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 /* Something is definitely wrong here. IPv4 addresses
  36  * in variables of type long?? BTW, we use inet_ntoa()
  37  * in the code. Manpage says that struct in_addr has a member of type long (!)
  38  * which holds IPv4 address, and the struct is passed by value (!!)
  39  */
  40 static unsigned long requested_ip; /* = 0 */
  41 static unsigned long server_addr;
  42 static unsigned long timeout;
  43 static int packet_num; /* = 0 */
  44 static int fd = -1;
  45
  46 #define LISTEN_NONE 0
  47 #define LISTEN_KERNEL 1
  48 #define LISTEN_RAW 2
  49 static int listen_mode;
  50
  51 struct client_config_t client_config = {
  52         /* Default options. */
  53         .abort_if_no_lease = 0,
  54         .foreground = 0,
  55         .quit_after_lease = 0,
  56         .release_on_quit = 0,
  57         .background_if_no_lease = 0,
  58         .interface = "eth0",
  59         .pidfile = NULL,
  60         .script = DEFAULT_SCRIPT,
  61         .clientid = NULL,
  62         .vendorclass = NULL,
  63         .hostname = NULL,
  64         .fqdn = NULL,
  65         .ifindex = 0,
  66         .retries = 3,
  67         .timeout = 3,
  68         .arp = "\0\0\0\0\0\0",          /* appease gcc-3.0 */
  69 };
  70
  71 /* just a little helper */
  72 static void change_mode(int new_mode)
  73 {
  74         DEBUG("entering %s listen mode",
  75                 new_mode ? (new_mode == 1 ? "kernel" : "raw") : "none");
  76         if (fd >= 0) close(fd);
  77         fd = -1;
  78         listen_mode = new_mode;
  79 }
  80
  81
  82 /* perform a renew */
  83 static void perform_renew(void)
  84 {
  85         bb_info_msg("Performing a DHCP renew");
  86         switch (state) {
  87         case BOUND:
  88                 change_mode(LISTEN_KERNEL);
  89         case RENEWING:
  90         case REBINDING:
  91                 state = RENEW_REQUESTED;
  92                 break;
  93         case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
  94                 udhcp_run_script(NULL, "deconfig");
  95         case REQUESTING:
  96         case RELEASED:
  97                 change_mode(LISTEN_RAW);
  98                 state = INIT_SELECTING;
  99                 break;
 100         case INIT_SELECTING:
 101                 break;
 102         }
 103
 104         /* start things over */
 105         packet_num = 0;
 106
 107         /* Kill any timeouts because the user wants this to hurry along */
 108         timeout = 0;
 109 }
 110
 111
 112 /* perform a release */
 113 static void perform_release(void)
 114 {
 115         char buffer[16];
 116         struct in_addr temp_addr;
 117
 118         /* send release packet */
 119         if (state == BOUND || state == RENEWING || state == REBINDING) {
 120                 temp_addr.s_addr = server_addr;
 121                 sprintf(buffer, "%s", inet_ntoa(temp_addr));
 122                 temp_addr.s_addr = requested_ip;
 123                 bb_info_msg("Unicasting a release of %s to %s",
 124                                 inet_ntoa(temp_addr), buffer);
 125                 send_release(server_addr, requested_ip); /* unicast */
 126                 udhcp_run_script(NULL, "deconfig");
 127         }
 128         bb_info_msg("Entering released state");
 129
 130         change_mode(LISTEN_NONE);
 131         state = RELEASED;
 132         timeout = 0x7fffffff;
 133 }
 134
 135
 136 static void client_background(void)
 137 {
 138         udhcp_background(client_config.pidfile);
 139         client_config.foreground = 1; /* Do not fork again. */
 140         client_config.background_if_no_lease = 0;
 141 }
 142
 143
 144 int udhcpc_main(int argc, char *argv[])
 145 {
 146         uint8_t *temp, *message;
 147         unsigned long t1 = 0, t2 = 0, xid = 0;
 148         unsigned long start = 0, lease = 0;
 149         fd_set rfds;
 150         int retval;
 151         struct timeval tv;
 152         int c, len;
 153         struct dhcpMessage packet;
 154         struct in_addr temp_addr;
 155         long now;
 156         int max_fd;
 157         int sig;
 158         int no_clientid = 0;
 159
 160         static const struct option arg_options[] = {
 161                 {"clientid",    required_argument,      0, 'c'},
 162                 {"clientid-none", no_argument,          0, 'C'},
 163                 {"vendorclass", required_argument,      0, 'V'},
 164                 {"foreground",  no_argument,            0, 'f'},
 165                 {"background",  no_argument,            0, 'b'},
 166                 {"hostname",    required_argument,      0, 'H'},
 167                 {"hostname",    required_argument,      0, 'h'},
 168                 {"fqdn",        required_argument,      0, 'F'},
 169                 {"interface",   required_argument,      0, 'i'},
 170                 {"now",         no_argument,            0, 'n'},
 171                 {"pidfile",     required_argument,      0, 'p'},
 172                 {"quit",        no_argument,            0, 'q'},
 173                 {"release",     no_argument,            0, 'R'},
 174                 {"request",     required_argument,      0, 'r'},
 175                 {"script",      required_argument,      0, 's'},
 176                 {"timeout",     required_argument,      0, 'T'},
 177                 {"version",     no_argument,            0, 'v'},
 178                 {"retries",     required_argument,      0, 't'},
 179                 {0, 0, 0, 0}
 180         };
 181
 182         /* get options */
 183         while (1) {
 184                 int option_index = 0;
 185                 c = getopt_long(argc, argv, "c:CV:fbH:h:F:i:np:qRr:s:T:t:v", arg_options, &option_index);
 186                 if (c == -1) break;
 187
 188                 switch (c) {
 189                 case 'c':
 190                         if (no_clientid) bb_show_usage();
 191                         len = strlen(optarg) > 255 ? 255 : strlen(optarg);
 192                         free(client_config.clientid);
 193                         client_config.clientid = xmalloc(len + 2);
 194                         client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
 195                         client_config.clientid[OPT_LEN] = len;
 196                         client_config.clientid[OPT_DATA] = '\0';
 197                         strncpy((char*)client_config.clientid + OPT_DATA, optarg, len);
 198                         break;
 199                 case 'C':
 200                         if (client_config.clientid) bb_show_usage();
 201                         no_clientid = 1;
 202                         break;
 203                 case 'V':
 204                         len = strlen(optarg) > 255 ? 255 : strlen(optarg);
 205                         free(client_config.vendorclass);
 206                         client_config.vendorclass = xmalloc(len + 2);
 207                         client_config.vendorclass[OPT_CODE] = DHCP_VENDOR;
 208                         client_config.vendorclass[OPT_LEN] = len;
 209                         strncpy((char*)client_config.vendorclass + OPT_DATA, optarg, len);
 210                         break;
 211                 case 'f':
 212                         client_config.foreground = 1;
 213                         break;
 214                 case 'b':
 215                         client_config.background_if_no_lease = 1;
 216                         break;
 217                 case 'h':
 218                 case 'H':
 219                         len = strlen(optarg) > 255 ? 255 : strlen(optarg);
 220                         free(client_config.hostname);
 221                         client_config.hostname = xmalloc(len + 2);
 222                         client_config.hostname[OPT_CODE] = DHCP_HOST_NAME;
 223                         client_config.hostname[OPT_LEN] = len;
 224                         strncpy((char*)client_config.hostname + 2, optarg, len);
 225                         break;
 226                 case 'F':
 227                         len = strlen(optarg) > 255 ? 255 : strlen(optarg);
 228                         free(client_config.fqdn);
 229                         client_config.fqdn = xmalloc(len + 5);
 230                         client_config.fqdn[OPT_CODE] = DHCP_FQDN;
 231                         client_config.fqdn[OPT_LEN] = len + 3;
 232                         /* Flags: 0000NEOS
 233                         S: 1 => Client requests Server to update A RR in DNS as well as PTR
 234                         O: 1 => Server indicates to client that DNS has been updated regardless
 235                         E: 1 => Name data is DNS format, i.e. <4>host<6>domain<4>com<0> not "host.domain.com"
 236                         N: 1 => Client requests Server to not update DNS
 237                         */
 238                         client_config.fqdn[OPT_LEN + 1] = 0x1;
 239                         client_config.fqdn[OPT_LEN + 2] = 0;
 240                         client_config.fqdn[OPT_LEN + 3] = 0;
 241                         strncpy((char*)client_config.fqdn + 5, optarg, len);
 242                         break;
 243                 case 'i':
 244                         client_config.interface =  optarg;
 245                         break;
 246                 case 'n':
 247                         client_config.abort_if_no_lease = 1;
 248                         break;
 249                 case 'p':
 250                         client_config.pidfile = optarg;
 251                         break;
 252                 case 'q':
 253                         client_config.quit_after_lease = 1;
 254                         break;
 255                 case 'R':
 256                         client_config.release_on_quit = 1;
 257                         break;
 258                 case 'r':
 259                         requested_ip = inet_addr(optarg);
 260                         break;
 261                 case 's':
 262                         client_config.script = optarg;
 263                         break;
 264                 case 'T':
 265                         client_config.timeout = xatoi_u(optarg);
 266                         break;
 267                 case 't':
 268                         client_config.retries = xatoi_u(optarg);
 269                         break;
 270                 case 'v':
 271                         printf("version %s\n\n", BB_VER);
 272                         return 0;
 273                         break;
 274                 default:
 275                         bb_show_usage();
 276                 }
 277         }
 278
 279         /* Start the log, sanitize fd's, and write a pid file */
 280         udhcp_start_log_and_pid(client_config.pidfile);
 281
 282         if (read_interface(client_config.interface, &client_config.ifindex,
 283                            NULL, client_config.arp) < 0)
 284                 return 1;
 285
 286         /* if not set, and not suppressed, setup the default client ID */
 287         if (!client_config.clientid && !no_clientid) {
 288                 client_config.clientid = xmalloc(6 + 3);
 289                 client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
 290                 client_config.clientid[OPT_LEN] = 7;
 291                 client_config.clientid[OPT_DATA] = 1;
 292                 memcpy(client_config.clientid + 3, client_config.arp, 6);
 293         }
 294
 295         if (!client_config.vendorclass) {
 296                 client_config.vendorclass = xmalloc(sizeof("udhcp "BB_VER) + 2);
 297                 client_config.vendorclass[OPT_CODE] = DHCP_VENDOR;
 298                 client_config.vendorclass[OPT_LEN] = sizeof("udhcp "BB_VER) - 1;
 299                 client_config.vendorclass[OPT_DATA] = 1;
 300                 memcpy(&client_config.vendorclass[OPT_DATA],
 301                         "udhcp "BB_VER, sizeof("udhcp "BB_VER) - 1);
 302         }
 303
 304
 305         /* setup the signal pipe */
 306         udhcp_sp_setup();
 307
 308         state = INIT_SELECTING;
 309         udhcp_run_script(NULL, "deconfig");
 310         change_mode(LISTEN_RAW);
 311
 312         for (;;) {
 313
 314                 tv.tv_sec = timeout - uptime();
 315                 tv.tv_usec = 0;
 316
 317                 if (listen_mode != LISTEN_NONE && fd < 0) {
 318                         if (listen_mode == LISTEN_KERNEL)
 319                                 fd = listen_socket(INADDR_ANY, CLIENT_PORT, client_config.interface);
 320                         else
 321                                 fd = raw_socket(client_config.ifindex);
 322                         if (fd < 0) {
 323                                 bb_perror_msg("FATAL: cannot listen on socket");
 324                                 return 0;
 325                         }
 326                 }
 327                 max_fd = udhcp_sp_fd_set(&rfds, fd);
 328
 329                 if (tv.tv_sec > 0) {
 330                         DEBUG("Waiting on select...");
 331                         retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
 332                 } else retval = 0; /* If we already timed out, fall through */
 333
 334                 now = uptime();
 335                 if (retval == 0) {
 336                         /* timeout dropped to zero */
 337                         switch (state) {
 338                         case INIT_SELECTING:
 339                                 if (packet_num < client_config.retries) {
 340                                         if (packet_num == 0)
 341                                                 xid = random_xid();
 342
 343                                         /* send discover packet */
 344                                         send_discover(xid, requested_ip); /* broadcast */
 345
 346                                         timeout = now + client_config.timeout;
 347                                         packet_num++;
 348                                 } else {
 349                                         udhcp_run_script(NULL, "leasefail");
 350                                         if (client_config.background_if_no_lease) {
 351                                                 bb_info_msg("No lease, forking to background");
 352                                                 client_background();
 353                                         } else if (client_config.abort_if_no_lease) {
 354                                                 bb_info_msg("No lease, failing");
 355                                                 return 1;
 356                                         }
 357                                         /* wait to try again */
 358                                         packet_num = 0;
 359                                         timeout = now + 60;
 360                                 }
 361                                 break;
 362                         case RENEW_REQUESTED:
 363                         case REQUESTING:
 364                                 if (packet_num < client_config.retries) {
 365                                         /* send request packet */
 366                                         if (state == RENEW_REQUESTED)
 367                                                 send_renew(xid, server_addr, requested_ip); /* unicast */
 368                                         else send_selecting(xid, server_addr, requested_ip); /* broadcast */
 369
 370                                         timeout = now + ((packet_num == 2) ? 10 : 2);
 371                                         packet_num++;
 372                                 } else {
 373                                         /* timed out, go back to init state */
 374                                         if (state == RENEW_REQUESTED) udhcp_run_script(NULL, "deconfig");
 375                                         state = INIT_SELECTING;
 376                                         timeout = now;
 377                                         packet_num = 0;
 378                                         change_mode(LISTEN_RAW);
 379                                 }
 380                                 break;
 381                         case BOUND:
 382                                 /* Lease is starting to run out, time to enter renewing state */
 383                                 state = RENEWING;
 384                                 change_mode(LISTEN_KERNEL);
 385                                 DEBUG("Entering renew state");
 386                                 /* fall right through */
 387                         case RENEWING:
 388                                 /* Either set a new T1, or enter REBINDING state */
 389                                 if ((t2 - t1) <= (lease / 14400 + 1)) {
 390                                         /* timed out, enter rebinding state */
 391                                         state = REBINDING;
 392                                         timeout = now + (t2 - t1);
 393                                         DEBUG("Entering rebinding state");
 394                                 } else {
 395                                         /* send a request packet */
 396                                         send_renew(xid, server_addr, requested_ip); /* unicast */
 397
 398                                         t1 = (t2 - t1) / 2 + t1;
 399                                         timeout = t1 + start;
 400                                 }
 401                                 break;
 402                         case REBINDING:
 403                                 /* Either set a new T2, or enter INIT state */
 404                                 if ((lease - t2) <= (lease / 14400 + 1)) {
 405                                         /* timed out, enter init state */
 406                                         state = INIT_SELECTING;
 407                                         bb_info_msg("Lease lost, entering init state");
 408                                         udhcp_run_script(NULL, "deconfig");
 409                                         timeout = now;
 410                                         packet_num = 0;
 411                                         change_mode(LISTEN_RAW);
 412                                 } else {
 413                                         /* send a request packet */
 414                                         send_renew(xid, 0, requested_ip); /* broadcast */
 415
 416                                         t2 = (lease - t2) / 2 + t2;
 417                                         timeout = t2 + start;
 418                                 }
 419                                 break;
 420                         case RELEASED:
 421                                 /* yah, I know, *you* say it would never happen */
 422                                 timeout = 0x7fffffff;
 423                                 break;
 424                         }
 425                 } else if (retval > 0 && listen_mode != LISTEN_NONE && FD_ISSET(fd, &rfds)) {
 426                         /* a packet is ready, read it */
 427
 428                         if (listen_mode == LISTEN_KERNEL)
 429                                 len = udhcp_get_packet(&packet, fd);
 430                         else len = get_raw_packet(&packet, fd);
 431
 432                         if (len == -1 && errno != EINTR) {
 433                                 DEBUG("error on read, %s, reopening socket", strerror(errno));
 434                                 change_mode(listen_mode); /* just close and reopen */
 435                         }
 436                         if (len < 0) continue;
 437
 438                         if (packet.xid != xid) {
 439                                 DEBUG("Ignoring XID %lx (our xid is %lx)",
 440                                         (unsigned long) packet.xid, xid);
 441                                 continue;
 442                         }
 443
 444                         /* Ignore packets that aren't for us */
 445                         if (memcmp(packet.chaddr, client_config.arp, 6)) {
 446                                 DEBUG("Packet does not have our chaddr - ignoring");
 447                                 continue;
 448                         }
 449
 450                         if ((message = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
 451                                 bb_error_msg("cannot get option from packet - ignoring");
 452                                 continue;
 453                         }
 454
 455                         switch (state) {
 456                         case INIT_SELECTING:
 457                                 /* Must be a DHCPOFFER to one of our xid's */
 458                                 if (*message == DHCPOFFER) {
 459                                         temp = get_option(&packet, DHCP_SERVER_ID);
 460                                         if (temp) {
 461                                                 server_addr = *(uint32_t*)temp;
 462                                                 xid = packet.xid;
 463                                                 requested_ip = packet.yiaddr;
 464
 465                                                 /* enter requesting state */
 466                                                 state = REQUESTING;
 467                                                 timeout = now;
 468                                                 packet_num = 0;
 469                                         } else {
 470                                                 bb_error_msg("no server ID in message");
 471                                         }
 472                                 }
 473                                 break;
 474                         case RENEW_REQUESTED:
 475                         case REQUESTING:
 476                         case RENEWING:
 477                         case REBINDING:
 478                                 if (*message == DHCPACK) {
 479                                         temp = get_option(&packet, DHCP_LEASE_TIME);
 480                                         if (!temp) {
 481                                                 bb_error_msg("no lease time with ACK, using 1 hour lease");
 482                                                 lease = 60 * 60;
 483                                         } else {
 484                                                 lease = ntohl(*(uint32_t*)temp);
 485                                         }
 486
 487                                         /* enter bound state */
 488                                         t1 = lease / 2;
 489
 490                                         /* little fixed point for n * .875 */
 491                                         t2 = (lease * 0x7) >> 3;
 492                                         temp_addr.s_addr = packet.yiaddr;
 493                                         bb_info_msg("Lease of %s obtained, lease time %ld",
 494                                                 inet_ntoa(temp_addr), lease);
 495                                         start = now;
 496                                         timeout = t1 + start;
 497                                         requested_ip = packet.yiaddr;
 498                                         udhcp_run_script(&packet,
 499                                                    ((state == RENEWING || state == REBINDING) ? "renew" : "bound"));
 500
 501                                         state = BOUND;
 502                                         change_mode(LISTEN_NONE);
 503                                         if (client_config.quit_after_lease) {
 504                                                 if (client_config.release_on_quit)
 505                                                         perform_release();
 506                                                 return 0;
 507                                         }
 508                                         if (!client_config.foreground)
 509                                                 client_background();
 510
 511                                 } else if (*message == DHCPNAK) {
 512                                         /* return to init state */
 513                                         bb_info_msg("Received DHCP NAK");
 514                                         udhcp_run_script(&packet, "nak");
 515                                         if (state != REQUESTING)
 516                                                 udhcp_run_script(NULL, "deconfig");
 517                                         state = INIT_SELECTING;
 518                                         timeout = now;
 519                                         requested_ip = 0;
 520                                         packet_num = 0;
 521                                         change_mode(LISTEN_RAW);
 522                                         sleep(3); /* avoid excessive network traffic */
 523                                 }
 524                                 break;
 525                         /* case BOUND, RELEASED: - ignore all packets */
 526                         }
 527                 } else if (retval > 0 && (sig = udhcp_sp_read(&rfds))) {
 528                         switch (sig) {
 529                         case SIGUSR1:
 530                                 perform_renew();
 531                                 break;
 532                         case SIGUSR2:
 533                                 perform_release();
 534                                 break;
 535                         case SIGTERM:
 536                                 bb_info_msg("Received SIGTERM");
 537                                 if (client_config.release_on_quit)
 538                                         perform_release();
 539                                 return 0;
 540                         }
 541                 } else if (retval == -1 && errno == EINTR) {
 542                         /* a signal was caught */
 543                 } else {
 544                         /* An error occured */
 545                         bb_perror_msg("select");
 546                 }
 547
 548         }
 549         return 0;
 550 }