git.maemo.org Git - udhcp/blob - 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 <sys/time.h>
  23 #include <sys/file.h>
  24 #include <unistd.h>
  25 #include <getopt.h>
  26 #include <stdlib.h>
  27 #include <sys/socket.h>
  28 #include <netinet/in.h>
  29 #include <arpa/inet.h>
  30 #include <signal.h>
  31 #include <time.h>
  32 #include <string.h>
  33 #include <sys/ioctl.h>
  34 #include <net/if.h>
  35 #include <errno.h>
  36
  37 #include "dhcpd.h"
  38 #include "dhcpc.h"
  39 #include "options.h"
  40 #include "clientpacket.h"
  41 #include "clientsocket.h"
  42 #include "script.h"
  43 #include "socket.h"
  44 #include "common.h"
  45 #include "signalpipe.h"
  46
  47 static int state;
  48 static unsigned long requested_ip; /* = 0 */
  49 static unsigned long server_addr;
  50 static unsigned long timeout;
  51 static int packet_num; /* = 0 */
  52 static int fd = -1;
  53
  54 #define LISTEN_NONE 0
  55 #define LISTEN_KERNEL 1
  56 #define LISTEN_RAW 2
  57 static int listen_mode;
  58
  59 struct client_config_t client_config = {
  60         /* Default options. */
  61         abort_if_no_lease: 0,
  62         foreground: 0,
  63         quit_after_lease: 0,
  64         background_if_no_lease: 0,
  65         interface: "eth0",
  66         pidfile: NULL,
  67         script: DEFAULT_SCRIPT,
  68         clientid: NULL,
  69         hostname: NULL,
  70         fqdn: NULL,
  71         ifindex: 0,
  72         arp: "\0\0\0\0\0\0",            /* appease gcc-3.0 */
  73 };
  74
  75 #ifndef IN_BUSYBOX
  76 static void __attribute__ ((noreturn)) show_usage(void)
  77 {
  78         printf(
  79 "Usage: udhcpc [OPTIONS]\n\n"
  80 "  -c, --clientid=CLIENTID         Client identifier\n"
  81 "  -H, --hostname=HOSTNAME         Client hostname\n"
  82 "  -h                              Alias for -H\n"
  83 "  -F, --fqdn=FQDN                 Client fully qualified domain name\n"
  84 "  -f, --foreground                Do not fork after getting lease\n"
  85 "  -b, --background                Fork to background if lease cannot be\n"
  86 "                                  immediately negotiated.\n"
  87 "  -i, --interface=INTERFACE       Interface to use (default: eth0)\n"
  88 "  -n, --now                       Exit with failure if lease cannot be\n"
  89 "                                  immediately negotiated.\n"
  90 "  -p, --pidfile=file              Store process ID of daemon in file\n"
  91 "  -q, --quit                      Quit after obtaining lease\n"
  92 "  -r, --request=IP                IP address to request (default: none)\n"
  93 "  -s, --script=file               Run file at dhcp events (default:\n"
  94 "                                  " DEFAULT_SCRIPT ")\n"
  95 "  -v, --version                   Display version\n"
  96         );
  97         exit(0);
  98 }
  99 #else
 100 #define show_usage bb_show_usage
 101 extern void show_usage(void) __attribute__ ((noreturn));
 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         if (fd >= 0) 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                 break;
 136         }
 137
 138         /* start things over */
 139         packet_num = 0;
 140
 141         /* Kill any timeouts because the user wants this to hurry along */
 142         timeout = 0;
 143 }
 144
 145
 146 /* perform a release */
 147 static void perform_release(void)
 148 {
 149         char buffer[16];
 150         struct in_addr temp_addr;
 151
 152         /* send release packet */
 153         if (state == BOUND || state == RENEWING || state == REBINDING) {
 154                 temp_addr.s_addr = server_addr;
 155                 sprintf(buffer, "%s", inet_ntoa(temp_addr));
 156                 temp_addr.s_addr = requested_ip;
 157                 LOG(LOG_INFO, "Unicasting a release of %s to %s",
 158                                 inet_ntoa(temp_addr), buffer);
 159                 send_release(server_addr, requested_ip); /* unicast */
 160                 run_script(NULL, "deconfig");
 161         }
 162         LOG(LOG_INFO, "Entering released state");
 163
 164         change_mode(LISTEN_NONE);
 165         state = RELEASED;
 166         timeout = 0x7fffffff;
 167 }
 168
 169
 170 static void client_background(void)
 171 {
 172         background(client_config.pidfile);
 173         client_config.foreground = 1; /* Do not fork again. */
 174         client_config.background_if_no_lease = 0;
 175 }
 176
 177
 178 #ifdef COMBINED_BINARY
 179 int udhcpc_main(int argc, char *argv[])
 180 #else
 181 int main(int argc, char *argv[])
 182 #endif
 183 {
 184         uint8_t *temp, *message;
 185         unsigned long t1 = 0, t2 = 0, xid = 0;
 186         unsigned long start = 0, lease;
 187         fd_set rfds;
 188         int retval;
 189         struct timeval tv;
 190         int c, len;
 191         struct dhcpMessage packet;
 192         struct in_addr temp_addr;
 193         long now;
 194         int max_fd;
 195         int sig;
 196
 197         static const struct option arg_options[] = {
 198                 {"clientid",    required_argument,      0, 'c'},
 199                 {"foreground",  no_argument,            0, 'f'},
 200                 {"background",  no_argument,            0, 'b'},
 201                 {"hostname",    required_argument,      0, 'H'},
 202                 {"hostname",    required_argument,      0, 'h'},
 203                 {"fqdn",        required_argument,      0, 'F'},
 204                 {"interface",   required_argument,      0, 'i'},
 205                 {"now",         no_argument,            0, 'n'},
 206                 {"pidfile",     required_argument,      0, 'p'},
 207                 {"quit",        no_argument,            0, 'q'},
 208                 {"request",     required_argument,      0, 'r'},
 209                 {"script",      required_argument,      0, 's'},
 210                 {"version",     no_argument,            0, 'v'},
 211                 {0, 0, 0, 0}
 212         };
 213
 214         /* get options */
 215         while (1) {
 216                 int option_index = 0;
 217                 c = getopt_long(argc, argv, "c:fbH:h:F:i:np:qr:s:v", arg_options, &option_index);
 218                 if (c == -1) break;
 219
 220                 switch (c) {
 221                 case 'c':
 222                         len = strlen(optarg) > 255 ? 255 : strlen(optarg);
 223                         if (client_config.clientid) free(client_config.clientid);
 224                         client_config.clientid = xmalloc(len + 2);
 225                         client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
 226                         client_config.clientid[OPT_LEN] = len;
 227                         client_config.clientid[OPT_DATA] = '\0';
 228                         strncpy(client_config.clientid + OPT_DATA, optarg, len);
 229                         break;
 230                 case 'f':
 231                         client_config.foreground = 1;
 232                         break;
 233                 case 'b':
 234                         client_config.background_if_no_lease = 1;
 235                         break;
 236                 case 'h':
 237                 case 'H':
 238                         len = strlen(optarg) > 255 ? 255 : strlen(optarg);
 239                         if (client_config.hostname) free(client_config.hostname);
 240                         client_config.hostname = xmalloc(len + 2);
 241                         client_config.hostname[OPT_CODE] = DHCP_HOST_NAME;
 242                         client_config.hostname[OPT_LEN] = len;
 243                         strncpy(client_config.hostname + 2, optarg, len);
 244                         break;
 245                 case 'F':
 246                         len = strlen(optarg) > 255 ? 255 : strlen(optarg);
 247                         if (client_config.fqdn) free(client_config.fqdn);
 248                         client_config.fqdn = xmalloc(len + 5);
 249                         client_config.fqdn[OPT_CODE] = DHCP_FQDN;
 250                         client_config.fqdn[OPT_LEN] = len + 3;
 251                         /* Flags: 0000NEOS
 252                         S: 1 => Client requests Server to update A RR in DNS as well as PTR
 253                         O: 1 => Server indicates to client that DNS has been updated regardless
 254                         E: 1 => Name data is DNS format, i.e. <4>host<6>domain<4>com<0> not "host.domain.com"
 255                         N: 1 => Client requests Server to not update DNS
 256                         */
 257                         client_config.fqdn[OPT_LEN + 1] = 0x1;
 258                         client_config.fqdn[OPT_LEN + 2] = 0;
 259                         client_config.fqdn[OPT_LEN + 3] = 0;
 260                         strncpy(client_config.fqdn + 5, optarg, len);
 261                         break;
 262                 case 'i':
 263                         client_config.interface =  optarg;
 264                         break;
 265                 case 'n':
 266                         client_config.abort_if_no_lease = 1;
 267                         break;
 268                 case 'p':
 269                         client_config.pidfile = optarg;
 270                         break;
 271                 case 'q':
 272                         client_config.quit_after_lease = 1;
 273                         break;
 274                 case 'r':
 275                         requested_ip = inet_addr(optarg);
 276                         break;
 277                 case 's':
 278                         client_config.script = optarg;
 279                         break;
 280                 case 'v':
 281                         printf("udhcpcd, version %s\n\n", VERSION);
 282                         return 0;
 283                         break;
 284                 default:
 285                         show_usage();
 286                 }
 287         }
 288
 289         /* Start the log, sanitize fd's, and write a pid file */
 290         start_log_and_pid("udhcpc", client_config.pidfile);
 291
 292         if (read_interface(client_config.interface, &client_config.ifindex,
 293                            NULL, client_config.arp) < 0)
 294                 return 1;
 295
 296         if (!client_config.clientid) {
 297                 client_config.clientid = xmalloc(6 + 3);
 298                 client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
 299                 client_config.clientid[OPT_LEN] = 7;
 300                 client_config.clientid[OPT_DATA] = 1;
 301                 memcpy(client_config.clientid + 3, client_config.arp, 6);
 302         }
 303
 304         /* setup the signal pipe */
 305         udhcp_sp_setup();
 306
 307         state = INIT_SELECTING;
 308         run_script(NULL, "deconfig");
 309         change_mode(LISTEN_RAW);
 310
 311         for (;;) {
 312
 313                 tv.tv_sec = timeout - uptime();
 314                 tv.tv_usec = 0;
 315
 316                 if (listen_mode != LISTEN_NONE && fd < 0) {
 317                         if (listen_mode == LISTEN_KERNEL)
 318                                 fd = listen_socket(INADDR_ANY, CLIENT_PORT, client_config.interface);
 319                         else
 320                                 fd = raw_socket(client_config.ifindex);
 321                         if (fd < 0) {
 322                                 LOG(LOG_ERR, "FATAL: couldn't listen on socket, %m");
 323                                 return 0;
 324                         }
 325                 }
 326                 max_fd = udhcp_sp_fd_set(&rfds, fd);
 327
 328                 if (tv.tv_sec > 0) {
 329                         DEBUG(LOG_INFO, "Waiting on select...");
 330                         retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
 331                 } else retval = 0; /* If we already timed out, fall through */
 332
 333                 now = uptime();
 334                 if (retval == 0) {
 335                         /* timeout dropped to zero */
 336                         switch (state) {
 337                         case INIT_SELECTING:
 338                                 if (packet_num < 3) {
 339                                         if (packet_num == 0)
 340                                                 xid = random_xid();
 341
 342                                         /* send discover packet */
 343                                         send_discover(xid, requested_ip); /* broadcast */
 344
 345                                         timeout = now + ((packet_num == 2) ? 4 : 2);
 346                                         packet_num++;
 347                                 } else {
 348                                         run_script(NULL, "leasefail");
 349                                         if (client_config.background_if_no_lease) {
 350                                                 LOG(LOG_INFO, "No lease, forking to background.");
 351                                                 client_background();
 352                                         } else if (client_config.abort_if_no_lease) {
 353                                                 LOG(LOG_INFO, "No lease, failing.");
 354                                                 return 1;
 355                                         }
 356                                         /* wait to try again */
 357                                         packet_num = 0;
 358                                         timeout = now + 60;
 359                                 }
 360                                 break;
 361                         case RENEW_REQUESTED:
 362                         case REQUESTING:
 363                                 if (packet_num < 3) {
 364                                         /* send request packet */
 365                                         if (state == RENEW_REQUESTED)
 366                                                 send_renew(xid, server_addr, requested_ip); /* unicast */
 367                                         else send_selecting(xid, server_addr, requested_ip); /* broadcast */
 368
 369                                         timeout = now + ((packet_num == 2) ? 10 : 2);
 370                                         packet_num++;
 371                                 } else {
 372                                         /* timed out, go back to init state */
 373                                         if (state == RENEW_REQUESTED) run_script(NULL, "deconfig");
 374                                         state = INIT_SELECTING;
 375                                         timeout = now;
 376                                         packet_num = 0;
 377                                         change_mode(LISTEN_RAW);
 378                                 }
 379                                 break;
 380                         case BOUND:
 381                                 /* Lease is starting to run out, time to enter renewing state */
 382                                 state = RENEWING;
 383                                 change_mode(LISTEN_KERNEL);
 384                                 DEBUG(LOG_INFO, "Entering renew state");
 385                                 /* fall right through */
 386                         case RENEWING:
 387                                 /* Either set a new T1, or enter REBINDING state */
 388                                 if ((t2 - t1) <= (lease / 14400 + 1)) {
 389                                         /* timed out, enter rebinding state */
 390                                         state = REBINDING;
 391                                         timeout = now + (t2 - t1);
 392                                         DEBUG(LOG_INFO, "Entering rebinding state");
 393                                 } else {
 394                                         /* send a request packet */
 395                                         send_renew(xid, server_addr, requested_ip); /* unicast */
 396
 397                                         t1 = (t2 - t1) / 2 + t1;
 398                                         timeout = t1 + start;
 399                                 }
 400                                 break;
 401                         case REBINDING:
 402                                 /* Either set a new T2, or enter INIT state */
 403                                 if ((lease - t2) <= (lease / 14400 + 1)) {
 404                                         /* timed out, enter init state */
 405                                         state = INIT_SELECTING;
 406                                         LOG(LOG_INFO, "Lease lost, entering init state");
 407                                         run_script(NULL, "deconfig");
 408                                         timeout = now;
 409                                         packet_num = 0;
 410                                         change_mode(LISTEN_RAW);
 411                                 } else {
 412                                         /* send a request packet */
 413                                         send_renew(xid, 0, requested_ip); /* broadcast */
 414
 415                                         t2 = (lease - t2) / 2 + t2;
 416                                         timeout = t2 + start;
 417                                 }
 418                                 break;
 419                         case RELEASED:
 420                                 /* yah, I know, *you* say it would never happen */
 421                                 timeout = 0x7fffffff;
 422                                 break;
 423                         }
 424                 } else if (retval > 0 && listen_mode != LISTEN_NONE && FD_ISSET(fd, &rfds)) {
 425                         /* a packet is ready, read it */
 426
 427                         if (listen_mode == LISTEN_KERNEL)
 428                                 len = get_packet(&packet, fd);
 429                         else len = get_raw_packet(&packet, fd);
 430
 431                         if (len == -1 && errno != EINTR) {
 432                                 DEBUG(LOG_INFO, "error on read, %m, reopening socket");
 433                                 change_mode(listen_mode); /* just close and reopen */
 434                         }
 435                         if (len < 0) continue;
 436
 437                         if (packet.xid != xid) {
 438                                 DEBUG(LOG_INFO, "Ignoring XID %lx (our xid is %lx)",
 439                                         (unsigned long) packet.xid, xid);
 440                                 continue;
 441                         }
 442
 443                         if ((message = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
 444                                 DEBUG(LOG_ERR, "couldnt get option from packet -- ignoring");
 445                                 continue;
 446                         }
 447
 448                         switch (state) {
 449                         case INIT_SELECTING:
 450                                 /* Must be a DHCPOFFER to one of our xid's */
 451                                 if (*message == DHCPOFFER) {
 452                                         if ((temp = get_option(&packet, DHCP_SERVER_ID))) {
 453                                                 memcpy(&server_addr, temp, 4);
 454                                                 xid = packet.xid;
 455                                                 requested_ip = packet.yiaddr;
 456
 457                                                 /* enter requesting state */
 458                                                 state = REQUESTING;
 459                                                 timeout = now;
 460                                                 packet_num = 0;
 461                                         } else {
 462                                                 DEBUG(LOG_ERR, "No server ID in message");
 463                                         }
 464                                 }
 465                                 break;
 466                         case RENEW_REQUESTED:
 467                         case REQUESTING:
 468                         case RENEWING:
 469                         case REBINDING:
 470                                 if (*message == DHCPACK) {
 471                                         if (!(temp = get_option(&packet, DHCP_LEASE_TIME))) {
 472                                                 LOG(LOG_ERR, "No lease time with ACK, using 1 hour lease");
 473                                                 lease = 60 * 60;
 474                                         } else {
 475                                                 memcpy(&lease, temp, 4);
 476                                                 lease = ntohl(lease);
 477                                         }
 478
 479                                         /* enter bound state */
 480                                         t1 = lease / 2;
 481
 482                                         /* little fixed point for n * .875 */
 483                                         t2 = (lease * 0x7) >> 3;
 484                                         temp_addr.s_addr = packet.yiaddr;
 485                                         LOG(LOG_INFO, "Lease of %s obtained, lease time %ld",
 486                                                 inet_ntoa(temp_addr), lease);
 487                                         start = now;
 488                                         timeout = t1 + start;
 489                                         requested_ip = packet.yiaddr;
 490                                         run_script(&packet,
 491                                                    ((state == RENEWING || state == REBINDING) ? "renew" : "bound"));
 492
 493                                         state = BOUND;
 494                                         change_mode(LISTEN_NONE);
 495                                         if (client_config.quit_after_lease)
 496                                                 return 0;
 497                                         if (!client_config.foreground)
 498                                                 client_background();
 499
 500                                 } else if (*message == DHCPNAK) {
 501                                         /* return to init state */
 502                                         LOG(LOG_INFO, "Received DHCP NAK");
 503                                         run_script(&packet, "nak");
 504                                         if (state != REQUESTING)
 505                                                 run_script(NULL, "deconfig");
 506                                         state = INIT_SELECTING;
 507                                         timeout = now;
 508                                         requested_ip = 0;
 509                                         packet_num = 0;
 510                                         change_mode(LISTEN_RAW);
 511                                         sleep(3); /* avoid excessive network traffic */
 512                                 }
 513                                 break;
 514                         /* case BOUND, RELEASED: - ignore all packets */
 515                         }
 516                 } else if (retval > 0 && (sig = udhcp_sp_read(&rfds))) {
 517                         switch (sig) {
 518                         case SIGUSR1:
 519                                 perform_renew();
 520                                 break;
 521                         case SIGUSR2:
 522                                 perform_release();
 523                                 break;
 524                         case SIGTERM:
 525                                 LOG(LOG_INFO, "Received SIGTERM");
 526                                 return 0;
 527                         }
 528                 } else if (retval == -1 && errno == EINTR) {
 529                         /* a signal was caught */
 530                 } else {
 531                         /* An error occured */
 532                         DEBUG(LOG_ERR, "Error on select");
 533                 }
 534
 535         }
 536         return 0;
 537 }