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