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