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 #include <syslog.h>
  13
  14 /* Override ENABLE_FEATURE_PIDFILE - ifupdown needs our pidfile to always exist */
  15 #define WANT_PIDFILE 1
  16 #include "common.h"
  17 #include "dhcpd.h"
  18 #include "dhcpc.h"
  19 #include "options.h"
  20
  21
  22 static int timeout; /* = 0. Must be signed */
  23 static uint32_t requested_ip; /* = 0 */
  24 static uint32_t server_addr;
  25 static int sockfd = -1;
  26
  27 #define LISTEN_NONE 0
  28 #define LISTEN_KERNEL 1
  29 #define LISTEN_RAW 2
  30 static smallint listen_mode;
  31
  32 static smallint state;
  33
  34 /* struct client_config_t client_config is in bb_common_bufsiz1 */
  35
  36
  37 /* just a little helper */
  38 static void change_listen_mode(int new_mode)
  39 {
  40         DEBUG("entering %s listen mode",
  41                 new_mode ? (new_mode == 1 ? "kernel" : "raw") : "none");
  42         if (sockfd >= 0) {
  43                 close(sockfd);
  44                 sockfd = -1;
  45         }
  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_listen_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_listen_mode(LISTEN_RAW);
  66                 state = INIT_SELECTING;
  67                 break;
  68         case INIT_SELECTING:
  69                 break;
  70         }
  71 }
  72
  73
  74 /* perform a release */
  75 static void perform_release(void)
  76 {
  77         char buffer[sizeof("255.255.255.255")];
  78         struct in_addr temp_addr;
  79
  80         /* send release packet */
  81         if (state == BOUND || state == RENEWING || state == REBINDING) {
  82                 temp_addr.s_addr = server_addr;
  83                 strcpy(buffer, inet_ntoa(temp_addr));
  84                 temp_addr.s_addr = requested_ip;
  85                 bb_info_msg("Unicasting a release of %s to %s",
  86                                 inet_ntoa(temp_addr), buffer);
  87                 send_release(server_addr, requested_ip); /* unicast */
  88                 udhcp_run_script(NULL, "deconfig");
  89         }
  90         bb_info_msg("Entering released state");
  91
  92         change_listen_mode(LISTEN_NONE);
  93         state = RELEASED;
  94         timeout = INT_MAX;
  95 }
  96
  97
  98 static void client_background(void)
  99 {
 100 #if !BB_MMU
 101         bb_error_msg("cannot background in uclinux (yet)");
 102 /* ... mainly because udhcpc calls client_background()
 103  * in _the _middle _of _udhcpc _run_, not at the start!
 104  * If that will be properly disabled for NOMMU, client_background()
 105  * will work on NOMMU too */
 106 #else
 107         bb_daemonize(0);
 108         logmode &= ~LOGMODE_STDIO;
 109         /* rewrite pidfile, as our pid is different now */
 110         write_pidfile(client_config.pidfile);
 111 #endif
 112         /* Do not fork again. */
 113         client_config.foreground = 1;
 114         client_config.background_if_no_lease = 0;
 115 }
 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 ATTRIBUTE_UNUSED, char **argv)
 133 {
 134         uint8_t *temp, *message;
 135         char *str_c, *str_V, *str_h, *str_F, *str_r, *str_T, *str_A, *str_t;
 136         USE_FEATURE_UDHCP_PORT(char *str_P;)
 137         llist_t *list_O = NULL;
 138 #if ENABLE_FEATURE_UDHCPC_ARPING
 139         char *str_W;
 140 #endif
 141         int tryagain_timeout = 20;
 142         int discover_timeout = 3;
 143         int discover_retries = 3;
 144         uint32_t xid = 0;
 145         uint32_t lease_seconds = 0; /* can be given as 32-bit quantity */
 146         int packet_num;
 147         /* t1, t2... what a wonderful names... */
 148         unsigned t1 = t1; /* for gcc */
 149         unsigned t2 = t2;
 150         unsigned timestamp_got_lease = timestamp_got_lease;
 151         unsigned opt;
 152         int max_fd;
 153         int retval;
 154         int len;
 155         struct timeval tv;
 156         struct in_addr temp_addr;
 157         struct dhcpMessage packet;
 158         fd_set rfds;
 159
 160         enum {
 161                 OPT_c = 1 << 0,
 162                 OPT_C = 1 << 1,
 163                 OPT_V = 1 << 2,
 164                 OPT_f = 1 << 3,
 165                 OPT_b = 1 << 4,
 166                 OPT_H = 1 << 5,
 167                 OPT_h = 1 << 6,
 168                 OPT_F = 1 << 7,
 169                 OPT_i = 1 << 8,
 170                 OPT_n = 1 << 9,
 171                 OPT_p = 1 << 10,
 172                 OPT_q = 1 << 11,
 173                 OPT_R = 1 << 12,
 174                 OPT_r = 1 << 13,
 175                 OPT_s = 1 << 14,
 176                 OPT_T = 1 << 15,
 177                 OPT_t = 1 << 16,
 178                 OPT_v = 1 << 17,
 179                 OPT_S = 1 << 18,
 180                 OPT_A = 1 << 19,
 181 #if ENABLE_FEATURE_UDHCPC_ARPING
 182                 OPT_a = 1 << 20,
 183                 OPT_W = 1 << 21,
 184 #endif
 185                 OPT_P = 1 << 22,
 186         };
 187 #if ENABLE_GETOPT_LONG
 188         static const char udhcpc_longopts[] ALIGN1 =
 189                 "clientid\0"       Required_argument "c"
 190                 "clientid-none\0"  No_argument       "C"
 191                 "vendorclass\0"    Required_argument "V"
 192                 "foreground\0"     No_argument       "f"
 193                 "background\0"     No_argument       "b"
 194                 "hostname\0"       Required_argument "H"
 195                 "fqdn\0"           Required_argument "F"
 196                 "interface\0"      Required_argument "i"
 197                 "now\0"            No_argument       "n"
 198                 "pidfile\0"        Required_argument "p"
 199                 "quit\0"           No_argument       "q"
 200                 "release\0"        No_argument       "R"
 201                 "request\0"        Required_argument "r"
 202                 "script\0"         Required_argument "s"
 203                 "timeout\0"        Required_argument "T"
 204                 "version\0"        No_argument       "v"
 205                 "retries\0"        Required_argument "t"
 206                 "tryagain\0"       Required_argument "A"
 207                 "syslog\0"         No_argument       "S"
 208 #if ENABLE_FEATURE_UDHCPC_ARPING
 209                 "arping\0"         No_argument       "a"
 210 #endif
 211                 "request-option\0" Required_argument "O"
 212 #if ENABLE_FEATURE_UDHCP_PORT
 213                 "client-port\0"    Required_argument "P"
 214 #endif
 215                 ;
 216 #endif
 217         /* Default options. */
 218 #if ENABLE_FEATURE_UDHCP_PORT
 219         SERVER_PORT = 67;
 220         CLIENT_PORT = 68;
 221 #endif
 222         client_config.interface = "eth0";
 223         client_config.script = DEFAULT_SCRIPT;
 224
 225         /* Parse command line */
 226         opt_complementary = "c--C:C--c:O::"; // Cc: mutually exclusive; O: list
 227 #if ENABLE_GETOPT_LONG
 228         applet_long_options = udhcpc_longopts;
 229 #endif
 230         opt = getopt32(argv, "c:CV:fbH:h:F:i:np:qRr:s:T:t:vSA:"
 231                 USE_FEATURE_UDHCPC_ARPING("aW:")
 232                 USE_FEATURE_UDHCP_PORT("P:")
 233                 "O:"
 234                 , &str_c, &str_V, &str_h, &str_h, &str_F
 235                 , &client_config.interface, &client_config.pidfile, &str_r
 236                 , &client_config.script, &str_T, &str_t, &str_A
 237                 USE_FEATURE_UDHCPC_ARPING(, &str_W)
 238                 USE_FEATURE_UDHCP_PORT(, &str_P)
 239                 , &list_O
 240                 );
 241
 242         if (opt & OPT_c)
 243                 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, str_c, 0);
 244         //if (opt & OPT_C)
 245         if (opt & OPT_V)
 246                 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
 247         if (opt & OPT_f)
 248                 client_config.foreground = 1;
 249         if (opt & OPT_b)
 250                 client_config.background_if_no_lease = 1;
 251         if (opt & (OPT_h|OPT_H))
 252                 client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
 253         if (opt & OPT_F) {
 254                 client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
 255                 /* Flags: 0000NEOS
 256                 S: 1 => Client requests Server to update A RR in DNS as well as PTR
 257                 O: 1 => Server indicates to client that DNS has been updated regardless
 258                 E: 1 => Name data is DNS format, i.e. <4>host<6>domain<4>com<0> not "host.domain.com"
 259                 N: 1 => Client requests Server to not update DNS
 260                 */
 261                 client_config.fqdn[OPT_DATA + 0] = 0x1;
 262                 /* client_config.fqdn[OPT_DATA + 1] = 0; - redundant */
 263                 /* client_config.fqdn[OPT_DATA + 2] = 0; - redundant */
 264         }
 265         // if (opt & OPT_i) client_config.interface = ...
 266         if (opt & OPT_n)
 267                 client_config.abort_if_no_lease = 1;
 268         // if (opt & OPT_p) client_config.pidfile = ...
 269         if (opt & OPT_q)
 270                 client_config.quit_after_lease = 1;
 271         if (opt & OPT_R)
 272                 client_config.release_on_quit = 1;
 273         if (opt & OPT_r)
 274                 requested_ip = inet_addr(str_r);
 275         // if (opt & OPT_s) client_config.script = ...
 276         if (opt & OPT_T)
 277                 discover_timeout = xatoi_u(str_T);
 278         if (opt & OPT_t)
 279                 discover_retries = xatoi_u(str_t);
 280         if (opt & OPT_A)
 281                 tryagain_timeout = xatoi_u(str_A);
 282         if (opt & OPT_v) {
 283                 puts("version "BB_VER);
 284                 return 0;
 285         }
 286         if (opt & OPT_S) {
 287                 openlog(applet_name, LOG_PID, LOG_LOCAL0);
 288                 logmode |= LOGMODE_SYSLOG;
 289         }
 290 #if ENABLE_FEATURE_UDHCP_PORT
 291         if (opt & OPT_P) {
 292                 CLIENT_PORT = xatou16(str_P);
 293                 SERVER_PORT = CLIENT_PORT - 1;
 294         }
 295 #endif
 296         while (list_O) {
 297                 int n = index_in_strings(dhcp_option_strings, list_O->data);
 298                 if (n < 0)
 299                         bb_error_msg_and_die("unknown option '%s'", list_O->data);
 300                 n = dhcp_options[n].code;
 301                 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
 302                 list_O = list_O->link;
 303         }
 304
 305         if (read_interface(client_config.interface, &client_config.ifindex,
 306                            NULL, client_config.arp))
 307                 return 1;
 308
 309         /* Make sure fd 0,1,2 are open */
 310         bb_sanitize_stdio();
 311         /* Equivalent of doing a fflush after every \n */
 312         setlinebuf(stdout);
 313
 314         /* Create pidfile */
 315         write_pidfile(client_config.pidfile);
 316         /* if (!..) bb_perror_msg("cannot create pidfile %s", pidfile); */
 317
 318         /* Goes to stdout and possibly syslog */
 319         bb_info_msg("%s (v"BB_VER") started", applet_name);
 320
 321         /* if not set, and not suppressed, setup the default client ID */
 322         if (!client_config.clientid && !(opt & OPT_C)) {
 323                 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
 324                 client_config.clientid[OPT_DATA] = 1;
 325                 memcpy(client_config.clientid + OPT_DATA+1, client_config.arp, 6);
 326         }
 327
 328         if (!client_config.vendorclass)
 329                 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, "udhcp "BB_VER, 0);
 330
 331         /* setup the signal pipe */
 332         udhcp_sp_setup();
 333
 334         state = INIT_SELECTING;
 335         udhcp_run_script(NULL, "deconfig");
 336         change_listen_mode(LISTEN_RAW);
 337         packet_num = 0;
 338
 339         /* Main event loop. select() waits on signal pipe and possibly
 340          * on sockfd.
 341          * "continue" statements in code below jump to the top of the loop.
 342          */
 343         for (;;) {
 344                 tv.tv_sec = timeout;
 345                 tv.tv_usec = 0;
 346
 347                 if (listen_mode != LISTEN_NONE && sockfd < 0) {
 348                         if (listen_mode == LISTEN_KERNEL)
 349                                 sockfd = listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
 350                         else
 351                                 sockfd = raw_socket(client_config.ifindex);
 352                 }
 353                 max_fd = udhcp_sp_fd_set(&rfds, sockfd);
 354
 355                 retval = 0; /* If we already timed out, fall through, else... */
 356                 if (tv.tv_sec > 0) {
 357                         DEBUG("Waiting on select...");
 358                         retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
 359                 }
 360
 361                 if (retval < 0) {
 362                         /* EINTR? signal was caught, don't panic */
 363                         if (errno != EINTR) {
 364                                 /* Else: an error occured, panic! */
 365                                 bb_perror_msg_and_die("select");
 366                         }
 367                         continue;
 368                 }
 369
 370                 /* If timeout dropped to zero, time to become active:
 371                  * resend discover/renew/whatever
 372                  */
 373                 if (retval == 0) {
 374                         switch (state) {
 375                         case INIT_SELECTING:
 376                                 if (packet_num < discover_retries) {
 377                                         if (packet_num == 0)
 378                                                 xid = random_xid();
 379
 380                                         /* send discover packet */
 381                                         send_discover(xid, requested_ip); /* broadcast */
 382
 383                                         timeout = discover_timeout;
 384                                         packet_num++;
 385                                         continue;
 386                                 }
 387                                 udhcp_run_script(NULL, "leasefail");
 388                                 if (client_config.background_if_no_lease) {
 389                                         bb_info_msg("No lease, forking to background");
 390                                         client_background();
 391                                 } else if (client_config.abort_if_no_lease) {
 392                                         bb_info_msg("No lease, failing");
 393                                         retval = 1;
 394                                         goto ret;
 395                                 }
 396                                 /* wait to try again */
 397                                 timeout = tryagain_timeout;
 398                                 packet_num = 0;
 399                                 continue;
 400                         case RENEW_REQUESTED:
 401                         case REQUESTING:
 402                                 if (packet_num < discover_retries) {
 403                                         /* send request packet */
 404                                         if (state == RENEW_REQUESTED)
 405                                                 send_renew(xid, server_addr, requested_ip); /* unicast */
 406                                         else send_selecting(xid, server_addr, requested_ip); /* broadcast */
 407
 408                                         timeout = ((packet_num == 2) ? 10 : 2);
 409                                         packet_num++;
 410                                         continue;
 411                                 }
 412                                 /* timed out, go back to init state */
 413                                 if (state == RENEW_REQUESTED)
 414                                         udhcp_run_script(NULL, "deconfig");
 415                                 change_listen_mode(LISTEN_RAW);
 416                                 state = INIT_SELECTING;
 417                                 timeout = 0;
 418                                 packet_num = 0;
 419                                 continue;
 420                         case BOUND:
 421                                 /* Lease is starting to run out, time to enter renewing state */
 422                                 change_listen_mode(LISTEN_KERNEL);
 423                                 DEBUG("Entering renew state");
 424                                 state = RENEWING;
 425                                 /* fall right through */
 426                         case RENEWING:
 427                                 /* Either set a new T1, or enter REBINDING state */
 428                                 if ((t2 - t1) > (lease_seconds / (4*60*60) + 1)) {
 429                                         /* send a request packet */
 430                                         send_renew(xid, server_addr, requested_ip); /* unicast */
 431                                         t1 += (t2 - t1) / 2;
 432                                         timeout = t1 - ((int)monotonic_sec() - timestamp_got_lease);
 433                                         continue;
 434                                 }
 435                                 /* Timed out, enter rebinding state */
 436                                 DEBUG("Entering rebinding state");
 437                                 state = REBINDING;
 438                                 timeout = (t2 - t1);
 439                                 continue;
 440                         case REBINDING:
 441                                 /* Lease is *really* about to run out,
 442                                  * try to find DHCP server using broadcast */
 443                                 if ((lease_seconds - t2) > (lease_seconds / (4*60*60) + 1)) {
 444                                         /* send a request packet */
 445                                         send_renew(xid, 0, requested_ip); /* broadcast */
 446                                         t2 += (lease_seconds - t2) / 2;
 447                                         timeout = t2 - ((int)monotonic_sec() - timestamp_got_lease);
 448                                         continue;
 449                                 }
 450                                 /* Timed out, enter init state */
 451                                 bb_info_msg("Lease lost, entering init state");
 452                                 udhcp_run_script(NULL, "deconfig");
 453                                 change_listen_mode(LISTEN_RAW);
 454                                 state = INIT_SELECTING;
 455                                 timeout = 0;
 456                                 packet_num = 0;
 457                                 continue;
 458                         /* case RELEASED: */
 459                         }
 460                         /* yah, I know, *you* say it would never happen */
 461                         timeout = INT_MAX;
 462                         continue; /* back to main loop */
 463                 }
 464
 465                 /* select() didn't timeout, something did happen. */
 466                 /* Is is a packet? */
 467                 if (listen_mode != LISTEN_NONE && FD_ISSET(sockfd, &rfds)) {
 468                         /* A packet is ready, read it */
 469
 470                         if (listen_mode == LISTEN_KERNEL)
 471                                 len = udhcp_recv_packet(&packet, sockfd);
 472                         else
 473                                 len = get_raw_packet(&packet, sockfd);
 474
 475                         if (len == -1) { /* error is severe, reopen socket */
 476                                 DEBUG("error on read, %s, reopening socket", strerror(errno));
 477                                 change_listen_mode(listen_mode); /* just close and reopen */
 478                         }
 479                         if (len < 0) continue;
 480
 481                         if (packet.xid != xid) {
 482                                 DEBUG("Ignoring XID %x (our xid is %x)",
 483                                         (unsigned)packet.xid, (unsigned)xid);
 484                                 continue;
 485                         }
 486
 487                         /* Ignore packets that aren't for us */
 488                         if (memcmp(packet.chaddr, client_config.arp, 6)) {
 489                                 DEBUG("Packet does not have our chaddr - ignoring");
 490                                 continue;
 491                         }
 492
 493                         message = get_option(&packet, DHCP_MESSAGE_TYPE);
 494                         if (message == NULL) {
 495                                 bb_error_msg("cannot get message type from packet - ignoring");
 496                                 continue;
 497                         }
 498
 499                         switch (state) {
 500                         case INIT_SELECTING:
 501                                 /* Must be a DHCPOFFER to one of our xid's */
 502                                 if (*message == DHCPOFFER) {
 503                         /* TODO: why we don't just fetch server's IP from IP header? */
 504                                         temp = get_option(&packet, DHCP_SERVER_ID);
 505                                         if (!temp) {
 506                                                 bb_error_msg("no server ID in message");
 507                                                 continue;
 508                                                 /* still selecting - this server looks bad */
 509                                         }
 510                                         /* can be misaligned, thus memcpy */
 511                                         memcpy(&server_addr, temp, 4);
 512                                         xid = packet.xid;
 513                                         requested_ip = packet.yiaddr;
 514
 515                                         /* enter requesting state */
 516                                         state = REQUESTING;
 517                                         timeout = 0;
 518                                         packet_num = 0;
 519                                 }
 520                                 continue;
 521                         case RENEW_REQUESTED:
 522                         case REQUESTING:
 523                         case RENEWING:
 524                         case REBINDING:
 525                                 if (*message == DHCPACK) {
 526                                         temp = get_option(&packet, DHCP_LEASE_TIME);
 527                                         if (!temp) {
 528                                                 bb_error_msg("no lease time with ACK, using 1 hour lease");
 529                                                 lease_seconds = 60 * 60;
 530                                         } else {
 531                                                 /* can be misaligned, thus memcpy */
 532                                                 memcpy(&lease_seconds, temp, 4);
 533                                                 lease_seconds = ntohl(lease_seconds);
 534                                         }
 535 #if ENABLE_FEATURE_UDHCPC_ARPING
 536                                         if (opt & OPT_a) {
 537                                                 if (!arpping(packet.yiaddr,
 538                                                             (uint32_t) 0,
 539                                                             client_config.arp,
 540                                                             client_config.interface)
 541                                                 ) {
 542                                                         bb_info_msg("offered address is in use "
 543                                                                 "(got ARP reply), declining");
 544                                                         send_decline(xid, server_addr, packet.yiaddr);
 545
 546                                                         if (state != REQUESTING)
 547                                                                 udhcp_run_script(NULL, "deconfig");
 548                                                         change_listen_mode(LISTEN_RAW);
 549                                                         state = INIT_SELECTING;
 550                                                         requested_ip = 0;
 551                                                         timeout = tryagain_timeout;
 552                                                         packet_num = 0;
 553                                                         continue; /* back to main loop */
 554                                                 }
 555                                         }
 556 #endif
 557                                         /* enter bound state */
 558                                         t1 = lease_seconds / 2;
 559
 560                                         /* little fixed point for n * .875 */
 561                                         t2 = (lease_seconds * 7) >> 3;
 562                                         temp_addr.s_addr = packet.yiaddr;
 563                                         bb_info_msg("Lease of %s obtained, lease time %u",
 564                                                 inet_ntoa(temp_addr), (unsigned)lease_seconds);
 565                                         timestamp_got_lease = monotonic_sec();
 566                                         timeout = t1;
 567                                         requested_ip = packet.yiaddr;
 568                                         udhcp_run_script(&packet,
 569                                                    ((state == RENEWING || state == REBINDING) ? "renew" : "bound"));
 570
 571                                         state = BOUND;
 572                                         change_listen_mode(LISTEN_NONE);
 573                                         if (client_config.quit_after_lease) {
 574                                                 if (client_config.release_on_quit)
 575                                                         perform_release();
 576                                                 goto ret0;
 577                                         }
 578                                         if (!client_config.foreground)
 579                                                 client_background();
 580
 581                                         continue; /* back to main loop */
 582                                 }
 583                                 if (*message == DHCPNAK) {
 584                                         /* return to init state */
 585                                         bb_info_msg("Received DHCP NAK");
 586                                         udhcp_run_script(&packet, "nak");
 587                                         if (state != REQUESTING)
 588                                                 udhcp_run_script(NULL, "deconfig");
 589                                         change_listen_mode(LISTEN_RAW);
 590                                         sleep(3); /* avoid excessive network traffic */
 591                                         state = INIT_SELECTING;
 592                                         requested_ip = 0;
 593                                         timeout = 0;
 594                                         packet_num = 0;
 595                                 }
 596                                 continue;
 597                         /* case BOUND, RELEASED: - ignore all packets */
 598                         }
 599                         continue; /* back to main loop */
 600                 }
 601
 602                 /* select() didn't timeout, something did happen.
 603                  * But it wasn't a packet. It's a signal pipe then. */
 604                 {
 605                         int signo = udhcp_sp_read(&rfds);
 606                         switch (signo) {
 607                         case SIGUSR1:
 608                                 perform_renew();
 609                                 /* start things over */
 610                                 packet_num = 0;
 611                                 /* Kill any timeouts because the user wants this to hurry along */
 612                                 timeout = 0;
 613                                 break;
 614                         case SIGUSR2:
 615                                 perform_release();
 616                                 break;
 617                         case SIGTERM:
 618                                 bb_info_msg("Received SIGTERM");
 619                                 if (client_config.release_on_quit)
 620                                         perform_release();
 621                                 goto ret0;
 622                         }
 623                 }
 624         } /* for (;;) - main loop ends */
 625
 626  ret0:
 627         retval = 0;
 628  ret:
 629         /*if (client_config.pidfile) - remove_pidfile has it's own check */
 630                 remove_pidfile(client_config.pidfile);
 631         return retval;
 632 }