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