src/resolver.c

   1 /*
   2  *
   3  *  Connection Manager
   4  *
   5  *  Copyright (C) 2007-2012  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 #define _GNU_SOURCE
  27 #include <stdio.h>
  28 #include <errno.h>
  29 #include <fcntl.h>
  30 #include <unistd.h>
  31 #include <string.h>
  32 #include <sys/stat.h>
  33 #include <resolv.h>
  34
  35 #include "connman.h"
  36
  37 #define RESOLVER_FLAG_PUBLIC (1 << 0)
  38
  39 struct entry_data {
  40         char *interface;
  41         char *domain;
  42         char *server;
  43         unsigned int flags;
  44         guint timeout;
  45 };
  46
  47 static GSList *entry_list = NULL;
  48 static connman_bool_t dnsproxy_enabled = FALSE;
  49
  50 struct resolvfile_entry {
  51         char *interface;
  52         char *domain;
  53         char *server;
  54 };
  55
  56 static GList *resolvfile_list = NULL;
  57
  58 static void resolvfile_remove_entries(GList *entries)
  59 {
  60         GList *list;
  61
  62         for (list = entries; list; list = list->next) {
  63                 struct resolvfile_entry *entry = list->data;
  64
  65                 resolvfile_list = g_list_remove(resolvfile_list, entry);
  66
  67                 g_free(entry->server);
  68                 g_free(entry->domain);
  69                 g_free(entry->interface);
  70                 g_free(entry);
  71         }
  72
  73         g_list_free(entries);
  74 }
  75
  76 static int resolvfile_export(void)
  77 {
  78         GList *list;
  79         GString *content;
  80         int fd, err;
  81         unsigned int count;
  82         mode_t old_umask;
  83
  84         content = g_string_new("# Generated by Connection Manager\n");
  85
  86         /*
  87          * Domains and nameservers are added in reverse so that the most
  88          * recently appended entry is the primary one. No more than
  89          * MAXDNSRCH/MAXNS entries are used.
  90          */
  91
  92         for (count = 0, list = g_list_last(resolvfile_list);
  93                                                 list && (count < MAXDNSRCH);
  94                                                 list = g_list_previous(list)) {
  95                 struct resolvfile_entry *entry = list->data;
  96
  97                 if (!entry->domain)
  98                         continue;
  99
 100                 if (count == 0)
 101                         g_string_append_printf(content, "search ");
 102
 103                 g_string_append_printf(content, "%s ", entry->domain);
 104                 count++;
 105         }
 106
 107         if (count)
 108                 g_string_append_printf(content, "\n");
 109
 110         for (count = 0, list = g_list_last(resolvfile_list);
 111                                                 list && (count < MAXNS);
 112                                                 list = g_list_previous(list)) {
 113                 struct resolvfile_entry *entry = list->data;
 114
 115                 if (!entry->server)
 116                         continue;
 117
 118                 g_string_append_printf(content, "nameserver %s\n",
 119                                                                 entry->server);
 120                 count++;
 121         }
 122
 123         old_umask = umask(022);
 124
 125         fd = open("/etc/resolv.conf", O_RDWR | O_CREAT | O_CLOEXEC,
 126                                         S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
 127         if (fd < 0) {
 128                 err = -errno;
 129                 goto done;
 130         }
 131
 132         if (ftruncate(fd, 0) < 0) {
 133                 err = -errno;
 134                 goto failed;
 135         }
 136
 137         err = 0;
 138
 139         if (write(fd, content->str, content->len) < 0)
 140                 err = -errno;
 141
 142 failed:
 143         close(fd);
 144
 145 done:
 146         g_string_free(content, TRUE);
 147         umask(old_umask);
 148
 149         return err;
 150 }
 151
 152 int __connman_resolvfile_append(const char *interface, const char *domain,
 153                                                         const char *server)
 154 {
 155         struct resolvfile_entry *entry;
 156
 157         DBG("interface %s server %s", interface, server);
 158
 159         if (interface == NULL)
 160                 return -ENOENT;
 161
 162         entry = g_try_new0(struct resolvfile_entry, 1);
 163         if (entry == NULL)
 164                 return -ENOMEM;
 165
 166         entry->interface = g_strdup(interface);
 167         entry->domain = g_strdup(domain);
 168         entry->server = g_strdup(server);
 169
 170         resolvfile_list = g_list_append(resolvfile_list, entry);
 171
 172         return resolvfile_export();
 173 }
 174
 175 int __connman_resolvfile_remove(const char *interface, const char *domain,
 176                                                         const char *server)
 177 {
 178         GList *list, *matches = NULL;
 179
 180         DBG("interface %s server %s", interface, server);
 181
 182         for (list = resolvfile_list; list; list = g_list_next(list)) {
 183                 struct resolvfile_entry *entry = list->data;
 184
 185                 if (interface != NULL &&
 186                                 g_strcmp0(entry->interface, interface) != 0)
 187                         continue;
 188
 189                 if (domain != NULL && g_strcmp0(entry->domain, domain) != 0)
 190                         continue;
 191
 192                 if (g_strcmp0(entry->server, server) != 0)
 193                         continue;
 194
 195                 matches = g_list_append(matches, entry);
 196         }
 197
 198         resolvfile_remove_entries(matches);
 199
 200         return resolvfile_export();
 201 }
 202
 203 static void remove_entries(GSList *entries)
 204 {
 205         GSList *list;
 206
 207         for (list = entries; list; list = list->next) {
 208                 struct entry_data *entry = list->data;
 209
 210                 entry_list = g_slist_remove(entry_list, entry);
 211
 212                 if (dnsproxy_enabled == TRUE) {
 213                         __connman_dnsproxy_remove(entry->interface, entry->domain,
 214                                                         entry->server);
 215                 } else {
 216                         __connman_resolvfile_remove(entry->interface, entry->domain,
 217                                                         entry->server);
 218                 }
 219
 220                 if (entry->timeout)
 221                         g_source_remove(entry->timeout);
 222                 g_free(entry->server);
 223                 g_free(entry->domain);
 224                 g_free(entry->interface);
 225                 g_free(entry);
 226         }
 227
 228         g_slist_free(entries);
 229 }
 230
 231 static gboolean resolver_expire_cb(gpointer user_data)
 232 {
 233         struct entry_data *entry = user_data;
 234         GSList *list;
 235         int index;
 236
 237         DBG("interface %s domain %s server %s",
 238                         entry->interface, entry->domain, entry->server);
 239
 240         list = g_slist_append(NULL, entry);
 241
 242         index = connman_inet_ifindex(entry->interface);
 243         if (index >= 0) {
 244                 struct connman_service *service;
 245                 service = __connman_service_lookup_from_index(index);
 246                 if (service != NULL)
 247                         __connman_service_nameserver_remove(service,
 248                                                         entry->server, TRUE);
 249         }
 250
 251         remove_entries(list);
 252
 253         return FALSE;
 254 }
 255
 256 static int append_resolver(const char *interface, const char *domain,
 257                                 const char *server, unsigned int lifetime,
 258                                                         unsigned int flags)
 259 {
 260         struct entry_data *entry;
 261
 262         DBG("interface %s domain %s server %s lifetime %d flags %d",
 263                                 interface, domain, server, lifetime, flags);
 264
 265         if (server == NULL && domain == NULL)
 266                 return -EINVAL;
 267
 268         entry = g_try_new0(struct entry_data, 1);
 269         if (entry == NULL)
 270                 return -ENOMEM;
 271
 272         entry->interface = g_strdup(interface);
 273         entry->domain = g_strdup(domain);
 274         entry->server = g_strdup(server);
 275         entry->flags = flags;
 276         if (lifetime) {
 277                 int index;
 278                 entry->timeout = g_timeout_add_seconds(lifetime,
 279                                                 resolver_expire_cb, entry);
 280
 281                 /*
 282                  * We update the service only for those nameservers
 283                  * that are automagically added via netlink (lifetime > 0)
 284                  */
 285                 index = connman_inet_ifindex(interface);
 286                 if (index >= 0) {
 287                         struct connman_service *service;
 288                         service = __connman_service_lookup_from_index(index);
 289                         if (service != NULL)
 290                                 __connman_service_nameserver_append(service,
 291                                                                 server, TRUE);
 292                 }
 293         }
 294         entry_list = g_slist_append(entry_list, entry);
 295
 296         if (dnsproxy_enabled == TRUE)
 297                 __connman_dnsproxy_append(interface, domain, server);
 298         else
 299                 __connman_resolvfile_append(interface, domain, server);
 300
 301         return 0;
 302 }
 303
 304 /**
 305  * connman_resolver_append:
 306  * @interface: network interface
 307  * @domain: domain limitation
 308  * @server: server address
 309  *
 310  * Append resolver server address to current list
 311  */
 312 int connman_resolver_append(const char *interface, const char *domain,
 313                                                 const char *server)
 314 {
 315         GSList *list, *matches = NULL;
 316
 317         DBG("interface %s domain %s server %s", interface, domain, server);
 318
 319         if (server == NULL && domain == NULL)
 320                 return -EINVAL;
 321
 322         for (list = entry_list; list; list = list->next) {
 323                 struct entry_data *entry = list->data;
 324
 325                 if (entry->timeout > 0 ||
 326                                 g_strcmp0(entry->interface, interface) != 0 ||
 327                                 g_strcmp0(entry->domain, domain) != 0 ||
 328                                 g_strcmp0(entry->server, server) != 0)
 329                         continue;
 330
 331                 matches = g_slist_append(matches, entry);
 332         }
 333
 334         if (matches != NULL)
 335                 remove_entries(matches);
 336
 337         return append_resolver(interface, domain, server, 0, 0);
 338 }
 339
 340 /**
 341  * connman_resolver_append_lifetime:
 342  * @interface: network interface
 343  * @domain: domain limitation
 344  * @server: server address
 345  * @timeout: server lifetime in seconds
 346  *
 347  * Append resolver server address to current list
 348  */
 349 int connman_resolver_append_lifetime(const char *interface, const char *domain,
 350                                 const char *server, unsigned int lifetime)
 351 {
 352         GSList *list;
 353
 354         DBG("interface %s domain %s server %s lifetime %d",
 355                                 interface, domain, server, lifetime);
 356
 357         if (server == NULL)
 358                 return -EINVAL;
 359
 360         for (list = entry_list; list; list = list->next) {
 361                 struct entry_data *entry = list->data;
 362
 363                 if (!entry->timeout ||
 364                                 g_strcmp0(entry->interface, interface) ||
 365                                 g_strcmp0(entry->domain, domain) ||
 366                                 g_strcmp0(entry->server, server))
 367                         continue;
 368
 369                 g_source_remove(entry->timeout);
 370
 371                 if (lifetime == 0) {
 372                         resolver_expire_cb(entry);
 373                         return 0;
 374                 }
 375
 376                 entry->timeout = g_timeout_add_seconds(lifetime,
 377                                                 resolver_expire_cb, entry);
 378                 return 0;
 379         }
 380
 381         return append_resolver(interface, domain, server, lifetime, 0);
 382 }
 383
 384 /**
 385  * connman_resolver_remove:
 386  * @interface: network interface
 387  * @domain: domain limitation
 388  * @server: server address
 389  *
 390  * Remover resolver server address from current list
 391  */
 392 int connman_resolver_remove(const char *interface, const char *domain,
 393                                                         const char *server)
 394 {
 395         GSList *list, *matches = NULL;
 396
 397         DBG("interface %s domain %s server %s", interface, domain, server);
 398
 399         if (server == NULL)
 400                 return -EINVAL;
 401
 402         for (list = entry_list; list; list = list->next) {
 403                 struct entry_data *entry = list->data;
 404
 405                 if (interface != NULL &&
 406                                 g_strcmp0(entry->interface, interface) != 0)
 407                         continue;
 408
 409                 if (domain != NULL && g_strcmp0(entry->domain, domain) != 0)
 410                         continue;
 411
 412                 if (g_strcmp0(entry->server, server) != 0)
 413                         continue;
 414
 415                 matches = g_slist_append(matches, entry);
 416         }
 417
 418         if (matches == NULL)
 419                 return -ENOENT;
 420
 421         remove_entries(matches);
 422
 423         return 0;
 424 }
 425
 426 /**
 427  * connman_resolver_remove_all:
 428  * @interface: network interface
 429  *
 430  * Remove all resolver server address for the specified interface
 431  */
 432 int connman_resolver_remove_all(const char *interface)
 433 {
 434         GSList *list, *matches = NULL;
 435
 436         DBG("interface %s", interface);
 437
 438         if (interface == NULL)
 439                 return -EINVAL;
 440
 441         for (list = entry_list; list; list = list->next) {
 442                 struct entry_data *entry = list->data;
 443
 444                 if (g_strcmp0(entry->interface, interface) != 0)
 445                         continue;
 446
 447                 matches = g_slist_append(matches, entry);
 448         }
 449
 450         if (matches == NULL)
 451                 return -ENOENT;
 452
 453         remove_entries(matches);
 454
 455         return 0;
 456 }
 457
 458 /**
 459  * connman_resolver_flush:
 460  *
 461  * Flush pending resolver requests
 462  */
 463 void connman_resolver_flush(void)
 464 {
 465         if (dnsproxy_enabled == TRUE)
 466                 __connman_dnsproxy_flush();
 467
 468         return;
 469 }
 470
 471 int __connman_resolver_redo_servers(const char *interface)
 472 {
 473         GSList *list;
 474
 475         if (dnsproxy_enabled == FALSE)
 476                 return 0;
 477
 478         DBG("interface %s", interface);
 479
 480         if (interface == NULL)
 481                 return -EINVAL;
 482
 483         for (list = entry_list; list; list = list->next) {
 484                 struct entry_data *entry = list->data;
 485
 486                 if (entry->timeout == 0 ||
 487                                 g_strcmp0(entry->interface, interface) != 0)
 488                         continue;
 489
 490                 /*
 491                  * We remove the server, and then re-create so that it will
 492                  * use proper source addresses when sending DNS queries.
 493                  */
 494                 __connman_dnsproxy_remove(entry->interface, entry->domain,
 495                                         entry->server);
 496
 497                 __connman_dnsproxy_append(entry->interface, entry->domain,
 498                                         entry->server);
 499         }
 500
 501         return 0;
 502 }
 503
 504 static void free_entry(gpointer data)
 505 {
 506         struct entry_data *entry = data;
 507         g_free(entry->interface);
 508         g_free(entry->domain);
 509         g_free(entry->server);
 510         g_free(entry);
 511 }
 512
 513 static void free_resolvfile(gpointer data)
 514 {
 515         struct resolvfile_entry *entry = data;
 516         g_free(entry->interface);
 517         g_free(entry->domain);
 518         g_free(entry->server);
 519         g_free(entry);
 520 }
 521
 522 int __connman_resolver_init(connman_bool_t dnsproxy)
 523 {
 524         int i;
 525         char **ns;
 526
 527         DBG("dnsproxy %d", dnsproxy);
 528
 529         if (dnsproxy == FALSE)
 530                 return 0;
 531
 532         if (__connman_dnsproxy_init() < 0) {
 533                 /* Fall back to resolv.conf */
 534                 return 0;
 535         }
 536
 537         dnsproxy_enabled = TRUE;
 538
 539         ns = connman_setting_get_string_list("FallbackNameservers");
 540         for (i = 0; ns != NULL && ns[i] != NULL; i += 1) {
 541                 DBG("server %s", ns[i]);
 542                 append_resolver(NULL, NULL, ns[i], 0, RESOLVER_FLAG_PUBLIC);
 543         }
 544
 545         return 0;
 546 }
 547
 548 void __connman_resolver_cleanup(void)
 549 {
 550         DBG("");
 551
 552         if (dnsproxy_enabled == TRUE)
 553                 __connman_dnsproxy_cleanup();
 554         else {
 555                 GList *list;
 556                 GSList *slist;
 557
 558                 for (list = resolvfile_list; list; list = g_list_next(list))
 559                         free_resolvfile(list->data);
 560                 g_list_free(resolvfile_list);
 561                 resolvfile_list = NULL;
 562
 563                 for (slist = entry_list; slist; slist = g_slist_next(slist))
 564                         free_entry(slist->data);
 565                 g_slist_free(entry_list);
 566                 entry_list = NULL;
 567         }
 568 }