1/* $Id$ */ 2 3/*** 4 This file is part of avahi. 5 6 avahi is free software; you can redistribute it and/or modify it 7 under the terms of the GNU Lesser General Public License as 8 published by the Free Software Foundation; either version 2.1 of the 9 License, or (at your option) any later version. 10 11 avahi is distributed in the hope that it will be useful, but WITHOUT 12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General 14 Public License for more details. 15 16 You should have received a copy of the GNU Lesser General Public 17 License along with avahi; if not, write to the Free Software 18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 19 USA. 20***/ 21 22#ifdef HAVE_CONFIG_H 23#include <config.h> 24#endif 25 26#include <fcntl.h> 27#include <unistd.h> 28#include <sys/select.h> 29#include <sys/socket.h> 30#include <sys/un.h> 31#include <errno.h> 32#include <string.h> 33#include <stdio.h> 34#include <sys/ioctl.h> 35#include <net/if.h> 36#include <signal.h> 37#include <sys/wait.h> 38#include <getopt.h> 39#include <assert.h> 40#include <inttypes.h> 41#include <stdlib.h> 42 43#include <avahi-common/llist.h> 44#include <avahi-common/malloc.h> 45#include <avahi-common/address.h> 46 47#include <libdaemon/dfork.h> 48#include <libdaemon/dsignal.h> 49#include <libdaemon/dlog.h> 50#include <libdaemon/dpid.h> 51#include <libdaemon/dexec.h> 52 53#define BROWSE_DNS_SERVERS "BROWSE-DNS-SERVERS\n" 54 55#define ENV_INTERFACE_DNS_SERVERS "AVAHI_INTERFACE_DNS_SERVERS" 56#define ENV_DNS_SERVERS "AVAHI_DNS_SERVERS" 57#define ENV_INTERFACE "AVAHI_INTERFACE" 58 59static enum { 60 ACKWAIT, 61 BROWSING 62} state = ACKWAIT; 63 64static enum { 65 DAEMON_RUN, 66 DAEMON_KILL, 67 DAEMON_REFRESH, 68 DAEMON_VERSION, 69 DAEMON_HELP, 70 DAEMON_CHECK 71} command = DAEMON_RUN; 72 73static int quit = 0; 74static int daemonize = 0; 75 76#if !HAVE_DECL_ENVIRON 77extern char **environ; 78#endif 79 80typedef struct DNSServerInfo DNSServerInfo; 81 82struct DNSServerInfo { 83 AvahiIfIndex interface; 84 AvahiProtocol protocol; 85 char *address; 86 AVAHI_LLIST_FIELDS(DNSServerInfo, servers); 87}; 88 89static AVAHI_LLIST_HEAD(DNSServerInfo, servers); 90 91static void server_info_free(DNSServerInfo *i) { 92 assert(i); 93 94 avahi_free(i->address); 95 96 AVAHI_LLIST_REMOVE(DNSServerInfo, servers, servers, i); 97 avahi_free(i); 98} 99 100static DNSServerInfo* get_server_info(AvahiIfIndex interface, AvahiProtocol protocol, const char *address) { 101 DNSServerInfo *i; 102 assert(address); 103 104 for (i = servers; i; i = i->servers_next) 105 if (i->interface == interface && 106 i->protocol == protocol && 107 strcmp(i->address, address) == 0) 108 return i; 109 110 return NULL; 111} 112 113static DNSServerInfo* new_server_info(AvahiIfIndex interface, AvahiProtocol protocol, const char *address) { 114 DNSServerInfo *i; 115 116 assert(address); 117 118 i = avahi_new(DNSServerInfo, 1); 119 i->interface = interface; 120 i->protocol = protocol; 121 i->address = avahi_strdup(address); 122 123 AVAHI_LLIST_PREPEND(DNSServerInfo, servers, servers, i); 124 125 return i; 126} 127 128static int set_cloexec(int fd) { 129 int n; 130 131 assert(fd >= 0); 132 133 if ((n = fcntl(fd, F_GETFD)) < 0) 134 return -1; 135 136 if (n & FD_CLOEXEC) 137 return 0; 138 139 return fcntl(fd, F_SETFD, n|FD_CLOEXEC); 140} 141 142static int open_socket(void) { 143 int fd = -1; 144 struct sockaddr_un sa; 145 146 if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) { 147 daemon_log(LOG_ERR, "socket(): %s", strerror(errno)); 148 goto fail; 149 } 150 151 if (set_cloexec(fd) < 0) { 152 daemon_log(LOG_ERR, "fcntl(): %s", strerror(errno)); 153 goto fail; 154 } 155 156 memset(&sa, 0, sizeof(sa)); 157 sa.sun_family = AF_UNIX; 158 strncpy(sa.sun_path, AVAHI_SOCKET, sizeof(sa.sun_path)-1); 159 sa.sun_path[sizeof(sa.sun_path)-1] = 0; 160 161 if (connect(fd, (struct sockaddr*) &sa, sizeof(sa)) < 0) { 162 daemon_log(LOG_ERR, "connect(): %s", strerror(errno)); 163 daemon_log(LOG_INFO, "Failed to connect to the daemon. This probably means that you"); 164 daemon_log(LOG_INFO, "didn't start avahi-daemon before avahi-dnsconfd."); 165 goto fail; 166 } 167 168 return fd; 169 170fail: 171 if (fd >= 0) 172 close(fd); 173 174 return -1; 175} 176 177static ssize_t loop_write(int fd, const void*data, size_t size) { 178 179 ssize_t ret = 0; 180 assert(fd >= 0 && data && size); 181 182 while (size > 0) { 183 ssize_t r; 184 185 if ((r = write(fd, data, size)) < 0) 186 return r; 187 188 if (r == 0) 189 break; 190 191 ret += r; 192 data = (const uint8_t*) data + r; 193 size -= r; 194 } 195 196 return ret; 197} 198 199static char *concat_dns_servers(AvahiIfIndex interface) { 200 DNSServerInfo *i; 201 char *r = NULL; 202 203 for (i = servers; i; i = i->servers_next) 204 if (i->interface == interface || interface <= 0) { 205 DNSServerInfo *j; 206 char *t; 207 208 /* Filter out double entries */ 209 for (j = servers; j != i; j = j->servers_next) 210 if (j->interface == interface || interface <= 0) 211 if (strcmp(i->address, j->address) == 0) 212 break; 213 214 if (j != i) 215 continue; 216 217 if (!r) 218 t = avahi_strdup(i->address); 219 else 220 t = avahi_strdup_printf("%s %s", r, i->address); 221 222 avahi_free(r); 223 r = t; 224 } 225 226 return r; 227} 228 229static void set_env(const char *name, const char *value) { 230 char **e; 231 size_t l; 232 233 assert(name); 234 assert(value); 235 236 l = strlen(name); 237 238 for (e = environ; *e; e++) { 239 /* Search for the variable */ 240 if (strlen(*e) < l+1) 241 continue; 242 243 if (strncmp(*e, name, l) != 0 || (*e)[l] != '=') 244 continue; 245 246 /* We simply free the record, sicne we know that we created it previously */ 247 avahi_free(*e); 248 *e = avahi_strdup_printf("%s=%s", name, value); 249 return; 250 } 251 252 assert(0); 253} 254 255static void run_script(int new, AvahiIfIndex interface, AvahiProtocol protocol, const char *address) { 256 char *p; 257 int ret; 258 char ia[16], pa[16]; 259 char name[IF_NAMESIZE]; 260 261 assert(interface > 0); 262 263 if (!if_indextoname(interface, name)) 264 return; 265 266 p = concat_dns_servers(interface); 267 set_env(ENV_INTERFACE_DNS_SERVERS, p ? p : ""); 268 avahi_free(p); 269 270 p = concat_dns_servers(-1); 271 set_env(ENV_DNS_SERVERS, p ? p : ""); 272 avahi_free(p); 273 274 set_env(ENV_INTERFACE, name); 275 276 snprintf(ia, sizeof(ia), "%i", (int) interface); 277 snprintf(pa, sizeof(pa), "%i", (int) protocol); 278 279 if (daemon_exec("/", &ret, AVAHI_DNSCONF_SCRIPT, AVAHI_DNSCONF_SCRIPT, new ? "+" : "-", address, ia, pa, avahi_proto_to_string(protocol), NULL) < 0) 280 daemon_log(LOG_WARNING, "Failed to run script"); 281 else if (ret != 0) 282 daemon_log(LOG_WARNING, "Script returned with non-zero exit code %i", ret); 283} 284 285static int new_line(const char *l) { 286 assert(l); 287 288 if (state == ACKWAIT) { 289 if (*l != '+') { 290 daemon_log(LOG_ERR, "Avahi command failed: %s", l); 291 return -1; 292 } 293 294 daemon_log(LOG_INFO, "Successfully connected to Avahi daemon."); 295 state = BROWSING; 296 } else { 297 AvahiIfIndex interface; 298 AvahiProtocol protocol; 299 int i_interface, i_protocol, port; 300 char a[AVAHI_ADDRESS_STR_MAX]; 301 302 assert(state == BROWSING); 303 304 if (*l != '<' && *l != '>') { 305 daemon_log(LOG_ERR, "Avahi sent us an invalid browsing line: %s", l); 306 return -1; 307 } 308 309 if (sscanf(l+1, "%i %i %39s %i", &i_interface, &i_protocol, a, &port) != 4) { 310 daemon_log(LOG_ERR, "Failed to parse browsing line: %s", l); 311 return -1; 312 } 313 314 interface = (AvahiIfIndex) i_interface; 315 protocol = (AvahiProtocol) i_protocol; 316 317 if (*l == '>') { 318 if (port != 53) 319 daemon_log(LOG_WARNING, "DNS server with port address != 53 found, ignoring"); 320 else { 321 daemon_log(LOG_INFO, "New DNS Server %s (interface: %i.%s)", a, interface, avahi_proto_to_string(protocol)); 322 new_server_info(interface, protocol, a); 323 run_script(1, interface, protocol, a); 324 } 325 } else { 326 DNSServerInfo *i; 327 328 if (port == 53) 329 if ((i = get_server_info(interface, protocol, a))) { 330 daemon_log(LOG_INFO, "DNS Server %s removed (interface: %i.%s)", a, interface, avahi_proto_to_string(protocol)); 331 server_info_free(i); 332 run_script(0, interface, protocol, a); 333 } 334 } 335 336 } 337 338 return 0; 339} 340 341static int do_connect(void) { 342 int fd = -1; 343 344 if ((fd = open_socket()) < 0) 345 goto fail; 346 347 if (loop_write(fd, BROWSE_DNS_SERVERS, sizeof(BROWSE_DNS_SERVERS)-1) < 0) { 348 daemon_log(LOG_ERR, "write(): %s", strerror(errno)); 349 goto fail; 350 } 351 352 state = ACKWAIT; 353 return fd; 354 355fail: 356 if (fd >= 0) 357 close(fd); 358 359 return -1; 360} 361 362static void free_dns_server_info_list(void) { 363 while (servers) { 364 AvahiIfIndex interface = servers->interface; 365 AvahiProtocol protocol = servers->protocol; 366 char *address = avahi_strdup(servers->address); 367 server_info_free(servers); 368 369 run_script(0, interface, protocol, address); 370 avahi_free(address); 371 } 372} 373 374static void help(FILE *f, const char *argv0) { 375 fprintf(f, 376 "%s [options]\n" 377 " -h --help Show this help\n" 378 " -D --daemonize Daemonize after startup\n" 379 " -k --kill Kill a running daemon\n" 380 " -r --refresh Request a running daemon to refresh DNS server data\n" 381 " -c --check Return 0 if a daemon is already running\n" 382 " -V --version Show version\n", 383 argv0); 384} 385 386static int parse_command_line(int argc, char *argv[]) { 387 int c; 388 389 static const struct option long_options[] = { 390 { "help", no_argument, NULL, 'h' }, 391 { "daemonize", no_argument, NULL, 'D' }, 392 { "kill", no_argument, NULL, 'k' }, 393 { "version", no_argument, NULL, 'V' }, 394 { "refresh", no_argument, NULL, 'r' }, 395 { "check", no_argument, NULL, 'c' }, 396 { NULL, 0, NULL, 0 } 397 }; 398 399 while ((c = getopt_long(argc, argv, "hDkVrc", long_options, NULL)) >= 0) { 400 401 switch(c) { 402 case 'h': 403 command = DAEMON_HELP; 404 break; 405 case 'D': 406 daemonize = 1; 407 break; 408 case 'k': 409 command = DAEMON_KILL; 410 break; 411 case 'V': 412 command = DAEMON_VERSION; 413 break; 414 case 'r': 415 command = DAEMON_REFRESH; 416 break; 417 case 'c': 418 command = DAEMON_CHECK; 419 break; 420 default: 421 return -1; 422 } 423 } 424 425 if (optind < argc) { 426 fprintf(stderr, "Too many arguments\n"); 427 return -1; 428 } 429 430 return 0; 431} 432 433static int run_daemon(void) { 434 int fd = -1, ret = -1; 435 char buf[1024]; 436 size_t buflen = 0; 437 438 AVAHI_LLIST_HEAD_INIT(DNSServerInfo, servers); 439 440 daemon_signal_init(SIGINT, SIGTERM, SIGCHLD, SIGHUP, 0); 441 442 /* Allocate some memory for our environment variables */ 443 putenv(avahi_strdup(ENV_INTERFACE"=")); 444 putenv(avahi_strdup(ENV_DNS_SERVERS"=")); 445 putenv(avahi_strdup(ENV_INTERFACE_DNS_SERVERS"=")); 446 447 if ((fd = do_connect()) < 0) 448 goto finish; 449 450 if (daemonize) 451 daemon_retval_send(0); 452 453 ret = 0; 454 455 while (!quit) { 456 fd_set rfds, wfds; 457 458 FD_ZERO(&rfds); 459 FD_ZERO(&wfds); 460 461 FD_SET(fd, &rfds); 462 FD_SET(daemon_signal_fd(), &rfds); 463 464 for (;;) { 465 if (select(fd+1, &rfds, NULL, NULL, NULL) < 0) { 466 if (errno == EINTR) 467 continue; 468 469 daemon_log(LOG_ERR, "select(): %s", strerror(errno)); 470 goto finish; 471 } 472 473 break; 474 } 475 476 if (FD_ISSET(daemon_signal_fd(), &rfds)) { 477 478 int sig; 479 480 if ((sig = daemon_signal_next()) <= 0) { 481 daemon_log(LOG_ERR, "daemon_signal_next() failed"); 482 goto finish; 483 } 484 485 switch(sig) { 486 case SIGINT: 487 case SIGTERM: 488 daemon_log(LOG_INFO, "Got %s, quitting.", sig == SIGINT ? "SIGINT" : "SIGTERM"); 489 ret = 0; 490 goto finish; 491 492 case SIGCHLD: 493 waitpid(-1, NULL, WNOHANG); 494 break; 495 496 case SIGHUP: 497 daemon_log(LOG_INFO, "Refreshing DNS Server list"); 498 499 close(fd); 500 free_dns_server_info_list(); 501 502 if ((fd = do_connect()) < 0) 503 goto finish; 504 505 break; 506 } 507 508 } else if (FD_ISSET(fd, &rfds)) { 509 ssize_t r; 510 char *n; 511 512 if ((r = read(fd, buf, sizeof(buf) - buflen - 1)) <= 0) { 513 daemon_log(LOG_ERR, "read(): %s", r < 0 ? strerror(errno) : "EOF"); 514 goto finish; 515 } 516 517 buflen += r; 518 assert(buflen <= sizeof(buf)-1); 519 520 while ((n = memchr(buf, '\n', buflen))) { 521 *(n++) = 0; 522 523 if (new_line(buf) < 0) 524 goto finish; 525 526 buflen -= (n - buf); 527 memmove(buf, n, buflen); 528 } 529 530 if (buflen >= sizeof(buf)-1) { 531 /* The incoming line is horribly long */ 532 buf[sizeof(buf)-1] = 0; 533 534 if (new_line(buf) < 0) 535 goto finish; 536 537 buflen = 0; 538 } 539 } 540 } 541 542finish: 543 544 free_dns_server_info_list(); 545 546 if (fd >= 0) 547 close(fd); 548 549 daemon_signal_done(); 550 551 if (ret != 0 && daemonize) 552 daemon_retval_send(1); 553 554 return ret; 555} 556 557static const char* pid_file_proc(void) { 558 return AVAHI_RUNTIME_DIR"/avahi-dnsconfd.pid"; 559} 560 561int main(int argc, char *argv[]) { 562 char *argv0; 563 int r = 1; 564 int wrote_pid_file = 0; 565 566 if ((argv0 = strrchr(argv[0], '/'))) 567 argv0++; 568 else 569 argv0 = argv[0]; 570 571 daemon_pid_file_ident = daemon_log_ident = argv0; 572 daemon_pid_file_proc = pid_file_proc; 573 574 if (parse_command_line(argc, argv) < 0) 575 goto finish; 576 577 if (command == DAEMON_RUN) { 578 pid_t pid; 579 580 if (getuid() != 0) { 581 daemon_log(LOG_ERR, "This program is intended to be run as root."); 582 goto finish; 583 } 584 585 if ((pid = daemon_pid_file_is_running()) >= 0) { 586 daemon_log(LOG_ERR, "Daemon already running on PID %u", pid); 587 goto finish; 588 } 589 590 if (daemonize) { 591 daemon_retval_init(); 592 593 if ((pid = daemon_fork()) < 0) 594 goto finish; 595 else if (pid != 0) { 596 int ret; 597 /** Parent **/ 598 599 if ((ret = daemon_retval_wait(20)) < 0) { 600 daemon_log(LOG_ERR, "Could not receive return value from daemon process."); 601 goto finish; 602 } 603 604 r = ret; 605 goto finish; 606 } 607 608 /* Child */ 609 } 610 611 chdir("/"); 612 613 if (daemon_pid_file_create() < 0) { 614 daemon_log(LOG_ERR, "Failed to create PID file: %s", strerror(errno)); 615 616 if (daemonize) 617 daemon_retval_send(1); 618 goto finish; 619 } else 620 wrote_pid_file = 1; 621 622 if (run_daemon() < 0) 623 goto finish; 624 625 r = 0; 626 } else if (command == DAEMON_HELP) { 627 help(stdout, argv0); 628 629 r = 0; 630 } else if (command == DAEMON_VERSION) { 631 printf("%s "PACKAGE_VERSION"\n", argv0); 632 633 r = 0; 634 } else if (command == DAEMON_KILL) { 635 if (daemon_pid_file_kill_wait(SIGTERM, 5) < 0) { 636 daemon_log(LOG_WARNING, "Failed to kill daemon: %s", strerror(errno)); 637 goto finish; 638 } 639 640 r = 0; 641 } else if (command == DAEMON_REFRESH) { 642 if (daemon_pid_file_kill(SIGHUP) < 0) { 643 daemon_log(LOG_WARNING, "Failed to kill daemon: %s", strerror(errno)); 644 goto finish; 645 } 646 647 r = 0; 648 } else if (command == DAEMON_CHECK) 649 r = (daemon_pid_file_is_running() >= 0) ? 0 : 1; 650 651 652finish: 653 654 if (daemonize) 655 daemon_retval_done(); 656 657 if (wrote_pid_file) 658 daemon_pid_file_remove(); 659 660 return r; 661} 662