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 <getopt.h>
  12
  13 #include "common.h"
  14 #include "dhcpd.h"
  15 #include "dhcpc.h"
  16 #include "options.h"
  17
  18
  19 static int state;
  20 /* Something is definitely wrong here. IPv4 addresses
  21  * in variables of type long?? BTW, we use inet_ntoa()
  22  * in the code. Manpage says that struct in_addr has a member of type long (!)
  23  * which holds IPv4 address, and the struct is passed by value (!!)
  24  */
  25 static unsigned long requested_ip; /* = 0 */
  26 static unsigned long server_addr;
  27 static unsigned long timeout;
  28 static int packet_num; /* = 0 */
  29 static int fd = -1;
  30
  31 #define LISTEN_NONE 0
  32 #define LISTEN_KERNEL 1
  33 #define LISTEN_RAW 2
  34 static int listen_mode;
  35
  36 struct client_config_t client_config;
  37
  38
  39 /* just a little helper */
  40 static void change_mode(int new_mode)
  41 {
  42         DEBUG("entering %s listen mode",
  43                 new_mode ? (new_mode == 1 ? "kernel" : "raw") : "none");
  44         if (fd >= 0) close(fd);
  45         fd = -1;
  46         listen_mode = new_mode;
  47 }
  48
  49
  50 /* perform a renew */
  51 static void perform_renew(void)
  52 {
  53         bb_info_msg("Performing a DHCP renew");
  54         switch (state) {
  55         case BOUND:
  56                 change_mode(LISTEN_KERNEL);
  57         case RENEWING:
  58         case REBINDING:
  59                 state = RENEW_REQUESTED;
  60                 break;
  61         case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
  62                 udhcp_run_script(NULL, "deconfig");
  63         case REQUESTING:
  64         case RELEASED:
  65                 change_mode(LISTEN_RAW);
  66                 state = INIT_SELECTING;
  67                 break;
  68         case INIT_SELECTING:
  69                 break;
  70         }
  71
  72         /* start things over */
  73         packet_num = 0;
  74
  75         /* Kill any timeouts because the user wants this to hurry along */
  76         timeout = 0;
  77 }
  78
  79
  80 /* perform a release */
  81 static void perform_release(void)
  82 {
  83         char buffer[16];
  84         struct in_addr temp_addr;
  85
  86         /* send release packet */
  87         if (state == BOUND || state == RENEWING || state == REBINDING) {
  88                 temp_addr.s_addr = server_addr;
  89                 sprintf(buffer, "%s", inet_ntoa(temp_addr));
  90                 temp_addr.s_addr = requested_ip;
  91                 bb_info_msg("Unicasting a release of %s to %s",
  92                                 inet_ntoa(temp_addr), buffer);
  93                 send_release(server_addr, requested_ip); /* unicast */
  94                 udhcp_run_script(NULL, "deconfig");
  95         }
  96         bb_info_msg("Entering released state");
  97
  98         change_mode(LISTEN_NONE);
  99         state = RELEASED;
 100         timeout = 0x7fffffff;
 101 }
 102
 103
 104 static void client_background(void)
 105 {
 106         udhcp_background(client_config.pidfile);
 107         client_config.foreground = 1; /* Do not fork again. */
 108         client_config.background_if_no_lease = 0;
 109 }
 110
 111
 112 static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
 113 {
 114         uint8_t *storage;
 115         int len = strlen(str);
 116         if (len > 255) len = 255;
 117         storage = xzalloc(len + extra + OPT_DATA);
 118         storage[OPT_CODE] = code;
 119         storage[OPT_LEN] = len + extra;
 120         memcpy(storage + extra + OPT_DATA, str, len);
 121         return storage;
 122 }
 123
 124
 125 int udhcpc_main(int argc, char *argv[])
 126 {
 127         uint8_t *temp, *message;
 128         char *str_c, *str_V, *str_h, *str_F, *str_r, *str_T, *str_t;
 129         unsigned long t1 = 0, t2 = 0, xid = 0;
 130         unsigned long start = 0, lease = 0;
 131         long now;
 132         unsigned opt;
 133         int max_fd;
 134         int sig;
 135         int retval;
 136         int len;
 137         int no_clientid = 0;
 138         fd_set rfds;
 139         struct timeval tv;
 140         struct dhcpMessage packet;
 141         struct in_addr temp_addr;
 142
 143         enum {
 144                 OPT_c = 1 << 0,
 145                 OPT_C = 1 << 1,
 146                 OPT_V = 1 << 2,
 147                 OPT_f = 1 << 3,
 148                 OPT_b = 1 << 4,
 149                 OPT_H = 1 << 5,
 150                 OPT_h = 1 << 6,
 151                 OPT_F = 1 << 7,
 152                 OPT_i = 1 << 8,
 153                 OPT_n = 1 << 9,
 154                 OPT_p = 1 << 10,
 155                 OPT_q = 1 << 11,
 156                 OPT_R = 1 << 12,
 157                 OPT_r = 1 << 13,
 158                 OPT_s = 1 << 14,
 159                 OPT_T = 1 << 15,
 160                 OPT_t = 1 << 16,
 161                 OPT_v = 1 << 17,
 162         };
 163 #if ENABLE_GETOPT_LONG
 164         static const struct option arg_options[] = {
 165                 { "clientid",   required_argument,      0, 'c' },
 166                 { "clientid-none", no_argument,         0, 'C' },
 167                 { "vendorclass", required_argument,     0, 'V' },
 168                 { "foreground", no_argument,            0, 'f' },
 169                 { "background", no_argument,            0, 'b' },
 170                 { "hostname",   required_argument,      0, 'H' },
 171                 { "hostname",   required_argument,      0, 'h' },
 172                 { "fqdn",       required_argument,      0, 'F' },
 173                 { "interface",  required_argument,      0, 'i' },
 174                 { "now",        no_argument,            0, 'n' },
 175                 { "pidfile",    required_argument,      0, 'p' },
 176                 { "quit",       no_argument,            0, 'q' },
 177                 { "release",    no_argument,            0, 'R' },
 178                 { "request",    required_argument,      0, 'r' },
 179                 { "script",     required_argument,      0, 's' },
 180                 { "timeout",    required_argument,      0, 'T' },
 181                 { "version",    no_argument,            0, 'v' },
 182                 { "retries",    required_argument,      0, 't' },
 183                 { 0, 0, 0, 0 }
 184         };
 185 #endif
 186         /* Default options. */
 187         client_config.interface = "eth0";
 188         client_config.script = DEFAULT_SCRIPT;
 189         client_config.retries = 3;
 190         client_config.timeout = 3;
 191
 192         /* Parse command line */
 193         opt_complementary = "?:c--C:C--c" // mutually exclusive
 194                             ":hH:Hh"; // -h and -H are the same
 195 #if ENABLE_GETOPT_LONG
 196         applet_long_options = arg_options;
 197 #endif
 198         opt = getopt32(argc, argv, "c:CV:fbH:h:F:i:np:qRr:s:T:t:v",
 199                 &str_c, &str_V, &str_h, &str_h, &str_F,
 200                 &client_config.interface, &client_config.pidfile, &str_r,
 201                 &client_config.script, &str_T, &str_t
 202                 );
 203
 204         if (opt & OPT_c)
 205                 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, str_c, 0);
 206         if (opt & OPT_C)
 207                 no_clientid = 1;
 208         if (opt & OPT_V)
 209                 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
 210         if (opt & OPT_f)
 211                 client_config.foreground = 1;
 212         if (opt & OPT_b)
 213                 client_config.background_if_no_lease = 1;
 214         if (opt & OPT_h)
 215                 client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
 216         if (opt & OPT_F) {
 217                 client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
 218                 /* Flags: 0000NEOS
 219                 S: 1 => Client requests Server to update A RR in DNS as well as PTR
 220                 O: 1 => Server indicates to client that DNS has been updated regardless
 221                 E: 1 => Name data is DNS format, i.e. <4>host<6>domain<4>com<0> not "host.domain.com"
 222                 N: 1 => Client requests Server to not update DNS
 223                 */
 224                 client_config.fqdn[OPT_DATA + 0] = 0x1;
 225                 /* client_config.fqdn[OPT_DATA + 1] = 0; - redundant */
 226                 /* client_config.fqdn[OPT_DATA + 2] = 0; - redundant */
 227         }
 228         // if (opt & OPT_i) client_config.interface = ...
 229         if (opt & OPT_n)
 230                 client_config.abort_if_no_lease = 1;
 231         // if (opt & OPT_p) client_config.pidfile = ...
 232         if (opt & OPT_q)
 233                 client_config.quit_after_lease = 1;
 234         if (opt & OPT_R)
 235                 client_config.release_on_quit = 1;
 236         if (opt & OPT_r)
 237                 requested_ip = inet_addr(str_r);
 238         // if (opt & OPT_s) client_config.script = ...
 239         if (opt & OPT_T)
 240                 client_config.timeout = xatoi_u(str_T);
 241         if (opt & OPT_t)
 242                 client_config.retries = xatoi_u(str_t);
 243         if (opt & OPT_v) {
 244                 printf("version %s\n\n", BB_VER);
 245                 return 0;
 246         }
 247
 248         /* Start the log, sanitize fd's, and write a pid file */
 249         udhcp_start_log_and_pid(client_config.pidfile);
 250
 251         if (read_interface(client_config.interface, &client_config.ifindex,
 252                            NULL, client_config.arp) < 0)
 253                 return 1;
 254
 255         /* if not set, and not suppressed, setup the default client ID */
 256         if (!client_config.clientid && !no_clientid) {
 257                 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
 258                 client_config.clientid[OPT_DATA] = 1;
 259                 memcpy(client_config.clientid + OPT_DATA+1, client_config.arp, 6);
 260         }
 261
 262         if (!client_config.vendorclass)
 263                 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, "udhcp "BB_VER, 0);
 264
 265         /* setup the signal pipe */
 266         udhcp_sp_setup();
 267
 268         state = INIT_SELECTING;
 269         udhcp_run_script(NULL, "deconfig");
 270         change_mode(LISTEN_RAW);
 271
 272         for (;;) {
 273                 tv.tv_sec = timeout - uptime();
 274                 tv.tv_usec = 0;
 275
 276                 if (listen_mode != LISTEN_NONE && fd < 0) {
 277                         if (listen_mode == LISTEN_KERNEL)
 278                                 fd = listen_socket(INADDR_ANY, CLIENT_PORT, client_config.interface);
 279                         else
 280                                 fd = raw_socket(client_config.ifindex);
 281                         if (fd < 0) {
 282                                 bb_perror_msg("FATAL: cannot listen on socket");
 283                                 return 0;
 284                         }
 285                 }
 286                 max_fd = udhcp_sp_fd_set(&rfds, fd);
 287
 288                 if (tv.tv_sec > 0) {
 289                         DEBUG("Waiting on select...");
 290                         retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
 291                 } else retval = 0; /* If we already timed out, fall through */
 292
 293                 now = uptime();
 294                 if (retval == 0) {
 295                         /* timeout dropped to zero */
 296                         switch (state) {
 297                         case INIT_SELECTING:
 298                                 if (packet_num < client_config.retries) {
 299                                         if (packet_num == 0)
 300                                                 xid = random_xid();
 301
 302                                         /* send discover packet */
 303                                         send_discover(xid, requested_ip); /* broadcast */
 304
 305                                         timeout = now + client_config.timeout;
 306                                         packet_num++;
 307                                 } else {
 308                                         udhcp_run_script(NULL, "leasefail");
 309                                         if (client_config.background_if_no_lease) {
 310                                                 bb_info_msg("No lease, forking to background");
 311                                                 client_background();
 312                                         } else if (client_config.abort_if_no_lease) {
 313                                                 bb_info_msg("No lease, failing");
 314                                                 return 1;
 315                                         }
 316                                         /* wait to try again */
 317                                         packet_num = 0;
 318                                         timeout = now + 60;
 319                                 }
 320                                 break;
 321                         case RENEW_REQUESTED:
 322                         case REQUESTING:
 323                                 if (packet_num < client_config.retries) {
 324                                         /* send request packet */
 325                                         if (state == RENEW_REQUESTED)
 326                                                 send_renew(xid, server_addr, requested_ip); /* unicast */
 327                                         else send_selecting(xid, server_addr, requested_ip); /* broadcast */
 328
 329                                         timeout = now + ((packet_num == 2) ? 10 : 2);
 330                                         packet_num++;
 331                                 } else {
 332                                         /* timed out, go back to init state */
 333                                         if (state == RENEW_REQUESTED) udhcp_run_script(NULL, "deconfig");
 334                                         state = INIT_SELECTING;
 335                                         timeout = now;
 336                                         packet_num = 0;
 337                                         change_mode(LISTEN_RAW);
 338                                 }
 339                                 break;
 340                         case BOUND:
 341                                 /* Lease is starting to run out, time to enter renewing state */
 342                                 state = RENEWING;
 343                                 change_mode(LISTEN_KERNEL);
 344                                 DEBUG("Entering renew state");
 345                                 /* fall right through */
 346                         case RENEWING:
 347                                 /* Either set a new T1, or enter REBINDING state */
 348                                 if ((t2 - t1) <= (lease / 14400 + 1)) {
 349                                         /* timed out, enter rebinding state */
 350                                         state = REBINDING;
 351                                         timeout = now + (t2 - t1);
 352                                         DEBUG("Entering rebinding state");
 353                                 } else {
 354                                         /* send a request packet */
 355                                         send_renew(xid, server_addr, requested_ip); /* unicast */
 356
 357                                         t1 = (t2 - t1) / 2 + t1;
 358                                         timeout = t1 + start;
 359                                 }
 360                                 break;
 361                         case REBINDING:
 362                                 /* Either set a new T2, or enter INIT state */
 363                                 if ((lease - t2) <= (lease / 14400 + 1)) {
 364                                         /* timed out, enter init state */
 365                                         state = INIT_SELECTING;
 366                                         bb_info_msg("Lease lost, entering init state");
 367                                         udhcp_run_script(NULL, "deconfig");
 368                                         timeout = now;
 369                                         packet_num = 0;
 370                                         change_mode(LISTEN_RAW);
 371                                 } else {
 372                                         /* send a request packet */
 373                                         send_renew(xid, 0, requested_ip); /* broadcast */
 374
 375                                         t2 = (lease - t2) / 2 + t2;
 376                                         timeout = t2 + start;
 377                                 }
 378                                 break;
 379                         case RELEASED:
 380                                 /* yah, I know, *you* say it would never happen */
 381                                 timeout = 0x7fffffff;
 382                                 break;
 383                         }
 384                 } else if (retval > 0 && listen_mode != LISTEN_NONE && FD_ISSET(fd, &rfds)) {
 385                         /* a packet is ready, read it */
 386
 387                         if (listen_mode == LISTEN_KERNEL)
 388                                 len = udhcp_get_packet(&packet, fd);
 389                         else len = get_raw_packet(&packet, fd);
 390
 391                         if (len == -1 && errno != EINTR) {
 392                                 DEBUG("error on read, %s, reopening socket", strerror(errno));
 393                                 change_mode(listen_mode); /* just close and reopen */
 394                         }
 395                         if (len < 0) continue;
 396
 397                         if (packet.xid != xid) {
 398                                 DEBUG("Ignoring XID %lx (our xid is %lx)",
 399                                         (unsigned long) packet.xid, xid);
 400                                 continue;
 401                         }
 402
 403                         /* Ignore packets that aren't for us */
 404                         if (memcmp(packet.chaddr, client_config.arp, 6)) {
 405                                 DEBUG("Packet does not have our chaddr - ignoring");
 406                                 continue;
 407                         }
 408
 409                         if ((message = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
 410                                 bb_error_msg("cannot get option from packet - ignoring");
 411                                 continue;
 412                         }
 413
 414                         switch (state) {
 415                         case INIT_SELECTING:
 416                                 /* Must be a DHCPOFFER to one of our xid's */
 417                                 if (*message == DHCPOFFER) {
 418                                         temp = get_option(&packet, DHCP_SERVER_ID);
 419                                         if (temp) {
 420                                                 server_addr = *(uint32_t*)temp;
 421                                                 xid = packet.xid;
 422                                                 requested_ip = packet.yiaddr;
 423
 424                                                 /* enter requesting state */
 425                                                 state = REQUESTING;
 426                                                 timeout = now;
 427                                                 packet_num = 0;
 428                                         } else {
 429                                                 bb_error_msg("no server ID in message");
 430                                         }
 431                                 }
 432                                 break;
 433                         case RENEW_REQUESTED:
 434                         case REQUESTING:
 435                         case RENEWING:
 436                         case REBINDING:
 437                                 if (*message == DHCPACK) {
 438                                         temp = get_option(&packet, DHCP_LEASE_TIME);
 439                                         if (!temp) {
 440                                                 bb_error_msg("no lease time with ACK, using 1 hour lease");
 441                                                 lease = 60 * 60;
 442                                         } else {
 443                                                 lease = ntohl(*(uint32_t*)temp);
 444                                         }
 445
 446                                         /* enter bound state */
 447                                         t1 = lease / 2;
 448
 449                                         /* little fixed point for n * .875 */
 450                                         t2 = (lease * 0x7) >> 3;
 451                                         temp_addr.s_addr = packet.yiaddr;
 452                                         bb_info_msg("Lease of %s obtained, lease time %ld",
 453                                                 inet_ntoa(temp_addr), lease);
 454                                         start = now;
 455                                         timeout = t1 + start;
 456                                         requested_ip = packet.yiaddr;
 457                                         udhcp_run_script(&packet,
 458                                                    ((state == RENEWING || state == REBINDING) ? "renew" : "bound"));
 459
 460                                         state = BOUND;
 461                                         change_mode(LISTEN_NONE);
 462                                         if (client_config.quit_after_lease) {
 463                                                 if (client_config.release_on_quit)
 464                                                         perform_release();
 465                                                 return 0;
 466                                         }
 467                                         if (!client_config.foreground)
 468                                                 client_background();
 469
 470                                 } else if (*message == DHCPNAK) {
 471                                         /* return to init state */
 472                                         bb_info_msg("Received DHCP NAK");
 473                                         udhcp_run_script(&packet, "nak");
 474                                         if (state != REQUESTING)
 475                                                 udhcp_run_script(NULL, "deconfig");
 476                                         state = INIT_SELECTING;
 477                                         timeout = now;
 478                                         requested_ip = 0;
 479                                         packet_num = 0;
 480                                         change_mode(LISTEN_RAW);
 481                                         sleep(3); /* avoid excessive network traffic */
 482                                 }
 483                                 break;
 484                         /* case BOUND, RELEASED: - ignore all packets */
 485                         }
 486                 } else if (retval > 0 && (sig = udhcp_sp_read(&rfds))) {
 487                         switch (sig) {
 488                         case SIGUSR1:
 489                                 perform_renew();
 490                                 break;
 491                         case SIGUSR2:
 492                                 perform_release();
 493                                 break;
 494                         case SIGTERM:
 495                                 bb_info_msg("Received SIGTERM");
 496                                 if (client_config.release_on_quit)
 497                                         perform_release();
 498                                 return 0;
 499                         }
 500                 } else if (retval == -1 && errno == EINTR) {
 501                         /* a signal was caught */
 502                 } else {
 503                         /* An error occured */
 504                         bb_perror_msg("select");
 505                 }
 506
 507         }
 508         return 0;
 509 }