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 *domainname;
  48         char *hostname;
  49 };
  50
  51 typedef struct DHCPLease DHCPLease;
  52
  53 struct sd_dhcp_client {
  54         DHCPState state;
  55         sd_event *event;
  56         int event_priority;
  57         sd_event_source *timeout_resend;
  58         int index;
  59         int fd;
  60         union sockaddr_union link;
  61         sd_event_source *receive_message;
  62         uint8_t *req_opts;
  63         size_t req_opts_allocated;
  64         size_t req_opts_size;
  65         be32_t last_addr;
  66         struct ether_addr mac_addr;
  67         uint32_t xid;
  68         usec_t start_time;
  69         unsigned int attempt;
  70         usec_t request_sent;
  71         sd_event_source *timeout_t1;
  72         sd_event_source *timeout_t2;
  73         sd_event_source *timeout_expire;
  74         sd_dhcp_client_cb_t cb;
  75         void *userdata;
  76         DHCPLease *lease;
  77 };
  78
  79 static const uint8_t default_req_opts[] = {
  80         DHCP_OPTION_SUBNET_MASK,
  81         DHCP_OPTION_ROUTER,
  82         DHCP_OPTION_HOST_NAME,
  83         DHCP_OPTION_DOMAIN_NAME,
  84         DHCP_OPTION_DOMAIN_NAME_SERVER,
  85         DHCP_OPTION_NTP_SERVER,
  86 };
  87
  88 static int client_receive_message(sd_event_source *s, int fd,
  89                                   uint32_t revents, void *userdata);
  90
  91 int sd_dhcp_client_set_callback(sd_dhcp_client *client, sd_dhcp_client_cb_t cb,
  92                                 void *userdata) {
  93         assert_return(client, -EINVAL);
  94
  95         client->cb = cb;
  96         client->userdata = userdata;
  97
  98         return 0;
  99 }
 100
 101 int sd_dhcp_client_set_request_option(sd_dhcp_client *client, uint8_t option) {
 102         size_t i;
 103
 104         assert_return(client, -EINVAL);
 105         assert_return (client->state == DHCP_STATE_INIT, -EBUSY);
 106
 107         switch(option) {
 108         case DHCP_OPTION_PAD:
 109         case DHCP_OPTION_OVERLOAD:
 110         case DHCP_OPTION_MESSAGE_TYPE:
 111         case DHCP_OPTION_PARAMETER_REQUEST_LIST:
 112         case DHCP_OPTION_END:
 113                 return -EINVAL;
 114
 115         default:
 116                 break;
 117         }
 118
 119         for (i = 0; i < client->req_opts_size; i++)
 120                 if (client->req_opts[i] == option)
 121                         return -EEXIST;
 122
 123         if (!GREEDY_REALLOC(client->req_opts, client->req_opts_allocated,
 124                             client->req_opts_size + 1))
 125                 return -ENOMEM;
 126
 127         client->req_opts[client->req_opts_size++] = option;
 128
 129         return 0;
 130 }
 131
 132 int sd_dhcp_client_set_request_address(sd_dhcp_client *client,
 133                                        const struct in_addr *last_addr) {
 134         assert_return(client, -EINVAL);
 135         assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
 136
 137         if (last_addr)
 138                 client->last_addr = last_addr->s_addr;
 139         else
 140                 client->last_addr = INADDR_ANY;
 141
 142         return 0;
 143 }
 144
 145 int sd_dhcp_client_set_index(sd_dhcp_client *client, int interface_index) {
 146         assert_return(client, -EINVAL);
 147         assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
 148         assert_return(interface_index >= -1, -EINVAL);
 149
 150         client->index = interface_index;
 151
 152         return 0;
 153 }
 154
 155 int sd_dhcp_client_set_mac(sd_dhcp_client *client,
 156                            const struct ether_addr *addr) {
 157         assert_return(client, -EINVAL);
 158         assert_return(client->state == DHCP_STATE_INIT, -EBUSY);
 159
 160         memcpy(&client->mac_addr, addr, ETH_ALEN);
 161
 162         return 0;
 163 }
 164
 165 int sd_dhcp_client_get_address(sd_dhcp_client *client, struct in_addr *addr) {
 166         assert_return(client, -EINVAL);
 167         assert_return(addr, -EINVAL);
 168
 169         switch (client->state) {
 170         case DHCP_STATE_INIT:
 171         case DHCP_STATE_SELECTING:
 172         case DHCP_STATE_INIT_REBOOT:
 173         case DHCP_STATE_REBOOTING:
 174         case DHCP_STATE_REQUESTING:
 175                 return -EADDRNOTAVAIL;
 176
 177         case DHCP_STATE_BOUND:
 178         case DHCP_STATE_RENEWING:
 179         case DHCP_STATE_REBINDING:
 180                 addr->s_addr = client->lease->address;
 181
 182                 break;
 183         }
 184
 185         return 0;
 186 }
 187
 188 int sd_dhcp_client_get_mtu(sd_dhcp_client *client, uint16_t *mtu) {
 189         assert_return(client, -EINVAL);
 190         assert_return(mtu, -EINVAL);
 191
 192         switch (client->state) {
 193         case DHCP_STATE_INIT:
 194         case DHCP_STATE_SELECTING:
 195         case DHCP_STATE_INIT_REBOOT:
 196         case DHCP_STATE_REBOOTING:
 197         case DHCP_STATE_REQUESTING:
 198                 return -EADDRNOTAVAIL;
 199
 200         case DHCP_STATE_BOUND:
 201         case DHCP_STATE_RENEWING:
 202         case DHCP_STATE_REBINDING:
 203                 if (client->lease->mtu)
 204                         *mtu = client->lease->mtu;
 205                 else
 206                         return -ENOENT;
 207
 208                 break;
 209         }
 210
 211         return 0;
 212 }
 213
 214 int sd_dhcp_client_get_dns(sd_dhcp_client *client, struct in_addr **addr, size_t *addr_size) {
 215         assert_return(client, -EINVAL);
 216         assert_return(addr, -EINVAL);
 217         assert_return(addr_size, -EINVAL);
 218
 219         switch (client->state) {
 220         case DHCP_STATE_INIT:
 221         case DHCP_STATE_SELECTING:
 222         case DHCP_STATE_INIT_REBOOT:
 223         case DHCP_STATE_REBOOTING:
 224         case DHCP_STATE_REQUESTING:
 225                 return -EADDRNOTAVAIL;
 226
 227         case DHCP_STATE_BOUND:
 228         case DHCP_STATE_RENEWING:
 229         case DHCP_STATE_REBINDING:
 230                 if (client->lease->dns_size) {
 231                         *addr_size = client->lease->dns_size;
 232                         *addr = client->lease->dns;
 233                 } else
 234                         return -ENOENT;
 235
 236                 break;
 237         }
 238
 239         return 0;
 240 }
 241
 242 int sd_dhcp_client_get_domainname(sd_dhcp_client *client, const char **domainname) {
 243         assert_return(client, -EINVAL);
 244         assert_return(domainname, -EINVAL);
 245
 246         switch (client->state) {
 247         case DHCP_STATE_INIT:
 248         case DHCP_STATE_SELECTING:
 249         case DHCP_STATE_INIT_REBOOT:
 250         case DHCP_STATE_REBOOTING:
 251         case DHCP_STATE_REQUESTING:
 252                 return -EADDRNOTAVAIL;
 253
 254         case DHCP_STATE_BOUND:
 255         case DHCP_STATE_RENEWING:
 256         case DHCP_STATE_REBINDING:
 257                 if (client->lease->domainname)
 258                         *domainname = client->lease->domainname;
 259                 else
 260                         return -ENOENT;
 261
 262                 break;
 263         }
 264
 265         return 0;
 266 }
 267
 268 int sd_dhcp_client_get_hostname(sd_dhcp_client *client, const char **hostname) {
 269         assert_return(client, -EINVAL);
 270         assert_return(hostname, -EINVAL);
 271
 272         switch (client->state) {
 273         case DHCP_STATE_INIT:
 274         case DHCP_STATE_SELECTING:
 275         case DHCP_STATE_INIT_REBOOT:
 276         case DHCP_STATE_REBOOTING:
 277         case DHCP_STATE_REQUESTING:
 278                 return -EADDRNOTAVAIL;
 279
 280         case DHCP_STATE_BOUND:
 281         case DHCP_STATE_RENEWING:
 282         case DHCP_STATE_REBINDING:
 283                 if (client->lease->hostname)
 284                         *hostname = client->lease->hostname;
 285                 else
 286                         return -ENOENT;
 287
 288                 break;
 289         }
 290
 291         return 0;
 292 }
 293
 294 int sd_dhcp_client_prefixlen(const struct in_addr *addr) {
 295         int len = 0;
 296         uint32_t mask;
 297
 298         assert_return(addr, -EADDRNOTAVAIL);
 299
 300         mask = be32toh(addr->s_addr);
 301         while (mask) {
 302                 len++;
 303                 mask = mask << 1;
 304         }
 305
 306         return len;
 307 }
 308
 309 int sd_dhcp_client_get_router(sd_dhcp_client *client, struct in_addr *addr) {
 310         assert_return(client, -EINVAL);
 311         assert_return(addr, -EINVAL);
 312
 313         switch (client->state) {
 314         case DHCP_STATE_INIT:
 315         case DHCP_STATE_SELECTING:
 316         case DHCP_STATE_INIT_REBOOT:
 317         case DHCP_STATE_REBOOTING:
 318         case DHCP_STATE_REQUESTING:
 319                 return -EADDRNOTAVAIL;
 320
 321         case DHCP_STATE_BOUND:
 322         case DHCP_STATE_RENEWING:
 323         case DHCP_STATE_REBINDING:
 324                 addr->s_addr = client->lease->router;
 325
 326                 break;
 327         }
 328
 329         return 0;
 330 }
 331
 332 int sd_dhcp_client_get_netmask(sd_dhcp_client *client, struct in_addr *addr) {
 333         assert_return(client, -EINVAL);
 334         assert_return(addr, -EINVAL);
 335
 336         switch (client->state) {
 337         case DHCP_STATE_INIT:
 338         case DHCP_STATE_SELECTING:
 339         case DHCP_STATE_INIT_REBOOT:
 340         case DHCP_STATE_REBOOTING:
 341         case DHCP_STATE_REQUESTING:
 342                 return -EADDRNOTAVAIL;
 343
 344         case DHCP_STATE_BOUND:
 345         case DHCP_STATE_RENEWING:
 346         case DHCP_STATE_REBINDING:
 347                 addr->s_addr = client->lease->subnet_mask;
 348
 349                 break;
 350         }
 351
 352         return 0;
 353 }
 354
 355 static int client_notify(sd_dhcp_client *client, int event) {
 356         if (client->cb)
 357                 client->cb(client, event, client->userdata);
 358
 359         return 0;
 360 }
 361
 362 static void lease_free(DHCPLease *lease) {
 363         if (!lease)
 364                 return;
 365
 366         free(lease->hostname);
 367         free(lease->domainname);
 368         free(lease->dns);
 369         free(lease);
 370 }
 371
 372 DEFINE_TRIVIAL_CLEANUP_FUNC(DHCPLease*, lease_free);
 373 #define _cleanup_lease_free_ _cleanup_(lease_freep)
 374
 375 static int client_stop(sd_dhcp_client *client, int error) {
 376         assert_return(client, -EINVAL);
 377
 378         client->receive_message =
 379                 sd_event_source_unref(client->receive_message);
 380
 381         if (client->fd >= 0)
 382                 close(client->fd);
 383         client->fd = -1;
 384
 385         client->timeout_resend = sd_event_source_unref(client->timeout_resend);
 386
 387         client->timeout_t1 = sd_event_source_unref(client->timeout_t1);
 388         client->timeout_t2 = sd_event_source_unref(client->timeout_t2);
 389         client->timeout_expire = sd_event_source_unref(client->timeout_expire);
 390
 391         client->attempt = 1;
 392
 393         client_notify(client, error);
 394
 395         switch (client->state) {
 396
 397         case DHCP_STATE_INIT:
 398         case DHCP_STATE_SELECTING:
 399         case DHCP_STATE_REQUESTING:
 400         case DHCP_STATE_BOUND:
 401
 402                 client->start_time = 0;
 403                 client->state = DHCP_STATE_INIT;
 404                 break;
 405
 406         case DHCP_STATE_INIT_REBOOT:
 407         case DHCP_STATE_REBOOTING:
 408         case DHCP_STATE_RENEWING:
 409         case DHCP_STATE_REBINDING:
 410
 411                 break;
 412         }
 413
 414         if (client->lease) {
 415                 lease_free(client->lease);
 416                 client->lease = NULL;
 417         }
 418
 419         return 0;
 420 }
 421
 422 static int client_packet_init(sd_dhcp_client *client, uint8_t type,
 423                               DHCPMessage *message, uint16_t secs,
 424                               uint8_t **opt, size_t *optlen) {
 425         int err;
 426         be16_t max_size;
 427
 428         *opt = (uint8_t *)(message + 1);
 429
 430         if (*optlen < 4)
 431                 return -ENOBUFS;
 432         *optlen -= 4;
 433
 434         message->op = BOOTREQUEST;
 435         message->htype = 1;
 436         message->hlen = ETHER_ADDR_LEN;
 437         message->xid = htobe32(client->xid);
 438
 439         /* Although 'secs' field is a SHOULD in RFC 2131, certain DHCP servers
 440            refuse to issue an DHCP lease if 'secs' is set to zero */
 441         message->secs = htobe16(secs);
 442
 443         if (client->state == DHCP_STATE_RENEWING ||
 444             client->state == DHCP_STATE_REBINDING)
 445                 message->ciaddr = client->lease->address;
 446
 447         memcpy(&message->chaddr, &client->mac_addr, ETH_ALEN);
 448         (*opt)[0] = 0x63;
 449         (*opt)[1] = 0x82;
 450         (*opt)[2] = 0x53;
 451         (*opt)[3] = 0x63;
 452
 453         *opt += 4;
 454
 455         err = dhcp_option_append(opt, optlen, DHCP_OPTION_MESSAGE_TYPE, 1,
 456                                  &type);
 457         if (err < 0)
 458                 return err;
 459
 460         /* Some DHCP servers will refuse to issue an DHCP lease if the Cliient
 461            Identifier option is not set */
 462         err = dhcp_option_append(opt, optlen, DHCP_OPTION_CLIENT_IDENTIFIER,
 463                                  ETH_ALEN, &client->mac_addr);
 464         if (err < 0)
 465                 return err;
 466
 467         if (type == DHCP_DISCOVER || type == DHCP_REQUEST) {
 468                 err = dhcp_option_append(opt, optlen,
 469                                          DHCP_OPTION_PARAMETER_REQUEST_LIST,
 470                                          client->req_opts_size,
 471                                          client->req_opts);
 472                 if (err < 0)
 473                         return err;
 474
 475                 /* Some DHCP servers will send bigger DHCP packets than the
 476                    defined default size unless the Maximum Messge Size option
 477                    is explicitely set */
 478                 max_size = htobe16(DHCP_IP_UDP_SIZE + DHCP_MESSAGE_SIZE +
 479                                    DHCP_CLIENT_MIN_OPTIONS_SIZE);
 480                 err = dhcp_option_append(opt, optlen,
 481                                          DHCP_OPTION_MAXIMUM_MESSAGE_SIZE,
 482                                          2, &max_size);
 483                 if (err < 0)
 484                         return err;
 485         }
 486
 487         return 0;
 488 }
 489
 490 static uint16_t client_checksum(void *buf, int len) {
 491         uint32_t sum;
 492         uint16_t *check;
 493         int i;
 494         uint8_t *odd;
 495
 496         sum = 0;
 497         check = buf;
 498
 499         for (i = 0; i < len / 2 ; i++)
 500                 sum += check[i];
 501
 502         if (len & 0x01) {
 503                 odd = buf;
 504                 sum += odd[len - 1];
 505         }
 506
 507         while (sum >> 16)
 508                 sum = (sum & 0xffff) + (sum >> 16);
 509
 510         return ~sum;
 511 }
 512
 513 static void client_append_ip_headers(DHCPPacket *packet, uint16_t len) {
 514         packet->ip.version = IPVERSION;
 515         packet->ip.ihl = DHCP_IP_SIZE / 4;
 516         packet->ip.tot_len = htobe16(len);
 517
 518         packet->ip.protocol = IPPROTO_UDP;
 519         packet->ip.saddr = INADDR_ANY;
 520         packet->ip.daddr = INADDR_BROADCAST;
 521
 522         packet->udp.source = htobe16(DHCP_PORT_CLIENT);
 523         packet->udp.dest = htobe16(DHCP_PORT_SERVER);
 524         packet->udp.len = htobe16(len - DHCP_IP_SIZE);
 525
 526         packet->ip.check = packet->udp.len;
 527         packet->udp.check = client_checksum(&packet->ip.ttl, len - 8);
 528
 529         packet->ip.ttl = IPDEFTTL;
 530         packet->ip.check = 0;
 531         packet->ip.check = client_checksum(&packet->ip, DHCP_IP_SIZE);
 532 }
 533
 534 static int client_send_discover(sd_dhcp_client *client, uint16_t secs) {
 535         int err = 0;
 536         _cleanup_free_ DHCPPacket *discover;
 537         size_t optlen, len;
 538         uint8_t *opt;
 539
 540         optlen = DHCP_CLIENT_MIN_OPTIONS_SIZE;
 541         len = sizeof(DHCPPacket) + optlen;
 542
 543         discover = malloc0(len);
 544
 545         if (!discover)
 546                 return -ENOMEM;
 547
 548         err = client_packet_init(client, DHCP_DISCOVER, &discover->dhcp,
 549                                  secs, &opt, &optlen);
 550         if (err < 0)
 551                 return err;
 552
 553         if (client->last_addr != INADDR_ANY) {
 554                 err = dhcp_option_append(&opt, &optlen,
 555                                          DHCP_OPTION_REQUESTED_IP_ADDRESS,
 556                                          4, &client->last_addr);
 557                 if (err < 0)
 558                         return err;
 559         }
 560
 561         err = dhcp_option_append(&opt, &optlen, DHCP_OPTION_END, 0, NULL);
 562         if (err < 0)
 563                 return err;
 564
 565         client_append_ip_headers(discover, len);
 566
 567         err = dhcp_network_send_raw_socket(client->fd, &client->link,
 568                                            discover, len);
 569
 570         return err;
 571 }
 572
 573 static int client_send_request(sd_dhcp_client *client, uint16_t secs) {
 574         _cleanup_free_ DHCPPacket *request;
 575         size_t optlen, len;
 576         int err;
 577         uint8_t *opt;
 578
 579         optlen = DHCP_CLIENT_MIN_OPTIONS_SIZE;
 580         len = DHCP_MESSAGE_SIZE + optlen;
 581
 582         request = malloc0(len);
 583         if (!request)
 584                 return -ENOMEM;
 585
 586         err = client_packet_init(client, DHCP_REQUEST, &request->dhcp, secs,
 587                                  &opt, &optlen);
 588         if (err < 0)
 589                 return err;
 590
 591         if (client->state == DHCP_STATE_REQUESTING) {
 592                 err = dhcp_option_append(&opt, &optlen,
 593                                          DHCP_OPTION_REQUESTED_IP_ADDRESS,
 594                                          4, &client->lease->address);
 595                 if (err < 0)
 596                         return err;
 597
 598                 err = dhcp_option_append(&opt, &optlen,
 599                                          DHCP_OPTION_SERVER_IDENTIFIER,
 600                                          4, &client->lease->server_address);
 601                 if (err < 0)
 602                         return err;
 603         }
 604
 605         err = dhcp_option_append(&opt, &optlen, DHCP_OPTION_END, 0, NULL);
 606         if (err < 0)
 607                 return err;
 608
 609         if (client->state == DHCP_STATE_RENEWING) {
 610                 err = dhcp_network_send_udp_socket(client->fd,
 611                                                    client->lease->server_address,
 612                                                    &request->dhcp,
 613                                                    len - DHCP_IP_UDP_SIZE);
 614         } else {
 615                 client_append_ip_headers(request, len);
 616
 617                 err = dhcp_network_send_raw_socket(client->fd, &client->link,
 618                                                    request, len);
 619         }
 620
 621         return err;
 622 }
 623
 624 static int client_timeout_resend(sd_event_source *s, uint64_t usec,
 625                                  void *userdata) {
 626         sd_dhcp_client *client = userdata;
 627         usec_t next_timeout = 0;
 628         uint32_t time_left;
 629         uint16_t secs;
 630         int r = 0;
 631
 632         assert(s);
 633         assert(client);
 634         assert(client->event);
 635
 636         switch (client->state) {
 637         case DHCP_STATE_RENEWING:
 638
 639                 time_left = (client->lease->t2 - client->lease->t1)/2;
 640                 if (time_left < 60)
 641                         time_left = 60;
 642
 643                 next_timeout = usec + time_left * USEC_PER_SEC;
 644
 645                 break;
 646
 647         case DHCP_STATE_REBINDING:
 648
 649                 time_left = (client->lease->lifetime - client->lease->t2)/2;
 650                 if (time_left < 60)
 651                         time_left = 60;
 652
 653                 next_timeout = usec + time_left * USEC_PER_SEC;
 654                 break;
 655
 656         case DHCP_STATE_INIT:
 657         case DHCP_STATE_INIT_REBOOT:
 658         case DHCP_STATE_REBOOTING:
 659         case DHCP_STATE_SELECTING:
 660         case DHCP_STATE_REQUESTING:
 661         case DHCP_STATE_BOUND:
 662
 663                 if (client->attempt < 64)
 664                         client->attempt *= 2;
 665
 666                 next_timeout = usec + (client->attempt - 1) * USEC_PER_SEC;
 667
 668                 break;
 669         }
 670
 671         next_timeout += (random_u32() & 0x1fffff);
 672
 673         r = sd_event_add_monotonic(client->event, next_timeout,
 674                                      10 * USEC_PER_MSEC,
 675                                      client_timeout_resend, client,
 676                                      &client->timeout_resend);
 677         if (r < 0)
 678                 goto error;
 679
 680         r = sd_event_source_set_priority(client->timeout_resend, client->event_priority);
 681         if (r < 0)
 682                 goto error;
 683
 684         secs = (usec - client->start_time) / USEC_PER_SEC;
 685
 686         switch (client->state) {
 687         case DHCP_STATE_INIT:
 688                 r = client_send_discover(client, secs);
 689                 if (r >= 0) {
 690                         client->state = DHCP_STATE_SELECTING;
 691                         client->attempt = 1;
 692                 } else {
 693                         if (client->attempt >= 64)
 694                                 goto error;
 695                 }
 696
 697                 break;
 698
 699         case DHCP_STATE_SELECTING:
 700                 r = client_send_discover(client, secs);
 701                 if (r < 0 && client->attempt >= 64)
 702                         goto error;
 703
 704                 break;
 705
 706         case DHCP_STATE_REQUESTING:
 707         case DHCP_STATE_RENEWING:
 708         case DHCP_STATE_REBINDING:
 709                 r = client_send_request(client, secs);
 710                 if (r < 0 && client->attempt >= 64)
 711                          goto error;
 712
 713                 client->request_sent = usec;
 714
 715                 break;
 716
 717         case DHCP_STATE_INIT_REBOOT:
 718         case DHCP_STATE_REBOOTING:
 719         case DHCP_STATE_BOUND:
 720
 721                 break;
 722         }
 723
 724         return 0;
 725
 726 error:
 727         client_stop(client, r);
 728
 729         /* Errors were dealt with when stopping the client, don't spill
 730            errors into the event loop handler */
 731         return 0;
 732 }
 733
 734 static int client_initialize_events(sd_dhcp_client *client, usec_t usec) {
 735         int r;
 736
 737         assert(client);
 738         assert(client->event);
 739
 740         r = sd_event_add_io(client->event, client->fd, EPOLLIN,
 741                             client_receive_message, client,
 742                             &client->receive_message);
 743         if (r < 0)
 744                 goto error;
 745
 746         r = sd_event_source_set_priority(client->receive_message, client->event_priority);
 747         if (r < 0)
 748                 goto error;
 749
 750         r = sd_event_add_monotonic(client->event, usec, 0,
 751                                    client_timeout_resend, client,
 752                                    &client->timeout_resend);
 753         if (r < 0)
 754                 goto error;
 755
 756         r = sd_event_source_set_priority(client->timeout_resend, client->event_priority);
 757
 758 error:
 759         if (r < 0)
 760                 client_stop(client, r);
 761
 762         return 0;
 763
 764 }
 765
 766 static int client_timeout_expire(sd_event_source *s, uint64_t usec,
 767                                  void *userdata) {
 768         sd_dhcp_client *client = userdata;
 769
 770         client_stop(client, DHCP_EVENT_EXPIRED);
 771
 772         return 0;
 773 }
 774
 775 static int client_timeout_t2(sd_event_source *s, uint64_t usec, void *userdata) {
 776         sd_dhcp_client *client = userdata;
 777         int r;
 778
 779         if (client->fd >= 0) {
 780                 client->receive_message =
 781                         sd_event_source_unref(client->receive_message);
 782                 close(client->fd);
 783                 client->fd = -1;
 784         }
 785
 786         client->state = DHCP_STATE_REBINDING;
 787         client->attempt = 1;
 788
 789         r = dhcp_network_bind_raw_socket(client->index, &client->link);
 790         if (r < 0) {
 791                 client_stop(client, r);
 792                 return 0;
 793         }
 794
 795         client->fd = r;
 796
 797         return client_initialize_events(client, usec);
 798 }
 799
 800 static int client_timeout_t1(sd_event_source *s, uint64_t usec, void *userdata) {
 801         sd_dhcp_client *client = userdata;
 802         int r;
 803
 804         client->state = DHCP_STATE_RENEWING;
 805         client->attempt = 1;
 806
 807         r = dhcp_network_bind_udp_socket(client->index,
 808                                          client->lease->address);
 809         if (r < 0) {
 810                 client_stop(client, r);
 811                 return 0;
 812         }
 813
 814         client->fd = r;
 815
 816         return client_initialize_events(client, usec);
 817 }
 818
 819 static int client_parse_offer(uint8_t code, uint8_t len, const uint8_t *option,
 820                               void *user_data) {
 821         DHCPLease *lease = user_data;
 822         be32_t val;
 823
 824         switch(code) {
 825
 826         case DHCP_OPTION_IP_ADDRESS_LEASE_TIME:
 827                 if (len == 4) {
 828                         memcpy(&val, option, 4);
 829                         lease->lifetime = be32toh(val);
 830                 }
 831
 832                 break;
 833
 834         case DHCP_OPTION_SERVER_IDENTIFIER:
 835                 if (len >= 4)
 836                         memcpy(&lease->server_address, option, 4);
 837
 838                 break;
 839
 840         case DHCP_OPTION_SUBNET_MASK:
 841                 if (len >= 4)
 842                         memcpy(&lease->subnet_mask, option, 4);
 843
 844                 break;
 845
 846         case DHCP_OPTION_ROUTER:
 847                 if (len >= 4)
 848                         memcpy(&lease->router, option, 4);
 849
 850                 break;
 851
 852         case DHCP_OPTION_DOMAIN_NAME_SERVER:
 853                 if (len >= 4) {
 854                         unsigned i;
 855
 856                         lease->dns_size = len / 4;
 857
 858                         free(lease->dns);
 859                         lease->dns = new0(struct in_addr, lease->dns_size);
 860                         if (!lease->dns)
 861                                 return -ENOMEM;
 862
 863                         for (i = 0; i < lease->dns_size; i++) {
 864                                 memcpy(&lease->dns[i].s_addr, option + 4 * i, 4);
 865                         }
 866                 }
 867
 868                 break;
 869
 870         case DHCP_OPTION_INTERFACE_MTU:
 871                 if (len >= 2) {
 872                         be16_t mtu;
 873
 874                         memcpy(&mtu, option, 2);
 875                         lease->mtu = be16toh(mtu);
 876
 877                         if (lease->mtu < 68)
 878                                 lease->mtu = 0;
 879                 }
 880
 881                 break;
 882
 883         case DHCP_OPTION_DOMAIN_NAME:
 884                 if (len >= 1) {
 885                         free(lease->domainname);
 886                         lease->domainname = strndup((const char *)option, len);
 887                 }
 888
 889                 break;
 890
 891         case DHCP_OPTION_HOST_NAME:
 892                 if (len >= 1) {
 893                         free(lease->hostname);
 894                         lease->hostname = strndup((const char *)option, len);
 895                 }
 896
 897                 break;
 898
 899         case DHCP_OPTION_RENEWAL_T1_TIME:
 900                 if (len == 4) {
 901                         memcpy(&val, option, 4);
 902                         lease->t1 = be32toh(val);
 903                 }
 904
 905                 break;
 906
 907         case DHCP_OPTION_REBINDING_T2_TIME:
 908                 if (len == 4) {
 909                         memcpy(&val, option, 4);
 910                         lease->t2 = be32toh(val);
 911                 }
 912
 913                 break;
 914         }
 915
 916         return 0;
 917 }
 918
 919 static int client_verify_headers(sd_dhcp_client *client, DHCPPacket *message,
 920                                  size_t len) {
 921         size_t hdrlen;
 922
 923         if (len < (DHCP_IP_UDP_SIZE + DHCP_MESSAGE_SIZE))
 924                 return -EINVAL;
 925
 926         hdrlen = message->ip.ihl * 4;
 927         if (hdrlen < 20 || hdrlen > len || client_checksum(&message->ip,
 928                                                            hdrlen))
 929                 return -EINVAL;
 930
 931         message->ip.check = message->udp.len;
 932         message->ip.ttl = 0;
 933
 934         if (hdrlen + be16toh(message->udp.len) > len ||
 935             client_checksum(&message->ip.ttl, be16toh(message->udp.len) + 12))
 936                 return -EINVAL;
 937
 938         if (be16toh(message->udp.source) != DHCP_PORT_SERVER ||
 939             be16toh(message->udp.dest) != DHCP_PORT_CLIENT)
 940                 return -EINVAL;
 941
 942         if (message->dhcp.op != BOOTREPLY)
 943                 return -EINVAL;
 944
 945         if (be32toh(message->dhcp.xid) != client->xid)
 946                 return -EINVAL;
 947
 948         if (memcmp(&message->dhcp.chaddr[0], &client->mac_addr.ether_addr_octet,
 949                     ETHER_ADDR_LEN))
 950                 return -EINVAL;
 951
 952         return 0;
 953 }
 954
 955 static int client_receive_offer(sd_dhcp_client *client, DHCPPacket *offer,
 956                                 size_t len) {
 957         _cleanup_lease_free_ DHCPLease *lease = NULL;
 958         int r;
 959
 960         r = client_verify_headers(client, offer, len);
 961         if (r < 0)
 962                 return r;
 963
 964         lease = new0(DHCPLease, 1);
 965         if (!lease)
 966                 return -ENOMEM;
 967
 968         len = len - DHCP_IP_UDP_SIZE;
 969         r = dhcp_option_parse(&offer->dhcp, len, client_parse_offer,
 970                               lease);
 971         if (r != DHCP_OFFER)
 972                 return -ENOMSG;
 973
 974         lease->address = offer->dhcp.yiaddr;
 975
 976         if (lease->address == INADDR_ANY ||
 977             lease->server_address == INADDR_ANY ||
 978             lease->subnet_mask == INADDR_ANY ||
 979             lease->lifetime == 0)
 980                 return -ENOMSG;
 981
 982         client->lease = lease;
 983         lease = NULL;
 984
 985         return 0;
 986 }
 987
 988 static int client_receive_ack(sd_dhcp_client *client, const uint8_t *buf,
 989                               size_t len) {
 990         DHCPPacket *ack;
 991         DHCPMessage *dhcp;
 992         _cleanup_lease_free_ DHCPLease *lease = NULL;
 993         int r;
 994
 995         if (client->state == DHCP_STATE_RENEWING) {
 996                 dhcp = (DHCPMessage *)buf;
 997         } else {
 998                 ack = (DHCPPacket *)buf;
 999
1000                 r = client_verify_headers(client, ack, len);
1001                 if (r < 0)
1002                         return r;
1003
1004                 dhcp = &ack->dhcp;
1005                 len -= DHCP_IP_UDP_SIZE;
1006         }
1007
1008         lease = new0(DHCPLease, 1);
1009         if (!lease)
1010                 return -ENOMEM;
1011
1012         r = dhcp_option_parse(dhcp, len, client_parse_offer, lease);
1013         if (r == DHCP_NAK)
1014                 return DHCP_EVENT_NO_LEASE;
1015
1016         if (r != DHCP_ACK)
1017                 return -ENOMSG;
1018
1019         lease->address = dhcp->yiaddr;
1020
1021         if (lease->address == INADDR_ANY ||
1022             lease->server_address == INADDR_ANY ||
1023             lease->subnet_mask == INADDR_ANY || lease->lifetime == 0)
1024                 return -ENOMSG;
1025
1026         r = DHCP_EVENT_IP_ACQUIRE;
1027         if (client->lease) {
1028                 if (client->lease->address != lease->address ||
1029                     client->lease->subnet_mask != lease->subnet_mask ||
1030                     client->lease->router != lease->router) {
1031                         r = DHCP_EVENT_IP_CHANGE;
1032                 }
1033
1034                 lease_free(client->lease);
1035         }
1036
1037         client->lease = lease;
1038         lease = NULL;
1039
1040         return r;
1041 }
1042
1043 static uint64_t client_compute_timeout(uint64_t request_sent,
1044                                        uint32_t lifetime) {
1045         return request_sent + (lifetime - 3) * USEC_PER_SEC +
1046                 + (random_u32() & 0x1fffff);
1047 }
1048
1049 static int client_set_lease_timeouts(sd_dhcp_client *client, uint64_t usec) {
1050         uint64_t next_timeout;
1051         int r;
1052
1053         assert(client);
1054         assert(client->event);
1055
1056         if (client->lease->lifetime < 10)
1057                 return -EINVAL;
1058
1059         client->timeout_t1 = sd_event_source_unref(client->timeout_t1);
1060         client->timeout_t2 = sd_event_source_unref(client->timeout_t2);
1061         client->timeout_expire = sd_event_source_unref(client->timeout_expire);
1062
1063         if (!client->lease->t1)
1064                 client->lease->t1 = client->lease->lifetime / 2;
1065
1066         next_timeout = client_compute_timeout(client->request_sent,
1067                                               client->lease->t1);
1068         if (next_timeout < usec)
1069                 return -EINVAL;
1070
1071         r = sd_event_add_monotonic(client->event, next_timeout,
1072                                      10 * USEC_PER_MSEC,
1073                                      client_timeout_t1, client,
1074                                      &client->timeout_t1);
1075         if (r < 0)
1076                 return r;
1077
1078         r = sd_event_source_set_priority(client->timeout_t1, client->event_priority);
1079         if (r < 0)
1080                 return r;
1081
1082         if (!client->lease->t2)
1083                 client->lease->t2 = client->lease->lifetime * 7 / 8;
1084
1085         if (client->lease->t2 < client->lease->t1)
1086                 return -EINVAL;
1087
1088         if (client->lease->lifetime < client->lease->t2)
1089                 return -EINVAL;
1090
1091         next_timeout = client_compute_timeout(client->request_sent,
1092                                               client->lease->t2);
1093         if (next_timeout < usec)
1094                 return -EINVAL;
1095
1096         r = sd_event_add_monotonic(client->event, next_timeout,
1097                                      10 * USEC_PER_MSEC,
1098                                      client_timeout_t2, client,
1099                                      &client->timeout_t2);
1100         if (r < 0)
1101                 return r;
1102
1103         r = sd_event_source_set_priority(client->timeout_t2, client->event_priority);
1104         if (r < 0)
1105                 return r;
1106
1107         next_timeout = client_compute_timeout(client->request_sent,
1108                                               client->lease->lifetime);
1109         if (next_timeout < usec)
1110                 return -EINVAL;
1111
1112         r = sd_event_add_monotonic(client->event, next_timeout,
1113                                      10 * USEC_PER_MSEC,
1114                                      client_timeout_expire, client,
1115                                      &client->timeout_expire);
1116         if (r < 0)
1117                 return r;
1118
1119         r = sd_event_source_set_priority(client->timeout_expire, client->event_priority);
1120         if (r < 0)
1121                 return r;
1122
1123         return 0;
1124 }
1125
1126 static int client_receive_message(sd_event_source *s, int fd,
1127                                   uint32_t revents, void *userdata) {
1128         sd_dhcp_client *client = userdata;
1129         uint8_t buf[sizeof(DHCPPacket) + DHCP_CLIENT_MIN_OPTIONS_SIZE];
1130         int buflen = sizeof(buf);
1131         int len, r = 0, notify_event = 0;
1132         DHCPPacket *message;
1133         usec_t time_now;
1134
1135         assert(s);
1136         assert(client);
1137         assert(client->event);
1138
1139         len = read(fd, &buf, buflen);
1140         if (len < 0)
1141                 return 0;
1142
1143         r = sd_event_get_now_monotonic(client->event, &time_now);
1144         if (r < 0)
1145                 goto error;
1146
1147         switch (client->state) {
1148         case DHCP_STATE_SELECTING:
1149
1150                 message = (DHCPPacket *)&buf;
1151
1152                 if (client_receive_offer(client, message, len) >= 0) {
1153
1154                         client->timeout_resend =
1155                                 sd_event_source_unref(client->timeout_resend);
1156
1157                         client->state = DHCP_STATE_REQUESTING;
1158                         client->attempt = 1;
1159
1160                         r = sd_event_add_monotonic(client->event, time_now, 0,
1161                                                    client_timeout_resend,
1162                                                    client,
1163                                                    &client->timeout_resend);
1164                         if (r < 0)
1165                                 goto error;
1166
1167                         r = sd_event_source_set_priority(client->timeout_resend, client->event_priority);
1168                         if (r < 0)
1169                                 goto error;
1170                 }
1171
1172                 break;
1173
1174         case DHCP_STATE_REQUESTING:
1175         case DHCP_STATE_RENEWING:
1176         case DHCP_STATE_REBINDING:
1177
1178                 r = client_receive_ack(client, buf, len);
1179
1180                 if (r == DHCP_EVENT_NO_LEASE)
1181                         goto error;
1182
1183                 if (r >= 0) {
1184                         client->timeout_resend =
1185                                 sd_event_source_unref(client->timeout_resend);
1186
1187                         if (client->state == DHCP_STATE_REQUESTING)
1188                                 notify_event = DHCP_EVENT_IP_ACQUIRE;
1189                         else if (r != DHCP_EVENT_IP_ACQUIRE)
1190                                 notify_event = r;
1191
1192                         client->state = DHCP_STATE_BOUND;
1193                         client->attempt = 1;
1194
1195                         client->last_addr = client->lease->address;
1196
1197                         r = client_set_lease_timeouts(client, time_now);
1198                         if (r < 0)
1199                                 goto error;
1200
1201                         if (notify_event)
1202                                 client_notify(client, notify_event);
1203
1204                         client->receive_message =
1205                                 sd_event_source_unref(client->receive_message);
1206                         close(client->fd);
1207                         client->fd = -1;
1208                 }
1209
1210                 r = 0;
1211
1212                 break;
1213
1214         case DHCP_STATE_INIT:
1215         case DHCP_STATE_INIT_REBOOT:
1216         case DHCP_STATE_REBOOTING:
1217         case DHCP_STATE_BOUND:
1218
1219                 break;
1220         }
1221
1222 error:
1223         if (r < 0 || r == DHCP_EVENT_NO_LEASE)
1224                 return client_stop(client, r);
1225
1226         return 0;
1227 }
1228
1229 int sd_dhcp_client_start(sd_dhcp_client *client) {
1230         int r;
1231
1232         assert_return(client, -EINVAL);
1233         assert_return(client->event, -EINVAL);
1234         assert_return(client->index > 0, -EINVAL);
1235         assert_return(client->state == DHCP_STATE_INIT ||
1236                       client->state == DHCP_STATE_INIT_REBOOT, -EBUSY);
1237
1238         client->xid = random_u32();
1239
1240         r = dhcp_network_bind_raw_socket(client->index, &client->link);
1241
1242         if (r < 0) {
1243                 client_stop(client, r);
1244                 return r;
1245         }
1246
1247         client->fd = r;
1248         client->start_time = now(CLOCK_MONOTONIC);
1249
1250         return client_initialize_events(client, client->start_time);
1251 }
1252
1253 int sd_dhcp_client_stop(sd_dhcp_client *client) {
1254         return client_stop(client, DHCP_EVENT_STOP);
1255 }
1256
1257 int sd_dhcp_client_attach_event(sd_dhcp_client *client, sd_event *event, int priority) {
1258         int r;
1259
1260         assert_return(client, -EINVAL);
1261         assert_return(!client->event, -EBUSY);
1262
1263         if (event)
1264                 client->event = sd_event_ref(event);
1265         else {
1266                 r = sd_event_default(&client->event);
1267                 if (r < 0)
1268                         return 0;
1269         }
1270
1271         client->event_priority = priority;
1272
1273         return 0;
1274 }
1275
1276 int sd_dhcp_client_detach_event(sd_dhcp_client *client) {
1277         assert_return(client, -EINVAL);
1278
1279         client->event = sd_event_unref(client->event);
1280
1281         return 0;
1282 }
1283
1284 sd_event *sd_dhcp_client_get_event(sd_dhcp_client *client) {
1285         if (!client)
1286                 return NULL;
1287
1288         return client->event;
1289 }
1290
1291 void sd_dhcp_client_free(sd_dhcp_client *client) {
1292         if (!client)
1293                 return;
1294
1295         sd_dhcp_client_stop(client);
1296         sd_dhcp_client_detach_event(client);
1297
1298         free(client->req_opts);
1299         free(client);
1300 }
1301
1302 DEFINE_TRIVIAL_CLEANUP_FUNC(sd_dhcp_client*, sd_dhcp_client_free);
1303 #define _cleanup_dhcp_client_free_ _cleanup_(sd_dhcp_client_freep)
1304
1305 int sd_dhcp_client_new(sd_dhcp_client **ret) {
1306         _cleanup_dhcp_client_free_ sd_dhcp_client *client = NULL;
1307
1308         assert_return(ret, -EINVAL);
1309
1310         client = new0(sd_dhcp_client, 1);
1311         if (!client)
1312                 return -ENOMEM;
1313
1314         client->state = DHCP_STATE_INIT;
1315         client->index = -1;
1316         client->fd = -1;
1317         client->attempt = 1;
1318
1319         client->req_opts_size = ELEMENTSOF(default_req_opts);
1320
1321         client->req_opts = memdup(default_req_opts, client->req_opts_size);
1322         if (!client->req_opts)
1323                 return -ENOMEM;
1324
1325         *ret = client;
1326         client = NULL;
1327
1328         return 0;
1329 }