src/odhcp6c.c

   1 /**
   2  * Copyright (C) 2012-2013 Steven Barth <steven@midlink.org>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License v2 as published by
   6  * the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  */
  14
  15 #include <time.h>
  16 #include <errno.h>
  17 #include <fcntl.h>
  18 #include <stdio.h>
  19 #include <stdlib.h>
  20 #include <stddef.h>
  21 #include <unistd.h>
  22 #include <syslog.h>
  23 #include <signal.h>
  24 #include <string.h>
  25 #include <stdbool.h>
  26
  27 #include <net/if.h>
  28 #include <sys/wait.h>
  29 #include <sys/syscall.h>
  30 #include <arpa/inet.h>
  31
  32 #include "odhcp6c.h"
  33 #include "ra.h"
  34
  35 #ifdef EXT_BFD_PING
  36 #include "bfd.h"
  37 #endif
  38
  39
  40 static void sighandler(int signal);
  41 static int usage(void);
  42
  43 static uint8_t *state_data[_STATE_MAX] = {NULL};
  44 static size_t state_len[_STATE_MAX] = {0};
  45
  46 static volatile bool signal_io = false;
  47 static volatile bool signal_usr1 = false;
  48 static volatile bool signal_usr2 = false;
  49 static volatile bool signal_term = false;
  50
  51 static int urandom_fd = -1, allow_slaac_only = 0;
  52 static bool bound = false, release = true;
  53 static time_t last_update = 0;
  54
  55 int main(_unused int argc, char* const argv[])
  56 {
  57         // Allocate ressources
  58         const char *pidfile = NULL;
  59         const char *script = "/usr/sbin/odhcp6c-update";
  60         ssize_t l;
  61         uint8_t buf[134];
  62         char *optpos;
  63         uint16_t opttype;
  64         enum odhcp6c_ia_mode ia_na_mode = IA_MODE_TRY;
  65         enum odhcp6c_ia_mode ia_pd_mode = IA_MODE_NONE;
  66         int ia_pd_iaid_index = 0;
  67         static struct in6_addr ifid = IN6ADDR_ANY_INIT;
  68         int sol_timeout = DHCPV6_SOL_MAX_RT;
  69
  70 #ifdef EXT_BFD_PING
  71         int bfd_interval = 0, bfd_loss = 3;
  72 #endif
  73
  74         bool help = false, daemonize = false;
  75         int logopt = LOG_PID;
  76         int c;
  77         unsigned int client_options = DHCPV6_CLIENT_FQDN | DHCPV6_ACCEPT_RECONFIGURE;
  78
  79         while ((c = getopt(argc, argv, "S::N:V:P:FB:c:i:r:Rs:kt:hedp:fa")) != -1) {
  80                 switch (c) {
  81                 case 'S':
  82                         allow_slaac_only = (optarg) ? atoi(optarg) : -1;
  83                         break;
  84
  85                 case 'N':
  86                         if (!strcmp(optarg, "force")) {
  87                                 ia_na_mode = IA_MODE_FORCE;
  88                                 allow_slaac_only = -1;
  89                         } else if (!strcmp(optarg, "none")) {
  90                                 ia_na_mode = IA_MODE_NONE;
  91                         } else if (!strcmp(optarg, "try")) {
  92                                 ia_na_mode = IA_MODE_TRY;
  93                         } else{
  94                                 help = true;
  95                         }
  96                         break;
  97
  98                 case 'V':
  99                         l = script_unhexlify(buf, sizeof(buf), optarg);
 100                         if (!l)
 101                                 help=true;
 102
 103                         odhcp6c_add_state(STATE_VENDORCLASS, buf, l);
 104
 105                         break;
 106                 case 'P':
 107                         if (ia_pd_mode == IA_MODE_NONE)
 108                                 ia_pd_mode = IA_MODE_TRY;
 109
 110                         if (allow_slaac_only >= 0 && allow_slaac_only < 10)
 111                                 allow_slaac_only = 10;
 112
 113                         char *iaid_begin;
 114                         int iaid_len = 0;
 115
 116                         int prefix_length = strtoul(optarg, &iaid_begin, 10);
 117
 118                         if (*iaid_begin != '\0' && *iaid_begin != ',') {
 119                                 syslog(LOG_ERR, "invalid argument: '%s'", optarg);
 120                                 return 1;
 121                         }
 122
 123                         struct odhcp6c_request_prefix prefix = { 0, prefix_length };
 124
 125                         if (*iaid_begin == ',' && (iaid_len = strlen(iaid_begin)) > 1)
 126                                 memcpy(&prefix.iaid, iaid_begin + 1, iaid_len > 4 ? 4 : iaid_len);
 127                         else
 128                                 prefix.iaid = ++ia_pd_iaid_index;
 129
 130                         odhcp6c_add_state(STATE_IA_PD_INIT, &prefix, sizeof(prefix));
 131
 132                         break;
 133
 134                 case 'F':
 135                         allow_slaac_only = -1;
 136                         ia_pd_mode = IA_MODE_FORCE;
 137                         break;
 138
 139 #ifdef EXT_BFD_PING
 140                 case 'B':
 141                         bfd_interval = atoi(optarg);
 142                         break;
 143 #endif
 144
 145                 case 'c':
 146                         l = script_unhexlify(&buf[4], sizeof(buf) - 4, optarg);
 147                         if (l > 0) {
 148                                 buf[0] = 0;
 149                                 buf[1] = DHCPV6_OPT_CLIENTID;
 150                                 buf[2] = 0;
 151                                 buf[3] = l;
 152                                 odhcp6c_add_state(STATE_CLIENT_ID, buf, l + 4);
 153                         } else {
 154                                 help = true;
 155                         }
 156                         break;
 157
 158                 case 'i':
 159                         if (inet_pton(AF_INET6, optarg, &ifid) != 1)
 160                                 help = true;
 161                         break;
 162
 163                 case 'r':
 164                         optpos = optarg;
 165                         while (optpos[0]) {
 166                                 opttype = htons(strtoul(optarg, &optpos, 10));
 167                                 if (optpos == optarg)
 168                                         break;
 169                                 else if (optpos[0])
 170                                         optarg = &optpos[1];
 171                                 odhcp6c_add_state(STATE_ORO, &opttype, 2);
 172                         }
 173                         break;
 174
 175                 case 'R':
 176                         client_options |= DHCPV6_STRICT_OPTIONS;
 177                         break;
 178
 179                 case 's':
 180                         script = optarg;
 181                         break;
 182
 183                 case 'k':
 184                         release = false;
 185                         break;
 186
 187                 case 't':
 188                         sol_timeout = atoi(optarg);
 189                         break;
 190
 191                 case 'e':
 192                         logopt |= LOG_PERROR;
 193                         break;
 194
 195                 case 'd':
 196                         daemonize = true;
 197                         break;
 198
 199                 case 'p':
 200                         pidfile = optarg;
 201                         break;
 202
 203                 case 'f':
 204                         client_options &= ~DHCPV6_CLIENT_FQDN;
 205                         break;
 206
 207                 case 'a':
 208                         client_options &= ~DHCPV6_ACCEPT_RECONFIGURE;
 209                         break;
 210
 211                 default:
 212                         help = true;
 213                         break;
 214                 }
 215         }
 216
 217         openlog("odhcp6c", logopt, LOG_DAEMON);
 218         const char *ifname = argv[optind];
 219
 220         if (help || !ifname)
 221                 return usage();
 222
 223         signal(SIGIO, sighandler);
 224         signal(SIGHUP, sighandler);
 225         signal(SIGINT, sighandler);
 226         signal(SIGCHLD, sighandler);
 227         signal(SIGTERM, sighandler);
 228         signal(SIGUSR1, sighandler);
 229         signal(SIGUSR2, sighandler);
 230
 231         if ((urandom_fd = open("/dev/urandom", O_CLOEXEC | O_RDONLY)) < 0 ||
 232                         init_dhcpv6(ifname, client_options, sol_timeout) ||
 233                         ra_init(ifname, &ifid) || script_init(script, ifname)) {
 234                 syslog(LOG_ERR, "failed to initialize: %s", strerror(errno));
 235                 return 3;
 236         }
 237
 238         if (daemonize) {
 239                 openlog("odhcp6c", LOG_PID, LOG_DAEMON); // Disable LOG_PERROR
 240                 if (daemon(0, 0)) {
 241                         syslog(LOG_ERR, "Failed to daemonize: %s",
 242                                         strerror(errno));
 243                         return 4;
 244                 }
 245
 246                 char pidbuf[128];
 247                 if (!pidfile) {
 248                         snprintf(pidbuf, sizeof(pidbuf),
 249                                         "/var/run/odhcp6c.%s.pid", ifname);
 250                         pidfile = pidbuf;
 251                 }
 252
 253                 int fd = open(pidfile, O_WRONLY | O_CREAT);
 254                 if (fd >= 0) {
 255                         char buf[8];
 256                         int len = snprintf(buf, sizeof(buf), "%i\n", getpid());
 257                         write(fd, buf, len);
 258                         close(fd);
 259                 }
 260         }
 261
 262         script_call("started");
 263
 264         while (!signal_term) { // Main logic
 265                 odhcp6c_clear_state(STATE_SERVER_ID);
 266                 odhcp6c_clear_state(STATE_IA_NA);
 267                 odhcp6c_clear_state(STATE_IA_PD);
 268                 odhcp6c_clear_state(STATE_SNTP_IP);
 269                 odhcp6c_clear_state(STATE_NTP_IP);
 270                 odhcp6c_clear_state(STATE_NTP_FQDN);
 271                 odhcp6c_clear_state(STATE_SIP_IP);
 272                 odhcp6c_clear_state(STATE_SIP_FQDN);
 273                 dhcpv6_set_ia_mode(ia_na_mode, ia_pd_mode);
 274                 bound = false;
 275
 276                 syslog(LOG_NOTICE, "(re)starting transaction on %s", ifname);
 277
 278                 signal_usr1 = signal_usr2 = false;
 279                 int mode = dhcpv6_request(DHCPV6_MSG_SOLICIT);
 280                 odhcp6c_signal_process();
 281
 282                 if (mode < 0)
 283                         continue;
 284
 285                 do {
 286                         int res = dhcpv6_request(mode == DHCPV6_STATELESS ?
 287                                         DHCPV6_MSG_INFO_REQ : DHCPV6_MSG_REQUEST);
 288                         bool signalled = odhcp6c_signal_process();
 289
 290                         if (res > 0)
 291                                 break;
 292                         else if (signalled) {
 293                                 mode = -1;
 294                                 break;
 295                         }
 296
 297                         mode = dhcpv6_promote_server_cand();
 298                 } while (mode > DHCPV6_UNKNOWN);
 299
 300                 if (mode < 0)
 301                         continue;
 302
 303                 switch (mode) {
 304                 case DHCPV6_STATELESS:
 305                         bound = true;
 306                         syslog(LOG_NOTICE, "entering stateless-mode on %s", ifname);
 307
 308                         while (!signal_usr2 && !signal_term) {
 309                                 signal_usr1 = false;
 310                                 script_call("informed");
 311
 312                                 int res = dhcpv6_poll_reconfigure();
 313                                 odhcp6c_signal_process();
 314
 315                                 if (res > 0)
 316                                         continue;
 317
 318                                 if (signal_usr1) {
 319                                         signal_usr1 = false; // Acknowledged
 320                                         continue;
 321                                 }
 322                                 if (signal_usr2 || signal_term)
 323                                         break;
 324
 325                                 res = dhcpv6_request(DHCPV6_MSG_INFO_REQ);
 326                                 odhcp6c_signal_process();
 327                                 if (signal_usr1)
 328                                         continue;
 329                                 else if (res < 0)
 330                                         break;
 331                         }
 332                         break;
 333
 334                 case DHCPV6_STATEFUL:
 335                         script_call("bound");
 336                         bound = true;
 337                         syslog(LOG_NOTICE, "entering stateful-mode on %s", ifname);
 338 #ifdef EXT_BFD_PING
 339                         if (bfd_interval > 0)
 340                                 bfd_start(ifname, bfd_loss, bfd_interval);
 341 #endif
 342
 343                         while (!signal_usr2 && !signal_term) {
 344                                 // Renew Cycle
 345                                 // Wait for T1 to expire or until we get a reconfigure
 346                                 int res = dhcpv6_poll_reconfigure();
 347                                 odhcp6c_signal_process();
 348                                 if (res > 0) {
 349                                         script_call("updated");
 350                                         continue;
 351                                 }
 352
 353                                 // Handle signal, if necessary
 354                                 if (signal_usr1)
 355                                         signal_usr1 = false; // Acknowledged
 356                                 if (signal_usr2 || signal_term)
 357                                         break; // Other signal type
 358
 359                                 // Send renew as T1 expired
 360                                 size_t ia_pd_len, ia_na_len;
 361                                 odhcp6c_get_state(STATE_IA_PD, &ia_pd_len);
 362                                 odhcp6c_get_state(STATE_IA_NA, &ia_na_len);
 363
 364                                 // If we have any IAs, send renew, otherwise request
 365                                 if (ia_pd_len == 0 && ia_na_len == 0)
 366                                         res = dhcpv6_request(DHCPV6_MSG_REQUEST);
 367                                 else
 368                                         res = dhcpv6_request(DHCPV6_MSG_RENEW);
 369
 370                                 odhcp6c_signal_process();
 371                                 if (res > 0) { // Renew was succesfull
 372                                         // Publish updates
 373                                         script_call("updated");
 374                                         continue; // Renew was successful
 375                                 }
 376
 377                                 odhcp6c_clear_state(STATE_SERVER_ID); // Remove binding
 378
 379                                 // If we have IAs, try rebind otherwise restart
 380                                 res = dhcpv6_request(DHCPV6_MSG_REBIND);
 381                                 odhcp6c_signal_process();
 382
 383                                 if (res > 0)
 384                                         script_call("rebound");
 385                                 else {
 386 #ifdef EXT_BFD_PING
 387                                         bfd_stop();
 388 #endif
 389                                         break;
 390                                 }
 391                         }
 392                         break;
 393
 394                 default:
 395                         break;
 396                 }
 397
 398                 size_t ia_pd_len, ia_na_len, server_id_len;
 399                 odhcp6c_get_state(STATE_IA_PD, &ia_pd_len);
 400                 odhcp6c_get_state(STATE_IA_NA, &ia_na_len);
 401                 odhcp6c_get_state(STATE_SERVER_ID, &server_id_len);
 402
 403                 // Add all prefixes to lost prefixes
 404                 bound = false;
 405                 script_call("unbound");
 406
 407                 if (server_id_len > 0 && (ia_pd_len > 0 || ia_na_len > 0) && release)
 408                         dhcpv6_request(DHCPV6_MSG_RELEASE);
 409
 410                 odhcp6c_clear_state(STATE_IA_NA);
 411                 odhcp6c_clear_state(STATE_IA_PD);
 412         }
 413
 414         script_call("stopped");
 415         return 0;
 416 }
 417
 418
 419 static int usage(void)
 420 {
 421         const char buf[] =
 422         "Usage: odhcp6c [options] <interface>\n"
 423         "\nFeature options:\n"
 424         "       -S <time>       Wait at least <time> sec for a DHCP-server (0)\n"
 425         "       -N <mode>       Mode for requesting addresses [try|force|none]\n"
 426         "       -P <length>     Request IPv6-Prefix (0 = auto)\n"
 427         "       -F              Force IPv6-Prefix\n"
 428         "       -V <hex-string> Set vendor-class option. string length must be a multiple of 2\n"
 429 #ifdef EXT_BFD_PING
 430         "       -B <interval>   Enable BFD ping check\n"
 431 #endif
 432         "       -c <clientid>   Override client-ID (base-16 encoded)\n"
 433         "       -i <iface-id>   Use a custom interface identifier for RA handling\n"
 434         "       -r <options>    Options to be requested (comma-separated)\n"
 435         "       -R              Do not request any options except those specified with -r\n"
 436         "       -s <script>     Status update script (/usr/sbin/odhcp6c-update)\n"
 437         "       -a              Don't send Accept Reconfigure option\n"
 438         "       -f              Don't send Client FQDN option\n"
 439         "       -k              Don't send a RELEASE when stopping\n"
 440         "       -t <seconds>    Maximum timeout for DHCPv6-SOLICIT (120)\n"
 441         "\nInvocation options:\n"
 442         "       -p <pidfile>    Set pidfile (/var/run/odhcp6c.pid)\n"
 443         "       -d              Daemonize\n"
 444         "       -e              Write logmessages to stderr\n"
 445         //"     -v              Increase logging verbosity\n"
 446         "       -h              Show this help\n\n";
 447         write(STDERR_FILENO, buf, sizeof(buf));
 448         return 1;
 449 }
 450
 451
 452 // Don't want to pull-in librt and libpthread just for a monotonic clock...
 453 uint64_t odhcp6c_get_milli_time(void)
 454 {
 455         struct timespec t = {0, 0};
 456         syscall(SYS_clock_gettime, CLOCK_MONOTONIC, &t);
 457         return t.tv_sec * 1000 + t.tv_nsec / 1000000;
 458 }
 459
 460
 461 static uint8_t* odhcp6c_resize_state(enum odhcp6c_state state, ssize_t len)
 462 {
 463         if (len == 0)
 464                 return state_data[state] + state_len[state];
 465         else if (state_len[state] + len > 1024)
 466                 return NULL;
 467
 468         uint8_t *n = realloc(state_data[state], state_len[state] + len);
 469         if (n || state_len[state] + len == 0) {
 470                 state_data[state] = n;
 471                 n += state_len[state];
 472                 state_len[state] += len;
 473         }
 474         return n;
 475 }
 476
 477
 478 bool odhcp6c_signal_process(void)
 479 {
 480         while (signal_io) {
 481                 signal_io = false;
 482
 483                 bool ra_updated = ra_process();
 484
 485                 if (ra_link_up())
 486                         signal_usr2 = true;
 487
 488                 if (ra_updated && (bound || allow_slaac_only == 0))
 489                         script_call("ra-updated"); // Immediate process urgent events
 490                 else if (ra_updated && !bound && allow_slaac_only > 0)
 491                         script_delay_call("ra-updated", allow_slaac_only);
 492
 493 #ifdef EXT_BFD_PING
 494                 bfd_receive();
 495 #endif
 496         }
 497
 498         return signal_usr1 || signal_usr2 || signal_term;
 499 }
 500
 501
 502 void odhcp6c_clear_state(enum odhcp6c_state state)
 503 {
 504         state_len[state] = 0;
 505 }
 506
 507
 508 void odhcp6c_add_state(enum odhcp6c_state state, const void *data, size_t len)
 509 {
 510         uint8_t *n = odhcp6c_resize_state(state, len);
 511         if (n)
 512                 memcpy(n, data, len);
 513 }
 514
 515 void odhcp6c_insert_state(enum odhcp6c_state state, size_t offset, const void *data, size_t len)
 516 {
 517         ssize_t len_after = state_len[state] - offset;
 518         if (len_after < 0)
 519                 return;
 520
 521         uint8_t *n = odhcp6c_resize_state(state, len);
 522         if (n) {
 523                 uint8_t *sdata = state_data[state];
 524
 525                 memmove(sdata + offset + len, sdata + offset, len_after);
 526                 memcpy(sdata + offset, data, len);
 527         }
 528 }
 529
 530 size_t odhcp6c_remove_state(enum odhcp6c_state state, size_t offset, size_t len)
 531 {
 532         uint8_t *data = state_data[state];
 533         ssize_t len_after = state_len[state] - (offset + len);
 534         if (len_after < 0)
 535                 return state_len[state];
 536
 537         memmove(data + offset, data + offset + len, len_after);
 538         return state_len[state] -= len;
 539 }
 540
 541
 542 void* odhcp6c_move_state(enum odhcp6c_state state, size_t *len)
 543 {
 544         *len = state_len[state];
 545         void *data = state_data[state];
 546
 547         state_len[state] = 0;
 548         state_data[state] = NULL;
 549
 550         return data;
 551 }
 552
 553
 554 void* odhcp6c_get_state(enum odhcp6c_state state, size_t *len)
 555 {
 556         *len = state_len[state];
 557         return state_data[state];
 558 }
 559
 560
 561 struct odhcp6c_entry* odhcp6c_find_entry(enum odhcp6c_state state, const struct odhcp6c_entry *new)
 562 {
 563         size_t len, cmplen = offsetof(struct odhcp6c_entry, target) + new->length / 8;
 564         struct odhcp6c_entry *start = odhcp6c_get_state(state, &len);
 565         struct odhcp6c_entry *x = NULL;
 566
 567         for (struct odhcp6c_entry *c = start; !x && c < &start[len/sizeof(*c)]; ++c)
 568                 if (!memcmp(c, new, cmplen))
 569                         return c;
 570
 571         return NULL;
 572 }
 573
 574
 575 bool odhcp6c_update_entry_safe(enum odhcp6c_state state, struct odhcp6c_entry *new, uint32_t safe)
 576 {
 577         size_t len;
 578         struct odhcp6c_entry *x = odhcp6c_find_entry(state, new);
 579         struct odhcp6c_entry *start = odhcp6c_get_state(state, &len);
 580
 581         if (x && x->valid > new->valid && new->valid < safe)
 582                 new->valid = safe;
 583
 584         if (new->valid > 0) {
 585                 if (x) {
 586                         if (new->valid >= x->valid && new->valid - x->valid < 60 &&
 587                                         new->preferred >= x->preferred &&
 588                                         new->preferred - x->preferred < 60 &&
 589                                         x->class == new->class)
 590                                 return false;
 591                         x->valid = new->valid;
 592                         x->preferred = new->preferred;
 593                         x->t1 = new->t1;
 594                         x->t2 = new->t2;
 595                         x->class = new->class;
 596                         x->iaid = new->iaid;
 597                 } else {
 598                         odhcp6c_add_state(state, new, sizeof(*new));
 599                 }
 600         } else if (x) {
 601                 odhcp6c_remove_state(state, (x - start) * sizeof(*x), sizeof(*x));
 602         }
 603         return true;
 604 }
 605
 606
 607 bool odhcp6c_update_entry(enum odhcp6c_state state, struct odhcp6c_entry *new)
 608 {
 609         return odhcp6c_update_entry_safe(state, new, 0);
 610 }
 611
 612
 613 static void odhcp6c_expire_list(enum odhcp6c_state state, uint32_t elapsed)
 614 {
 615         size_t len;
 616         struct odhcp6c_entry *start = odhcp6c_get_state(state, &len);
 617         for (struct odhcp6c_entry *c = start; c < &start[len / sizeof(*c)]; ++c) {
 618                 if (c->t1 < elapsed)
 619                         c->t1 = 0;
 620                 else if (c->t1 != UINT32_MAX)
 621                         c->t1 -= elapsed;
 622
 623                 if (c->t2 < elapsed)
 624                         c->t2 = 0;
 625                 else if (c->t2 != UINT32_MAX)
 626                         c->t2 -= elapsed;
 627
 628                 if (c->preferred < elapsed)
 629                         c->preferred = 0;
 630                 else if (c->preferred != UINT32_MAX)
 631                         c->preferred -= elapsed;
 632
 633                 if (c->valid < elapsed)
 634                         c->valid = 0;
 635                 else if (c->valid != UINT32_MAX)
 636                         c->valid -= elapsed;
 637
 638                 if (!c->valid)
 639                         odhcp6c_remove_state(state, (c - start) * sizeof(*c), sizeof(*c));
 640         }
 641 }
 642
 643
 644 void odhcp6c_expire(void)
 645 {
 646         time_t now = odhcp6c_get_milli_time() / 1000;
 647         uint32_t elapsed = (last_update > 0) ? now - last_update : 0;
 648         last_update = now;
 649
 650         odhcp6c_expire_list(STATE_RA_PREFIX, elapsed);
 651         odhcp6c_expire_list(STATE_RA_ROUTE, elapsed);
 652         odhcp6c_expire_list(STATE_RA_DNS, elapsed);
 653         odhcp6c_expire_list(STATE_IA_NA, elapsed);
 654         odhcp6c_expire_list(STATE_IA_PD, elapsed);
 655 }
 656
 657
 658 uint32_t odhcp6c_elapsed(void)
 659 {
 660         return odhcp6c_get_milli_time() / 1000 - last_update;
 661 }
 662
 663
 664 void odhcp6c_random(void *buf, size_t len)
 665 {
 666         read(urandom_fd, buf, len);
 667 }
 668
 669 bool odhcp6c_is_bound(void)
 670 {
 671         return bound;
 672 }
 673
 674 static void sighandler(int signal)
 675 {
 676         if (signal == SIGCHLD)
 677                 while (waitpid(-1, NULL, WNOHANG) > 0);
 678         else if (signal == SIGUSR1)
 679                 signal_usr1 = true;
 680         else if (signal == SIGUSR2)
 681                 signal_usr2 = true;
 682         else if (signal == SIGIO)
 683                 signal_io = true;
 684         else
 685                 signal_term = true;
 686 }