetime - 3) * USEC_PER_SEC +
 990                 + (random_u32() & 0x1fffff);
 991 }
 992
 993 static int client_set_lease_timeouts(sd_dhcp_client *client, uint64_t usec) {
 994         uint64_t next_timeout;
 995         int r;
 996
 997         if (client->lease->lifetime < 10)
 998                 return -EINVAL;
 999
1000         client->timeout_t1 = sd_event_source_unref(client->timeout_t1);
1001         client->timeout_t2 = sd_event_source_unref(client->timeout_t2);
1002         client->timeout_expire = sd_event_source_unref(client->timeout_expire);
1003
1004         if (!client->lease->t1)
1005                 client->lease->t1 = client->lease->lifetime / 2;
1006
1007         next_timeout = client_compute_timeout(client->request_sent,
1008                                               client->lease->t1);
1009         if (next_timeout < usec)
1010                 return -EINVAL;
1011
1012         r = sd_event_add_monotonic(client->event, next_timeout,
1013                                      10 * USEC_PER_MSEC,
1014                                      client_timeout_t1, client,
1015                                      &client->timeout_t1);
1016         if (r < 0)
1017                 return r;
1018
1019         if (!client->lease->t2)
1020                 client->lease->t2 = client->lease->lifetime * 7 / 8;
1021
1022         if (client->lease->t2 < client->lease->t1)
1023                 return -EINVAL;
1024
1025         if (client->lease->lifetime < client->lease->t2)
1026                 return -EINVAL;
1027
1028         next_timeout = client_compute_timeout(client->request_sent,
1029                                               client->lease->t2);
1030         if (next_timeout < usec)
1031                 return -EINVAL;
1032
1033         r = sd_event_add_monotonic(client->event, next_timeout,
1034                                      10 * USEC_PER_MSEC,
1035                                      client_timeout_t2, client,
1036                                      &client->timeout_t2);
1037         if (r < 0)
1038                 return r;
1039
1040         next_timeout = client_compute_timeout(client->request_sent,
1041                                               client->lease->lifetime);
1042         if (next_timeout < usec)
1043                 return -EINVAL;
1044
1045         r = sd_event_add_monotonic(client->event, next_timeout,
1046                                      10 * USEC_PER_MSEC,
1047                                      client_timeout_expire, client,
1048                                      &client->timeout_expire);
1049         if (r < 0)
1050                 return r;
1051
1052         return 0;
1053 }
1054
1055 static int client_receive_message(sd_event_source *s, int fd,
1056                                   uint32_t revents, void *userdata) {
1057         sd_dhcp_client *client = userdata;
1058         uint8_t buf[sizeof(DHCPPacket) + DHCP_CLIENT_MIN_OPTIONS_SIZE];
1059         int buflen = sizeof(buf);
1060         int len, r = 0, notify_event = 0;
1061         DHCPPacket *message;
1062         usec_t time_now;
1063
1064         len = read(fd, &buf, buflen);
1065         if (len < 0)
1066                 return 0;
1067
1068         r = sd_event_get_now_monotonic(client->event, &time_now);
1069         if (r < 0)
1070                 goto error;
1071
1072         switch (client->state) {
1073         case DHCP_STATE_SELECTING:
1074
1075                 message = (DHCPPacket *)&buf;
1076
1077                 if (client_receive_offer(client, message, len) >= 0) {
1078
1079                         client->timeout_resend =
1080                                 sd_event_source_unref(client->timeout_resend);
1081
1082                         client->state = DHCP_STATE_REQUESTING;
1083                         client->attempt = 1;
1084
1085                         r = sd_event_add_monotonic(client->event, time_now, 0,
1086                                                    client_timeout_resend,
1087                                                    client,
1088                                                    &client->timeout_resend);
1089                         if (r < 0)
1090                                 goto error;
1091                 }
1092
1093                 break;
1094
1095         case DHCP_STATE_REQUESTING:
1096         case DHCP_STATE_RENEWING:
1097         case DHCP_STATE_REBINDING:
1098
1099                 r = client_receive_ack(client, buf, len);
1100
1101                 if (r == DHCP_EVENT_NO_LEASE)
1102                         goto error;
1103
1104                 if (r >= 0) {
1105                         client->timeout_resend =
1106                                 sd_event_source_unref(client->timeout_resend);
1107
1108                         if (client->state == DHCP_STATE_REQUESTING)
1109                                 notify_event = DHCP_EVENT_IP_ACQUIRE;
1110                         else if (r != DHCP_EVENT_IP_ACQUIRE)
1111                                 notify_event = r;
1112
1113                         client->state = DHCP_STATE_BOUND;
1114                         client->attempt = 1;
1115
1116                         client->last_addr = client->lease->address;
1117
1118                         r = client_set_lease_timeouts(client, time_now);
1119                         if (r < 0)
1120                                 goto error;
1121
1122                         if (notify_event)
1123                                 client_notify(client, notify_event);
1124
1125                         client->receive_message =
1126                                 sd_event_source_unref(client->receive_message);
1127                         close(client->fd);
1128                         client->fd = -1;
1129                 }
1130
1131                 r = 0;
1132
1133                 break;
1134
1135         case DHCP_STATE_INIT:
1136         case DHCP_STATE_INIT_REBOOT:
1137         case DHCP_STATE_REBOOTING:
1138         case DHCP_STATE_BOUND:
1139
1140                 break;
1141         }
1142
1143 error:
1144         if (r < 0 || r == DHCP_EVENT_NO_LEASE)
1145                 return client_stop(client, r);
1146
1147         return 0;
1148 }
1149
1150 int sd_dhcp_client_start(sd_dhcp_client *client) {
1151         int r;
1152
1153         assert_return(client, -EINVAL);
1154         assert_return(client->index > 0, -EINVAL);
1155         assert_return(client->state == DHCP_STATE_INIT ||
1156                       client->state == DHCP_STATE_INIT_REBOOT, -EBUSY);
1157
1158         client->xid = random_u32();
1159
1160         r = dhcp_network_bind_raw_socket(client->index, &client->link);
1161
1162         if (r < 0) {
1163                 client_stop(client, r);
1164                 return r;
1165         }
1166
1167         client->fd = r;
1168         client->start_time = now(CLOCK_MONOTONIC);
1169
1170         return client_initialize_events(client, client->start_time);
1171 }
1172
1173 int sd_dhcp_client_stop(sd_dhcp_client *client) {
1174         return client_stop(client, DHCP_EVENT_STOP);
1175 }
1176
1177 sd_dhcp_client *sd_dhcp_client_free(sd_dhcp_client *client) {
1178         assert_return(client, NULL);
1179
1180         sd_dhcp_client_stop(client);
1181
1182         sd_event_unref(client->event);
1183         free(client->req_opts);
1184         free(client);
1185
1186         return NULL;
1187 }
1188
1189 sd_dhcp_client *sd_dhcp_client_new(sd_event *event) {
1190         sd_dhcp_client *client;
1191
1192         assert_return(event, NULL);
1193
1194         client = new0(sd_dhcp_client, 1);
1195         if (!client)
1196                 return NULL;
1197
1198         client->event = sd_event_ref(event);
1199         client->state = DHCP_STATE_INIT;
1200         client->index = -1;
1201         client->fd = -1;
1202         client->attempt = 1;
1203
1204         client->req_opts_size = ELEMENTSOF(default_req_opts);
1205
1206         client->req_opts = memdup(default_req_opts, client->req_opts_size);
1207         if (!client->req_opts) {
1208                 free(client);
1209                 return NULL;
1210         }
1211
1212         return client;
1213 }