dnsmasq.c revision 33b344454b95ed99bad7d3fe4d493870923deaf6
1/* dnsmasq is Copyright (c) 2000-2009 Simon Kelley 2 3 This program is free software; you can redistribute it and/or modify 4 it under the terms of the GNU General Public License as published by 5 the Free Software Foundation; version 2 dated June, 1991, or 6 (at your option) version 3 dated 29 June, 2007. 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 You should have received a copy of the GNU General Public License 14 along with this program. If not, see <http://www.gnu.org/licenses/>. 15*/ 16 17#include "dnsmasq.h" 18 19struct daemon *daemon; 20 21static char *compile_opts = 22#ifndef HAVE_IPV6 23"no-" 24#endif 25"IPv6 " 26#ifndef HAVE_GETOPT_LONG 27"no-" 28#endif 29"GNU-getopt " 30#ifdef HAVE_BROKEN_RTC 31"no-RTC " 32#endif 33#ifdef NO_FORK 34"no-MMU " 35#endif 36#ifndef HAVE_DBUS 37"no-" 38#endif 39"DBus " 40#ifndef LOCALEDIR 41"no-" 42#endif 43"I18N " 44#ifndef HAVE_DHCP 45"no-" 46#endif 47"DHCP " 48#if defined(HAVE_DHCP) && !defined(HAVE_SCRIPT) 49"no-scripts " 50#endif 51#ifndef HAVE_TFTP 52"no-" 53#endif 54"TFTP"; 55 56 57 58static volatile pid_t pid = 0; 59static volatile int pipewrite; 60 61static int set_dns_listeners(time_t now, fd_set *set, int *maxfdp); 62static void check_dns_listeners(fd_set *set, time_t now); 63static void sig_handler(int sig); 64static void async_event(int pipe, time_t now); 65static void fatal_event(struct event_desc *ev); 66static void poll_resolv(void); 67#ifdef __ANDROID__ 68static int set_android_listeners(fd_set *set, int *maxfdp); 69static int check_android_listeners(fd_set *set); 70#endif 71 72int main (int argc, char **argv) 73{ 74 int bind_fallback = 0; 75 time_t now; 76 struct sigaction sigact; 77 struct iname *if_tmp; 78 int piperead, pipefd[2], err_pipe[2]; 79 struct passwd *ent_pw = NULL; 80#if defined(HAVE_DHCP) && defined(HAVE_SCRIPT) 81 uid_t script_uid = 0; 82 gid_t script_gid = 0; 83#endif 84 struct group *gp = NULL; 85 long i, max_fd = sysconf(_SC_OPEN_MAX); 86 char *baduser = NULL; 87 int log_err; 88#if defined(HAVE_LINUX_NETWORK) 89 cap_user_header_t hdr = NULL; 90 cap_user_data_t data = NULL; 91#endif 92 93#ifdef LOCALEDIR 94 setlocale(LC_ALL, ""); 95 bindtextdomain("dnsmasq", LOCALEDIR); 96 textdomain("dnsmasq"); 97#endif 98 99 sigact.sa_handler = sig_handler; 100 sigact.sa_flags = 0; 101 sigemptyset(&sigact.sa_mask); 102 sigaction(SIGUSR1, &sigact, NULL); 103 sigaction(SIGUSR2, &sigact, NULL); 104 sigaction(SIGHUP, &sigact, NULL); 105 sigaction(SIGTERM, &sigact, NULL); 106 sigaction(SIGALRM, &sigact, NULL); 107 sigaction(SIGCHLD, &sigact, NULL); 108 109 /* ignore SIGPIPE */ 110 sigact.sa_handler = SIG_IGN; 111 sigaction(SIGPIPE, &sigact, NULL); 112 113 umask(022); /* known umask, create leases and pid files as 0644 */ 114 115 read_opts(argc, argv, compile_opts); 116 117 if (daemon->edns_pktsz < PACKETSZ) 118 daemon->edns_pktsz = PACKETSZ; 119 daemon->packet_buff_sz = daemon->edns_pktsz > DNSMASQ_PACKETSZ ? 120 daemon->edns_pktsz : DNSMASQ_PACKETSZ; 121 daemon->packet = safe_malloc(daemon->packet_buff_sz); 122 123#ifdef HAVE_DHCP 124 if (!daemon->lease_file) 125 { 126 if (daemon->dhcp) 127 daemon->lease_file = LEASEFILE; 128 } 129#endif 130 131 /* Close any file descriptors we inherited apart from std{in|out|err} */ 132 for (i = 0; i < max_fd; i++) 133 if (i != STDOUT_FILENO && i != STDERR_FILENO && i != STDIN_FILENO) 134 close(i); 135 136#ifdef HAVE_LINUX_NETWORK 137 netlink_init(); 138#elif !(defined(IP_RECVDSTADDR) && \ 139 defined(IP_RECVIF) && \ 140 defined(IP_SENDSRCADDR)) 141 if (!(daemon->options & OPT_NOWILD)) 142 { 143 bind_fallback = 1; 144 daemon->options |= OPT_NOWILD; 145 } 146#endif 147 148#ifndef HAVE_TFTP 149 if (daemon->options & OPT_TFTP) 150 die(_("TFTP server not available: set HAVE_TFTP in src/config.h"), NULL, EC_BADCONF); 151#endif 152 153#ifdef HAVE_SOLARIS_NETWORK 154 if (daemon->max_logs != 0) 155 die(_("asychronous logging is not available under Solaris"), NULL, EC_BADCONF); 156#endif 157 158 rand_init(); 159 160 now = dnsmasq_time(); 161 162#ifdef HAVE_DHCP 163 if (daemon->dhcp) 164 { 165 /* Note that order matters here, we must call lease_init before 166 creating any file descriptors which shouldn't be leaked 167 to the lease-script init process. */ 168 lease_init(now); 169 dhcp_init(); 170 } 171#endif 172 173 if (!enumerate_interfaces()) 174 die(_("failed to find list of interfaces: %s"), NULL, EC_MISC); 175 176 if (daemon->options & OPT_NOWILD) 177 { 178 daemon->listeners = create_bound_listeners(); 179 180 for (if_tmp = daemon->if_names; if_tmp; if_tmp = if_tmp->next) 181 if (if_tmp->name && !if_tmp->used) 182 die(_("unknown interface %s"), if_tmp->name, EC_BADNET); 183 184 for (if_tmp = daemon->if_addrs; if_tmp; if_tmp = if_tmp->next) 185 if (!if_tmp->used) 186 { 187 prettyprint_addr(&if_tmp->addr, daemon->namebuff); 188 die(_("no interface with address %s"), daemon->namebuff, EC_BADNET); 189 } 190 } 191 else if ((daemon->port != 0 || (daemon->options & OPT_TFTP)) && 192 !(daemon->listeners = create_wildcard_listeners())) 193 die(_("failed to create listening socket: %s"), NULL, EC_BADNET); 194 195 if (daemon->port != 0) 196 cache_init(); 197 198 if (daemon->options & OPT_DBUS) 199#ifdef HAVE_DBUS 200 { 201 char *err; 202 daemon->dbus = NULL; 203 daemon->watches = NULL; 204 if ((err = dbus_init())) 205 die(_("DBus error: %s"), err, EC_MISC); 206 } 207#else 208 die(_("DBus not available: set HAVE_DBUS in src/config.h"), NULL, EC_BADCONF); 209#endif 210 211 if (daemon->port != 0) 212 pre_allocate_sfds(); 213 214#if defined(HAVE_DHCP) && defined(HAVE_SCRIPT) 215 /* Note getpwnam returns static storage */ 216 if (daemon->dhcp && daemon->lease_change_command && daemon->scriptuser) 217 { 218 if ((ent_pw = getpwnam(daemon->scriptuser))) 219 { 220 script_uid = ent_pw->pw_uid; 221 script_gid = ent_pw->pw_gid; 222 } 223 else 224 baduser = daemon->scriptuser; 225 } 226#endif 227 228 if (daemon->username && !(ent_pw = getpwnam(daemon->username))) 229 baduser = daemon->username; 230 else if (daemon->groupname && !(gp = getgrnam(daemon->groupname))) 231 baduser = daemon->groupname; 232 233 if (baduser) 234 die(_("unknown user or group: %s"), baduser, EC_BADCONF); 235 236 /* implement group defaults, "dip" if available, or group associated with uid */ 237 if (!daemon->group_set && !gp) 238 { 239 if (!(gp = getgrnam(CHGRP)) && ent_pw) 240 gp = getgrgid(ent_pw->pw_gid); 241 242 /* for error message */ 243 if (gp) 244 daemon->groupname = gp->gr_name; 245 } 246 247#if defined(HAVE_LINUX_NETWORK) 248 /* determine capability API version here, while we can still 249 call safe_malloc */ 250 if (ent_pw && ent_pw->pw_uid != 0) 251 { 252 int capsize = 1; /* for header version 1 */ 253 hdr = safe_malloc(sizeof(*hdr)); 254 255 /* find version supported by kernel */ 256 memset(hdr, 0, sizeof(*hdr)); 257 capget(hdr, NULL); 258 259 if (hdr->version != LINUX_CAPABILITY_VERSION_1) 260 { 261 /* if unknown version, use largest supported version (3) */ 262 if (hdr->version != LINUX_CAPABILITY_VERSION_2) 263 hdr->version = LINUX_CAPABILITY_VERSION_3; 264 capsize = 2; 265 } 266 267 data = safe_malloc(sizeof(*data) * capsize); 268 memset(data, 0, sizeof(*data) * capsize); 269 } 270#endif 271 272 /* Use a pipe to carry signals and other events back to the event loop 273 in a race-free manner and another to carry errors to daemon-invoking process */ 274 safe_pipe(pipefd, 1); 275 276 piperead = pipefd[0]; 277 pipewrite = pipefd[1]; 278 /* prime the pipe to load stuff first time. */ 279 send_event(pipewrite, EVENT_RELOAD, 0); 280 281 err_pipe[1] = -1; 282 283 if (!(daemon->options & OPT_DEBUG)) 284 { 285#ifndef __ANDROID__ 286 int nullfd; 287#endif 288 289 /* The following code "daemonizes" the process. 290 See Stevens section 12.4 */ 291 292 if (chdir("/") != 0) 293 die(_("cannot chdir to filesystem root: %s"), NULL, EC_MISC); 294 295#ifndef NO_FORK 296 if (!(daemon->options & OPT_NO_FORK)) 297 { 298 pid_t pid; 299 300 /* pipe to carry errors back to original process. 301 When startup is complete we close this and the process terminates. */ 302 safe_pipe(err_pipe, 0); 303 304 if ((pid = fork()) == -1) 305 /* fd == -1 since we've not forked, never returns. */ 306 send_event(-1, EVENT_FORK_ERR, errno); 307 308 if (pid != 0) 309 { 310 struct event_desc ev; 311 312 /* close our copy of write-end */ 313 close(err_pipe[1]); 314 315 /* check for errors after the fork */ 316 if (read_write(err_pipe[0], (unsigned char *)&ev, sizeof(ev), 1)) 317 fatal_event(&ev); 318 319 _exit(EC_GOOD); 320 } 321 322 close(err_pipe[0]); 323 324 /* NO calls to die() from here on. */ 325 326 setsid(); 327 328 if ((pid = fork()) == -1) 329 send_event(err_pipe[1], EVENT_FORK_ERR, errno); 330 331 if (pid != 0) 332 _exit(0); 333 } 334#endif 335 336 /* write pidfile _after_ forking ! */ 337 if (daemon->runfile) 338 { 339 FILE *pidfile; 340 341 /* only complain if started as root */ 342 if ((pidfile = fopen(daemon->runfile, "w"))) 343 { 344 fprintf(pidfile, "%d\n", (int) getpid()); 345 fclose(pidfile); 346 } 347 else if (getuid() == 0) 348 { 349 send_event(err_pipe[1], EVENT_PIDFILE, errno); 350 _exit(0); 351 } 352 } 353 354#ifndef __ANDROID__ 355 /* open stdout etc to /dev/null */ 356 nullfd = open("/dev/null", O_RDWR); 357 dup2(nullfd, STDOUT_FILENO); 358 dup2(nullfd, STDERR_FILENO); 359 dup2(nullfd, STDIN_FILENO); 360 close(nullfd); 361#endif 362 } 363 364 log_err = log_start(ent_pw, err_pipe[1]); 365 366 /* if we are to run scripts, we need to fork a helper before dropping root. */ 367 daemon->helperfd = -1; 368#if defined(HAVE_DHCP) && defined(HAVE_SCRIPT) 369 if (daemon->dhcp && daemon->lease_change_command) 370 daemon->helperfd = create_helper(pipewrite, err_pipe[1], script_uid, script_gid, max_fd); 371#endif 372 373 if (!(daemon->options & OPT_DEBUG) && getuid() == 0) 374 { 375 int bad_capabilities = 0; 376 gid_t dummy; 377 378 /* remove all supplimentary groups */ 379 if (gp && 380 (setgroups(0, &dummy) == -1 || 381 setgid(gp->gr_gid) == -1)) 382 { 383 send_event(err_pipe[1], EVENT_GROUP_ERR, errno); 384 _exit(0); 385 } 386 387 if (ent_pw && ent_pw->pw_uid != 0) 388 { 389#if defined(HAVE_LINUX_NETWORK) 390 /* On linux, we keep CAP_NETADMIN (for ARP-injection) and 391 CAP_NET_RAW (for icmp) if we're doing dhcp */ 392 data->effective = data->permitted = data->inheritable = 393 (1 << CAP_NET_ADMIN) | (1 << CAP_NET_RAW) | (1 << CAP_SETUID); 394 395 /* Tell kernel to not clear capabilities when dropping root */ 396 if (capset(hdr, data) == -1 || prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) == -1) 397 bad_capabilities = errno; 398 399#elif defined(HAVE_SOLARIS_NETWORK) 400 /* http://developers.sun.com/solaris/articles/program_privileges.html */ 401 priv_set_t *priv_set; 402 403 if (!(priv_set = priv_str_to_set("basic", ",", NULL)) || 404 priv_addset(priv_set, PRIV_NET_ICMPACCESS) == -1 || 405 priv_addset(priv_set, PRIV_SYS_NET_CONFIG) == -1) 406 bad_capabilities = errno; 407 408 if (priv_set && bad_capabilities == 0) 409 { 410 priv_inverse(priv_set); 411 412 if (setppriv(PRIV_OFF, PRIV_LIMIT, priv_set) == -1) 413 bad_capabilities = errno; 414 } 415 416 if (priv_set) 417 priv_freeset(priv_set); 418 419#endif 420 421 if (bad_capabilities != 0) 422 { 423 send_event(err_pipe[1], EVENT_CAP_ERR, bad_capabilities); 424 _exit(0); 425 } 426 427 /* finally drop root */ 428 if (setuid(ent_pw->pw_uid) == -1) 429 { 430 send_event(err_pipe[1], EVENT_USER_ERR, errno); 431 _exit(0); 432 } 433 434#ifdef HAVE_LINUX_NETWORK 435 data->effective = data->permitted = 436 (1 << CAP_NET_ADMIN) | (1 << CAP_NET_RAW); 437 data->inheritable = 0; 438 439 /* lose the setuid and setgid capbilities */ 440 if (capset(hdr, data) == -1) 441 { 442 send_event(err_pipe[1], EVENT_CAP_ERR, errno); 443 _exit(0); 444 } 445#endif 446 447 } 448 } 449 450#ifdef HAVE_LINUX_NETWORK 451 if (daemon->options & OPT_DEBUG) 452 prctl(PR_SET_DUMPABLE, 1, 0, 0, 0); 453#endif 454 455 if (daemon->port == 0) 456 my_syslog(LOG_INFO, _("started, version %s DNS disabled"), VERSION); 457 else if (daemon->cachesize != 0) 458 my_syslog(LOG_INFO, _("started, version %s cachesize %d"), VERSION, daemon->cachesize); 459 else 460 my_syslog(LOG_INFO, _("started, version %s cache disabled"), VERSION); 461 462 my_syslog(LOG_INFO, _("compile time options: %s"), compile_opts); 463 464#ifdef HAVE_DBUS 465 if (daemon->options & OPT_DBUS) 466 { 467 if (daemon->dbus) 468 my_syslog(LOG_INFO, _("DBus support enabled: connected to system bus")); 469 else 470 my_syslog(LOG_INFO, _("DBus support enabled: bus connection pending")); 471 } 472#endif 473 474 if (log_err != 0) 475 my_syslog(LOG_WARNING, _("warning: failed to change owner of %s: %s"), 476 daemon->log_file, strerror(log_err)); 477 478 if (bind_fallback) 479 my_syslog(LOG_WARNING, _("setting --bind-interfaces option because of OS limitations")); 480 481 if (!(daemon->options & OPT_NOWILD)) 482 for (if_tmp = daemon->if_names; if_tmp; if_tmp = if_tmp->next) 483 if (if_tmp->name && !if_tmp->used) 484 my_syslog(LOG_WARNING, _("warning: interface %s does not currently exist"), if_tmp->name); 485 486 if (daemon->port != 0 && (daemon->options & OPT_NO_RESOLV)) 487 { 488 if (daemon->resolv_files && !daemon->resolv_files->is_default) 489 my_syslog(LOG_WARNING, _("warning: ignoring resolv-file flag because no-resolv is set")); 490 daemon->resolv_files = NULL; 491 if (!daemon->servers) 492 my_syslog(LOG_WARNING, _("warning: no upstream servers configured")); 493 } 494 495 if (daemon->max_logs != 0) 496 my_syslog(LOG_INFO, _("asynchronous logging enabled, queue limit is %d messages"), daemon->max_logs); 497 498#ifdef HAVE_DHCP 499 if (daemon->dhcp) 500 { 501 struct dhcp_context *dhcp_tmp; 502 503 for (dhcp_tmp = daemon->dhcp; dhcp_tmp; dhcp_tmp = dhcp_tmp->next) 504 { 505 prettyprint_time(daemon->dhcp_buff2, dhcp_tmp->lease_time); 506 strcpy(daemon->dhcp_buff, inet_ntoa(dhcp_tmp->start)); 507 my_syslog(MS_DHCP | LOG_INFO, 508 (dhcp_tmp->flags & CONTEXT_STATIC) ? 509 _("DHCP, static leases only on %.0s%s, lease time %s") : 510 (dhcp_tmp->flags & CONTEXT_PROXY) ? 511 _("DHCP, proxy on subnet %.0s%s%.0s") : 512 _("DHCP, IP range %s -- %s, lease time %s"), 513 daemon->dhcp_buff, inet_ntoa(dhcp_tmp->end), daemon->dhcp_buff2); 514 } 515 } 516#endif 517 518#ifdef HAVE_TFTP 519 if (daemon->options & OPT_TFTP) 520 { 521#ifdef FD_SETSIZE 522 if (FD_SETSIZE < (unsigned)max_fd) 523 max_fd = FD_SETSIZE; 524#endif 525 526 my_syslog(MS_TFTP | LOG_INFO, "TFTP %s%s %s", 527 daemon->tftp_prefix ? _("root is ") : _("enabled"), 528 daemon->tftp_prefix ? daemon->tftp_prefix: "", 529 daemon->options & OPT_TFTP_SECURE ? _("secure mode") : ""); 530 531 /* This is a guess, it assumes that for small limits, 532 disjoint files might be served, but for large limits, 533 a single file will be sent to may clients (the file only needs 534 one fd). */ 535 536 max_fd -= 30; /* use other than TFTP */ 537 538 if (max_fd < 0) 539 max_fd = 5; 540 else if (max_fd < 100) 541 max_fd = max_fd/2; 542 else 543 max_fd = max_fd - 20; 544 545 /* if we have to use a limited range of ports, 546 that will limit the number of transfers */ 547 if (daemon->start_tftp_port != 0 && 548 daemon->end_tftp_port - daemon->start_tftp_port + 1 < max_fd) 549 max_fd = daemon->end_tftp_port - daemon->start_tftp_port + 1; 550 551 if (daemon->tftp_max > max_fd) 552 { 553 daemon->tftp_max = max_fd; 554 my_syslog(MS_TFTP | LOG_WARNING, 555 _("restricting maximum simultaneous TFTP transfers to %d"), 556 daemon->tftp_max); 557 } 558 } 559#endif 560 561 /* finished start-up - release original process */ 562 if (err_pipe[1] != -1) 563 close(err_pipe[1]); 564 565 if (daemon->port != 0) 566 check_servers(); 567 568 pid = getpid(); 569 570 while (1) 571 { 572 int maxfd = -1; 573 struct timeval t, *tp = NULL; 574 fd_set rset, wset, eset; 575 576 FD_ZERO(&rset); 577 FD_ZERO(&wset); 578 FD_ZERO(&eset); 579 580 /* if we are out of resources, find how long we have to wait 581 for some to come free, we'll loop around then and restart 582 listening for queries */ 583 if ((t.tv_sec = set_dns_listeners(now, &rset, &maxfd)) != 0) 584 { 585 t.tv_usec = 0; 586 tp = &t; 587 } 588#ifdef __ANDROID__ 589 set_android_listeners(&rset, &maxfd); 590#endif 591 592 /* Whilst polling for the dbus, or doing a tftp transfer, wake every quarter second */ 593 if (daemon->tftp_trans || 594 ((daemon->options & OPT_DBUS) && !daemon->dbus)) 595 { 596 t.tv_sec = 0; 597 t.tv_usec = 250000; 598 tp = &t; 599 } 600 601#ifdef HAVE_DBUS 602 set_dbus_listeners(&maxfd, &rset, &wset, &eset); 603#endif 604 605#ifdef HAVE_DHCP 606 if (daemon->dhcp) 607 { 608 FD_SET(daemon->dhcpfd, &rset); 609 bump_maxfd(daemon->dhcpfd, &maxfd); 610 } 611#endif 612 613#ifdef HAVE_LINUX_NETWORK 614 FD_SET(daemon->netlinkfd, &rset); 615 bump_maxfd(daemon->netlinkfd, &maxfd); 616#endif 617 618 FD_SET(piperead, &rset); 619 bump_maxfd(piperead, &maxfd); 620 621#ifdef HAVE_DHCP 622# ifdef HAVE_SCRIPT 623 while (helper_buf_empty() && do_script_run(now)); 624 625 if (!helper_buf_empty()) 626 { 627 FD_SET(daemon->helperfd, &wset); 628 bump_maxfd(daemon->helperfd, &maxfd); 629 } 630# else 631 /* need this for other side-effects */ 632 while (do_script_run(now)); 633# endif 634#endif 635 636 /* must do this just before select(), when we know no 637 more calls to my_syslog() can occur */ 638 set_log_writer(&wset, &maxfd); 639 640 if (select(maxfd+1, &rset, &wset, &eset, tp) < 0) 641 { 642 /* otherwise undefined after error */ 643 FD_ZERO(&rset); FD_ZERO(&wset); FD_ZERO(&eset); 644 } 645 646 now = dnsmasq_time(); 647 648 check_log_writer(&wset); 649 650 /* Check for changes to resolv files once per second max. */ 651 /* Don't go silent for long periods if the clock goes backwards. */ 652 if (daemon->last_resolv == 0 || 653 difftime(now, daemon->last_resolv) > 1.0 || 654 difftime(now, daemon->last_resolv) < -1.0) 655 { 656 daemon->last_resolv = now; 657 658 if (daemon->port != 0 && !(daemon->options & OPT_NO_POLL)) 659 poll_resolv(); 660 } 661 662 if (FD_ISSET(piperead, &rset)) 663 async_event(piperead, now); 664 665#ifdef HAVE_LINUX_NETWORK 666 if (FD_ISSET(daemon->netlinkfd, &rset)) 667 netlink_multicast(); 668#endif 669 670#ifdef HAVE_DBUS 671 /* if we didn't create a DBus connection, retry now. */ 672 if ((daemon->options & OPT_DBUS) && !daemon->dbus) 673 { 674 char *err; 675 if ((err = dbus_init())) 676 my_syslog(LOG_WARNING, _("DBus error: %s"), err); 677 if (daemon->dbus) 678 my_syslog(LOG_INFO, _("connected to system DBus")); 679 } 680 check_dbus_listeners(&rset, &wset, &eset); 681#endif 682 683#ifdef __ANDROID__ 684 check_android_listeners(&rset); 685#endif 686 687 check_dns_listeners(&rset, now); 688 689#ifdef HAVE_TFTP 690 check_tftp_listeners(&rset, now); 691#endif 692 693#ifdef HAVE_DHCP 694 if (daemon->dhcp && FD_ISSET(daemon->dhcpfd, &rset)) 695 dhcp_packet(now); 696 697# ifdef HAVE_SCRIPT 698 if (daemon->helperfd != -1 && FD_ISSET(daemon->helperfd, &wset)) 699 helper_write(); 700# endif 701#endif 702 703 } 704} 705 706static void sig_handler(int sig) 707{ 708 if (pid == 0) 709 { 710 /* ignore anything other than TERM during startup 711 and in helper proc. (helper ignore TERM too) */ 712 if (sig == SIGTERM) 713 exit(EC_MISC); 714 } 715 else if (pid != getpid()) 716 { 717 /* alarm is used to kill TCP children after a fixed time. */ 718 if (sig == SIGALRM) 719 _exit(0); 720 } 721 else 722 { 723 /* master process */ 724 int event, errsave = errno; 725 726 if (sig == SIGHUP) 727 event = EVENT_RELOAD; 728 else if (sig == SIGCHLD) 729 event = EVENT_CHILD; 730 else if (sig == SIGALRM) 731 event = EVENT_ALARM; 732 else if (sig == SIGTERM) 733 event = EVENT_TERM; 734 else if (sig == SIGUSR1) 735 event = EVENT_DUMP; 736 else if (sig == SIGUSR2) 737 event = EVENT_REOPEN; 738 else 739 return; 740 741 send_event(pipewrite, event, 0); 742 errno = errsave; 743 } 744} 745 746void send_event(int fd, int event, int data) 747{ 748 struct event_desc ev; 749 750 ev.event = event; 751 ev.data = data; 752 753 /* error pipe, debug mode. */ 754 if (fd == -1) 755 fatal_event(&ev); 756 else 757 /* pipe is non-blocking and struct event_desc is smaller than 758 PIPE_BUF, so this either fails or writes everything */ 759 while (write(fd, &ev, sizeof(ev)) == -1 && errno == EINTR); 760} 761 762static void fatal_event(struct event_desc *ev) 763{ 764 errno = ev->data; 765 766 switch (ev->event) 767 { 768 case EVENT_DIE: 769 exit(0); 770 771 case EVENT_FORK_ERR: 772 die(_("cannot fork into background: %s"), NULL, EC_MISC); 773 774 case EVENT_PIPE_ERR: 775 die(_("failed to create helper: %s"), NULL, EC_MISC); 776 777 case EVENT_CAP_ERR: 778 die(_("setting capabilities failed: %s"), NULL, EC_MISC); 779 780 case EVENT_USER_ERR: 781 case EVENT_HUSER_ERR: 782 die(_("failed to change user-id to %s: %s"), 783 ev->event == EVENT_USER_ERR ? daemon->username : daemon->scriptuser, 784 EC_MISC); 785 786 case EVENT_GROUP_ERR: 787 die(_("failed to change group-id to %s: %s"), daemon->groupname, EC_MISC); 788 789 case EVENT_PIDFILE: 790 die(_("failed to open pidfile %s: %s"), daemon->runfile, EC_FILE); 791 792 case EVENT_LOG_ERR: 793 die(_("cannot open %s: %s"), daemon->log_file ? daemon->log_file : "log", EC_FILE); 794 } 795} 796 797static void async_event(int pipe, time_t now) 798{ 799 pid_t p; 800 struct event_desc ev; 801 int i; 802 803 if (read_write(pipe, (unsigned char *)&ev, sizeof(ev), 1)) 804 switch (ev.event) 805 { 806 case EVENT_RELOAD: 807 clear_cache_and_reload(now); 808 if (daemon->port != 0 && daemon->resolv_files && (daemon->options & OPT_NO_POLL)) 809 { 810 reload_servers(daemon->resolv_files->name); 811 check_servers(); 812 } 813#ifdef HAVE_DHCP 814 rerun_scripts(); 815#endif 816 break; 817 818 case EVENT_DUMP: 819 if (daemon->port != 0) 820 dump_cache(now); 821 break; 822 823 case EVENT_ALARM: 824#ifdef HAVE_DHCP 825 if (daemon->dhcp) 826 { 827 lease_prune(NULL, now); 828 lease_update_file(now); 829 } 830#endif 831 break; 832 833 case EVENT_CHILD: 834 /* See Stevens 5.10 */ 835 while ((p = waitpid(-1, NULL, WNOHANG)) != 0) 836 if (p == -1) 837 { 838 if (errno != EINTR) 839 break; 840 } 841 else 842 for (i = 0 ; i < MAX_PROCS; i++) 843 if (daemon->tcp_pids[i] == p) 844 daemon->tcp_pids[i] = 0; 845 break; 846 847 case EVENT_KILLED: 848 my_syslog(LOG_WARNING, _("child process killed by signal %d"), ev.data); 849 break; 850 851 case EVENT_EXITED: 852 my_syslog(LOG_WARNING, _("child process exited with status %d"), ev.data); 853 break; 854 855 case EVENT_EXEC_ERR: 856 my_syslog(LOG_ERR, _("failed to execute %s: %s"), 857 daemon->lease_change_command, strerror(ev.data)); 858 break; 859 860 /* necessary for fatal errors in helper */ 861 case EVENT_HUSER_ERR: 862 case EVENT_DIE: 863 fatal_event(&ev); 864 break; 865 866 case EVENT_REOPEN: 867 /* Note: this may leave TCP-handling processes with the old file still open. 868 Since any such process will die in CHILD_LIFETIME or probably much sooner, 869 we leave them logging to the old file. */ 870 if (daemon->log_file != NULL) 871 log_reopen(daemon->log_file); 872 break; 873 874 case EVENT_TERM: 875 /* Knock all our children on the head. */ 876 for (i = 0; i < MAX_PROCS; i++) 877 if (daemon->tcp_pids[i] != 0) 878 kill(daemon->tcp_pids[i], SIGALRM); 879 880#if defined(HAVE_DHCP) && defined(HAVE_SCRIPT) 881 /* handle pending lease transitions */ 882 if (daemon->helperfd != -1) 883 { 884 /* block in writes until all done */ 885 if ((i = fcntl(daemon->helperfd, F_GETFL)) != -1) 886 fcntl(daemon->helperfd, F_SETFL, i & ~O_NONBLOCK); 887 do { 888 helper_write(); 889 } while (!helper_buf_empty() || do_script_run(now)); 890 close(daemon->helperfd); 891 } 892#endif 893 894 if (daemon->lease_stream) 895 fclose(daemon->lease_stream); 896 897 if (daemon->runfile) 898 unlink(daemon->runfile); 899 900 my_syslog(LOG_INFO, _("exiting on receipt of SIGTERM")); 901 flush_log(); 902 exit(EC_GOOD); 903 } 904} 905 906static void poll_resolv() 907{ 908 struct resolvc *res, *latest; 909 struct stat statbuf; 910 time_t last_change = 0; 911 /* There may be more than one possible file. 912 Go through and find the one which changed _last_. 913 Warn of any which can't be read. */ 914 for (latest = NULL, res = daemon->resolv_files; res; res = res->next) 915 if (stat(res->name, &statbuf) == -1) 916 { 917 if (!res->logged) 918 my_syslog(LOG_WARNING, _("failed to access %s: %s"), res->name, strerror(errno)); 919 res->logged = 1; 920 } 921 else 922 { 923 res->logged = 0; 924 if (statbuf.st_mtime != res->mtime) 925 { 926 res->mtime = statbuf.st_mtime; 927 if (difftime(statbuf.st_mtime, last_change) > 0.0) 928 { 929 last_change = statbuf.st_mtime; 930 latest = res; 931 } 932 } 933 } 934 935 if (latest) 936 { 937 static int warned = 0; 938 if (reload_servers(latest->name)) 939 { 940 my_syslog(LOG_INFO, _("reading %s"), latest->name); 941 warned = 0; 942 check_servers(); 943 if (daemon->options & OPT_RELOAD) 944 cache_reload(); 945 } 946 else 947 { 948 latest->mtime = 0; 949 if (!warned) 950 { 951 my_syslog(LOG_WARNING, _("no servers found in %s, will retry"), latest->name); 952 warned = 1; 953 } 954 } 955 } 956} 957 958void clear_cache_and_reload(time_t now) 959{ 960 if (daemon->port != 0) 961 cache_reload(); 962 963#ifdef HAVE_DHCP 964 if (daemon->dhcp) 965 { 966 if (daemon->options & OPT_ETHERS) 967 dhcp_read_ethers(); 968 reread_dhcp(); 969 dhcp_update_configs(daemon->dhcp_conf); 970 check_dhcp_hosts(0); 971 lease_update_from_configs(); 972 lease_update_file(now); 973 lease_update_dns(); 974 } 975#endif 976} 977 978#ifdef __ANDROID__ 979 980static int set_android_listeners(fd_set *set, int *maxfdp) { 981 FD_SET(STDIN_FILENO, set); 982 bump_maxfd(STDIN_FILENO, maxfdp); 983 return 0; 984} 985 986static int check_android_listeners(fd_set *set) { 987 if (FD_ISSET(STDIN_FILENO, set)) { 988 char buffer[1024]; 989 int rc; 990 991 if ((rc = read(STDIN_FILENO, buffer, sizeof(buffer) -1)) < 0) { 992 my_syslog(LOG_ERR, _("Error reading from stdin (%s)"), strerror(errno)); 993 return -1; 994 } 995 buffer[rc] = '\0'; 996 char *next = buffer; 997 char *cmd; 998 999 if (!(cmd = strsep(&next, ":"))) { 1000 my_syslog(LOG_ERR, _("Malformatted msg '%s'"), buffer); 1001 return -1; 1002 } 1003 1004 if (!strcmp(buffer, "update_dns")) { 1005 set_servers(&buffer[11]); 1006 check_servers(); 1007 } else { 1008 my_syslog(LOG_ERR, _("Unknown cmd '%s'"), cmd); 1009 return -1; 1010 } 1011 } 1012 return 0; 1013} 1014#endif 1015 1016static int set_dns_listeners(time_t now, fd_set *set, int *maxfdp) 1017{ 1018 struct serverfd *serverfdp; 1019 struct listener *listener; 1020 int wait = 0, i; 1021 1022#ifdef HAVE_TFTP 1023 int tftp = 0; 1024 struct tftp_transfer *transfer; 1025 for (transfer = daemon->tftp_trans; transfer; transfer = transfer->next) 1026 { 1027 tftp++; 1028 FD_SET(transfer->sockfd, set); 1029 bump_maxfd(transfer->sockfd, maxfdp); 1030 } 1031#endif 1032 1033 /* will we be able to get memory? */ 1034 if (daemon->port != 0) 1035 get_new_frec(now, &wait); 1036 1037 for (serverfdp = daemon->sfds; serverfdp; serverfdp = serverfdp->next) 1038 { 1039 FD_SET(serverfdp->fd, set); 1040 bump_maxfd(serverfdp->fd, maxfdp); 1041 } 1042 1043 if (daemon->port != 0 && !daemon->osport) 1044 for (i = 0; i < RANDOM_SOCKS; i++) 1045 if (daemon->randomsocks[i].refcount != 0) 1046 { 1047 FD_SET(daemon->randomsocks[i].fd, set); 1048 bump_maxfd(daemon->randomsocks[i].fd, maxfdp); 1049 } 1050 1051 for (listener = daemon->listeners; listener; listener = listener->next) 1052 { 1053 /* only listen for queries if we have resources */ 1054 if (listener->fd != -1 && wait == 0) 1055 { 1056 FD_SET(listener->fd, set); 1057 bump_maxfd(listener->fd, maxfdp); 1058 } 1059 1060 /* death of a child goes through the select loop, so 1061 we don't need to explicitly arrange to wake up here */ 1062 if (listener->tcpfd != -1) 1063 for (i = 0; i < MAX_PROCS; i++) 1064 if (daemon->tcp_pids[i] == 0) 1065 { 1066 FD_SET(listener->tcpfd, set); 1067 bump_maxfd(listener->tcpfd, maxfdp); 1068 break; 1069 } 1070 1071#ifdef HAVE_TFTP 1072 if (tftp <= daemon->tftp_max && listener->tftpfd != -1) 1073 { 1074 FD_SET(listener->tftpfd, set); 1075 bump_maxfd(listener->tftpfd, maxfdp); 1076 } 1077#endif 1078 1079 } 1080 1081 return wait; 1082} 1083 1084static void check_dns_listeners(fd_set *set, time_t now) 1085{ 1086 struct serverfd *serverfdp; 1087 struct listener *listener; 1088 int i; 1089 1090 for (serverfdp = daemon->sfds; serverfdp; serverfdp = serverfdp->next) 1091 if (FD_ISSET(serverfdp->fd, set)) 1092 reply_query(serverfdp->fd, serverfdp->source_addr.sa.sa_family, now); 1093 1094 if (daemon->port != 0 && !daemon->osport) 1095 for (i = 0; i < RANDOM_SOCKS; i++) 1096 if (daemon->randomsocks[i].refcount != 0 && 1097 FD_ISSET(daemon->randomsocks[i].fd, set)) 1098 reply_query(daemon->randomsocks[i].fd, daemon->randomsocks[i].family, now); 1099 1100 for (listener = daemon->listeners; listener; listener = listener->next) 1101 { 1102 if (listener->fd != -1 && FD_ISSET(listener->fd, set)) 1103 receive_query(listener, now); 1104 1105#ifdef HAVE_TFTP 1106 if (listener->tftpfd != -1 && FD_ISSET(listener->tftpfd, set)) 1107 tftp_request(listener, now); 1108#endif 1109 1110 if (listener->tcpfd != -1 && FD_ISSET(listener->tcpfd, set)) 1111 { 1112 int confd; 1113 struct irec *iface = NULL; 1114 pid_t p; 1115 1116 while((confd = accept(listener->tcpfd, NULL, NULL)) == -1 && errno == EINTR); 1117 1118 if (confd == -1) 1119 continue; 1120 1121 if (daemon->options & OPT_NOWILD) 1122 iface = listener->iface; 1123 else 1124 { 1125 union mysockaddr tcp_addr; 1126 socklen_t tcp_len = sizeof(union mysockaddr); 1127 /* Check for allowed interfaces when binding the wildcard address: 1128 we do this by looking for an interface with the same address as 1129 the local address of the TCP connection, then looking to see if that's 1130 an allowed interface. As a side effect, we get the netmask of the 1131 interface too, for localisation. */ 1132 1133 /* interface may be new since startup */ 1134 if (enumerate_interfaces() && 1135 getsockname(confd, (struct sockaddr *)&tcp_addr, &tcp_len) != -1) 1136 for (iface = daemon->interfaces; iface; iface = iface->next) 1137 if (sockaddr_isequal(&iface->addr, &tcp_addr)) 1138 break; 1139 } 1140 1141 if (!iface) 1142 { 1143 shutdown(confd, SHUT_RDWR); 1144 close(confd); 1145 } 1146#ifndef NO_FORK 1147 else if (!(daemon->options & OPT_DEBUG) && (p = fork()) != 0) 1148 { 1149 if (p != -1) 1150 { 1151 int i; 1152 for (i = 0; i < MAX_PROCS; i++) 1153 if (daemon->tcp_pids[i] == 0) 1154 { 1155 daemon->tcp_pids[i] = p; 1156 break; 1157 } 1158 } 1159 close(confd); 1160 } 1161#endif 1162 else 1163 { 1164 unsigned char *buff; 1165 struct server *s; 1166 int flags; 1167 struct in_addr dst_addr_4; 1168 1169 dst_addr_4.s_addr = 0; 1170 1171 /* Arrange for SIGALARM after CHILD_LIFETIME seconds to 1172 terminate the process. */ 1173 if (!(daemon->options & OPT_DEBUG)) 1174 alarm(CHILD_LIFETIME); 1175 1176 /* start with no upstream connections. */ 1177 for (s = daemon->servers; s; s = s->next) 1178 s->tcpfd = -1; 1179 1180 /* The connected socket inherits non-blocking 1181 attribute from the listening socket. 1182 Reset that here. */ 1183 if ((flags = fcntl(confd, F_GETFL, 0)) != -1) 1184 fcntl(confd, F_SETFL, flags & ~O_NONBLOCK); 1185 1186 if (listener->family == AF_INET) 1187 dst_addr_4 = iface->addr.in.sin_addr; 1188 1189 buff = tcp_request(confd, now, dst_addr_4, iface->netmask); 1190 1191 shutdown(confd, SHUT_RDWR); 1192 close(confd); 1193 1194 if (buff) 1195 free(buff); 1196 1197 for (s = daemon->servers; s; s = s->next) 1198 if (s->tcpfd != -1) 1199 { 1200 shutdown(s->tcpfd, SHUT_RDWR); 1201 close(s->tcpfd); 1202 } 1203#ifndef NO_FORK 1204 if (!(daemon->options & OPT_DEBUG)) 1205 { 1206 flush_log(); 1207 _exit(0); 1208 } 1209#endif 1210 } 1211 } 1212 } 1213} 1214 1215#ifdef HAVE_DHCP 1216int make_icmp_sock(void) 1217{ 1218 int fd; 1219 int zeroopt = 0; 1220 1221 if ((fd = socket (AF_INET, SOCK_RAW, IPPROTO_ICMP)) != -1) 1222 { 1223 if (!fix_fd(fd) || 1224 setsockopt(fd, SOL_SOCKET, SO_DONTROUTE, &zeroopt, sizeof(zeroopt)) == -1) 1225 { 1226 close(fd); 1227 fd = -1; 1228 } 1229 } 1230 1231 return fd; 1232} 1233 1234int icmp_ping(struct in_addr addr) 1235{ 1236 /* Try and get an ICMP echo from a machine. */ 1237 1238 /* Note that whilst in the three second wait, we check for 1239 (and service) events on the DNS and TFTP sockets, (so doing that 1240 better not use any resources our caller has in use...) 1241 but we remain deaf to signals or further DHCP packets. */ 1242 1243 int fd; 1244 struct sockaddr_in saddr; 1245 struct { 1246 struct ip ip; 1247 struct icmp icmp; 1248 } packet; 1249 unsigned short id = rand16(); 1250 unsigned int i, j; 1251 int gotreply = 0; 1252 time_t start, now; 1253 1254#if defined(HAVE_LINUX_NETWORK) || defined (HAVE_SOLARIS_NETWORK) 1255 if ((fd = make_icmp_sock()) == -1) 1256 return 0; 1257#else 1258 int opt = 2000; 1259 fd = daemon->dhcp_icmp_fd; 1260 setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &opt, sizeof(opt)); 1261#endif 1262 1263 saddr.sin_family = AF_INET; 1264 saddr.sin_port = 0; 1265 saddr.sin_addr = addr; 1266#ifdef HAVE_SOCKADDR_SA_LEN 1267 saddr.sin_len = sizeof(struct sockaddr_in); 1268#endif 1269 1270 memset(&packet.icmp, 0, sizeof(packet.icmp)); 1271 packet.icmp.icmp_type = ICMP_ECHO; 1272 packet.icmp.icmp_id = id; 1273 for (j = 0, i = 0; i < sizeof(struct icmp) / 2; i++) 1274 j += ((u16 *)&packet.icmp)[i]; 1275 while (j>>16) 1276 j = (j & 0xffff) + (j >> 16); 1277 packet.icmp.icmp_cksum = (j == 0xffff) ? j : ~j; 1278 1279 while (sendto(fd, (char *)&packet.icmp, sizeof(struct icmp), 0, 1280 (struct sockaddr *)&saddr, sizeof(saddr)) == -1 && 1281 retry_send()); 1282 1283 for (now = start = dnsmasq_time(); 1284 difftime(now, start) < (float)PING_WAIT;) 1285 { 1286 struct timeval tv; 1287 fd_set rset, wset; 1288 struct sockaddr_in faddr; 1289 int maxfd = fd; 1290 socklen_t len = sizeof(faddr); 1291 1292 tv.tv_usec = 250000; 1293 tv.tv_sec = 0; 1294 1295 FD_ZERO(&rset); 1296 FD_ZERO(&wset); 1297 FD_SET(fd, &rset); 1298 set_dns_listeners(now, &rset, &maxfd); 1299 set_log_writer(&wset, &maxfd); 1300 1301 if (select(maxfd+1, &rset, &wset, NULL, &tv) < 0) 1302 { 1303 FD_ZERO(&rset); 1304 FD_ZERO(&wset); 1305 } 1306 1307 now = dnsmasq_time(); 1308 1309 check_log_writer(&wset); 1310 check_dns_listeners(&rset, now); 1311 1312#ifdef HAVE_TFTP 1313 check_tftp_listeners(&rset, now); 1314#endif 1315 1316 if (FD_ISSET(fd, &rset) && 1317 recvfrom(fd, &packet, sizeof(packet), 0, 1318 (struct sockaddr *)&faddr, &len) == sizeof(packet) && 1319 saddr.sin_addr.s_addr == faddr.sin_addr.s_addr && 1320 packet.icmp.icmp_type == ICMP_ECHOREPLY && 1321 packet.icmp.icmp_seq == 0 && 1322 packet.icmp.icmp_id == id) 1323 { 1324 gotreply = 1; 1325 break; 1326 } 1327 } 1328 1329#if defined(HAVE_LINUX_NETWORK) || defined(HAVE_SOLARIS_NETWORK) 1330 close(fd); 1331#else 1332 opt = 1; 1333 setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &opt, sizeof(opt)); 1334#endif 1335 1336 return gotreply; 1337} 1338#endif 1339 1340 1341