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         .retries = 3,
  62         .timeout = 3,
  63         .arp = "\0\0\0\0\0\0",          /* appease gcc-3.0 */
  64 };
  65
  66 #ifndef IN_BUSYBOX
  67 static void ATTRIBUTE_NORETURN show_usage(void)
  68 {
  69         printf(
  70 "Usage: udhcpc [OPTIONS]\n\n"
  71 "  -c, --clientid=CLIENTID         Set client identifier - type is first char\n"
  72 "  -C, --clientid-none             Suppress default client identifier\n"
  73 "  -V, --vendorclass=CLASSID       Set vendor class identifier\n"
  74 "  -H, --hostname=HOSTNAME         Client hostname\n"
  75 "  -h                              Alias for -H\n"
  76 "  -F, --fqdn=FQDN                 Client fully qualified domain name\n"
  77 "  -f, --foreground                Do not fork after getting lease\n"
  78 "  -b, --background                Fork to background if lease cannot be\n"
  79 "                                  immediately negotiated.\n"
  80 "  -i, --interface=INTERFACE       Interface to use (default: eth0)\n"
  81 "  -n, --now                       Exit with failure if lease cannot be\n"
  82 "                                  immediately negotiated.\n"
  83 "  -p, --pidfile=file              Store process ID of daemon in file\n"
  84 "  -q, --quit                      Quit after obtaining lease\n"
  85 "  -r, --request=IP                IP address to request (default: none)\n"
  86 "  -s, --script=file               Run file at dhcp events (default:\n"
  87 "                                  " DEFAULT_SCRIPT ")\n"
  88 "  -T, --timeout=seconds           Try to get the lease for the amount of\n"
  89 "                                  seconds (default: 3)\n"
  90 "  -t, --retries=NUM               Send up to NUM request packets\n"
  91 "  -v, --version                   Display version\n"
  92         );
  93         exit(0);
  94 }
  95 #else
  96 #define show_usage bb_show_usage
  97 extern void show_usage(void) ATTRIBUTE_NORETURN;
  98 #endif
  99
 100
 101 /* just a little helper */
 102 static void change_mode(int new_mode)
 103 {
 104         DEBUG(LOG_INFO, "entering %s listen mode",
 105                 new_mode ? (new_mode == 1 ? "kernel" : "raw") : "none");
 106         if (fd >= 0) close(fd);
 107         fd = -1;
 108         listen_mode = new_mode;
 109 }
 110
 111
 112 /* perform a renew */
 113 static void perform_renew(void)
 114 {
 115         LOG(LOG_INFO, "Performing a DHCP renew");
 116         switch (state) {
 117         case BOUND:
 118                 change_mode(LISTEN_KERNEL);
 119         case RENEWING:
 120         case REBINDING:
 121                 state = RENEW_REQUESTED;
 122                 break;
 123         case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
 124                 run_script(NULL, "deconfig");
 125         case REQUESTING:
 126         case RELEASED:
 127                 change_mode(LISTEN_RAW);
 128                 state = INIT_SELECTING;
 129                 break;
 130         case INIT_SELECTING:
 131                 break;
 132         }
 133
 134         /* start things over */
 135         packet_num = 0;
 136
 137         /* Kill any timeouts because the user wants this to hurry along */
 138         timeout = 0;
 139 }
 140
 141
 142 /* perform a release */
 143 static void perform_release(void)
 144 {
 145         char buffer[16];
 146         struct in_addr temp_addr;
 147
 148         /* send release packet */
 149         if (state == BOUND || state == RENEWING || state == REBINDING) {
 150                 temp_addr.s_addr = server_addr;
 151                 sprintf(buffer, "%s", inet_ntoa(temp_addr));
 152                 temp_addr.s_addr = requested_ip;
 153                 LOG(LOG_INFO, "Unicasting a release of %s to %s",
 154                                 inet_ntoa(temp_addr), buffer);
 155                 send_release(server_addr, requested_ip); /* unicast */
 156                 run_script(NULL, "deconfig");
 157         }
 158         LOG(LOG_INFO, "Entering released state");
 159
 160         change_mode(LISTEN_NONE);
 161         state = RELEASED;
 162         timeout = 0x7fffffff;
 163 }
 164
 165
 166 static void client_background(void)
 167 {
 168         background(client_config.pidfile);
 169         client_config.foreground = 1; /* Do not fork again. */
 170         client_config.background_if_no_lease = 0;
 171 }
 172
 173
 174 #ifdef COMBINED_BINARY
 175 int udhcpc_main(int argc, char *argv[])
 176 #else
 177 int main(int argc, char *argv[])
 178 #endif
 179 {
 180         uint8_t *temp, *message;
 181         unsigned long t1 = 0, t2 = 0, xid = 0;
 182         unsigned long start = 0, lease;
 183         fd_set rfds;
 184         int retval;
 185         struct timeval tv;
 186         int c, len;
 187         struct dhcpMessage packet;
 188         struct in_addr temp_addr;
 189         long now;
 190         int max_fd;
 191         int sig;
 192         int no_clientid = 0;
 193
 194         static const struct option arg_options[] = {
 195                 {"clientid",    required_argument,      0, 'c'},
 196                 {"clientid-none", no_argument,          0, 'C'},
 197                 {"vendorclass", required_argument,      0, 'V'},
 198                 {"foreground",  no_argument,            0, 'f'},
 199                 {"background",  no_argument,            0, 'b'},
 200                 {"hostname",    required_argument,      0, 'H'},
 201                 {"hostname",    required_argument,      0, 'h'},
 202                 {"fqdn",        required_argument,      0, 'F'},
 203                 {"interface",   required_argument,      0, 'i'},
 204                 {"now",         no_argument,            0, 'n'},
 205                 {"pidfile",     required_argument,      0, 'p'},
 206                 {"quit",        no_argument,            0, 'q'},
 207                 {"request",     required_argument,      0, 'r'},
 208                 {"script",      required_argument,      0, 's'},
 209                 {"timeout",     required_argument,      0, 'T'},
 210                 {"version",     no_argument,            0, 'v'},
 211                 {"retries",     required_argument,      0, 't'},
 212                 {0, 0, 0, 0}
 213         };
 214
 215         /* get options */
 216         while (1) {
 217                 int option_index = 0;
 218                 c = getopt_long(argc, argv, "c:CV:fbH:h:F:i:np:qr:s:T:t:v", arg_options, &option_index);
 219                 if (c == -1) break;
 220
 221                 switch (c) {
 222                 case 'c':
 223                         if (no_clientid) show_usage();
 224                         len = strlen(optarg) > 255 ? 255 : strlen(optarg);
 225                         free(client_config.clientid);
 226                         client_config.clientid = xmalloc(len + 2);
 227                         client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
 228                         client_config.clientid[OPT_LEN] = len;
 229                         client_config.clientid[OPT_DATA] = '\0';
 230                         strncpy((char*)client_config.clientid + OPT_DATA, optarg, len);
 231                         break;
 232                 case 'C':
 233                         if (client_config.clientid) show_usage();
 234                         no_clientid = 1;
 235                         break;
 236                 case 'V':
 237                         len = strlen(optarg) > 255 ? 255 : strlen(optarg);
 238                         free(client_config.vendorclass);
 239                         client_config.vendorclass = xmalloc(len + 2);
 240                         client_config.vendorclass[OPT_CODE] = DHCP_VENDOR;
 241                         client_config.vendorclass[OPT_LEN] = len;
 242                         strncpy((char*)client_config.vendorclass + OPT_DATA, optarg, len);
 243                         break;
 244                 case 'f':
 245                         client_config.foreground = 1;
 246                         break;
 247                 case 'b':
 248                         client_config.background_if_no_lease = 1;
 249                         break;
 250                 case 'h':
 251                 case 'H':
 252                         len = strlen(optarg) > 255 ? 255 : strlen(optarg);
 253                         free(client_config.hostname);
 254                         client_config.hostname = xmalloc(len + 2);
 255                         client_config.hostname[OPT_CODE] = DHCP_HOST_NAME;
 256                         client_config.hostname[OPT_LEN] = len;
 257                         strncpy((char*)client_config.hostname + 2, optarg, len);
 258                         break;
 259                 case 'F':
 260                         len = strlen(optarg) > 255 ? 255 : strlen(optarg);
 261                         free(client_config.fqdn);
 262                         client_config.fqdn = xmalloc(len + 5);
 263                         client_config.fqdn[OPT_CODE] = DHCP_FQDN;
 264                         client_config.fqdn[OPT_LEN] = len + 3;
 265                         /* Flags: 0000NEOS
 266                         S: 1 => Client requests Server to update A RR in DNS as well as PTR
 267                         O: 1 => Server indicates to client that DNS has been updated regardless
 268                         E: 1 => Name data is DNS format, i.e. <4>host<6>domain<4>com<0> not "host.domain.com"
 269                         N: 1 => Client requests Server to not update DNS
 270                         */
 271                         client_config.fqdn[OPT_LEN + 1] = 0x1;
 272                         client_config.fqdn[OPT_LEN + 2] = 0;
 273                         client_config.fqdn[OPT_LEN + 3] = 0;
 274                         strncpy((char*)client_config.fqdn + 5, optarg, len);
 275                         break;
 276                 case 'i':
 277                         client_config.interface =  optarg;
 278                         break;
 279                 case 'n':
 280                         client_config.abort_if_no_lease = 1;
 281                         break;
 282                 case 'p':
 283                         client_config.pidfile = optarg;
 284                         break;
 285                 case 'q':
 286                         client_config.quit_after_lease = 1;
 287                         break;
 288                 case 'r':
 289                         requested_ip = inet_addr(optarg);
 290                         break;
 291                 case 's':
 292                         client_config.script = optarg;
 293                         break;
 294                 case 'T':
 295                         client_config.timeout = atoi(optarg);
 296                         break;
 297                 case 't':
 298                         client_config.retries = atoi(optarg);
 299                         break;
 300                 case 'v':
 301                         printf("udhcpcd, version %s\n\n", VERSION);
 302                         return 0;
 303                         break;
 304                 default:
 305                         show_usage();
 306                 }
 307         }
 308
 309         /* Start the log, sanitize fd's, and write a pid file */
 310         start_log_and_pid("udhcpc", client_config.pidfile);
 311
 312         if (read_interface(client_config.interface, &client_config.ifindex,
 313                            NULL, client_config.arp) < 0)
 314                 return 1;
 315
 316         /* if not set, and not suppressed, setup the default client ID */
 317         if (!client_config.clientid && !no_clientid) {
 318                 client_config.clientid = xmalloc(6 + 3);
 319                 client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
 320                 client_config.clientid[OPT_LEN] = 7;
 321                 client_config.clientid[OPT_DATA] = 1;
 322                 memcpy(client_config.clientid + 3, client_config.arp, 6);
 323         }
 324
 325         if (!client_config.vendorclass) {
 326                 client_config.vendorclass = xmalloc(sizeof("udhcp "VERSION) + 2);
 327                 client_config.vendorclass[OPT_CODE] = DHCP_VENDOR;
 328                 client_config.vendorclass[OPT_LEN] = sizeof("udhcp "VERSION) - 1;
 329                 client_config.vendorclass[OPT_DATA] = 1;
 330                 memcpy(&client_config.vendorclass[OPT_DATA],
 331                         "udhcp "VERSION, sizeof("udhcp "VERSION) - 1);
 332         }
 333
 334
 335         /* setup the signal pipe */
 336         udhcp_sp_setup();
 337
 338         state = INIT_SELECTING;
 339         run_script(NULL, "deconfig");
 340         change_mode(LISTEN_RAW);
 341
 342         for (;;) {
 343
 344                 tv.tv_sec = timeout - uptime();
 345                 tv.tv_usec = 0;
 346
 347                 if (listen_mode != LISTEN_NONE && fd < 0) {
 348                         if (listen_mode == LISTEN_KERNEL)
 349                                 fd = listen_socket(INADDR_ANY, CLIENT_PORT, client_config.interface);
 350                         else
 351                                 fd = raw_socket(client_config.ifindex);
 352                         if (fd < 0) {
 353                                 LOG(LOG_ERR, "FATAL: couldn't listen on socket, %m");
 354                                 return 0;
 355                         }
 356                 }
 357                 max_fd = udhcp_sp_fd_set(&rfds, fd);
 358
 359                 if (tv.tv_sec > 0) {
 360                         DEBUG(LOG_INFO, "Waiting on select...");
 361                         retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
 362                 } else retval = 0; /* If we already timed out, fall through */
 363
 364                 now = uptime();
 365                 if (retval == 0) {
 366                         /* timeout dropped to zero */
 367                         switch (state) {
 368                         case INIT_SELECTING:
 369                                 if (packet_num < client_config.retries) {
 370                                         if (packet_num == 0)
 371                                                 xid = random_xid();
 372
 373                                         /* send discover packet */
 374                                         send_discover(xid, requested_ip); /* broadcast */
 375
 376                                         timeout = now + client_config.timeout;
 377                                         packet_num++;
 378                                 } else {
 379                                         run_script(NULL, "leasefail");
 380                                         if (client_config.background_if_no_lease) {
 381                                                 LOG(LOG_INFO, "No lease, forking to background.");
 382                                                 client_background();
 383                                         } else if (client_config.abort_if_no_lease) {
 384                                                 LOG(LOG_INFO, "No lease, failing.");
 385                                                 return 1;
 386                                         }
 387                                         /* wait to try again */
 388                                         packet_num = 0;
 389                                         timeout = now + 60;
 390                                 }
 391                                 break;
 392                         case RENEW_REQUESTED:
 393                         case REQUESTING:
 394                                 if (packet_num < client_config.retries) {
 395                                         /* send request packet */
 396                                         if (state == RENEW_REQUESTED)
 397                                                 send_renew(xid, server_addr, requested_ip); /* unicast */
 398                                         else send_selecting(xid, server_addr, requested_ip); /* broadcast */
 399
 400                                         timeout = now + ((packet_num == 2) ? 10 : 2);
 401                                         packet_num++;
 402                                 } else {
 403                                         /* timed out, go back to init state */
 404                                         if (state == RENEW_REQUESTED) run_script(NULL, "deconfig");
 405                                         state = INIT_SELECTING;
 406                                         timeout = now;
 407                                         packet_num = 0;
 408                                         change_mode(LISTEN_RAW);
 409                                 }
 410                                 break;
 411                         case BOUND:
 412                                 /* Lease is starting to run out, time to enter renewing state */
 413                                 state = RENEWING;
 414                                 change_mode(LISTEN_KERNEL);
 415                                 DEBUG(LOG_INFO, "Entering renew state");
 416                                 /* fall right through */
 417                         case RENEWING:
 418                                 /* Either set a new T1, or enter REBINDING state */
 419                                 if ((t2 - t1) <= (lease / 14400 + 1)) {
 420                                         /* timed out, enter rebinding state */
 421                                         state = REBINDING;
 422                                         timeout = now + (t2 - t1);
 423                                         DEBUG(LOG_INFO, "Entering rebinding state");
 424                                 } else {
 425                                         /* send a request packet */
 426                                         send_renew(xid, server_addr, requested_ip); /* unicast */
 427
 428                                         t1 = (t2 - t1) / 2 + t1;
 429                                         timeout = t1 + start;
 430                                 }
 431                                 break;
 432                         case REBINDING:
 433                                 /* Either set a new T2, or enter INIT state */
 434                                 if ((lease - t2) <= (lease / 14400 + 1)) {
 435                                         /* timed out, enter init state */
 436                                         state = INIT_SELECTING;
 437                                         LOG(LOG_INFO, "Lease lost, entering init state");
 438                                         run_script(NULL, "deconfig");
 439                                         timeout = now;
 440                                         packet_num = 0;
 441                                         change_mode(LISTEN_RAW);
 442                                 } else {
 443                                         /* send a request packet */
 444                                         send_renew(xid, 0, requested_ip); /* broadcast */
 445
 446                                         t2 = (lease - t2) / 2 + t2;
 447                                         timeout = t2 + start;
 448                                 }
 449                                 break;
 450                         case RELEASED:
 451                                 /* yah, I know, *you* say it would never happen */
 452                                 timeout = 0x7fffffff;
 453                                 break;
 454                         }
 455                 } else if (retval > 0 && listen_mode != LISTEN_NONE && FD_ISSET(fd, &rfds)) {
 456                         /* a packet is ready, read it */
 457
 458                         if (listen_mode == LISTEN_KERNEL)
 459                                 len = get_packet(&packet, fd);
 460                         else len = get_raw_packet(&packet, fd);
 461
 462                         if (len == -1 && errno != EINTR) {
 463                                 DEBUG(LOG_INFO, "error on read, %m, reopening socket");
 464                                 change_mode(listen_mode); /* just close and reopen */
 465                         }
 466                         if (len < 0) continue;
 467
 468                         if (packet.xid != xid) {
 469                                 DEBUG(LOG_INFO, "Ignoring XID %lx (our xid is %lx)",
 470                                         (unsigned long) packet.xid, xid);
 471                                 continue;
 472                         }
 473
 474                         /* Ignore packets that aren't for us */
 475                         if (memcmp(packet.chaddr, client_config.arp, 6)) {
 476                                 DEBUG(LOG_INFO, "packet does not have our chaddr -- ignoring");
 477                                 continue;
 478                         }
 479
 480                         if ((message = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
 481                                 DEBUG(LOG_ERR, "couldnt get option from packet -- ignoring");
 482                                 continue;
 483                         }
 484
 485                         switch (state) {
 486                         case INIT_SELECTING:
 487                                 /* Must be a DHCPOFFER to one of our xid's */
 488                                 if (*message == DHCPOFFER) {
 489                                         if ((temp = get_option(&packet, DHCP_SERVER_ID))) {
 490                                                 memcpy(&server_addr, temp, 4);
 491                                                 xid = packet.xid;
 492                                                 requested_ip = packet.yiaddr;
 493
 494                                                 /* enter requesting state */
 495                                                 state = REQUESTING;
 496                                                 timeout = now;
 497                                                 packet_num = 0;
 498                                         } else {
 499                                                 DEBUG(LOG_ERR, "No server ID in message");
 500                                         }
 501                                 }
 502                                 break;
 503                         case RENEW_REQUESTED:
 504                         case REQUESTING:
 505                         case RENEWING:
 506                         case REBINDING:
 507                                 if (*message == DHCPACK) {
 508                                         if (!(temp = get_option(&packet, DHCP_LEASE_TIME))) {
 509                                                 LOG(LOG_ERR, "No lease time with ACK, using 1 hour lease");
 510                                                 lease = 60 * 60;
 511                                         } else {
 512                                                 memcpy(&lease, temp, 4);
 513                                                 lease = ntohl(lease);
 514                                         }
 515
 516                                         /* enter bound state */
 517                                         t1 = lease / 2;
 518
 519                                         /* little fixed point for n * .875 */
 520                                         t2 = (lease * 0x7) >> 3;
 521                                         temp_addr.s_addr = packet.yiaddr;
 522                                         LOG(LOG_INFO, "Lease of %s obtained, lease time %ld",
 523                                                 inet_ntoa(temp_addr), lease);
 524                                         start = now;
 525                                         timeout = t1 + start;
 526                                         requested_ip = packet.yiaddr;
 527                                         run_script(&packet,
 528                                                    ((state == RENEWING || state == REBINDING) ? "renew" : "bound"));
 529
 530                                         state = BOUND;
 531                                         change_mode(LISTEN_NONE);
 532                                         if (client_config.quit_after_lease)
 533                                                 return 0;
 534                                         if (!client_config.foreground)
 535                                                 client_background();
 536
 537                                 } else if (*message == DHCPNAK) {
 538                                         /* return to init state */
 539                                         LOG(LOG_INFO, "Received DHCP NAK");
 540                                         run_script(&packet, "nak");
 541                                         if (state != REQUESTING)
 542                                                 run_script(NULL, "deconfig");
 543                                         state = INIT_SELECTING;
 544                                         timeout = now;
 545                                         requested_ip = 0;
 546                                         packet_num = 0;
 547                                         change_mode(LISTEN_RAW);
 548                                         sleep(3); /* avoid excessive network traffic */
 549                                 }
 550                                 break;
 551                         /* case BOUND, RELEASED: - ignore all packets */
 552                         }
 553                 } else if (retval > 0 && (sig = udhcp_sp_read(&rfds))) {
 554                         switch (sig) {
 555                         case SIGUSR1:
 556                                 perform_renew();
 557                                 break;
 558                         case SIGUSR2:
 559                                 perform_release();
 560                                 break;
 561                         case SIGTERM:
 562                                 LOG(LOG_INFO, "Received SIGTERM");
 563                                 return 0;
 564                         }
 565                 } else if (retval == -1 && errno == EINTR) {
 566                         /* a signal was caught */
 567                 } else {
 568                         /* An error occured */
 569                         DEBUG(LOG_ERR, "Error on select");
 570                 }
 571
 572         }
 573         return 0;
 574 }