networking/udhcp/dhcpc.c

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