src/resolver.c

   1 /*
   2  *
   3  *  Connection Manager
   4  *
   5  *  Copyright (C) 2007-2013  Intel Corporation. All rights reserved.
   6  *
   7  *  This program is free software; you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License version 2 as
   9  *  published by the Free Software Foundation.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to the Free Software
  18  *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  19  *
  20  */
  21
  22 #ifdef HAVE_CONFIG_H
  23 #include <config.h>
  24 #endif
  25
  26 #include <stdio.h>
  27 #include <errno.h>
  28 #include <fcntl.h>
  29 #include <unistd.h>
  30 #include <string.h>
  31 #include <sys/stat.h>
  32 #include <resolv.h>
  33 #include <netdb.h>
  34
  35 #include "connman.h"
  36
  37 #define RESOLV_CONF_STATEDIR STATEDIR"/resolv.conf"
  38 #define RESOLV_CONF_ETC "/etc/resolv.conf"
  39
  40 #define RESOLVER_FLAG_PUBLIC (1 << 0)
  41
  42 /*
  43  * Threshold for RDNSS lifetime. Will be used to trigger RS
  44  * before RDNSS entries actually expire
  45  */
  46 #define RESOLVER_LIFETIME_REFRESH_THRESHOLD 0.8
  47
  48 struct entry_data {
  49         int index;
  50         char *domain;
  51         char *server;
  52         int family;
  53         unsigned int flags;
  54         unsigned int lifetime;
  55         guint timeout;
  56 };
  57
  58 static GSList *entry_list = NULL;
  59 static bool dnsproxy_enabled = false;
  60
  61 struct resolvfile_entry {
  62         int index;
  63         char *domain;
  64         char *server;
  65 };
  66
  67 static GList *resolvfile_list = NULL;
  68
  69 static void resolvfile_remove_entries(GList *entries)
  70 {
  71         GList *list;
  72
  73         for (list = entries; list; list = list->next) {
  74                 struct resolvfile_entry *entry = list->data;
  75
  76                 resolvfile_list = g_list_remove(resolvfile_list, entry);
  77
  78                 g_free(entry->server);
  79                 g_free(entry->domain);
  80                 g_free(entry);
  81         }
  82
  83         g_list_free(entries);
  84 }
  85
  86 static int resolvfile_export(void)
  87 {
  88         GList *list;
  89         GString *content;
  90         int fd, err;
  91         unsigned int count;
  92         mode_t old_umask;
  93
  94         content = g_string_new("# Generated by Connection Manager\n");
  95
  96         /*
  97          * Domains and nameservers are added in reverse so that the most
  98          * recently appended entry is the primary one. No more than
  99          * MAXDNSRCH/MAXNS entries are used.
 100          */
 101
 102         for (count = 0, list = g_list_first(resolvfile_list);
 103                                                 list && (count < MAXDNSRCH);
 104                                                 list = g_list_next(list)) {
 105                 struct resolvfile_entry *entry = list->data;
 106
 107                 if (!entry->domain)
 108                         continue;
 109
 110                 if (count == 0)
 111                         g_string_append_printf(content, "search ");
 112
 113                 g_string_append_printf(content, "%s ", entry->domain);
 114                 count++;
 115         }
 116
 117         if (count)
 118                 g_string_append_printf(content, "\n");
 119
 120         for (count = 0, list = g_list_first(resolvfile_list);
 121                                                 list && (count < MAXNS);
 122                                                 list = g_list_next(list)) {
 123                 struct resolvfile_entry *entry = list->data;
 124
 125                 if (!entry->server)
 126                         continue;
 127
 128                 g_string_append_printf(content, "nameserver %s\n",
 129                                                                 entry->server);
 130                 count++;
 131         }
 132
 133         old_umask = umask(022);
 134
 135         fd = open(RESOLV_CONF_STATEDIR, O_RDWR | O_CREAT | O_CLOEXEC,
 136                                         S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
 137         if (fd < 0) {
 138                 connman_warn_once("Cannot create "RESOLV_CONF_STATEDIR" "
 139                         "falling back to "RESOLV_CONF_ETC);
 140
 141                 fd = open(RESOLV_CONF_ETC, O_RDWR | O_CREAT | O_CLOEXEC,
 142                                         S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
 143
 144                 if (fd < 0) {
 145                         err = -errno;
 146                         goto done;
 147                 }
 148         }
 149
 150         if (ftruncate(fd, 0) < 0) {
 151                 err = -errno;
 152                 goto failed;
 153         }
 154
 155         err = 0;
 156
 157         if (write(fd, content->str, content->len) < 0)
 158                 err = -errno;
 159
 160 failed:
 161         close(fd);
 162
 163 done:
 164         g_string_free(content, TRUE);
 165         umask(old_umask);
 166
 167         return err;
 168 }
 169
 170 int __connman_resolvfile_append(int index, const char *domain,
 171                                                         const char *server)
 172 {
 173         struct resolvfile_entry *entry;
 174
 175         DBG("index %d server %s", index, server);
 176
 177         if (index < 0)
 178                 return -ENOENT;
 179
 180         entry = g_try_new0(struct resolvfile_entry, 1);
 181         if (!entry)
 182                 return -ENOMEM;
 183
 184         entry->index = index;
 185         entry->domain = g_strdup(domain);
 186         entry->server = g_strdup(server);
 187
 188         resolvfile_list = g_list_append(resolvfile_list, entry);
 189
 190         return resolvfile_export();
 191 }
 192
 193 int __connman_resolvfile_remove(int index, const char *domain,
 194                                                         const char *server)
 195 {
 196         GList *list, *matches = NULL;
 197
 198         DBG("index %d server %s", index, server);
 199
 200         for (list = resolvfile_list; list; list = g_list_next(list)) {
 201                 struct resolvfile_entry *entry = list->data;
 202
 203                 if (index >= 0 && entry->index != index)
 204                         continue;
 205
 206                 if (domain && g_strcmp0(entry->domain, domain) != 0)
 207                         continue;
 208
 209                 if (g_strcmp0(entry->server, server) != 0)
 210                         continue;
 211
 212                 matches = g_list_append(matches, entry);
 213         }
 214
 215         resolvfile_remove_entries(matches);
 216
 217         return resolvfile_export();
 218 }
 219
 220 void __connman_resolver_append_fallback_nameservers(void)
 221 {
 222         GSList *list;
 223
 224         for (list = entry_list; list; list = list->next) {
 225                 struct entry_data *entry = list->data;
 226
 227                 if (entry->index >= 0 && entry->server)
 228                         return;
 229         }
 230
 231         for (list = entry_list; list; list = list->next) {
 232                 struct entry_data *entry = list->data;
 233
 234                 if (entry->index != -1 || !entry->server)
 235                         continue;
 236
 237                 DBG("index %d server %s", entry->index, entry->server);
 238
 239                 if (dnsproxy_enabled) {
 240                         __connman_dnsproxy_append(entry->index, entry->domain,
 241                                         entry->server);
 242                 } else {
 243                         __connman_resolvfile_append(entry->index,
 244                                         entry->domain, entry->server);
 245                 }
 246         }
 247 }
 248
 249 static void remove_fallback_nameservers(void)
 250 {
 251         GSList *list;
 252
 253         for (list = entry_list; list; list = list->next) {
 254                 struct entry_data *entry = list->data;
 255
 256                 if (entry->index >= 0 || !entry->server)
 257                         continue;
 258
 259                 DBG("index %d server %s", entry->index, entry->server);
 260
 261                 if (dnsproxy_enabled) {
 262                         __connman_dnsproxy_remove(entry->index, entry->domain,
 263                                         entry->server);
 264                 } else {
 265                         __connman_resolvfile_remove(entry->index,
 266                                         entry->domain, entry->server);
 267                 }
 268         }
 269 }
 270
 271 static void remove_entries(GSList *entries)
 272 {
 273         GSList *list;
 274
 275         for (list = entries; list; list = list->next) {
 276                 struct entry_data *entry = list->data;
 277
 278                 entry_list = g_slist_remove(entry_list, entry);
 279
 280                 if (dnsproxy_enabled) {
 281                         __connman_dnsproxy_remove(entry->index, entry->domain,
 282                                                         entry->server);
 283                 } else {
 284                         __connman_resolvfile_remove(entry->index, entry->domain,
 285                                                         entry->server);
 286                 }
 287
 288                 if (entry->timeout)
 289                         g_source_remove(entry->timeout);
 290                 g_free(entry->server);
 291                 g_free(entry->domain);
 292                 g_free(entry);
 293         }
 294
 295         g_slist_free(entries);
 296
 297         __connman_resolver_append_fallback_nameservers();
 298 }
 299
 300 static gboolean resolver_expire_cb(gpointer user_data)
 301 {
 302         struct entry_data *entry = user_data;
 303         GSList *list;
 304
 305         DBG("index %d domain %s server %s",
 306                         entry->index, entry->domain, entry->server);
 307
 308         list = g_slist_prepend(NULL, entry);
 309
 310         if (entry->index >= 0) {
 311                 struct connman_service *service;
 312                 service = __connman_service_lookup_from_index(entry->index);
 313                 if (service)
 314                         __connman_service_nameserver_remove(service,
 315                                                         entry->server, true);
 316         }
 317
 318         remove_entries(list);
 319
 320         return FALSE;
 321 }
 322
 323 static gboolean resolver_refresh_cb(gpointer user_data)
 324 {
 325         struct entry_data *entry = user_data;
 326         unsigned int interval;
 327         struct connman_service *service = NULL;
 328
 329         /* Round up what we have left from lifetime */
 330         interval = entry->lifetime *
 331                 (1 - RESOLVER_LIFETIME_REFRESH_THRESHOLD) + 1.0;
 332
 333         DBG("RDNSS start index %d domain %s "
 334                         "server %s remaining lifetime %d",
 335                         entry->index, entry->domain,
 336                         entry->server, interval);
 337
 338         entry->timeout = g_timeout_add_seconds(interval,
 339                         resolver_expire_cb, entry);
 340
 341         if (entry->index >= 0) {
 342                 service = __connman_service_lookup_from_index(entry->index);
 343                 if (service) {
 344                         /*
 345                          * Send Router Solicitation to refresh RDNSS entries
 346                          * before their lifetime expires
 347                          */
 348                         __connman_network_refresh_rs_ipv6(
 349                                         __connman_service_get_network(service),
 350                                         entry->index);
 351                 }
 352         }
 353         return FALSE;
 354 }
 355
 356 static int append_resolver(int index, const char *domain,
 357                                 const char *server, unsigned int lifetime,
 358                                                         unsigned int flags)
 359 {
 360         struct entry_data *entry;
 361         unsigned int interval;
 362
 363         DBG("index %d domain %s server %s lifetime %d flags %d",
 364                                 index, domain, server, lifetime, flags);
 365
 366         if (!server && !domain)
 367                 return -EINVAL;
 368
 369         entry = g_try_new0(struct entry_data, 1);
 370         if (!entry)
 371                 return -ENOMEM;
 372
 373         entry->index = index;
 374         entry->domain = g_strdup(domain);
 375         entry->server = g_strdup(server);
 376         entry->flags = flags;
 377         entry->lifetime = lifetime;
 378
 379         if (server)
 380                 entry->family = connman_inet_check_ipaddress(server);
 381
 382         if (lifetime) {
 383                 interval = lifetime * RESOLVER_LIFETIME_REFRESH_THRESHOLD;
 384
 385                 DBG("RDNSS start index %d domain %s "
 386                                 "server %s lifetime threshold %d",
 387                                 index, domain, server, interval);
 388
 389                 entry->timeout = g_timeout_add_seconds(interval,
 390                                 resolver_refresh_cb, entry);
 391         }
 392
 393         if (entry->index >= 0 && entry->server)
 394                 remove_fallback_nameservers();
 395
 396         entry_list = g_slist_append(entry_list, entry);
 397
 398         if (dnsproxy_enabled)
 399                 __connman_dnsproxy_append(entry->index, domain, server);
 400         else
 401                 __connman_resolvfile_append(entry->index, domain, server);
 402
 403         /*
 404          * We update the service only for those nameservers
 405          * that are automagically added via netlink (lifetime > 0)
 406          */
 407         if (server && entry->index >= 0 && lifetime) {
 408                 struct connman_service *service;
 409                 service = __connman_service_lookup_from_index(entry->index);
 410                 if (service)
 411                         __connman_service_nameserver_append(service,
 412                                                         server, true);
 413         }
 414
 415         return 0;
 416 }
 417
 418 /**
 419  * connman_resolver_append:
 420  * @index: network interface index
 421  * @domain: domain limitation
 422  * @server: server address
 423  *
 424  * Append resolver server address to current list
 425  */
 426 int connman_resolver_append(int index, const char *domain,
 427                                                 const char *server)
 428 {
 429         GSList *list;
 430
 431         DBG("index %d domain %s server %s", index, domain, server);
 432
 433         if (!server && !domain)
 434                 return -EINVAL;
 435
 436         for (list = entry_list; list; list = list->next) {
 437                 struct entry_data *entry = list->data;
 438
 439                 if (entry->timeout > 0)
 440                         continue;
 441
 442                 if (entry->index == index &&
 443                                 g_strcmp0(entry->domain, domain) == 0 &&
 444                                 g_strcmp0(entry->server, server) == 0) {
 445                         if (dnsproxy_enabled)
 446                                 __connman_dnsproxy_append(entry->index, domain,
 447                                                 server);
 448
 449                         return -EEXIST;
 450                 }
 451         }
 452
 453         return append_resolver(index, domain, server, 0, 0);
 454 }
 455
 456 /**
 457  * connman_resolver_append_lifetime:
 458  * @index: network interface index
 459  * @domain: domain limitation
 460  * @server: server address
 461  * @timeout: server lifetime in seconds
 462  *
 463  * Append resolver server address to current list
 464  */
 465 int connman_resolver_append_lifetime(int index, const char *domain,
 466                                 const char *server, unsigned int lifetime)
 467 {
 468         GSList *list;
 469         unsigned int interval;
 470
 471         DBG("index %d domain %s server %s lifetime %d",
 472                                 index, domain, server, lifetime);
 473
 474         if (!server && !domain)
 475                 return -EINVAL;
 476
 477         for (list = entry_list; list; list = list->next) {
 478                 struct entry_data *entry = list->data;
 479
 480                 if (entry->timeout == 0 ||
 481                                 entry->index != index ||
 482                                 g_strcmp0(entry->domain, domain) != 0 ||
 483                                 g_strcmp0(entry->server, server) != 0)
 484                         continue;
 485
 486                 g_source_remove(entry->timeout);
 487
 488                 if (lifetime == 0) {
 489                         resolver_expire_cb(entry);
 490                         return 0;
 491                 }
 492
 493                 interval = lifetime * RESOLVER_LIFETIME_REFRESH_THRESHOLD;
 494
 495                 DBG("RDNSS start index %d domain %s "
 496                                 "server %s lifetime threshold %d",
 497                                 index, domain, server, interval);
 498
 499                 entry->timeout = g_timeout_add_seconds(interval,
 500                                 resolver_refresh_cb, entry);
 501                 return 0;
 502         }
 503
 504         return append_resolver(index, domain, server, lifetime, 0);
 505 }
 506
 507 /**
 508  * connman_resolver_remove:
 509  * @index: network interface index
 510  * @domain: domain limitation
 511  * @server: server address
 512  *
 513  * Remover resolver server address from current list
 514  */
 515 int connman_resolver_remove(int index, const char *domain, const char *server)
 516 {
 517         GSList *list, *matches = NULL;
 518
 519         DBG("index %d domain %s server %s", index, domain, server);
 520
 521         for (list = entry_list; list; list = list->next) {
 522                 struct entry_data *entry = list->data;
 523
 524                 if (entry->index != index)
 525                         continue;
 526
 527                 if (g_strcmp0(entry->domain, domain) != 0)
 528                         continue;
 529
 530                 if (g_strcmp0(entry->server, server) != 0)
 531                         continue;
 532
 533                 matches = g_slist_prepend(matches, entry);
 534                 break;
 535         }
 536
 537         if (!matches)
 538                 return -ENOENT;
 539
 540         remove_entries(matches);
 541
 542         return 0;
 543 }
 544
 545 /**
 546  * connman_resolver_remove_all:
 547  * @index: network interface index
 548  *
 549  * Remove all resolver server address for the specified interface index
 550  */
 551 int connman_resolver_remove_all(int index)
 552 {
 553         GSList *list, *matches = NULL;
 554
 555         DBG("index %d", index);
 556
 557         if (index < 0)
 558                 return -EINVAL;
 559
 560         for (list = entry_list; list; list = list->next) {
 561                 struct entry_data *entry = list->data;
 562
 563                 if (entry->index != index)
 564                         continue;
 565
 566                 matches = g_slist_prepend(matches, entry);
 567         }
 568
 569         if (!matches)
 570                 return -ENOENT;
 571
 572         remove_entries(matches);
 573
 574         return 0;
 575 }
 576
 577 int __connman_resolver_redo_servers(int index)
 578 {
 579         GSList *list;
 580
 581         if (!dnsproxy_enabled)
 582                 return 0;
 583
 584         DBG("index %d", index);
 585
 586         if (index < 0)
 587                 return -EINVAL;
 588
 589         for (list = entry_list; list; list = list->next) {
 590                 struct entry_data *entry = list->data;
 591
 592                 if (entry->timeout == 0 || entry->index != index)
 593                         continue;
 594
 595                 /*
 596                  * This function must only check IPv6 server addresses so
 597                  * do not remove IPv4 name servers unnecessarily.
 598                  */
 599                 if (entry->family != AF_INET6)
 600                         continue;
 601
 602                 /*
 603                  * We remove the server, and then re-create so that it will
 604                  * use proper source addresses when sending DNS queries.
 605                  */
 606                 __connman_dnsproxy_remove(entry->index, entry->domain,
 607                                         entry->server);
 608
 609                 __connman_dnsproxy_append(entry->index, entry->domain,
 610                                         entry->server);
 611         }
 612
 613         /*
 614          * We want to re-add all search domains back to search
 615          * domain lists as they just got removed for RDNSS IPv6-servers
 616          * (above).
 617          * Removal of search domains is not necessary
 618          * as there can be only one instance of each search domain
 619          * in the each dns-servers search domain list.
 620         */
 621
 622         for (list = entry_list; list; list = list->next) {
 623                 struct entry_data *entry = list->data;
 624
 625                 if (entry->index != index)
 626                         continue;
 627
 628                 if (entry->server)
 629                         continue;
 630
 631                 __connman_dnsproxy_append(entry->index, entry->domain,
 632                                         NULL);
 633         }
 634
 635         return 0;
 636 }
 637
 638 static void free_entry(gpointer data)
 639 {
 640         struct entry_data *entry = data;
 641         g_free(entry->domain);
 642         g_free(entry->server);
 643         g_free(entry);
 644 }
 645
 646 static void free_resolvfile(gpointer data)
 647 {
 648         struct resolvfile_entry *entry = data;
 649         g_free(entry->domain);
 650         g_free(entry->server);
 651         g_free(entry);
 652 }
 653
 654 int __connman_resolver_set_mdns(int index, bool enabled)
 655 {
 656         if (!dnsproxy_enabled)
 657                 return -ENOTSUP;
 658
 659         return __connman_dnsproxy_set_mdns(index, enabled);
 660 }
 661
 662 int __connman_resolver_init(gboolean dnsproxy)
 663 {
 664         int i;
 665         char **ns;
 666
 667         DBG("dnsproxy %d", dnsproxy);
 668
 669         /* get autoip nameservers */
 670         ns = __connman_inet_get_pnp_nameservers(NULL);
 671         for (i = 0; ns && ns[i]; i += 1) {
 672                 DBG("pnp server %s", ns[i]);
 673                 append_resolver(i, NULL, ns[i], 86400, 0);
 674         }
 675         g_strfreev(ns);
 676
 677         if (!dnsproxy)
 678                 return 0;
 679
 680         if (__connman_dnsproxy_init() < 0) {
 681                 /* Fall back to resolv.conf */
 682                 return 0;
 683         }
 684
 685         dnsproxy_enabled = true;
 686
 687         ns = connman_setting_get_string_list("FallbackNameservers");
 688         for (i = 0; ns && ns[i]; i += 1) {
 689                 DBG("server %s", ns[i]);
 690                 append_resolver(-1, NULL, ns[i], 0, RESOLVER_FLAG_PUBLIC);
 691         }
 692
 693         return 0;
 694 }
 695
 696 void __connman_resolver_cleanup(void)
 697 {
 698         DBG("");
 699
 700         if (dnsproxy_enabled)
 701                 __connman_dnsproxy_cleanup();
 702         else {
 703                 GList *list;
 704                 GSList *slist;
 705
 706                 for (list = resolvfile_list; list; list = g_list_next(list))
 707                         free_resolvfile(list->data);
 708                 g_list_free(resolvfile_list);
 709                 resolvfile_list = NULL;
 710
 711                 for (slist = entry_list; slist; slist = g_slist_next(slist))
 712                         free_entry(slist->data);
 713                 g_slist_free(entry_list);
 714                 entry_list = NULL;
 715         }
 716 }