networking/udhcp/dhcpc.c

   1 /* dhcpc.c
   2  *
   3  * udhcp DHCP client
   4  *
   5  * Russ Dill <Russ.Dill@asu.edu> July 2001
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20  */
  21
  22 #include <stdio.h>
  23 #include <sys/time.h>
  24 #include <sys/types.h>
  25 #include <sys/file.h>
  26 #include <unistd.h>
  27 #include <getopt.h>
  28 #include <stdlib.h>
  29 #include <sys/socket.h>
  30 #include <netinet/in.h>
  31 #include <arpa/inet.h>
  32 #include <signal.h>
  33 #include <time.h>
  34 #include <string.h>
  35 #include <sys/ioctl.h>
  36 #include <net/if.h>
  37 #include <errno.h>
  38
  39 #include "dhcpd.h"
  40 #include "dhcpc.h"
  41 #include "options.h"
  42 #include "clientpacket.h"
  43 #include "packet.h"
  44 #include "script.h"
  45 #include "socket.h"
  46 #include "debug.h"
  47 #include "pidfile.h"
  48
  49 static int state;
  50 static unsigned long requested_ip; /* = 0 */
  51 static unsigned long server_addr;
  52 static unsigned long timeout;
  53 static int packet_num; /* = 0 */
  54 static int fd;
  55 static int signal_pipe[2];
  56
  57 #define LISTEN_NONE 0
  58 #define LISTEN_KERNEL 1
  59 #define LISTEN_RAW 2
  60 static int listen_mode;
  61
  62 #define DEFAULT_SCRIPT  "/usr/share/udhcpc/default.script"
  63
  64 struct client_config_t client_config = {
  65         /* Default options. */
  66         abort_if_no_lease: 0,
  67         foreground: 0,
  68         quit_after_lease: 0,
  69         background_if_no_lease: 0,
  70         interface: "eth0",
  71         pidfile: NULL,
  72         script: DEFAULT_SCRIPT,
  73         clientid: NULL,
  74         hostname: NULL,
  75         ifindex: 0,
  76         arp: "\0\0\0\0\0\0",            /* appease gcc-3.0 */
  77 };
  78
  79 #ifndef BB_VER
  80 static void show_usage(void)
  81 {
  82         printf(
  83 "Usage: udhcpc [OPTIONS]\n\n"
  84 "  -c, --clientid=CLIENTID         Client identifier\n"
  85 "  -H, --hostname=HOSTNAME         Client hostname\n"
  86 "  -h                              Alias for -H\n"
  87 "  -f, --foreground                Do not fork after getting lease\n"
  88 "  -b, --background                Fork to background if lease cannot be\n"
  89 "                                  immediately negotiated.\n"
  90 "  -i, --interface=INTERFACE       Interface to use (default: eth0)\n"
  91 "  -n, --now                       Exit with failure if lease cannot be\n"
  92 "                                  immediately negotiated.\n"
  93 "  -p, --pidfile=file              Store process ID of daemon in file\n"
  94 "  -q, --quit                      Quit after obtaining lease\n"
  95 "  -r, --request=IP                IP address to request (default: none)\n"
  96 "  -s, --script=file               Run file at dhcp events (default:\n"
  97 "                                  " DEFAULT_SCRIPT ")\n"
  98 "  -v, --version                   Display version\n"
  99         );
 100         exit(0);
 101 }
 102 #endif
 103
 104
 105 /* just a little helper */
 106 static void change_mode(int new_mode)
 107 {
 108         DEBUG(LOG_INFO, "entering %s listen mode",
 109                 new_mode ? (new_mode == 1 ? "kernel" : "raw") : "none");
 110         close(fd);
 111         fd = -1;
 112         listen_mode = new_mode;
 113 }
 114
 115
 116 /* perform a renew */
 117 static void perform_renew(void)
 118 {
 119         LOG(LOG_INFO, "Performing a DHCP renew");
 120         switch (state) {
 121         case BOUND:
 122                 change_mode(LISTEN_KERNEL);
 123         case RENEWING:
 124         case REBINDING:
 125                 state = RENEW_REQUESTED;
 126                 break;
 127         case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
 128                 run_script(NULL, "deconfig");
 129         case REQUESTING:
 130         case RELEASED:
 131                 change_mode(LISTEN_RAW);
 132                 state = INIT_SELECTING;
 133                 break;
 134         case INIT_SELECTING:
 135         }
 136
 137         /* start things over */
 138         packet_num = 0;
 139
 140         /* Kill any timeouts because the user wants this to hurry along */
 141         timeout = 0;
 142 }
 143
 144
 145 /* perform a release */
 146 static void perform_release(void)
 147 {
 148         char buffer[16];
 149         struct in_addr temp_addr;
 150
 151         /* send release packet */
 152         if (state == BOUND || state == RENEWING || state == REBINDING) {
 153                 temp_addr.s_addr = server_addr;
 154                 sprintf(buffer, "%s", inet_ntoa(temp_addr));
 155                 temp_addr.s_addr = requested_ip;
 156                 LOG(LOG_INFO, "Unicasting a release of %s to %s",
 157                                 inet_ntoa(temp_addr), buffer);
 158                 send_release(server_addr, requested_ip); /* unicast */
 159                 run_script(NULL, "deconfig");
 160         }
 161         LOG(LOG_INFO, "Entering released state");
 162
 163         change_mode(LISTEN_NONE);
 164         state = RELEASED;
 165         timeout = 0x7fffffff;
 166 }
 167
 168
 169 /* Exit and cleanup */
 170 static void exit_client(int retval)
 171 {
 172         pidfile_delete(client_config.pidfile);
 173         CLOSE_LOG();
 174         exit(retval);
 175 }
 176
 177
 178 /* Signal handler */
 179 static void signal_handler(int sig)
 180 {
 181         if (send(signal_pipe[1], &sig, sizeof(sig), MSG_DONTWAIT) < 0) {
 182                 LOG(LOG_ERR, "Could not send signal: %s",
 183                         strerror(errno));
 184         }
 185 }
 186
 187
 188 static void background(void)
 189 {
 190         int pid_fd;
 191
 192         pid_fd = pidfile_acquire(client_config.pidfile); /* hold lock during fork. */
 193         while (pid_fd >= 0 && pid_fd < 3) pid_fd = dup(pid_fd); /* don't let daemon close it */
 194         if (daemon(0, 0) == -1) {
 195                 perror("fork");
 196                 exit_client(1);
 197         }
 198         client_config.foreground = 1; /* Do not fork again. */
 199         pidfile_write_release(pid_fd);
 200 }
 201
 202
 203 #ifdef COMBINED_BINARY
 204 int udhcpc_main(int argc, char *argv[])
 205 #else
 206 int main(int argc, char *argv[])
 207 #endif
 208 {
 209         unsigned char *temp, *message;
 210         unsigned long t1 = 0, t2 = 0, xid = 0;
 211         unsigned long start = 0, lease;
 212         fd_set rfds;
 213         int retval;
 214         struct timeval tv;
 215         int c, len;
 216         struct dhcpMessage packet;
 217         struct in_addr temp_addr;
 218         int pid_fd;
 219         time_t now;
 220         int max_fd;
 221         int sig;
 222
 223         static struct option arg_options[] = {
 224                 {"clientid",    required_argument,      0, 'c'},
 225                 {"foreground",  no_argument,            0, 'f'},
 226                 {"background",  no_argument,            0, 'b'},
 227                 {"hostname",    required_argument,      0, 'H'},
 228                 {"hostname",    required_argument,      0, 'h'},
 229                 {"interface",   required_argument,      0, 'i'},
 230                 {"now",         no_argument,            0, 'n'},
 231                 {"pidfile",     required_argument,      0, 'p'},
 232                 {"quit",        no_argument,            0, 'q'},
 233                 {"request",     required_argument,      0, 'r'},
 234                 {"script",      required_argument,      0, 's'},
 235                 {"version",     no_argument,            0, 'v'},
 236                 {"help",        no_argument,            0, '?'},
 237                 {0, 0, 0, 0}
 238         };
 239
 240         /* get options */
 241         while (1) {
 242                 int option_index = 0;
 243                 c = getopt_long(argc, argv, "c:fbH:h:i:np:qr:s:v", arg_options, &option_index);
 244                 if (c == -1) break;
 245
 246                 switch (c) {
 247                 case 'c':
 248                         len = strlen(optarg) > 255 ? 255 : strlen(optarg);
 249                         free(client_config.clientid);
 250                         client_config.clientid = xmalloc(len + 2);
 251                         client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
 252                         client_config.clientid[OPT_LEN] = len;
 253                         client_config.clientid[OPT_DATA] = '\0';
 254                         strncpy(client_config.clientid + OPT_DATA, optarg, len);
 255                         break;
 256                 case 'f':
 257                         client_config.foreground = 1;
 258                         break;
 259                 case 'b':
 260                         client_config.background_if_no_lease = 1;
 261                         break;
 262                 case 'h':
 263                 case 'H':
 264                         len = strlen(optarg) > 255 ? 255 : strlen(optarg);
 265                         free(client_config.hostname);
 266                         client_config.hostname = xmalloc(len + 2);
 267                         client_config.hostname[OPT_CODE] = DHCP_HOST_NAME;
 268                         client_config.hostname[OPT_LEN] = len;
 269                         strncpy(client_config.hostname + 2, 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 'v':
 290                         printf("udhcpcd, version %s\n\n", VERSION);
 291                         exit_client(0);
 292                         break;
 293                 default:
 294                         show_usage();
 295                 }
 296         }
 297
 298         OPEN_LOG("udhcpc");
 299         LOG(LOG_INFO, "udhcp client (v%s) started", VERSION);
 300
 301         pid_fd = pidfile_acquire(client_config.pidfile);
 302         pidfile_write_release(pid_fd);
 303
 304         if (read_interface(client_config.interface, &client_config.ifindex,
 305                            NULL, client_config.arp) < 0)
 306                 exit_client(1);
 307
 308         if (!client_config.clientid) {
 309                 client_config.clientid = xmalloc(6 + 3);
 310                 client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
 311                 client_config.clientid[OPT_LEN] = 7;
 312                 client_config.clientid[OPT_DATA] = 1;
 313                 memcpy(client_config.clientid + 3, client_config.arp, 6);
 314         }
 315
 316         /* setup signal handlers */
 317         socketpair(AF_UNIX, SOCK_STREAM, 0, signal_pipe);
 318         signal(SIGUSR1, signal_handler);
 319         signal(SIGUSR2, signal_handler);
 320         signal(SIGTERM, signal_handler);
 321
 322         state = INIT_SELECTING;
 323         run_script(NULL, "deconfig");
 324         change_mode(LISTEN_RAW);
 325
 326         for (;;) {
 327
 328                 tv.tv_sec = timeout - time(0);
 329                 tv.tv_usec = 0;
 330                 FD_ZERO(&rfds);
 331
 332                 if (listen_mode != LISTEN_NONE && fd < 0) {
 333                         if (listen_mode == LISTEN_KERNEL)
 334                                 fd = listen_socket(INADDR_ANY, CLIENT_PORT, client_config.interface);
 335                         else
 336                                 fd = raw_socket(client_config.ifindex);
 337                         if (fd < 0) {
 338                                 LOG(LOG_ERR, "FATAL: couldn't listen on socket, %s", strerror(errno));
 339                                 exit_client(0);
 340                         }
 341                 }
 342                 if (fd >= 0) FD_SET(fd, &rfds);
 343                 FD_SET(signal_pipe[0], &rfds);
 344
 345                 if (tv.tv_sec > 0) {
 346                         DEBUG(LOG_INFO, "Waiting on select...\n");
 347                         max_fd = signal_pipe[0] > fd ? signal_pipe[0] : fd;
 348                         retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
 349                 } else retval = 0; /* If we already timed out, fall through */
 350
 351                 now = time(0);
 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                                         if (client_config.background_if_no_lease) {
 367                                                 LOG(LOG_INFO, "No lease, forking to background.");
 368                                                 background();
 369                                         } else if (client_config.abort_if_no_lease) {
 370                                                 LOG(LOG_INFO, "No lease, failing.");
 371                                                 exit_client(1);
 372                                         }
 373                                         /* wait to try again */
 374                                         packet_num = 0;
 375                                         timeout = now + 60;
 376                                 }
 377                                 break;
 378                         case RENEW_REQUESTED:
 379                         case REQUESTING:
 380                                 if (packet_num < 3) {
 381                                         /* send request packet */
 382                                         if (state == RENEW_REQUESTED)
 383                                                 send_renew(xid, server_addr, requested_ip); /* unicast */
 384                                         else send_selecting(xid, server_addr, requested_ip); /* broadcast */
 385
 386                                         timeout = now + ((packet_num == 2) ? 10 : 2);
 387                                         packet_num++;
 388                                 } else {
 389                                         /* timed out, go back to init state */
 390                                         if (state == RENEW_REQUESTED) run_script(NULL, "deconfig");
 391                                         state = INIT_SELECTING;
 392                                         timeout = now;
 393                                         packet_num = 0;
 394                                         change_mode(LISTEN_RAW);
 395                                 }
 396                                 break;
 397                         case BOUND:
 398                                 /* Lease is starting to run out, time to enter renewing state */
 399                                 state = RENEWING;
 400                                 change_mode(LISTEN_KERNEL);
 401                                 DEBUG(LOG_INFO, "Entering renew state");
 402                                 /* fall right through */
 403                         case RENEWING:
 404                                 /* Either set a new T1, or enter REBINDING state */
 405                                 if ((t2 - t1) <= (lease / 14400 + 1)) {
 406                                         /* timed out, enter rebinding state */
 407                                         state = REBINDING;
 408                                         timeout = now + (t2 - t1);
 409                                         DEBUG(LOG_INFO, "Entering rebinding state");
 410                                 } else {
 411                                         /* send a request packet */
 412                                         send_renew(xid, server_addr, requested_ip); /* unicast */
 413
 414                                         t1 = (t2 - t1) / 2 + t1;
 415                                         timeout = t1 + start;
 416                                 }
 417                                 break;
 418                         case REBINDING:
 419                                 /* Either set a new T2, or enter INIT state */
 420                                 if ((lease - t2) <= (lease / 14400 + 1)) {
 421                                         /* timed out, enter init state */
 422                                         state = INIT_SELECTING;
 423                                         LOG(LOG_INFO, "Lease lost, entering init state");
 424                                         run_script(NULL, "deconfig");
 425                                         timeout = now;
 426                                         packet_num = 0;
 427                                         change_mode(LISTEN_RAW);
 428                                 } else {
 429                                         /* send a request packet */
 430                                         send_renew(xid, 0, requested_ip); /* broadcast */
 431
 432                                         t2 = (lease - t2) / 2 + t2;
 433                                         timeout = t2 + start;
 434                                 }
 435                                 break;
 436                         case RELEASED:
 437                                 /* yah, I know, *you* say it would never happen */
 438                                 timeout = 0x7fffffff;
 439                                 break;
 440                         }
 441                 } else if (retval > 0 && listen_mode != LISTEN_NONE && FD_ISSET(fd, &rfds)) {
 442                         /* a packet is ready, read it */
 443
 444                         if (listen_mode == LISTEN_KERNEL)
 445                                 len = get_packet(&packet, fd);
 446                         else len = get_raw_packet(&packet, fd);
 447
 448                         if (len == -1 && errno != EINTR) {
 449                                 DEBUG(LOG_INFO, "error on read, %s, reopening socket", strerror(errno));
 450                                 change_mode(listen_mode); /* just close and reopen */
 451                         }
 452                         if (len < 0) continue;
 453
 454                         if (packet.xid != xid) {
 455                                 DEBUG(LOG_INFO, "Ignoring XID %lx (our xid is %lx)",
 456                                         (unsigned long) packet.xid, xid);
 457                                 continue;
 458                         }
 459
 460                         if ((message = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
 461                                 DEBUG(LOG_ERR, "couldnt get option from packet -- ignoring");
 462                                 continue;
 463                         }
 464
 465                         switch (state) {
 466                         case INIT_SELECTING:
 467                                 /* Must be a DHCPOFFER to one of our xid's */
 468                                 if (*message == DHCPOFFER) {
 469                                         if ((temp = get_option(&packet, DHCP_SERVER_ID))) {
 470                                                 memcpy(&server_addr, temp, 4);
 471                                                 xid = packet.xid;
 472                                                 requested_ip = packet.yiaddr;
 473
 474                                                 /* enter requesting state */
 475                                                 state = REQUESTING;
 476                                                 timeout = now;
 477                                                 packet_num = 0;
 478                                         } else {
 479                                                 DEBUG(LOG_ERR, "No server ID in message");
 480                                         }
 481                                 }
 482                                 break;
 483                         case RENEW_REQUESTED:
 484                         case REQUESTING:
 485                         case RENEWING:
 486                         case REBINDING:
 487                                 if (*message == DHCPACK) {
 488                                         if (!(temp = get_option(&packet, DHCP_LEASE_TIME))) {
 489                                                 LOG(LOG_ERR, "No lease time with ACK, using 1 hour lease");
 490                                                 lease = 60 * 60;
 491                                         } else {
 492                                                 memcpy(&lease, temp, 4);
 493                                                 lease = ntohl(lease);
 494                                         }
 495
 496                                         /* enter bound state */
 497                                         t1 = lease / 2;
 498
 499                                         /* little fixed point for n * .875 */
 500                                         t2 = (lease * 0x7) >> 3;
 501                                         temp_addr.s_addr = packet.yiaddr;
 502                                         LOG(LOG_INFO, "Lease of %s obtained, lease time %ld",
 503                                                 inet_ntoa(temp_addr), lease);
 504                                         start = now;
 505                                         timeout = t1 + start;
 506                                         requested_ip = packet.yiaddr;
 507                                         run_script(&packet,
 508                                                    ((state == RENEWING || state == REBINDING) ? "renew" : "bound"));
 509
 510                                         state = BOUND;
 511                                         change_mode(LISTEN_NONE);
 512                                         if (client_config.quit_after_lease)
 513                                                 exit_client(0);
 514                                         if (!client_config.foreground)
 515                                                 background();
 516
 517                                 } else if (*message == DHCPNAK) {
 518                                         /* return to init state */
 519                                         LOG(LOG_INFO, "Received DHCP NAK");
 520                                         run_script(&packet, "nak");
 521                                         if (state != REQUESTING)
 522                                                 run_script(NULL, "deconfig");
 523                                         state = INIT_SELECTING;
 524                                         timeout = now;
 525                                         requested_ip = 0;
 526                                         packet_num = 0;
 527                                         change_mode(LISTEN_RAW);
 528                                         sleep(3); /* avoid excessive network traffic */
 529                                 }
 530                                 break;
 531                         /* case BOUND, RELEASED: - ignore all packets */
 532                         }
 533                 } else if (retval > 0 && FD_ISSET(signal_pipe[0], &rfds)) {
 534                         if (read(signal_pipe[0], &sig, sizeof(signal)) < 0) {
 535                                 DEBUG(LOG_ERR, "Could not read signal: %s",
 536                                         strerror(errno));
 537                                 continue; /* probably just EINTR */
 538                         }
 539                         switch (sig) {
 540                         case SIGUSR1:
 541                                 perform_renew();
 542                                 break;
 543                         case SIGUSR2:
 544                                 perform_release();
 545                                 break;
 546                         case SIGTERM:
 547                                 LOG(LOG_INFO, "Received SIGTERM");
 548                                 exit_client(0);
 549                         }
 550                 } else if (retval == -1 && errno == EINTR) {
 551                         /* a signal was caught */
 552                 } else {
 553                         /* An error occured */
 554                         DEBUG(LOG_ERR, "Error on select");
 555                 }
 556
 557         }
 558         return 0;
 559 }
 560