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