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 <syslog.h>
  12
  13 /* Override ENABLE_FEATURE_PIDFILE - ifupdown needs our pidfile to always exist */
  14 #define WANT_PIDFILE 1
  15 #include "common.h"
  16 #include "dhcpd.h"
  17 #include "dhcpc.h"
  18 #include "options.h"
  19
  20
  21 static int sockfd = -1;
  22
  23 #define LISTEN_NONE 0
  24 #define LISTEN_KERNEL 1
  25 #define LISTEN_RAW 2
  26 static smallint listen_mode;
  27
  28 #define INIT_SELECTING  0
  29 #define REQUESTING      1
  30 #define BOUND           2
  31 #define RENEWING        3
  32 #define REBINDING       4
  33 #define INIT_REBOOT     5
  34 #define RENEW_REQUESTED 6
  35 #define RELEASED        7
  36 static smallint state;
  37
  38 /* struct client_config_t client_config is in bb_common_bufsiz1 */
  39
  40
  41 /* just a little helper */
  42 static void change_listen_mode(int new_mode)
  43 {
  44         DEBUG("entering %s listen mode",
  45                 new_mode ? (new_mode == 1 ? "kernel" : "raw") : "none");
  46
  47         listen_mode = new_mode;
  48         if (sockfd >= 0) {
  49                 close(sockfd);
  50                 sockfd = -1;
  51         }
  52         if (new_mode == LISTEN_KERNEL)
  53                 sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
  54         else if (new_mode != LISTEN_NONE)
  55                 sockfd = udhcp_raw_socket(client_config.ifindex);
  56         /* else LISTEN_NONE: sockfd stay closed */
  57 }
  58
  59
  60 /* perform a renew */
  61 static void perform_renew(void)
  62 {
  63         bb_info_msg("Performing a DHCP renew");
  64         switch (state) {
  65         case BOUND:
  66                 change_listen_mode(LISTEN_KERNEL);
  67         case RENEWING:
  68         case REBINDING:
  69                 state = RENEW_REQUESTED;
  70                 break;
  71         case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
  72                 udhcp_run_script(NULL, "deconfig");
  73         case REQUESTING:
  74         case RELEASED:
  75                 change_listen_mode(LISTEN_RAW);
  76                 state = INIT_SELECTING;
  77                 break;
  78         case INIT_SELECTING:
  79                 break;
  80         }
  81 }
  82
  83
  84 /* perform a release */
  85 static void perform_release(uint32_t requested_ip, uint32_t server_addr)
  86 {
  87         char buffer[sizeof("255.255.255.255")];
  88         struct in_addr temp_addr;
  89
  90         /* send release packet */
  91         if (state == BOUND || state == RENEWING || state == REBINDING) {
  92                 temp_addr.s_addr = server_addr;
  93                 strcpy(buffer, inet_ntoa(temp_addr));
  94                 temp_addr.s_addr = requested_ip;
  95                 bb_info_msg("Unicasting a release of %s to %s",
  96                                 inet_ntoa(temp_addr), buffer);
  97                 send_release(server_addr, requested_ip); /* unicast */
  98                 udhcp_run_script(NULL, "deconfig");
  99         }
 100         bb_info_msg("Entering released state");
 101
 102         change_listen_mode(LISTEN_NONE);
 103         state = RELEASED;
 104 }
 105
 106
 107 #if BB_MMU
 108 static void client_background(void)
 109 {
 110         bb_daemonize(0);
 111         logmode &= ~LOGMODE_STDIO;
 112         /* rewrite pidfile, as our pid is different now */
 113         write_pidfile(client_config.pidfile);
 114 }
 115 #endif
 116
 117
 118 static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
 119 {
 120         uint8_t *storage;
 121         int len = strlen(str);
 122         if (len > 255) len = 255;
 123         storage = xzalloc(len + extra + OPT_DATA);
 124         storage[OPT_CODE] = code;
 125         storage[OPT_LEN] = len + extra;
 126         memcpy(storage + extra + OPT_DATA, str, len);
 127         return storage;
 128 }
 129
 130
 131 int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 132 int udhcpc_main(int argc UNUSED_PARAM, char **argv)
 133 {
 134         uint8_t *temp, *message;
 135         char *str_c, *str_V, *str_h, *str_F, *str_r;
 136         USE_FEATURE_UDHCP_PORT(char *str_P;)
 137         llist_t *list_O = NULL;
 138         int tryagain_timeout = 20;
 139         int discover_timeout = 3;
 140         int discover_retries = 3;
 141         uint32_t server_addr = server_addr; /* for compiler */
 142         uint32_t requested_ip = 0;
 143         uint32_t xid = 0;
 144         uint32_t lease_seconds = 0; /* can be given as 32-bit quantity */
 145         int packet_num;
 146         int timeout; /* must be signed */
 147         unsigned already_waited_sec;
 148         unsigned opt;
 149         int max_fd;
 150         int retval;
 151         struct timeval tv;
 152         struct dhcpMessage packet;
 153         fd_set rfds;
 154
 155 #if ENABLE_GETOPT_LONG
 156         static const char udhcpc_longopts[] ALIGN1 =
 157                 "clientid\0"       Required_argument "c"
 158                 "clientid-none\0"  No_argument       "C"
 159                 "vendorclass\0"    Required_argument "V"
 160                 "hostname\0"       Required_argument "H"
 161                 "fqdn\0"           Required_argument "F"
 162                 "interface\0"      Required_argument "i"
 163                 "now\0"            No_argument       "n"
 164                 "pidfile\0"        Required_argument "p"
 165                 "quit\0"           No_argument       "q"
 166                 "release\0"        No_argument       "R"
 167                 "request\0"        Required_argument "r"
 168                 "script\0"         Required_argument "s"
 169                 "timeout\0"        Required_argument "T"
 170                 "version\0"        No_argument       "v"
 171                 "retries\0"        Required_argument "t"
 172                 "tryagain\0"       Required_argument "A"
 173                 "syslog\0"         No_argument       "S"
 174                 "request-option\0" Required_argument "O"
 175                 "no-default-options\0" No_argument   "o"
 176                 "foreground\0"     No_argument       "f"
 177                 "background\0"     No_argument       "b"
 178                 USE_FEATURE_UDHCPC_ARPING("arping\0"    No_argument       "a")
 179                 USE_FEATURE_UDHCP_PORT("client-port\0"  Required_argument "P")
 180                 ;
 181 #endif
 182         enum {
 183                 OPT_c = 1 << 0,
 184                 OPT_C = 1 << 1,
 185                 OPT_V = 1 << 2,
 186                 OPT_H = 1 << 3,
 187                 OPT_h = 1 << 4,
 188                 OPT_F = 1 << 5,
 189                 OPT_i = 1 << 6,
 190                 OPT_n = 1 << 7,
 191                 OPT_p = 1 << 8,
 192                 OPT_q = 1 << 9,
 193                 OPT_R = 1 << 10,
 194                 OPT_r = 1 << 11,
 195                 OPT_s = 1 << 12,
 196                 OPT_T = 1 << 13,
 197                 OPT_t = 1 << 14,
 198                 OPT_v = 1 << 15,
 199                 OPT_S = 1 << 16,
 200                 OPT_A = 1 << 17,
 201                 OPT_O = 1 << 18,
 202                 OPT_o = 1 << 19,
 203                 OPT_f = 1 << 20,
 204 /* The rest has variable bit positions, need to be clever */
 205                 OPTBIT_f = 20,
 206                 USE_FOR_MMU(              OPTBIT_b,)
 207                 USE_FEATURE_UDHCPC_ARPING(OPTBIT_a,)
 208                 USE_FEATURE_UDHCP_PORT(   OPTBIT_P,)
 209                 USE_FOR_MMU(              OPT_b = 1 << OPTBIT_b,)
 210                 USE_FEATURE_UDHCPC_ARPING(OPT_a = 1 << OPTBIT_a,)
 211                 USE_FEATURE_UDHCP_PORT(   OPT_P = 1 << OPTBIT_P,)
 212         };
 213
 214         /* Default options. */
 215         USE_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
 216         USE_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
 217         client_config.interface = "eth0";
 218         client_config.script = DEFAULT_SCRIPT;
 219
 220         /* Parse command line */
 221         /* Cc: mutually exclusive; O: list; -T,-t,-A take numeric param */
 222         opt_complementary = "c--C:C--c:O::T+:t+:A+";
 223         USE_GETOPT_LONG(applet_long_options = udhcpc_longopts;)
 224         opt = getopt32(argv, "c:CV:H:h:F:i:np:qRr:s:T:t:vSA:O:of"
 225                 USE_FOR_MMU("b")
 226                 USE_FEATURE_UDHCPC_ARPING("a")
 227                 USE_FEATURE_UDHCP_PORT("P:")
 228                 , &str_c, &str_V, &str_h, &str_h, &str_F
 229                 , &client_config.interface, &client_config.pidfile, &str_r /* i,p */
 230                 , &client_config.script /* s */
 231                 , &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
 232                 , &list_O
 233                 USE_FEATURE_UDHCP_PORT(, &str_P)
 234                 );
 235         if (opt & OPT_c)
 236                 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, str_c, 0);
 237         if (opt & OPT_V)
 238                 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
 239         if (opt & (OPT_h|OPT_H))
 240                 client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
 241         if (opt & OPT_F) {
 242                 client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
 243                 /* Flags: 0000NEOS
 244                 S: 1 => Client requests Server to update A RR in DNS as well as PTR
 245                 O: 1 => Server indicates to client that DNS has been updated regardless
 246                 E: 1 => Name data is DNS format, i.e. <4>host<6>domain<3>com<0> not "host.domain.com"
 247                 N: 1 => Client requests Server to not update DNS
 248                 */
 249                 client_config.fqdn[OPT_DATA + 0] = 0x1;
 250                 /* client_config.fqdn[OPT_DATA + 1] = 0; - redundant */
 251                 /* client_config.fqdn[OPT_DATA + 2] = 0; - redundant */
 252         }
 253         if (opt & OPT_r)
 254                 requested_ip = inet_addr(str_r);
 255         if (opt & OPT_v) {
 256                 puts("version "BB_VER);
 257                 return 0;
 258         }
 259 #if ENABLE_FEATURE_UDHCP_PORT
 260         if (opt & OPT_P) {
 261                 CLIENT_PORT = xatou16(str_P);
 262                 SERVER_PORT = CLIENT_PORT - 1;
 263         }
 264 #endif
 265         if (opt & OPT_o)
 266                 client_config.no_default_options = 1;
 267         while (list_O) {
 268                 char *optstr = llist_pop(&list_O);
 269                 int n = index_in_strings(dhcp_option_strings, optstr);
 270                 if (n < 0)
 271                         bb_error_msg_and_die("unknown option '%s'", optstr);
 272                 n = dhcp_options[n].code;
 273                 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
 274         }
 275
 276         if (udhcp_read_interface(client_config.interface, &client_config.ifindex,
 277                            NULL, client_config.arp))
 278                 return 1;
 279 #if !BB_MMU
 280         /* on NOMMU reexec (i.e., background) early */
 281         if (!(opt & OPT_f)) {
 282                 bb_daemonize_or_rexec(0 /* flags */, argv);
 283                 logmode = 0;
 284         }
 285 #endif
 286         if (opt & OPT_S) {
 287                 openlog(applet_name, LOG_PID, LOG_LOCAL0);
 288                 logmode |= LOGMODE_SYSLOG;
 289         }
 290
 291         /* Make sure fd 0,1,2 are open */
 292         bb_sanitize_stdio();
 293         /* Equivalent of doing a fflush after every \n */
 294         setlinebuf(stdout);
 295
 296         /* Create pidfile */
 297         write_pidfile(client_config.pidfile);
 298
 299         /* Goes to stdout (unless NOMMU) and possibly syslog */
 300         bb_info_msg("%s (v"BB_VER") started", applet_name);
 301
 302         /* if not set, and not suppressed, setup the default client ID */
 303         if (!client_config.clientid && !(opt & OPT_C)) {
 304                 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
 305                 client_config.clientid[OPT_DATA] = 1;
 306                 memcpy(client_config.clientid + OPT_DATA+1, client_config.arp, 6);
 307         }
 308
 309         if (!client_config.vendorclass)
 310                 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, "udhcp "BB_VER, 0);
 311
 312         /* setup the signal pipe */
 313         udhcp_sp_setup();
 314
 315         state = INIT_SELECTING;
 316         udhcp_run_script(NULL, "deconfig");
 317         change_listen_mode(LISTEN_RAW);
 318         packet_num = 0;
 319         timeout = 0;
 320         already_waited_sec = 0;
 321
 322         /* Main event loop. select() waits on signal pipe and possibly
 323          * on sockfd.
 324          * "continue" statements in code below jump to the top of the loop.
 325          */
 326         for (;;) {
 327                 unsigned timestamp_before_wait;
 328
 329                 //bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
 330
 331                 /* Was opening raw or udp socket here
 332                  * if (listen_mode != LISTEN_NONE && sockfd < 0),
 333                  * but on fast network renew responses return faster
 334                  * than we open sockets. Thus this code is moved
 335                  * to change_listen_mode(). Thus we open listen socket
 336                  * BEFORE we send renew request (see "case BOUND:"). */
 337
 338                 max_fd = udhcp_sp_fd_set(&rfds, sockfd);
 339
 340                 tv.tv_sec = timeout - already_waited_sec;
 341                 tv.tv_usec = 0;
 342                 retval = 0; /* If we already timed out, fall through, else... */
 343                 if (tv.tv_sec > 0) {
 344                         timestamp_before_wait = (unsigned)monotonic_sec();
 345                         DEBUG("Waiting on select...");
 346                         retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
 347                         if (retval < 0) {
 348                                 /* EINTR? A signal was caught, don't panic */
 349                                 if (errno == EINTR)
 350                                         continue;
 351                                 /* Else: an error occured, panic! */
 352                                 bb_perror_msg_and_die("select");
 353                         }
 354                 }
 355
 356                 /* If timeout dropped to zero, time to become active:
 357                  * resend discover/renew/whatever
 358                  */
 359                 if (retval == 0) {
 360                         /* We will restart the wait in any case */
 361                         already_waited_sec = 0;
 362
 363                         switch (state) {
 364                         case INIT_SELECTING:
 365                                 if (packet_num < discover_retries) {
 366                                         if (packet_num == 0)
 367                                                 xid = random_xid();
 368
 369                                         send_discover(xid, requested_ip); /* broadcast */
 370
 371                                         timeout = discover_timeout;
 372                                         packet_num++;
 373                                         continue;
 374                                 }
 375  leasefail:
 376                                 udhcp_run_script(NULL, "leasefail");
 377 #if BB_MMU /* -b is not supported on NOMMU */
 378                                 if (opt & OPT_b) { /* background if no lease */
 379                                         bb_info_msg("No lease, forking to background");
 380                                         client_background();
 381                                         /* do not background again! */
 382                                         opt = ((opt & ~OPT_b) | OPT_f);
 383                                 } else
 384 #endif
 385                                 if (opt & OPT_n) { /* abort if no lease */
 386                                         bb_info_msg("No lease, failing");
 387                                         retval = 1;
 388                                         goto ret;
 389                                 }
 390                                 /* wait before trying again */
 391                                 timeout = tryagain_timeout;
 392                                 packet_num = 0;
 393                                 continue;
 394                         case RENEW_REQUESTED:
 395                         case REQUESTING:
 396                                 if (packet_num < discover_retries) {
 397                                         /* send request packet */
 398                                         if (state == RENEW_REQUESTED) /* unicast */
 399                                                 send_renew(xid, server_addr, requested_ip);
 400                                         else /* broadcast */
 401                                                 send_select(xid, server_addr, requested_ip);
 402
 403                                         timeout = discover_timeout;
 404                                         packet_num++;
 405                                         continue;
 406                                 }
 407                                 /* timed out, go back to init state */
 408                                 if (state == RENEW_REQUESTED)
 409                                         udhcp_run_script(NULL, "deconfig");
 410                                 change_listen_mode(LISTEN_RAW);
 411                                 /* "discover...select...discover..." loops
 412                                  * were seen in the wild. Treat them similarly
 413                                  * to "no response to discover" case */
 414                                 if (state == REQUESTING) {
 415                                         state = INIT_SELECTING;
 416                                         goto leasefail;
 417                                 }
 418                                 state = INIT_SELECTING;
 419                                 timeout = 0;
 420                                 packet_num = 0;
 421                                 continue;
 422                         case BOUND:
 423                                 /* Half of the lease passed, time to enter renewing state */
 424                                 change_listen_mode(LISTEN_KERNEL);
 425                                 DEBUG("Entering renew state");
 426                                 state = RENEWING;
 427                                 /* fall right through */
 428                         case RENEWING:
 429                                 if (timeout > 60) {
 430                                         /* send a request packet */
 431                                         send_renew(xid, server_addr, requested_ip); /* unicast */
 432                                         timeout >>= 1;
 433                                         continue;
 434                                 }
 435                                 /* Timed out, enter rebinding state */
 436                                 DEBUG("Entering rebinding state");
 437                                 state = REBINDING;
 438                                 /* fall right through */
 439                         case REBINDING:
 440                                 /* Lease is *really* about to run out,
 441                                  * try to find DHCP server using broadcast */
 442                                 if (timeout > 0) {
 443                                         /* send a request packet */
 444                                         send_renew(xid, 0 /* INADDR_ANY*/, requested_ip); /* broadcast */
 445                                         timeout >>= 1;
 446                                         continue;
 447                                 }
 448                                 /* Timed out, enter init state */
 449                                 bb_info_msg("Lease lost, entering init state");
 450                                 udhcp_run_script(NULL, "deconfig");
 451                                 change_listen_mode(LISTEN_RAW);
 452                                 state = INIT_SELECTING;
 453                                 /*timeout = 0; - already is */
 454                                 packet_num = 0;
 455                                 continue;
 456                         /* case RELEASED: */
 457                         }
 458                         /* yah, I know, *you* say it would never happen */
 459                         timeout = INT_MAX;
 460                         continue; /* back to main loop */
 461                 }
 462
 463                 /* select() didn't timeout, something did happen. */
 464                 /* Is it a packet? */
 465                 if (listen_mode != LISTEN_NONE && FD_ISSET(sockfd, &rfds)) {
 466                         int len;
 467                         /* A packet is ready, read it */
 468
 469                         if (listen_mode == LISTEN_KERNEL)
 470                                 len = udhcp_recv_kernel_packet(&packet, sockfd);
 471                         else
 472                                 len = udhcp_recv_raw_packet(&packet, sockfd);
 473                         if (len == -1) { /* error is severe, reopen socket */
 474                                 DEBUG("error on read, %s, reopening socket", strerror(errno));
 475                                 sleep(discover_timeout); /* 3 seconds by default */
 476                                 change_listen_mode(listen_mode); /* just close and reopen */
 477                         }
 478                         /* If this packet will turn out to be unrelated/bogus,
 479                          * we will go back and wait for next one.
 480                          * Be sure timeout is properly decreased. */
 481                         already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
 482                         if (len < 0)
 483                                 continue;
 484
 485                         if (packet.xid != xid) {
 486                                 DEBUG("Ignoring xid %x (our xid is %x)",
 487                                         (unsigned)packet.xid, (unsigned)xid);
 488                                 continue;
 489                         }
 490
 491                         /* Ignore packets that aren't for us */
 492                         if (memcmp(packet.chaddr, client_config.arp, 6)) {
 493                                 DEBUG("Packet does not have our chaddr - ignoring");
 494                                 continue;
 495                         }
 496
 497                         message = get_option(&packet, DHCP_MESSAGE_TYPE);
 498                         if (message == NULL) {
 499                                 bb_error_msg("cannot get message type from packet - ignoring");
 500                                 continue;
 501                         }
 502
 503                         switch (state) {
 504                         case INIT_SELECTING:
 505                                 /* Must be a DHCPOFFER to one of our xid's */
 506                                 if (*message == DHCPOFFER) {
 507                         /* TODO: why we don't just fetch server's IP from IP header? */
 508                                         temp = get_option(&packet, DHCP_SERVER_ID);
 509                                         if (!temp) {
 510                                                 bb_error_msg("no server ID in message");
 511                                                 continue;
 512                                                 /* still selecting - this server looks bad */
 513                                         }
 514                                         /* it IS unaligned sometimes, don't "optimize" */
 515                                         move_from_unaligned32(server_addr, temp);
 516                                         xid = packet.xid;
 517                                         requested_ip = packet.yiaddr;
 518
 519                                         /* enter requesting state */
 520                                         state = REQUESTING;
 521                                         timeout = 0;
 522                                         packet_num = 0;
 523                                         already_waited_sec = 0;
 524                                 }
 525                                 continue;
 526                         case RENEW_REQUESTED:
 527                         case REQUESTING:
 528                         case RENEWING:
 529                         case REBINDING:
 530                                 if (*message == DHCPACK) {
 531                                         temp = get_option(&packet, DHCP_LEASE_TIME);
 532                                         if (!temp) {
 533                                                 bb_error_msg("no lease time with ACK, using 1 hour lease");
 534                                                 lease_seconds = 60 * 60;
 535                                         } else {
 536                                                 /* it IS unaligned sometimes, don't "optimize" */
 537                                                 move_from_unaligned32(lease_seconds, temp);
 538                                                 lease_seconds = ntohl(lease_seconds);
 539                                                 lease_seconds &= 0x0fffffff; /* paranoia: must not be prone to overflows */
 540                                                 if (lease_seconds < 10) /* and not too small */
 541                                                         lease_seconds = 10;
 542                                         }
 543 #if ENABLE_FEATURE_UDHCPC_ARPING
 544                                         if (opt & OPT_a) {
 545 /* RFC 2131 3.1 paragraph 5:
 546  * "The client receives the DHCPACK message with configuration
 547  * parameters. The client SHOULD perform a final check on the
 548  * parameters (e.g., ARP for allocated network address), and notes
 549  * the duration of the lease specified in the DHCPACK message. At this
 550  * point, the client is configured. If the client detects that the
 551  * address is already in use (e.g., through the use of ARP),
 552  * the client MUST send a DHCPDECLINE message to the server and restarts
 553  * the configuration process..." */
 554                                                 if (!arpping(packet.yiaddr,
 555                                                             (uint32_t) 0,
 556                                                             client_config.arp,
 557                                                             client_config.interface)
 558                                                 ) {
 559                                                         bb_info_msg("offered address is in use "
 560                                                                 "(got ARP reply), declining");
 561                                                         send_decline(xid, server_addr, packet.yiaddr);
 562
 563                                                         if (state != REQUESTING)
 564                                                                 udhcp_run_script(NULL, "deconfig");
 565                                                         change_listen_mode(LISTEN_RAW);
 566                                                         state = INIT_SELECTING;
 567                                                         requested_ip = 0;
 568                                                         timeout = tryagain_timeout;
 569                                                         packet_num = 0;
 570                                                         already_waited_sec = 0;
 571                                                         continue; /* back to main loop */
 572                                                 }
 573                                         }
 574 #endif
 575                                         /* enter bound state */
 576                                         timeout = lease_seconds / 2;
 577                                         {
 578                                                 struct in_addr temp_addr;
 579                                                 temp_addr.s_addr = packet.yiaddr;
 580                                                 bb_info_msg("Lease of %s obtained, lease time %u",
 581                                                         inet_ntoa(temp_addr), (unsigned)lease_seconds);
 582                                         }
 583                                         requested_ip = packet.yiaddr;
 584                                         udhcp_run_script(&packet,
 585                                                         ((state == RENEWING || state == REBINDING) ? "renew" : "bound"));
 586
 587                                         state = BOUND;
 588                                         change_listen_mode(LISTEN_NONE);
 589                                         if (opt & OPT_q) { /* quit after lease */
 590                                                 if (opt & OPT_R) /* release on quit */
 591                                                         perform_release(requested_ip, server_addr);
 592                                                 goto ret0;
 593                                         }
 594 #if BB_MMU /* NOMMU case backgrounded earlier */
 595                                         if (!(opt & OPT_f)) {
 596                                                 client_background();
 597                                                 /* do not background again! */
 598                                                 opt = ((opt & ~OPT_b) | OPT_f);
 599                                         }
 600 #endif
 601                                         already_waited_sec = 0;
 602                                         continue; /* back to main loop */
 603                                 }
 604                                 if (*message == DHCPNAK) {
 605                                         /* return to init state */
 606                                         bb_info_msg("Received DHCP NAK");
 607                                         udhcp_run_script(&packet, "nak");
 608                                         if (state != REQUESTING)
 609                                                 udhcp_run_script(NULL, "deconfig");
 610                                         change_listen_mode(LISTEN_RAW);
 611                                         sleep(3); /* avoid excessive network traffic */
 612                                         state = INIT_SELECTING;
 613                                         requested_ip = 0;
 614                                         timeout = 0;
 615                                         packet_num = 0;
 616                                         already_waited_sec = 0;
 617                                 }
 618                                 continue;
 619                         /* case BOUND, RELEASED: - ignore all packets */
 620                         }
 621                         continue; /* back to main loop */
 622                 }
 623
 624                 /* select() didn't timeout, something did happen.
 625                  * But it wasn't a packet. It's a signal pipe then. */
 626                 {
 627                         int signo = udhcp_sp_read(&rfds);
 628                         switch (signo) {
 629                         case SIGUSR1:
 630                                 perform_renew();
 631                                 /* start things over */
 632                                 packet_num = 0;
 633                                 /* Kill any timeouts because the user wants this to hurry along */
 634                                 timeout = 0;
 635                                 break;
 636                         case SIGUSR2:
 637                                 perform_release(requested_ip, server_addr);
 638                                 timeout = INT_MAX;
 639                                 break;
 640                         case SIGTERM:
 641                                 bb_info_msg("Received SIGTERM");
 642                                 if (opt & OPT_R) /* release on quit */
 643                                         perform_release(requested_ip, server_addr);
 644                                 goto ret0;
 645                         }
 646                 }
 647         } /* for (;;) - main loop ends */
 648
 649  ret0:
 650         retval = 0;
 651  ret:
 652         /*if (client_config.pidfile) - remove_pidfile has its own check */
 653                 remove_pidfile(client_config.pidfile);
 654         return retval;
 655 }