src/resolver.c

   1 /*
   2  *
   3  *  Connection Manager
   4  *
   5  *  Copyright (C) 2007-2010  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
  34 #include "connman.h"
  35
  36 #define RESOLVER_FLAG_PUBLIC (1 << 0)
  37
  38 struct entry_data {
  39         struct connman_resolver *resolver;
  40         char *interface;
  41         char *domain;
  42         char *server;
  43         unsigned int flags;
  44 };
  45
  46 static GSList *entry_list = NULL;
  47 static GSList *resolver_list = NULL;
  48
  49 static void remove_entries(GSList *entries)
  50 {
  51         GSList *list;
  52
  53         for (list = entries; list; list = list->next) {
  54                 struct entry_data *entry = list->data;
  55                 struct connman_resolver *resolver = entry->resolver;
  56
  57                 entry_list = g_slist_remove(entry_list, entry);
  58
  59                 if (resolver && resolver->remove)
  60                         resolver->remove(entry->interface, entry->domain,
  61                                                                 entry->server);
  62
  63                 g_free(entry->server);
  64                 g_free(entry->domain);
  65                 g_free(entry->interface);
  66                 g_free(entry);
  67         }
  68
  69         g_slist_free(entries);
  70 }
  71
  72 static gint compare_priority(gconstpointer a, gconstpointer b)
  73 {
  74         const struct connman_resolver *resolver1 = a;
  75         const struct connman_resolver *resolver2 = b;
  76
  77         return resolver2->priority - resolver1->priority;
  78 }
  79
  80 /**
  81  * connman_resolver_register:
  82  * @resolver: resolver module
  83  *
  84  * Register a new resolver module
  85  *
  86  * Returns: %0 on success
  87  */
  88 int connman_resolver_register(struct connman_resolver *resolver)
  89 {
  90         GSList *list;
  91
  92         DBG("resolver %p name %s", resolver, resolver->name);
  93
  94         resolver_list = g_slist_insert_sorted(resolver_list, resolver,
  95                                                         compare_priority);
  96
  97         if (resolver->append == NULL)
  98                 return 0;
  99
 100         for (list = entry_list; list; list = list->next) {
 101                 struct entry_data *entry = list->data;
 102
 103                 if (entry->resolver)
 104                         continue;
 105
 106                 if (resolver->append(entry->interface, entry->domain,
 107                                                         entry->server) == 0)
 108                         entry->resolver = resolver;
 109         }
 110
 111         return 0;
 112 }
 113
 114 /**
 115  * connman_resolver_unregister:
 116  * @resolver: resolver module
 117  *
 118  * Remove a previously registered resolver module
 119  */
 120 void connman_resolver_unregister(struct connman_resolver *resolver)
 121 {
 122         GSList *list, *matches = NULL;
 123
 124         DBG("resolver %p name %s", resolver, resolver->name);
 125
 126         resolver_list = g_slist_remove(resolver_list, resolver);
 127
 128         for (list = entry_list; list; list = list->next) {
 129                 struct entry_data *entry = list->data;
 130
 131                 if (entry->resolver != resolver)
 132                         continue;
 133
 134                 matches = g_slist_append(matches, entry);
 135         }
 136
 137         remove_entries(matches);
 138 }
 139
 140 static int append_resolver(const char *interface, const char *domain,
 141                                         const char *server, unsigned int flags)
 142 {
 143         struct entry_data *entry;
 144         GSList *list;
 145
 146         DBG("interface %s domain %s server %s flags %d",
 147                                         interface, domain, server, flags);
 148
 149         if (server == NULL)
 150                 return -EINVAL;
 151
 152         entry = g_try_new0(struct entry_data, 1);
 153         if (entry == NULL)
 154                 return -ENOMEM;
 155
 156         entry->interface = g_strdup(interface);
 157         entry->domain = g_strdup(domain);
 158         entry->server = g_strdup(server);
 159         entry->flags = flags;
 160
 161         entry_list = g_slist_append(entry_list, entry);
 162
 163         for (list = resolver_list; list; list = list->next) {
 164                 struct connman_resolver *resolver = list->data;
 165
 166                 if (resolver->append == NULL)
 167                         continue;
 168
 169                 if (resolver->append(interface, domain, server) == 0) {
 170                         entry->resolver = resolver;
 171                         break;
 172                 }
 173         }
 174
 175         return 0;
 176 }
 177
 178 /**
 179  * connman_resolver_append:
 180  * @interface: network interface
 181  * @domain: domain limitation
 182  * @server: server address
 183  *
 184  * Append resolver server address to current list
 185  */
 186 int connman_resolver_append(const char *interface, const char *domain,
 187                                                         const char *server)
 188 {
 189         DBG("interface %s domain %s server %s", interface, domain, server);
 190
 191         return append_resolver(interface, domain, server, 0);
 192 }
 193
 194 /**
 195  * connman_resolver_remove:
 196  * @interface: network interface
 197  * @domain: domain limitation
 198  * @server: server address
 199  *
 200  * Remover resolver server address from current list
 201  */
 202 int connman_resolver_remove(const char *interface, const char *domain,
 203                                                         const char *server)
 204 {
 205         GSList *list, *matches = NULL;
 206
 207         DBG("interface %s domain %s server %s", interface, domain, server);
 208
 209         if (server == NULL)
 210                 return -EINVAL;
 211
 212         for (list = entry_list; list; list = list->next) {
 213                 struct entry_data *entry = list->data;
 214
 215                 if (interface != NULL &&
 216                                 g_strcmp0(entry->interface, interface) != 0)
 217                         continue;
 218
 219                 if (domain != NULL && g_strcmp0(entry->domain, domain) != 0)
 220                         continue;
 221
 222                 if (g_strcmp0(entry->server, server) != 0)
 223                         continue;
 224
 225                 matches = g_slist_append(matches, entry);
 226         }
 227
 228         if (matches == NULL)
 229                 return -ENOENT;
 230
 231         remove_entries(matches);
 232
 233         return 0;
 234 }
 235
 236 /**
 237  * connman_resolver_remove_all:
 238  * @interface: network interface
 239  *
 240  * Remove all resolver server address for the specified interface
 241  */
 242 int connman_resolver_remove_all(const char *interface)
 243 {
 244         GSList *list, *matches = NULL;
 245
 246         DBG("interface %s", interface);
 247
 248         if (interface == NULL)
 249                 return -EINVAL;
 250
 251         for (list = entry_list; list; list = list->next) {
 252                 struct entry_data *entry = list->data;
 253
 254                 if (g_strcmp0(entry->interface, interface) != 0)
 255                         continue;
 256
 257                 matches = g_slist_append(matches, entry);
 258         }
 259
 260         if (matches == NULL)
 261                 return -ENOENT;
 262
 263         remove_entries(matches);
 264
 265         return 0;
 266 }
 267
 268 /**
 269  * connman_resolver_append_public_server:
 270  * @server: server address
 271  *
 272  * Append public resolver server address to current list
 273  */
 274 int connman_resolver_append_public_server(const char *server)
 275 {
 276         DBG("server %s", server);
 277
 278         return append_resolver(NULL, NULL, server, RESOLVER_FLAG_PUBLIC);
 279 }
 280
 281 /**
 282  * connman_resolver_remove_public_server:
 283  * @server: server address
 284  *
 285  * Remove public resolver server address to current list
 286  */
 287 int connman_resolver_remove_public_server(const char *server)
 288 {
 289         DBG("server %s", server);
 290
 291         return connman_resolver_remove(NULL, NULL, server);
 292 }
 293
 294 /**
 295  * connman_resolver_flush:
 296  *
 297  * Flush pending resolver requests
 298  */
 299 void connman_resolver_flush(void)
 300 {
 301         GSList *list;
 302
 303         for (list = resolver_list; list; list = list->next) {
 304                 struct connman_resolver *resolver = list->data;
 305
 306                 if (resolver->flush == NULL)
 307                         continue;
 308
 309                 resolver->flush();
 310         }
 311
 312         return;
 313 }
 314
 315 struct resolvfile_entry {
 316         char *interface;
 317         char *domain;
 318         char *server;
 319 };
 320
 321 static GList *resolvfile_list = NULL;
 322
 323 static void resolvfile_remove_entries(GList *entries)
 324 {
 325         GList *list;
 326
 327         for (list = entries; list; list = list->next) {
 328                 struct resolvfile_entry *entry = list->data;
 329
 330                 resolvfile_list = g_list_remove(resolvfile_list, entry);
 331
 332                 g_free(entry->server);
 333                 g_free(entry->domain);
 334                 g_free(entry->interface);
 335                 g_free(entry);
 336         }
 337
 338         g_list_free(entries);
 339 }
 340
 341 static int resolvfile_export(void)
 342 {
 343         GList *list;
 344         GString *content;
 345         int fd, err;
 346         unsigned int count;
 347         mode_t old_umask;
 348
 349         content = g_string_new("# Generated by Connection Manager\n");
 350
 351         /*
 352          * Nameservers are added in reverse so that the most recently
 353          * appended entry is the primary nameserver. No more than MAXNS
 354          * nameservers are used.
 355          */
 356         for (count = 0, list = g_list_last(resolvfile_list);
 357                                                 list && (count < MAXNS);
 358                                                 list = g_list_previous(list)) {
 359                 struct resolvfile_entry *entry = list->data;
 360                 g_string_append_printf(content, "nameserver %s\n",
 361                                                                 entry->server);
 362                 count++;
 363         }
 364
 365         old_umask = umask(022);
 366
 367         fd = open("/etc/resolv.conf", O_RDWR | O_CREAT,
 368                                         S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
 369         if (fd < 0) {
 370                 err = -errno;
 371                 goto done;
 372         }
 373
 374         if (ftruncate(fd, 0) < 0) {
 375                 err = -errno;
 376                 goto failed;
 377         }
 378
 379         err = 0;
 380
 381         if (write(fd, content->str, content->len) < 0)
 382                 err = -errno;
 383
 384 failed:
 385         close(fd);
 386
 387 done:
 388         g_string_free(content, TRUE);
 389         umask(old_umask);
 390
 391         return err;
 392 }
 393
 394 static int resolvfile_append(const char *interface, const char *domain,
 395                                                         const char *server)
 396 {
 397         struct resolvfile_entry *entry;
 398
 399         DBG("interface %s server %s", interface, server);
 400
 401         if (interface == NULL)
 402                 return -ENOENT;
 403
 404         entry = g_try_new0(struct resolvfile_entry, 1);
 405         if (entry == NULL)
 406                 return -ENOMEM;
 407
 408         entry->interface = g_strdup(interface);
 409         entry->domain = g_strdup(domain);
 410         entry->server = g_strdup(server);
 411
 412         resolvfile_list = g_list_append(resolvfile_list, entry);
 413
 414         return resolvfile_export();
 415 }
 416
 417 static int resolvfile_remove(const char *interface, const char *domain,
 418                                                         const char *server)
 419 {
 420         GList *list, *matches = NULL;
 421
 422         DBG("interface %s server %s", interface, server);
 423
 424         for (list = resolvfile_list; list; list = g_list_next(list)) {
 425                 struct resolvfile_entry *entry = list->data;
 426
 427                 if (interface != NULL &&
 428                                 g_strcmp0(entry->interface, interface) != 0)
 429                         continue;
 430
 431                 if (domain != NULL && g_strcmp0(entry->domain, domain) != 0)
 432                         continue;
 433
 434                 if (g_strcmp0(entry->server, server) != 0)
 435                         continue;
 436
 437                 matches = g_list_append(matches, entry);
 438         }
 439
 440         resolvfile_remove_entries(matches);
 441
 442         return resolvfile_export();
 443 }
 444
 445 static struct connman_resolver resolvfile_resolver = {
 446         .name           = "resolvfile",
 447         .priority       = CONNMAN_RESOLVER_PRIORITY_LOW,
 448         .append         = resolvfile_append,
 449         .remove         = resolvfile_remove,
 450 };
 451
 452 int __connman_resolver_init(void)
 453 {
 454         DBG("");
 455
 456         return connman_resolver_register(&resolvfile_resolver);
 457 }
 458
 459 void __connman_resolver_cleanup(void)
 460 {
 461         DBG("");
 462
 463         connman_resolver_unregister(&resolvfile_resolver);
 464 }