networking/udhcp/dhcpc.c

   1 /* dhcpc.c
   2  *
   3  * udhcp DHCP client
   4  *
   5  * Russ Dill <Russ.Dill@asu.edu> July 2001
   6  *
   7  * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
   8  */
   9
  10 #include <sys/file.h>
  11 #include <unistd.h>
  12 #include <getopt.h>
  13 #include <stdlib.h>
  14 #include <sys/socket.h>
  15 #include <netinet/in.h>
  16 #include <arpa/inet.h>
  17 #include <signal.h>
  18 #include <time.h>
  19 #include <string.h>
  20 #include <sys/ioctl.h>
  21 #include <net/if.h>
  22 #include <errno.h>
  23
  24 #include "common.h"
  25 #include "dhcpd.h"
  26 #include "dhcpc.h"
  27 #include "options.h"
  28 #include "clientpacket.h"
  29 #include "clientsocket.h"
  30 #include "socket.h"
  31 #include "signalpipe.h"
  32
  33 static int state;
  34 static unsigned long requested_ip; /* = 0 */
  35 static unsigned long server_addr;
  36 static unsigned long timeout;
  37 static int packet_num; /* = 0 */
  38 static int fd = -1;
  39
  40 #define LISTEN_NONE 0
  41 #define LISTEN_KERNEL 1
  42 #define LISTEN_RAW 2
  43 static int listen_mode;
  44
  45 struct client_config_t client_config = {
  46         /* Default options. */
  47         .abort_if_no_lease = 0,
  48         .foreground = 0,
  49         .quit_after_lease = 0,
  50         .background_if_no_lease = 0,
  51         .interface = "eth0",
  52         .pidfile = NULL,
  53         .script = DEFAULT_SCRIPT,
  54         .clientid = NULL,
  55         .vendorclass = NULL,
  56         .hostname = NULL,
  57         .fqdn = NULL,
  58         .ifindex = 0,
  59         .retries = 3,
  60         .timeout = 3,
  61         .arp = "\0\0\0\0\0\0",          /* appease gcc-3.0 */
  62 };
  63
  64 #ifndef IN_BUSYBOX
  65 static void ATTRIBUTE_NORETURN show_usage(void)
  66 {
  67         printf(
  68 "Usage: udhcpc [OPTIONS]\n\n"
  69 "  -c, --clientid=CLIENTID         Set client identifier - type is first char\n"
  70 "  -C, --clientid-none             Suppress default client identifier\n"
  71 "  -V, --vendorclass=CLASSID       Set vendor class identifier\n"
  72 "  -H, --hostname=HOSTNAME         Client hostname\n"
  73 "  -h                              Alias for -H\n"
  74 "  -F, --fqdn=FQDN                 Client fully qualified domain name\n"
  75 "  -f, --foreground                Do not fork after getting lease\n"
  76 "  -b, --background                Fork to background if lease cannot be\n"
  77 "                                  immediately negotiated.\n"
  78 "  -i, --interface=INTERFACE       Interface to use (default: eth0)\n"
  79 "  -n, --now                       Exit with failure if lease cannot be\n"
  80 "                                  immediately negotiated.\n"
  81 "  -p, --pidfile=file              Store process ID of daemon in file\n"
  82 "  -q, --quit                      Quit after obtaining lease\n"
  83 "  -r, --request=IP                IP address to request (default: none)\n"
  84 "  -s, --script=file               Run file at dhcp events (default:\n"
  85 "                                  " DEFAULT_SCRIPT ")\n"
  86 "  -T, --timeout=seconds           Try to get the lease for the amount of\n"
  87 "                                  seconds (default: 3)\n"
  88 "  -t, --retries=NUM               Send up to NUM request packets\n"
  89 "  -v, --version                   Display version\n"
  90         );
  91         exit(0);
  92 }
  93 #else
  94 #define show_usage bb_show_usage
  95 extern void show_usage(void) ATTRIBUTE_NORETURN;
  96 #endif
  97
  98
  99 /* just a little helper */
 100 static void change_mode(int new_mode)
 101 {
 102         DEBUG(LOG_INFO, "entering %s listen mode",
 103                 new_mode ? (new_mode == 1 ? "kernel" : "raw") : "none");
 104         if (fd >= 0) close(fd);
 105         fd = -1;
 106         listen_mode = new_mode;
 107 }
 108
 109
 110 /* perform a renew */
 111 static void perform_renew(void)
 112 {
 113         LOG(LOG_INFO, "Performing a DHCP renew");
 114         switch (state) {
 115         case BOUND:
 116                 change_mode(LISTEN_KERNEL);
 117         case RENEWING:
 118         case REBINDING:
 119                 state = RENEW_REQUESTED;
 120                 break;
 121         case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
 122                 udhcp_run_script(NULL, "deconfig");
 123         case REQUESTING:
 124         case RELEASED:
 125                 change_mode(LISTEN_RAW);
 126                 state = INIT_SELECTING;
 127                 break;
 128         case INIT_SELECTING:
 129                 break;
 130         }
 131
 132         /* start things over */
 133         packet_num = 0;
 134
 135         /* Kill any timeouts because the user wants this to hurry along */
 136         timeout = 0;
 137 }
 138
 139
 140 /* perform a release */
 141 static void perform_release(void)
 142 {
 143         char buffer[16];
 144         struct in_addr temp_addr;
 145
 146         /* send release packet */
 147         if (state == BOUND || state == RENEWING || state == REBINDING) {
 148                 temp_addr.s_addr = server_addr;
 149                 sprintf(buffer, "%s", inet_ntoa(temp_addr));
 150                 temp_addr.s_addr = requested_ip;
 151                 LOG(LOG_INFO, "Unicasting a release of %s to %s",
 152                                 inet_ntoa(temp_addr), buffer);
 153                 send_release(server_addr, requested_ip); /* unicast */
 154                 udhcp_run_script(NULL, "deconfig");
 155         }
 156         LOG(LOG_INFO, "Entering released state");
 157
 158         change_mode(LISTEN_NONE);
 159         state = RELEASED;
 160         timeout = 0x7fffffff;
 161 }
 162
 163
 164 static void client_background(void)
 165 {
 166         udhcp_background(client_config.pidfile);
 167         client_config.foreground = 1; /* Do not fork again. */
 168         client_config.background_if_no_lease = 0;
 169 }
 170
 171
 172 #ifdef COMBINED_BINARY
 173 int udhcpc_main(int argc, char *argv[])
 174 #else
 175 int main(int argc, char *argv[])
 176 #endif
 177 {
 178         uint8_t *temp, *message;
 179         unsigned long t1 = 0, t2 = 0, xid = 0;
 180         unsigned long start = 0, lease;
 181         fd_set rfds;
 182         int retval;
 183         struct timeval tv;
 184         int c, len;
 185         struct dhcpMessage packet;
 186         struct in_addr temp_addr;
 187         long now;
 188         int max_fd;
 189         int sig;
 190         int no_clientid = 0;
 191
 192         static const struct option arg_options[] = {
 193                 {"clientid",    required_argument,      0, 'c'},
 194                 {"clientid-none", no_argument,          0, 'C'},
 195                 {"vendorclass", required_argument,      0, 'V'},
 196                 {"foreground",  no_argument,            0, 'f'},
 197                 {"background",  no_argument,            0, 'b'},
 198                 {"hostname",    required_argument,      0, 'H'},
 199                 {"hostname",    required_argument,      0, 'h'},
 200                 {"fqdn",        required_argument,      0, 'F'},
 201                 {"interface",   required_argument,      0, 'i'},
 202                 {"now",         no_argument,            0, 'n'},
 203                 {"pidfile",     required_argument,      0, 'p'},
 204                 {"quit",        no_argument,            0, 'q'},
 205                 {"request",     required_argument,      0, 'r'},
 206                 {"script",      required_argument,      0, 's'},
 207                 {"timeout",     required_argument,      0, 'T'},
 208                 {"version",     no_argument,            0, 'v'},
 209                 {"retries",     required_argument,      0, 't'},
 210                 {0, 0, 0, 0}
 211         };
 212
 213         /* get options */
 214         while (1) {
 215                 int option_index = 0;
 216                 c = getopt_long(argc, argv, "c:CV:fbH:h:F:i:np:qr:s:T:t:v", arg_options, &option_index);
 217                 if (c == -1) break;
 218
 219                 switch (c) {
 220                 case 'c':
 221                         if (no_clientid) show_usage();
 222                         len = strlen(optarg) > 255 ? 255 : strlen(optarg);
 223                         free(client_config.clientid);
 224                         client_config.clientid = xmalloc(len + 2);
 225                         client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
 226                         client_config.clientid[OPT_LEN] = len;
 227                         client_config.clientid[OPT_DATA] = '\0';
 228                         strncpy((char*)client_config.clientid + OPT_DATA, optarg, len);
 229                         break;
 230                 case 'C':
 231                         if (client_config.clientid) show_usage();
 232                         no_clientid = 1;
 233                         break;
 234                 case 'V':
 235                         len = strlen(optarg) > 255 ? 255 : strlen(optarg);
 236                         free(client_config.vendorclass);
 237                         client_config.vendorclass = xmalloc(len + 2);
 238                         client_config.vendorclass[OPT_CODE] = DHCP_VENDOR;
 239                         client_config.vendorclass[OPT_LEN] = len;
 240                         strncpy((char*)client_config.vendorclass + OPT_DATA, optarg, len);
 241                         break;
 242                 case 'f':
 243                         client_config.foreground = 1;
 244                         break;
 245                 case 'b':
 246                         client_config.background_if_no_lease = 1;
 247                         break;
 248                 case 'h':
 249                 case 'H':
 250                         len = strlen(optarg) > 255 ? 255 : strlen(optarg);
 251                         free(client_config.hostname);
 252                         client_config.hostname = xmalloc(len + 2);
 253                         client_config.hostname[OPT_CODE] = DHCP_HOST_NAME;
 254                         client_config.hostname[OPT_LEN] = len;
 255                         strncpy((char*)client_config.hostname + 2, optarg, len);
 256                         break;
 257                 case 'F':
 258                         len = strlen(optarg) > 255 ? 255 : strlen(optarg);
 259                         free(client_config.fqdn);
 260                         client_config.fqdn = xmalloc(len + 5);
 261                         client_config.fqdn[OPT_CODE] = DHCP_FQDN;
 262                         client_config.fqdn[OPT_LEN] = len + 3;
 263                         /* Flags: 0000NEOS
 264                         S: 1 => Client requests Server to update A RR in DNS as well as PTR
 265                         O: 1 => Server indicates to client that DNS has been updated regardless
 266                         E: 1 => Name data is DNS format, i.e. <4>host<6>domain<4>com<0> not "host.domain.com"
 267                         N: 1 => Client requests Server to not update DNS
 268                         */
 269                         client_config.fqdn[OPT_LEN + 1] = 0x1;
 270                         client_config.fqdn[OPT_LEN + 2] = 0;
 271                         client_config.fqdn[OPT_LEN + 3] = 0;
 272                         strncpy((char*)client_config.fqdn + 5, optarg, len);
 273                         break;
 274                 case 'i':
 275                         client_config.interface =  optarg;
 276                         break;
 277                 case 'n':
 278                         client_config.abort_if_no_lease = 1;
 279                         break;
 280                 case 'p':
 281                         client_config.pidfile = optarg;
 282                         break;
 283                 case 'q':
 284                         client_config.quit_after_lease = 1;
 285                         break;
 286                 case 'r':
 287                         requested_ip = inet_addr(optarg);
 288                         break;
 289                 case 's':
 290                         client_config.script = optarg;
 291                         break;
 292                 case 'T':
 293                         client_config.timeout = atoi(optarg);
 294                         break;
 295                 case 't':
 296                         client_config.retries = atoi(optarg);
 297                         break;
 298                 case 'v':
 299                         printf("version %s\n\n", BB_VER);
 300                         return 0;
 301                         break;
 302                 default:
 303                         show_usage();
 304                 }
 305         }
 306
 307         /* Start the log, sanitize fd's, and write a pid file */
 308         udhcp_start_log_and_pid("udhcpc", client_config.pidfile);
 309
 310         if (read_interface(client_config.interface, &client_config.ifindex,
 311                            NULL, client_config.arp) < 0)
 312                 return 1;
 313
 314         /* if not set, and not suppressed, setup the default client ID */
 315         if (!client_config.clientid && !no_clientid) {
 316                 client_config.clientid = xmalloc(6 + 3);
 317                 client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
 318                 client_config.clientid[OPT_LEN] = 7;
 319                 client_config.clientid[OPT_DATA] = 1;
 320                 memcpy(client_config.clientid + 3, client_config.arp, 6);
 321         }
 322
 323         if (!client_config.vendorclass) {
 324                 client_config.vendorclass = xmalloc(sizeof("udhcp "BB_VER) + 2);
 325                 client_config.vendorclass[OPT_CODE] = DHCP_VENDOR;
 326                 client_config.vendorclass[OPT_LEN] = sizeof("udhcp "BB_VER) - 1;
 327                 client_config.vendorclass[OPT_DATA] = 1;
 328                 memcpy(&client_config.vendorclass[OPT_DATA],
 329                         "udhcp "BB_VER, sizeof("udhcp "BB_VER) - 1);
 330         }
 331
 332
 333         /* setup the signal pipe */
 334         udhcp_sp_setup();
 335
 336         state = INIT_SELECTING;
 337         udhcp_run_script(NULL, "deconfig");
 338         change_mode(LISTEN_RAW);
 339
 340         for (;;) {
 341
 342                 tv.tv_sec = timeout - uptime();
 343                 tv.tv_usec = 0;
 344
 345                 if (listen_mode != LISTEN_NONE && fd < 0) {
 346                         if (listen_mode == LISTEN_KERNEL)
 347                                 fd = listen_socket(INADDR_ANY, CLIENT_PORT, client_config.interface);
 348                         else
 349                                 fd = raw_socket(client_config.ifindex);
 350                         if (fd < 0) {
 351                                 LOG(LOG_ERR, "FATAL: couldn't listen on socket, %m");
 352                                 return 0;
 353                         }
 354                 }
 355                 max_fd = udhcp_sp_fd_set(&rfds, fd);
 356
 357                 if (tv.tv_sec > 0) {
 358                         DEBUG(LOG_INFO, "Waiting on select...");
 359                         retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
 360                 } else retval = 0; /* If we already timed out, fall through */
 361
 362                 now = uptime();
 363                 if (retval == 0) {
 364                         /* timeout dropped to zero */
 365                         switch (state) {
 366                         case INIT_SELECTING:
 367                                 if (packet_num < client_config.retries) {
 368                                         if (packet_num == 0)
 369                                                 xid = random_xid();
 370
 371                                         /* send discover packet */
 372                                         send_discover(xid, requested_ip); /* broadcast */
 373
 374                                         timeout = now + client_config.timeout;
 375                                         packet_num++;
 376                                 } else {
 377                                         udhcp_run_script(NULL, "leasefail");
 378                                         if (client_config.background_if_no_lease) {
 379                                                 LOG(LOG_INFO, "No lease, forking to background.");
 380                                                 client_background();
 381                                         } else if (client_config.abort_if_no_lease) {
 382                                                 LOG(LOG_INFO, "No lease, failing.");
 383                                                 return 1;
 384                                         }
 385                                         /* wait to try again */
 386                                         packet_num = 0;
 387                                         timeout = now + 60;
 388                                 }
 389                                 break;
 390                         case RENEW_REQUESTED:
 391                         case REQUESTING:
 392                                 if (packet_num < client_config.retries) {
 393                                         /* send request packet */
 394                                         if (state == RENEW_REQUESTED)
 395                                                 send_renew(xid, server_addr, requested_ip); /* unicast */
 396                                         else send_selecting(xid, server_addr, requested_ip); /* broadcast */
 397
 398                                         timeout = now + ((packet_num == 2) ? 10 : 2);
 399                                         packet_num++;
 400                                 } else {
 401                                         /* timed out, go back to init state */
 402                                         if (state == RENEW_REQUESTED) udhcp_run_script(NULL, "deconfig");
 403                                         state = INIT_SELECTING;
 404                                         timeout = now;
 405                                         packet_num = 0;
 406                                         change_mode(LISTEN_RAW);
 407                                 }
 408                                 break;
 409                         case BOUND:
 410                                 /* Lease is starting to run out, time to enter renewing state */
 411                                 state = RENEWING;
 412                                 change_mode(LISTEN_KERNEL);
 413                                 DEBUG(LOG_INFO, "Entering renew state");
 414                                 /* fall right through */
 415                         case RENEWING:
 416                                 /* Either set a new T1, or enter REBINDING state */
 417                                 if ((t2 - t1) <= (lease / 14400 + 1)) {
 418                                         /* timed out, enter rebinding state */
 419                                         state = REBINDING;
 420                                         timeout = now + (t2 - t1);
 421                                         DEBUG(LOG_INFO, "Entering rebinding state");
 422                                 } else {
 423                                         /* send a request packet */
 424                                         send_renew(xid, server_addr, requested_ip); /* unicast */
 425
 426                                         t1 = (t2 - t1) / 2 + t1;
 427                                         timeout = t1 + start;
 428                                 }
 429                                 break;
 430                         case REBINDING:
 431                                 /* Either set a new T2, or enter INIT state */
 432                                 if ((lease - t2) <= (lease / 14400 + 1)) {
 433                                         /* timed out, enter init state */
 434                                         state = INIT_SELECTING;
 435                                         LOG(LOG_INFO, "Lease lost, entering init state");
 436                                         udhcp_run_script(NULL, "deconfig");
 437                                         timeout = now;
 438                                         packet_num = 0;
 439                                         change_mode(LISTEN_RAW);
 440                                 } else {
 441                                         /* send a request packet */
 442                                         send_renew(xid, 0, requested_ip); /* broadcast */
 443
 444                                         t2 = (lease - t2) / 2 + t2;
 445                                         timeout = t2 + start;
 446                                 }
 447                                 break;
 448                         case RELEASED:
 449                                 /* yah, I know, *you* say it would never happen */
 450                                 timeout = 0x7fffffff;
 451                                 break;
 452                         }
 453                 } else if (retval > 0 && listen_mode != LISTEN_NONE && FD_ISSET(fd, &rfds)) {
 454                         /* a packet is ready, read it */
 455
 456                         if (listen_mode == LISTEN_KERNEL)
 457                                 len = udhcp_get_packet(&packet, fd);
 458                         else len = get_raw_packet(&packet, fd);
 459
 460                         if (len == -1 && errno != EINTR) {
 461                                 DEBUG(LOG_INFO, "error on read, %m, reopening socket");
 462                                 change_mode(listen_mode); /* just close and reopen */
 463                         }
 464                         if (len < 0) continue;
 465
 466                         if (packet.xid != xid) {
 467                                 DEBUG(LOG_INFO, "Ignoring XID %lx (our xid is %lx)",
 468                                         (unsigned long) packet.xid, xid);
 469                                 continue;
 470                         }
 471
 472                         /* Ignore packets that aren't for us */
 473                         if (memcmp(packet.chaddr, client_config.arp, 6)) {
 474                                 DEBUG(LOG_INFO, "packet does not have our chaddr -- ignoring");
 475                                 continue;
 476                         }
 477
 478                         if ((message = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
 479                                 DEBUG(LOG_ERR, "couldnt get option from packet -- ignoring");
 480                                 continue;
 481                         }
 482
 483                         switch (state) {
 484                         case INIT_SELECTING:
 485                                 /* Must be a DHCPOFFER to one of our xid's */
 486                                 if (*message == DHCPOFFER) {
 487                                         if ((temp = get_option(&packet, DHCP_SERVER_ID))) {
 488                                                 memcpy(&server_addr, temp, 4);
 489                                                 xid = packet.xid;
 490                                                 requested_ip = packet.yiaddr;
 491
 492                                                 /* enter requesting state */
 493                                                 state = REQUESTING;
 494                                                 timeout = now;
 495                                                 packet_num = 0;
 496                                         } else {
 497                                                 DEBUG(LOG_ERR, "No server ID in message");
 498                                         }
 499                                 }
 500                                 break;
 501                         case RENEW_REQUESTED:
 502                         case REQUESTING:
 503                         case RENEWING:
 504                         case REBINDING:
 505                                 if (*message == DHCPACK) {
 506                                         if (!(temp = get_option(&packet, DHCP_LEASE_TIME))) {
 507                                                 LOG(LOG_ERR, "No lease time with ACK, using 1 hour lease");
 508                                                 lease = 60 * 60;
 509                                         } else {
 510                                                 memcpy(&lease, temp, 4);
 511                                                 lease = ntohl(lease);
 512                                         }
 513
 514                                         /* enter bound state */
 515                                         t1 = lease / 2;
 516
 517                                         /* little fixed point for n * .875 */
 518                                         t2 = (lease * 0x7) >> 3;
 519                                         temp_addr.s_addr = packet.yiaddr;
 520                                         LOG(LOG_INFO, "Lease of %s obtained, lease time %ld",
 521                                                 inet_ntoa(temp_addr), lease);
 522                                         start = now;
 523                                         timeout = t1 + start;
 524                                         requested_ip = packet.yiaddr;
 525                                         udhcp_run_script(&packet,
 526                                                    ((state == RENEWING || state == REBINDING) ? "renew" : "bound"));
 527
 528                                         state = BOUND;
 529                                         change_mode(LISTEN_NONE);
 530                                         if (client_config.quit_after_lease)
 531                                                 return 0;
 532                                         if (!client_config.foreground)
 533                                                 client_background();
 534
 535                                 } else if (*message == DHCPNAK) {
 536                                         /* return to init state */
 537                                         LOG(LOG_INFO, "Received DHCP NAK");
 538                                         udhcp_run_script(&packet, "nak");
 539                                         if (state != REQUESTING)
 540                                                 udhcp_run_script(NULL, "deconfig");
 541                                         state = INIT_SELECTING;
 542                                         timeout = now;
 543                                         requested_ip = 0;
 544                                         packet_num = 0;
 545                                         change_mode(LISTEN_RAW);
 546                                         sleep(3); /* avoid excessive network traffic */
 547                                 }
 548                                 break;
 549                         /* case BOUND, RELEASED: - ignore all packets */
 550                         }
 551                 } else if (retval > 0 && (sig = udhcp_sp_read(&rfds))) {
 552                         switch (sig) {
 553                         case SIGUSR1:
 554                                 perform_renew();
 555                                 break;
 556                         case SIGUSR2:
 557                                 perform_release();
 558                                 break;
 559                         case SIGTERM:
 560                                 LOG(LOG_INFO, "Received SIGTERM");
 561                                 return 0;
 562                         }
 563                 } else if (retval == -1 && errno == EINTR) {
 564                         /* a signal was caught */
 565                 } else {
 566                         /* An error occured */
 567                         DEBUG(LOG_ERR, "Error on select");
 568                 }
 569
 570         }
 571         return 0;
 572 }