networking/udhcp/dhcpc.c

   1 /* vi: set sw=4 ts=4: */
   2 /* dhcpc.c
   3  *
   4  * udhcp DHCP client
   5  *
   6  * Russ Dill <Russ.Dill@asu.edu> July 2001
   7  *
   8  * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
   9  */
  10
  11 #include <getopt.h>
  12
  13 #include "common.h"
  14 #include "dhcpd.h"
  15 #include "dhcpc.h"
  16 #include "options.h"
  17
  18
  19 static int state;
  20 /* Something is definitely wrong here. IPv4 addresses
  21  * in variables of type long?? BTW, we use inet_ntoa()
  22  * in the code. Manpage says that struct in_addr has a member of type long (!)
  23  * which holds IPv4 address, and the struct is passed by value (!!)
  24  */
  25 static unsigned long requested_ip; /* = 0 */
  26 static unsigned long server_addr;
  27 static unsigned long timeout;
  28 static int packet_num; /* = 0 */
  29 static int fd = -1;
  30
  31 #define LISTEN_NONE 0
  32 #define LISTEN_KERNEL 1
  33 #define LISTEN_RAW 2
  34 static int listen_mode;
  35
  36 struct client_config_t client_config = {
  37         /* Default options. */
  38         .abort_if_no_lease = 0,
  39         .foreground = 0,
  40         .quit_after_lease = 0,
  41         .release_on_quit = 0,
  42         .background_if_no_lease = 0,
  43         .interface = "eth0",
  44         .pidfile = NULL,
  45         .script = DEFAULT_SCRIPT,
  46         .clientid = NULL,
  47         .vendorclass = NULL,
  48         .hostname = NULL,
  49         .fqdn = NULL,
  50         .ifindex = 0,
  51         .retries = 3,
  52         .timeout = 3,
  53         .arp = "\0\0\0\0\0\0",          /* appease gcc-3.0 */
  54 };
  55
  56 /* just a little helper */
  57 static void change_mode(int new_mode)
  58 {
  59         DEBUG("entering %s listen mode",
  60                 new_mode ? (new_mode == 1 ? "kernel" : "raw") : "none");
  61         if (fd >= 0) close(fd);
  62         fd = -1;
  63         listen_mode = new_mode;
  64 }
  65
  66
  67 /* perform a renew */
  68 static void perform_renew(void)
  69 {
  70         bb_info_msg("Performing a DHCP renew");
  71         switch (state) {
  72         case BOUND:
  73                 change_mode(LISTEN_KERNEL);
  74         case RENEWING:
  75         case REBINDING:
  76                 state = RENEW_REQUESTED;
  77                 break;
  78         case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
  79                 udhcp_run_script(NULL, "deconfig");
  80         case REQUESTING:
  81         case RELEASED:
  82                 change_mode(LISTEN_RAW);
  83                 state = INIT_SELECTING;
  84                 break;
  85         case INIT_SELECTING:
  86                 break;
  87         }
  88
  89         /* start things over */
  90         packet_num = 0;
  91
  92         /* Kill any timeouts because the user wants this to hurry along */
  93         timeout = 0;
  94 }
  95
  96
  97 /* perform a release */
  98 static void perform_release(void)
  99 {
 100         char buffer[16];
 101         struct in_addr temp_addr;
 102
 103         /* send release packet */
 104         if (state == BOUND || state == RENEWING || state == REBINDING) {
 105                 temp_addr.s_addr = server_addr;
 106                 sprintf(buffer, "%s", inet_ntoa(temp_addr));
 107                 temp_addr.s_addr = requested_ip;
 108                 bb_info_msg("Unicasting a release of %s to %s",
 109                                 inet_ntoa(temp_addr), buffer);
 110                 send_release(server_addr, requested_ip); /* unicast */
 111                 udhcp_run_script(NULL, "deconfig");
 112         }
 113         bb_info_msg("Entering released state");
 114
 115         change_mode(LISTEN_NONE);
 116         state = RELEASED;
 117         timeout = 0x7fffffff;
 118 }
 119
 120
 121 static void client_background(void)
 122 {
 123         udhcp_background(client_config.pidfile);
 124         client_config.foreground = 1; /* Do not fork again. */
 125         client_config.background_if_no_lease = 0;
 126 }
 127
 128
 129 int udhcpc_main(int argc, char *argv[])
 130 {
 131         uint8_t *temp, *message;
 132         unsigned long t1 = 0, t2 = 0, xid = 0;
 133         unsigned long start = 0, lease = 0;
 134         fd_set rfds;
 135         int retval;
 136         struct timeval tv;
 137         int c, len;
 138         struct dhcpMessage packet;
 139         struct in_addr temp_addr;
 140         long now;
 141         int max_fd;
 142         int sig;
 143         int no_clientid = 0;
 144
 145         static const struct option arg_options[] = {
 146                 {"clientid",    required_argument,      0, 'c'},
 147                 {"clientid-none", no_argument,          0, 'C'},
 148                 {"vendorclass", required_argument,      0, 'V'},
 149                 {"foreground",  no_argument,            0, 'f'},
 150                 {"background",  no_argument,            0, 'b'},
 151                 {"hostname",    required_argument,      0, 'H'},
 152                 {"hostname",    required_argument,      0, 'h'},
 153                 {"fqdn",        required_argument,      0, 'F'},
 154                 {"interface",   required_argument,      0, 'i'},
 155                 {"now",         no_argument,            0, 'n'},
 156                 {"pidfile",     required_argument,      0, 'p'},
 157                 {"quit",        no_argument,            0, 'q'},
 158                 {"release",     no_argument,            0, 'R'},
 159                 {"request",     required_argument,      0, 'r'},
 160                 {"script",      required_argument,      0, 's'},
 161                 {"timeout",     required_argument,      0, 'T'},
 162                 {"version",     no_argument,            0, 'v'},
 163                 {"retries",     required_argument,      0, 't'},
 164                 {0, 0, 0, 0}
 165         };
 166
 167         /* get options */
 168         while (1) {
 169                 int option_index = 0;
 170                 c = getopt_long(argc, argv, "c:CV:fbH:h:F:i:np:qRr:s:T:t:v", arg_options, &option_index);
 171                 if (c == -1) break;
 172
 173                 switch (c) {
 174                 case 'c':
 175                         if (no_clientid) bb_show_usage();
 176                         len = strlen(optarg) > 255 ? 255 : strlen(optarg);
 177                         free(client_config.clientid);
 178                         client_config.clientid = xmalloc(len + 2);
 179                         client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
 180                         client_config.clientid[OPT_LEN] = len;
 181                         client_config.clientid[OPT_DATA] = '\0';
 182                         strncpy((char*)client_config.clientid + OPT_DATA, optarg, len);
 183                         break;
 184                 case 'C':
 185                         if (client_config.clientid) bb_show_usage();
 186                         no_clientid = 1;
 187                         break;
 188                 case 'V':
 189                         len = strlen(optarg) > 255 ? 255 : strlen(optarg);
 190                         free(client_config.vendorclass);
 191                         client_config.vendorclass = xmalloc(len + 2);
 192                         client_config.vendorclass[OPT_CODE] = DHCP_VENDOR;
 193                         client_config.vendorclass[OPT_LEN] = len;
 194                         strncpy((char*)client_config.vendorclass + OPT_DATA, optarg, len);
 195                         break;
 196                 case 'f':
 197                         client_config.foreground = 1;
 198                         break;
 199                 case 'b':
 200                         client_config.background_if_no_lease = 1;
 201                         break;
 202                 case 'h':
 203                 case 'H':
 204                         len = strlen(optarg) > 255 ? 255 : strlen(optarg);
 205                         free(client_config.hostname);
 206                         client_config.hostname = xmalloc(len + 2);
 207                         client_config.hostname[OPT_CODE] = DHCP_HOST_NAME;
 208                         client_config.hostname[OPT_LEN] = len;
 209                         strncpy((char*)client_config.hostname + 2, optarg, len);
 210                         break;
 211                 case 'F':
 212                         len = strlen(optarg) > 255 ? 255 : strlen(optarg);
 213                         free(client_config.fqdn);
 214                         client_config.fqdn = xmalloc(len + 5);
 215                         client_config.fqdn[OPT_CODE] = DHCP_FQDN;
 216                         client_config.fqdn[OPT_LEN] = len + 3;
 217                         /* Flags: 0000NEOS
 218                         S: 1 => Client requests Server to update A RR in DNS as well as PTR
 219                         O: 1 => Server indicates to client that DNS has been updated regardless
 220                         E: 1 => Name data is DNS format, i.e. <4>host<6>domain<4>com<0> not "host.domain.com"
 221                         N: 1 => Client requests Server to not update DNS
 222                         */
 223                         client_config.fqdn[OPT_LEN + 1] = 0x1;
 224                         client_config.fqdn[OPT_LEN + 2] = 0;
 225                         client_config.fqdn[OPT_LEN + 3] = 0;
 226                         strncpy((char*)client_config.fqdn + 5, optarg, len);
 227                         break;
 228                 case 'i':
 229                         client_config.interface =  optarg;
 230                         break;
 231                 case 'n':
 232                         client_config.abort_if_no_lease = 1;
 233                         break;
 234                 case 'p':
 235                         client_config.pidfile = optarg;
 236                         break;
 237                 case 'q':
 238                         client_config.quit_after_lease = 1;
 239                         break;
 240                 case 'R':
 241                         client_config.release_on_quit = 1;
 242                         break;
 243                 case 'r':
 244                         requested_ip = inet_addr(optarg);
 245                         break;
 246                 case 's':
 247                         client_config.script = optarg;
 248                         break;
 249                 case 'T':
 250                         client_config.timeout = xatoi_u(optarg);
 251                         break;
 252                 case 't':
 253                         client_config.retries = xatoi_u(optarg);
 254                         break;
 255                 case 'v':
 256                         printf("version %s\n\n", BB_VER);
 257                         return 0;
 258                         break;
 259                 default:
 260                         bb_show_usage();
 261                 }
 262         }
 263
 264         /* Start the log, sanitize fd's, and write a pid file */
 265         udhcp_start_log_and_pid(client_config.pidfile);
 266
 267         if (read_interface(client_config.interface, &client_config.ifindex,
 268                            NULL, client_config.arp) < 0)
 269                 return 1;
 270
 271         /* if not set, and not suppressed, setup the default client ID */
 272         if (!client_config.clientid && !no_clientid) {
 273                 client_config.clientid = xmalloc(6 + 3);
 274                 client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
 275                 client_config.clientid[OPT_LEN] = 7;
 276                 client_config.clientid[OPT_DATA] = 1;
 277                 memcpy(client_config.clientid + 3, client_config.arp, 6);
 278         }
 279
 280         if (!client_config.vendorclass) {
 281                 client_config.vendorclass = xmalloc(sizeof("udhcp "BB_VER) + 2);
 282                 client_config.vendorclass[OPT_CODE] = DHCP_VENDOR;
 283                 client_config.vendorclass[OPT_LEN] = sizeof("udhcp "BB_VER) - 1;
 284                 client_config.vendorclass[OPT_DATA] = 1;
 285                 memcpy(&client_config.vendorclass[OPT_DATA],
 286                         "udhcp "BB_VER, sizeof("udhcp "BB_VER) - 1);
 287         }
 288
 289
 290         /* setup the signal pipe */
 291         udhcp_sp_setup();
 292
 293         state = INIT_SELECTING;
 294         udhcp_run_script(NULL, "deconfig");
 295         change_mode(LISTEN_RAW);
 296
 297         for (;;) {
 298
 299                 tv.tv_sec = timeout - uptime();
 300                 tv.tv_usec = 0;
 301
 302                 if (listen_mode != LISTEN_NONE && fd < 0) {
 303                         if (listen_mode == LISTEN_KERNEL)
 304                                 fd = listen_socket(INADDR_ANY, CLIENT_PORT, client_config.interface);
 305                         else
 306                                 fd = raw_socket(client_config.ifindex);
 307                         if (fd < 0) {
 308                                 bb_perror_msg("FATAL: cannot listen on socket");
 309                                 return 0;
 310                         }
 311                 }
 312                 max_fd = udhcp_sp_fd_set(&rfds, fd);
 313
 314                 if (tv.tv_sec > 0) {
 315                         DEBUG("Waiting on select...");
 316                         retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
 317                 } else retval = 0; /* If we already timed out, fall through */
 318
 319                 now = uptime();
 320                 if (retval == 0) {
 321                         /* timeout dropped to zero */
 322                         switch (state) {
 323                         case INIT_SELECTING:
 324                                 if (packet_num < client_config.retries) {
 325                                         if (packet_num == 0)
 326                                                 xid = random_xid();
 327
 328                                         /* send discover packet */
 329                                         send_discover(xid, requested_ip); /* broadcast */
 330
 331                                         timeout = now + client_config.timeout;
 332                                         packet_num++;
 333                                 } else {
 334                                         udhcp_run_script(NULL, "leasefail");
 335                                         if (client_config.background_if_no_lease) {
 336                                                 bb_info_msg("No lease, forking to background");
 337                                                 client_background();
 338                                         } else if (client_config.abort_if_no_lease) {
 339                                                 bb_info_msg("No lease, failing");
 340                                                 return 1;
 341                                         }
 342                                         /* wait to try again */
 343                                         packet_num = 0;
 344                                         timeout = now + 60;
 345                                 }
 346                                 break;
 347                         case RENEW_REQUESTED:
 348                         case REQUESTING:
 349                                 if (packet_num < client_config.retries) {
 350                                         /* send request packet */
 351                                         if (state == RENEW_REQUESTED)
 352                                                 send_renew(xid, server_addr, requested_ip); /* unicast */
 353                                         else send_selecting(xid, server_addr, requested_ip); /* broadcast */
 354
 355                                         timeout = now + ((packet_num == 2) ? 10 : 2);
 356                                         packet_num++;
 357                                 } else {
 358                                         /* timed out, go back to init state */
 359                                         if (state == RENEW_REQUESTED) udhcp_run_script(NULL, "deconfig");
 360                                         state = INIT_SELECTING;
 361                                         timeout = now;
 362                                         packet_num = 0;
 363                                         change_mode(LISTEN_RAW);
 364                                 }
 365                                 break;
 366                         case BOUND:
 367                                 /* Lease is starting to run out, time to enter renewing state */
 368                                 state = RENEWING;
 369                                 change_mode(LISTEN_KERNEL);
 370                                 DEBUG("Entering renew state");
 371                                 /* fall right through */
 372                         case RENEWING:
 373                                 /* Either set a new T1, or enter REBINDING state */
 374                                 if ((t2 - t1) <= (lease / 14400 + 1)) {
 375                                         /* timed out, enter rebinding state */
 376                                         state = REBINDING;
 377                                         timeout = now + (t2 - t1);
 378                                         DEBUG("Entering rebinding state");
 379                                 } else {
 380                                         /* send a request packet */
 381                                         send_renew(xid, server_addr, requested_ip); /* unicast */
 382
 383                                         t1 = (t2 - t1) / 2 + t1;
 384                                         timeout = t1 + start;
 385                                 }
 386                                 break;
 387                         case REBINDING:
 388                                 /* Either set a new T2, or enter INIT state */
 389                                 if ((lease - t2) <= (lease / 14400 + 1)) {
 390                                         /* timed out, enter init state */
 391                                         state = INIT_SELECTING;
 392                                         bb_info_msg("Lease lost, entering init state");
 393                                         udhcp_run_script(NULL, "deconfig");
 394                                         timeout = now;
 395                                         packet_num = 0;
 396                                         change_mode(LISTEN_RAW);
 397                                 } else {
 398                                         /* send a request packet */
 399                                         send_renew(xid, 0, requested_ip); /* broadcast */
 400
 401                                         t2 = (lease - t2) / 2 + t2;
 402                                         timeout = t2 + start;
 403                                 }
 404                                 break;
 405                         case RELEASED:
 406                                 /* yah, I know, *you* say it would never happen */
 407                                 timeout = 0x7fffffff;
 408                                 break;
 409                         }
 410                 } else if (retval > 0 && listen_mode != LISTEN_NONE && FD_ISSET(fd, &rfds)) {
 411                         /* a packet is ready, read it */
 412
 413                         if (listen_mode == LISTEN_KERNEL)
 414                                 len = udhcp_get_packet(&packet, fd);
 415                         else len = get_raw_packet(&packet, fd);
 416
 417                         if (len == -1 && errno != EINTR) {
 418                                 DEBUG("error on read, %s, reopening socket", strerror(errno));
 419                                 change_mode(listen_mode); /* just close and reopen */
 420                         }
 421                         if (len < 0) continue;
 422
 423                         if (packet.xid != xid) {
 424                                 DEBUG("Ignoring XID %lx (our xid is %lx)",
 425                                         (unsigned long) packet.xid, xid);
 426                                 continue;
 427                         }
 428
 429                         /* Ignore packets that aren't for us */
 430                         if (memcmp(packet.chaddr, client_config.arp, 6)) {
 431                                 DEBUG("Packet does not have our chaddr - ignoring");
 432                                 continue;
 433                         }
 434
 435                         if ((message = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
 436                                 bb_error_msg("cannot get option from packet - ignoring");
 437                                 continue;
 438                         }
 439
 440                         switch (state) {
 441                         case INIT_SELECTING:
 442                                 /* Must be a DHCPOFFER to one of our xid's */
 443                                 if (*message == DHCPOFFER) {
 444                                         temp = get_option(&packet, DHCP_SERVER_ID);
 445                                         if (temp) {
 446                                                 server_addr = *(uint32_t*)temp;
 447                                                 xid = packet.xid;
 448                                                 requested_ip = packet.yiaddr;
 449
 450                                                 /* enter requesting state */
 451                                                 state = REQUESTING;
 452                                                 timeout = now;
 453                                                 packet_num = 0;
 454                                         } else {
 455                                                 bb_error_msg("no server ID in message");
 456                                         }
 457                                 }
 458                                 break;
 459                         case RENEW_REQUESTED:
 460                         case REQUESTING:
 461                         case RENEWING:
 462                         case REBINDING:
 463                                 if (*message == DHCPACK) {
 464                                         temp = get_option(&packet, DHCP_LEASE_TIME);
 465                                         if (!temp) {
 466                                                 bb_error_msg("no lease time with ACK, using 1 hour lease");
 467                                                 lease = 60 * 60;
 468                                         } else {
 469                                                 lease = ntohl(*(uint32_t*)temp);
 470                                         }
 471
 472                                         /* enter bound state */
 473                                         t1 = lease / 2;
 474
 475                                         /* little fixed point for n * .875 */
 476                                         t2 = (lease * 0x7) >> 3;
 477                                         temp_addr.s_addr = packet.yiaddr;
 478                                         bb_info_msg("Lease of %s obtained, lease time %ld",
 479                                                 inet_ntoa(temp_addr), lease);
 480                                         start = now;
 481                                         timeout = t1 + start;
 482                                         requested_ip = packet.yiaddr;
 483                                         udhcp_run_script(&packet,
 484                                                    ((state == RENEWING || state == REBINDING) ? "renew" : "bound"));
 485
 486                                         state = BOUND;
 487                                         change_mode(LISTEN_NONE);
 488                                         if (client_config.quit_after_lease) {
 489                                                 if (client_config.release_on_quit)
 490                                                         perform_release();
 491                                                 return 0;
 492                                         }
 493                                         if (!client_config.foreground)
 494                                                 client_background();
 495
 496                                 } else if (*message == DHCPNAK) {
 497                                         /* return to init state */
 498                                         bb_info_msg("Received DHCP NAK");
 499                                         udhcp_run_script(&packet, "nak");
 500                                         if (state != REQUESTING)
 501                                                 udhcp_run_script(NULL, "deconfig");
 502                                         state = INIT_SELECTING;
 503                                         timeout = now;
 504                                         requested_ip = 0;
 505                                         packet_num = 0;
 506                                         change_mode(LISTEN_RAW);
 507                                         sleep(3); /* avoid excessive network traffic */
 508                                 }
 509                                 break;
 510                         /* case BOUND, RELEASED: - ignore all packets */
 511                         }
 512                 } else if (retval > 0 && (sig = udhcp_sp_read(&rfds))) {
 513                         switch (sig) {
 514                         case SIGUSR1:
 515                                 perform_renew();
 516                                 break;
 517                         case SIGUSR2:
 518                                 perform_release();
 519                                 break;
 520                         case SIGTERM:
 521                                 bb_info_msg("Received SIGTERM");
 522                                 if (client_config.release_on_quit)
 523                                         perform_release();
 524                                 return 0;
 525                         }
 526                 } else if (retval == -1 && errno == EINTR) {
 527                         /* a signal was caught */
 528                 } else {
 529                         /* An error occured */
 530                         bb_perror_msg("select");
 531                 }
 532
 533         }
 534         return 0;
 535 }