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