networking/udhcp/dhcpc.c

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