gio/gresolver.c

   1 /* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
   2
   3 /* GIO - GLib Input, Output and Streaming Library
   4  *
   5  * Copyright (C) 2008 Red Hat, Inc.
   6  *
   7  * This library is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2 of the License, or (at your option) any later version.
  11  *
  12  * This library is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General
  18  * Public License along with this library; if not, write to the
  19  * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  20  * Boston, MA 02111-1307, USA.
  21  */
  22
  23 #include "config.h"
  24 #include <glib.h>
  25 #include "glibintl.h"
  26
  27 #include "gresolver.h"
  28 #include "gnetworkingprivate.h"
  29 #include "gasyncresult.h"
  30 #include "ginetaddress.h"
  31 #include "gsimpleasyncresult.h"
  32 #include "gtask.h"
  33 #include "gsrvtarget.h"
  34 #include "gthreadedresolver.h"
  35
  36 #ifdef G_OS_UNIX
  37 #include <sys/stat.h>
  38 #endif
  39
  40 #include <stdlib.h>
  41
  42
  43 /**
  44  * SECTION:gresolver
  45  * @short_description: Asynchronous and cancellable DNS resolver
  46  * @include: gio/gio.h
  47  *
  48  * #GResolver provides cancellable synchronous and asynchronous DNS
  49  * resolution, for hostnames (g_resolver_lookup_by_address(),
  50  * g_resolver_lookup_by_name() and their async variants) and SRV
  51  * (service) records (g_resolver_lookup_service()).
  52  *
  53  * #GNetworkAddress and #GNetworkService provide wrappers around
  54  * #GResolver functionality that also implement #GSocketConnectable,
  55  * making it easy to connect to a remote host/service.
  56  */
  57
  58 enum {
  59   RELOAD,
  60   LAST_SIGNAL
  61 };
  62
  63 static guint signals[LAST_SIGNAL] = { 0 };
  64
  65 struct _GResolverPrivate {
  66 #ifdef G_OS_UNIX
  67   time_t resolv_conf_timestamp;
  68 #else
  69   int dummy;
  70 #endif
  71 };
  72
  73 /**
  74  * GResolver:
  75  *
  76  * The object that handles DNS resolution. Use g_resolver_get_default()
  77  * to get the default resolver.
  78  */
  79 G_DEFINE_TYPE_WITH_CODE (GResolver, g_resolver, G_TYPE_OBJECT,
  80                          g_networking_init ();)
  81
  82 static GList *
  83 srv_records_to_targets (GList *records)
  84 {
  85   const gchar *hostname;
  86   guint16 port, priority, weight;
  87   GSrvTarget *target;
  88   GList *l;
  89
  90   for (l = records; l != NULL; l = g_list_next (l))
  91     {
  92       g_variant_get (l->data, "(qqq&s)", &priority, &weight, &port, &hostname);
  93       target = g_srv_target_new (hostname, port, priority, weight);
  94       g_variant_unref (l->data);
  95       l->data = target;
  96     }
  97
  98   return g_srv_target_list_sort (records);
  99 }
 100
 101 static GList *
 102 g_resolver_real_lookup_service (GResolver            *resolver,
 103                                 const gchar          *rrname,
 104                                 GCancellable         *cancellable,
 105                                 GError              **error)
 106 {
 107   GList *records;
 108
 109   records = G_RESOLVER_GET_CLASS (resolver)->lookup_records (resolver,
 110                                                              rrname,
 111                                                              G_RESOLVER_RECORD_SRV,
 112                                                              cancellable,
 113                                                              error);
 114
 115   return srv_records_to_targets (records);
 116 }
 117
 118 static void
 119 g_resolver_real_lookup_service_async (GResolver            *resolver,
 120                                       const gchar          *rrname,
 121                                       GCancellable         *cancellable,
 122                                       GAsyncReadyCallback   callback,
 123                                       gpointer              user_data)
 124 {
 125   G_RESOLVER_GET_CLASS (resolver)->lookup_records_async (resolver,
 126                                                          rrname,
 127                                                          G_RESOLVER_RECORD_SRV,
 128                                                          cancellable,
 129                                                          callback,
 130                                                          user_data);
 131 }
 132
 133 static GList *
 134 g_resolver_real_lookup_service_finish (GResolver            *resolver,
 135                                        GAsyncResult         *result,
 136                                        GError              **error)
 137 {
 138   GList *records;
 139
 140   records = G_RESOLVER_GET_CLASS (resolver)->lookup_records_finish (resolver,
 141                                                                     result,
 142                                                                     error);
 143
 144   return srv_records_to_targets (records);
 145 }
 146
 147 static void
 148 g_resolver_class_init (GResolverClass *resolver_class)
 149 {
 150   /* Automatically pass these over to the lookup_records methods */
 151   resolver_class->lookup_service = g_resolver_real_lookup_service;
 152   resolver_class->lookup_service_async = g_resolver_real_lookup_service_async;
 153   resolver_class->lookup_service_finish = g_resolver_real_lookup_service_finish;
 154
 155   g_type_class_add_private (resolver_class, sizeof (GResolverPrivate));
 156
 157   /**
 158    * GResolver::reload:
 159    * @resolver: a #GResolver
 160    *
 161    * Emitted when the resolver notices that the system resolver
 162    * configuration has changed.
 163    **/
 164   signals[RELOAD] =
 165     g_signal_new (I_("reload"),
 166                   G_TYPE_RESOLVER,
 167                   G_SIGNAL_RUN_LAST,
 168                   G_STRUCT_OFFSET (GResolverClass, reload),
 169                   NULL, NULL,
 170                   g_cclosure_marshal_VOID__VOID,
 171                   G_TYPE_NONE, 0);
 172 }
 173
 174 static void
 175 g_resolver_init (GResolver *resolver)
 176 {
 177 #ifdef G_OS_UNIX
 178   struct stat st;
 179 #endif
 180
 181   resolver->priv = G_TYPE_INSTANCE_GET_PRIVATE (resolver, G_TYPE_RESOLVER, GResolverPrivate);
 182
 183 #ifdef G_OS_UNIX
 184   if (stat (_PATH_RESCONF, &st) == 0)
 185     resolver->priv->resolv_conf_timestamp = st.st_mtime;
 186 #endif
 187 }
 188
 189 static GResolver *default_resolver;
 190
 191 /**
 192  * g_resolver_get_default:
 193  *
 194  * Gets the default #GResolver. You should unref it when you are done
 195  * with it. #GResolver may use its reference count as a hint about how
 196  * many threads it should allocate for concurrent DNS resolutions.
 197  *
 198  * Return value: (transfer full): the default #GResolver.
 199  *
 200  * Since: 2.22
 201  */
 202 GResolver *
 203 g_resolver_get_default (void)
 204 {
 205   if (!default_resolver)
 206     default_resolver = g_object_new (G_TYPE_THREADED_RESOLVER, NULL);
 207
 208   return g_object_ref (default_resolver);
 209 }
 210
 211 /**
 212  * g_resolver_set_default:
 213  * @resolver: the new default #GResolver
 214  *
 215  * Sets @resolver to be the application's default resolver (reffing
 216  * @resolver, and unreffing the previous default resolver, if any).
 217  * Future calls to g_resolver_get_default() will return this resolver.
 218  *
 219  * This can be used if an application wants to perform any sort of DNS
 220  * caching or "pinning"; it can implement its own #GResolver that
 221  * calls the original default resolver for DNS operations, and
 222  * implements its own cache policies on top of that, and then set
 223  * itself as the default resolver for all later code to use.
 224  *
 225  * Since: 2.22
 226  */
 227 void
 228 g_resolver_set_default (GResolver *resolver)
 229 {
 230   if (default_resolver)
 231     g_object_unref (default_resolver);
 232   default_resolver = g_object_ref (resolver);
 233 }
 234
 235
 236 static void
 237 g_resolver_maybe_reload (GResolver *resolver)
 238 {
 239 #ifdef G_OS_UNIX
 240   struct stat st;
 241
 242   if (stat (_PATH_RESCONF, &st) == 0)
 243     {
 244       if (st.st_mtime != resolver->priv->resolv_conf_timestamp)
 245         {
 246           resolver->priv->resolv_conf_timestamp = st.st_mtime;
 247           res_init ();
 248           g_signal_emit (resolver, signals[RELOAD], 0);
 249         }
 250     }
 251 #endif
 252 }
 253
 254 /* filter out duplicates, cf. https://bugzilla.gnome.org/show_bug.cgi?id=631379 */
 255 static void
 256 remove_duplicates (GList *addrs)
 257 {
 258   GList *l;
 259   GList *ll;
 260   GList *lll;
 261
 262   /* TODO: if this is too slow (it's O(n^2) but n is typically really
 263    * small), we can do something more clever but note that we must not
 264    * change the order of elements...
 265    */
 266   for (l = addrs; l != NULL; l = l->next)
 267     {
 268       GInetAddress *address = G_INET_ADDRESS (l->data);
 269       for (ll = l->next; ll != NULL; ll = lll)
 270         {
 271           GInetAddress *other_address = G_INET_ADDRESS (ll->data);
 272           lll = ll->next;
 273           if (g_inet_address_equal (address, other_address))
 274             {
 275               g_object_unref (other_address);
 276               /* we never return the first element */
 277               g_warn_if_fail (g_list_delete_link (addrs, ll) == addrs);
 278             }
 279         }
 280     }
 281 }
 282
 283
 284 /**
 285  * g_resolver_lookup_by_name:
 286  * @resolver: a #GResolver
 287  * @hostname: the hostname to look up
 288  * @cancellable: (allow-none): a #GCancellable, or %NULL
 289  * @error: return location for a #GError, or %NULL
 290  *
 291  * Synchronously resolves @hostname to determine its associated IP
 292  * address(es). @hostname may be an ASCII-only or UTF-8 hostname, or
 293  * the textual form of an IP address (in which case this just becomes
 294  * a wrapper around g_inet_address_new_from_string()).
 295  *
 296  * On success, g_resolver_lookup_by_name() will return a #GList of
 297  * #GInetAddress, sorted in order of preference and guaranteed to not
 298  * contain duplicates. That is, if using the result to connect to
 299  * @hostname, you should attempt to connect to the first address
 300  * first, then the second if the first fails, etc. If you are using
 301  * the result to listen on a socket, it is appropriate to add each
 302  * result using e.g. g_socket_listener_add_address().
 303  *
 304  * If the DNS resolution fails, @error (if non-%NULL) will be set to a
 305  * value from #GResolverError.
 306  *
 307  * If @cancellable is non-%NULL, it can be used to cancel the
 308  * operation, in which case @error (if non-%NULL) will be set to
 309  * %G_IO_ERROR_CANCELLED.
 310  *
 311  * If you are planning to connect to a socket on the resolved IP
 312  * address, it may be easier to create a #GNetworkAddress and use its
 313  * #GSocketConnectable interface.
 314  *
 315  * Return value: (element-type GInetAddress) (transfer full): a #GList
 316  * of #GInetAddress, or %NULL on error. You
 317  * must unref each of the addresses and free the list when you are
 318  * done with it. (You can use g_resolver_free_addresses() to do this.)
 319  *
 320  * Since: 2.22
 321  */
 322 GList *
 323 g_resolver_lookup_by_name (GResolver     *resolver,
 324                            const gchar   *hostname,
 325                            GCancellable  *cancellable,
 326                            GError       **error)
 327 {
 328   GInetAddress *addr;
 329   GList *addrs;
 330   gchar *ascii_hostname = NULL;
 331
 332   g_return_val_if_fail (G_IS_RESOLVER (resolver), NULL);
 333   g_return_val_if_fail (hostname != NULL, NULL);
 334
 335   /* Check if @hostname is just an IP address */
 336   addr = g_inet_address_new_from_string (hostname);
 337   if (addr)
 338     return g_list_append (NULL, addr);
 339
 340   if (g_hostname_is_non_ascii (hostname))
 341     hostname = ascii_hostname = g_hostname_to_ascii (hostname);
 342
 343   g_resolver_maybe_reload (resolver);
 344   addrs = G_RESOLVER_GET_CLASS (resolver)->
 345     lookup_by_name (resolver, hostname, cancellable, error);
 346
 347   remove_duplicates (addrs);
 348
 349   g_free (ascii_hostname);
 350   return addrs;
 351 }
 352
 353 /**
 354  * g_resolver_lookup_by_name_async:
 355  * @resolver: a #GResolver
 356  * @hostname: the hostname to look up the address of
 357  * @cancellable: (allow-none): a #GCancellable, or %NULL
 358  * @callback: (scope async): callback to call after resolution completes
 359  * @user_data: (closure): data for @callback
 360  *
 361  * Begins asynchronously resolving @hostname to determine its
 362  * associated IP address(es), and eventually calls @callback, which
 363  * must call g_resolver_lookup_by_name_finish() to get the result.
 364  * See g_resolver_lookup_by_name() for more details.
 365  *
 366  * Since: 2.22
 367  */
 368 void
 369 g_resolver_lookup_by_name_async (GResolver           *resolver,
 370                                  const gchar         *hostname,
 371                                  GCancellable        *cancellable,
 372                                  GAsyncReadyCallback  callback,
 373                                  gpointer             user_data)
 374 {
 375   GInetAddress *addr;
 376   gchar *ascii_hostname = NULL;
 377
 378   g_return_if_fail (G_IS_RESOLVER (resolver));
 379   g_return_if_fail (hostname != NULL);
 380
 381   /* Check if @hostname is just an IP address */
 382   addr = g_inet_address_new_from_string (hostname);
 383   if (addr)
 384     {
 385       GTask *task;
 386
 387       task = g_task_new (resolver, cancellable, callback, user_data);
 388       g_task_set_source_tag (task, g_resolver_lookup_by_name_async);
 389       g_task_return_pointer (task, g_list_append (NULL, addr),
 390                              (GDestroyNotify) g_resolver_free_addresses);
 391       g_object_unref (task);
 392       return;
 393     }
 394
 395   if (g_hostname_is_non_ascii (hostname))
 396     hostname = ascii_hostname = g_hostname_to_ascii (hostname);
 397
 398   g_resolver_maybe_reload (resolver);
 399   G_RESOLVER_GET_CLASS (resolver)->
 400     lookup_by_name_async (resolver, hostname, cancellable, callback, user_data);
 401
 402   g_free (ascii_hostname);
 403 }
 404
 405 /**
 406  * g_resolver_lookup_by_name_finish:
 407  * @resolver: a #GResolver
 408  * @result: the result passed to your #GAsyncReadyCallback
 409  * @error: return location for a #GError, or %NULL
 410  *
 411  * Retrieves the result of a call to
 412  * g_resolver_lookup_by_name_async().
 413  *
 414  * If the DNS resolution failed, @error (if non-%NULL) will be set to
 415  * a value from #GResolverError. If the operation was cancelled,
 416  * @error will be set to %G_IO_ERROR_CANCELLED.
 417  *
 418  * Return value: (element-type GInetAddress) (transfer full): a #GList
 419  * of #GInetAddress, or %NULL on error. See g_resolver_lookup_by_name()
 420  * for more details.
 421  *
 422  * Since: 2.22
 423  */
 424 GList *
 425 g_resolver_lookup_by_name_finish (GResolver     *resolver,
 426                                   GAsyncResult  *result,
 427                                   GError       **error)
 428 {
 429   GList *addrs;
 430
 431   g_return_val_if_fail (G_IS_RESOLVER (resolver), NULL);
 432
 433   if (g_async_result_legacy_propagate_error (result, error))
 434     return NULL;
 435   else if (g_async_result_is_tagged (result, g_resolver_lookup_by_name_async))
 436     {
 437       /* Handle the stringified-IP-addr case */
 438       return g_task_propagate_pointer (G_TASK (result), error);
 439     }
 440
 441   addrs = G_RESOLVER_GET_CLASS (resolver)->
 442     lookup_by_name_finish (resolver, result, error);
 443
 444   remove_duplicates (addrs);
 445
 446   return addrs;
 447 }
 448
 449 /**
 450  * g_resolver_free_addresses: (skip)
 451  * @addresses: a #GList of #GInetAddress
 452  *
 453  * Frees @addresses (which should be the return value from
 454  * g_resolver_lookup_by_name() or g_resolver_lookup_by_name_finish()).
 455  * (This is a convenience method; you can also simply free the results
 456  * by hand.)
 457  *
 458  * Since: 2.22
 459  */
 460 void
 461 g_resolver_free_addresses (GList *addresses)
 462 {
 463   GList *a;
 464
 465   for (a = addresses; a; a = a->next)
 466     g_object_unref (a->data);
 467   g_list_free (addresses);
 468 }
 469
 470 /**
 471  * g_resolver_lookup_by_address:
 472  * @resolver: a #GResolver
 473  * @address: the address to reverse-resolve
 474  * @cancellable: (allow-none): a #GCancellable, or %NULL
 475  * @error: return location for a #GError, or %NULL
 476  *
 477  * Synchronously reverse-resolves @address to determine its
 478  * associated hostname.
 479  *
 480  * If the DNS resolution fails, @error (if non-%NULL) will be set to
 481  * a value from #GResolverError.
 482  *
 483  * If @cancellable is non-%NULL, it can be used to cancel the
 484  * operation, in which case @error (if non-%NULL) will be set to
 485  * %G_IO_ERROR_CANCELLED.
 486  *
 487  * Return value: a hostname (either ASCII-only, or in ASCII-encoded
 488  *     form), or %NULL on error.
 489  *
 490  * Since: 2.22
 491  */
 492 gchar *
 493 g_resolver_lookup_by_address (GResolver     *resolver,
 494                               GInetAddress  *address,
 495                               GCancellable  *cancellable,
 496                               GError       **error)
 497 {
 498   g_return_val_if_fail (G_IS_RESOLVER (resolver), NULL);
 499   g_return_val_if_fail (G_IS_INET_ADDRESS (address), NULL);
 500
 501   g_resolver_maybe_reload (resolver);
 502   return G_RESOLVER_GET_CLASS (resolver)->
 503     lookup_by_address (resolver, address, cancellable, error);
 504 }
 505
 506 /**
 507  * g_resolver_lookup_by_address_async:
 508  * @resolver: a #GResolver
 509  * @address: the address to reverse-resolve
 510  * @cancellable: (allow-none): a #GCancellable, or %NULL
 511  * @callback: (scope async): callback to call after resolution completes
 512  * @user_data: (closure): data for @callback
 513  *
 514  * Begins asynchronously reverse-resolving @address to determine its
 515  * associated hostname, and eventually calls @callback, which must
 516  * call g_resolver_lookup_by_address_finish() to get the final result.
 517  *
 518  * Since: 2.22
 519  */
 520 void
 521 g_resolver_lookup_by_address_async (GResolver           *resolver,
 522                                     GInetAddress        *address,
 523                                     GCancellable        *cancellable,
 524                                     GAsyncReadyCallback  callback,
 525                                     gpointer             user_data)
 526 {
 527   g_return_if_fail (G_IS_RESOLVER (resolver));
 528   g_return_if_fail (G_IS_INET_ADDRESS (address));
 529
 530   g_resolver_maybe_reload (resolver);
 531   G_RESOLVER_GET_CLASS (resolver)->
 532     lookup_by_address_async (resolver, address, cancellable, callback, user_data);
 533 }
 534
 535 /**
 536  * g_resolver_lookup_by_address_finish:
 537  * @resolver: a #GResolver
 538  * @result: the result passed to your #GAsyncReadyCallback
 539  * @error: return location for a #GError, or %NULL
 540  *
 541  * Retrieves the result of a previous call to
 542  * g_resolver_lookup_by_address_async().
 543  *
 544  * If the DNS resolution failed, @error (if non-%NULL) will be set to
 545  * a value from #GResolverError. If the operation was cancelled,
 546  * @error will be set to %G_IO_ERROR_CANCELLED.
 547  *
 548  * Return value: a hostname (either ASCII-only, or in ASCII-encoded
 549  * form), or %NULL on error.
 550  *
 551  * Since: 2.22
 552  */
 553 gchar *
 554 g_resolver_lookup_by_address_finish (GResolver     *resolver,
 555                                      GAsyncResult  *result,
 556                                      GError       **error)
 557 {
 558   g_return_val_if_fail (G_IS_RESOLVER (resolver), NULL);
 559
 560   if (g_async_result_legacy_propagate_error (result, error))
 561     return NULL;
 562
 563   return G_RESOLVER_GET_CLASS (resolver)->
 564     lookup_by_address_finish (resolver, result, error);
 565 }
 566
 567 static gchar *
 568 g_resolver_get_service_rrname (const char *service,
 569                                const char *protocol,
 570                                const char *domain)
 571 {
 572   gchar *rrname, *ascii_domain = NULL;
 573
 574   if (g_hostname_is_non_ascii (domain))
 575     domain = ascii_domain = g_hostname_to_ascii (domain);
 576
 577   rrname = g_strdup_printf ("_%s._%s.%s", service, protocol, domain);
 578
 579   g_free (ascii_domain);
 580   return rrname;
 581 }
 582
 583 /**
 584  * g_resolver_lookup_service:
 585  * @resolver: a #GResolver
 586  * @service: the service type to look up (eg, "ldap")
 587  * @protocol: the networking protocol to use for @service (eg, "tcp")
 588  * @domain: the DNS domain to look up the service in
 589  * @cancellable: (allow-none): a #GCancellable, or %NULL
 590  * @error: return location for a #GError, or %NULL
 591  *
 592  * Synchronously performs a DNS SRV lookup for the given @service and
 593  * @protocol in the given @domain and returns an array of #GSrvTarget.
 594  * @domain may be an ASCII-only or UTF-8 hostname. Note also that the
 595  * @service and @protocol arguments <emphasis>do not</emphasis>
 596  * include the leading underscore that appears in the actual DNS
 597  * entry.
 598  *
 599  * On success, g_resolver_lookup_service() will return a #GList of
 600  * #GSrvTarget, sorted in order of preference. (That is, you should
 601  * attempt to connect to the first target first, then the second if
 602  * the first fails, etc.)
 603  *
 604  * If the DNS resolution fails, @error (if non-%NULL) will be set to
 605  * a value from #GResolverError.
 606  *
 607  * If @cancellable is non-%NULL, it can be used to cancel the
 608  * operation, in which case @error (if non-%NULL) will be set to
 609  * %G_IO_ERROR_CANCELLED.
 610  *
 611  * If you are planning to connect to the service, it is usually easier
 612  * to create a #GNetworkService and use its #GSocketConnectable
 613  * interface.
 614  *
 615  * Return value: (element-type GSrvTarget) (transfer full): a #GList of #GSrvTarget,
 616  * or %NULL on error. You must free each of the targets and the list when you are
 617  * done with it. (You can use g_resolver_free_targets() to do this.)
 618  *
 619  * Since: 2.22
 620  */
 621 GList *
 622 g_resolver_lookup_service (GResolver     *resolver,
 623                            const gchar   *service,
 624                            const gchar   *protocol,
 625                            const gchar   *domain,
 626                            GCancellable  *cancellable,
 627                            GError       **error)
 628 {
 629   GList *targets;
 630   gchar *rrname;
 631
 632   g_return_val_if_fail (G_IS_RESOLVER (resolver), NULL);
 633   g_return_val_if_fail (service != NULL, NULL);
 634   g_return_val_if_fail (protocol != NULL, NULL);
 635   g_return_val_if_fail (domain != NULL, NULL);
 636
 637   rrname = g_resolver_get_service_rrname (service, protocol, domain);
 638
 639   g_resolver_maybe_reload (resolver);
 640   targets = G_RESOLVER_GET_CLASS (resolver)->
 641     lookup_service (resolver, rrname, cancellable, error);
 642
 643   g_free (rrname);
 644   return targets;
 645 }
 646
 647 /**
 648  * g_resolver_lookup_service_async:
 649  * @resolver: a #GResolver
 650  * @service: the service type to look up (eg, "ldap")
 651  * @protocol: the networking protocol to use for @service (eg, "tcp")
 652  * @domain: the DNS domain to look up the service in
 653  * @cancellable: (allow-none): a #GCancellable, or %NULL
 654  * @callback: (scope async): callback to call after resolution completes
 655  * @user_data: (closure): data for @callback
 656  *
 657  * Begins asynchronously performing a DNS SRV lookup for the given
 658  * @service and @protocol in the given @domain, and eventually calls
 659  * @callback, which must call g_resolver_lookup_service_finish() to
 660  * get the final result. See g_resolver_lookup_service() for more
 661  * details.
 662  *
 663  * Since: 2.22
 664  */
 665 void
 666 g_resolver_lookup_service_async (GResolver           *resolver,
 667                                  const gchar         *service,
 668                                  const gchar         *protocol,
 669                                  const gchar         *domain,
 670                                  GCancellable        *cancellable,
 671                                  GAsyncReadyCallback  callback,
 672                                  gpointer             user_data)
 673 {
 674   gchar *rrname;
 675
 676   g_return_if_fail (G_IS_RESOLVER (resolver));
 677   g_return_if_fail (service != NULL);
 678   g_return_if_fail (protocol != NULL);
 679   g_return_if_fail (domain != NULL);
 680
 681   rrname = g_resolver_get_service_rrname (service, protocol, domain);
 682
 683   g_resolver_maybe_reload (resolver);
 684   G_RESOLVER_GET_CLASS (resolver)->
 685     lookup_service_async (resolver, rrname, cancellable, callback, user_data);
 686
 687   g_free (rrname);
 688 }
 689
 690 /**
 691  * g_resolver_lookup_service_finish:
 692  * @resolver: a #GResolver
 693  * @result: the result passed to your #GAsyncReadyCallback
 694  * @error: return location for a #GError, or %NULL
 695  *
 696  * Retrieves the result of a previous call to
 697  * g_resolver_lookup_service_async().
 698  *
 699  * If the DNS resolution failed, @error (if non-%NULL) will be set to
 700  * a value from #GResolverError. If the operation was cancelled,
 701  * @error will be set to %G_IO_ERROR_CANCELLED.
 702  *
 703  * Return value: (element-type GSrvTarget) (transfer full): a #GList of #GSrvTarget,
 704  * or %NULL on error. See g_resolver_lookup_service() for more details.
 705  *
 706  * Since: 2.22
 707  */
 708 GList *
 709 g_resolver_lookup_service_finish (GResolver     *resolver,
 710                                   GAsyncResult  *result,
 711                                   GError       **error)
 712 {
 713   g_return_val_if_fail (G_IS_RESOLVER (resolver), NULL);
 714
 715   if (g_async_result_legacy_propagate_error (result, error))
 716     return NULL;
 717
 718   return G_RESOLVER_GET_CLASS (resolver)->
 719     lookup_service_finish (resolver, result, error);
 720 }
 721
 722 /**
 723  * g_resolver_free_targets: (skip)
 724  * @targets: a #GList of #GSrvTarget
 725  *
 726  * Frees @targets (which should be the return value from
 727  * g_resolver_lookup_service() or g_resolver_lookup_service_finish()).
 728  * (This is a convenience method; you can also simply free the
 729  * results by hand.)
 730  *
 731  * Since: 2.22
 732  */
 733 void
 734 g_resolver_free_targets (GList *targets)
 735 {
 736   GList *t;
 737
 738   for (t = targets; t; t = t->next)
 739     g_srv_target_free (t->data);
 740   g_list_free (targets);
 741 }
 742
 743 /**
 744  * g_resolver_lookup_records:
 745  * @resolver: a #GResolver
 746  * @rrname: the DNS name to lookup the record for
 747  * @record_type: the type of DNS record to lookup
 748  * @cancellable: (allow-none): a #GCancellable, or %NULL
 749  * @error: return location for a #GError, or %NULL
 750  *
 751  * Synchronously performs a DNS record lookup for the given @rrname and returns
 752  * a list of records as #GVariant tuples. See #GResolverRecordType for
 753  * information on what the records contain for each @record_type.
 754  *
 755  * If the DNS resolution fails, @error (if non-%NULL) will be set to
 756  * a value from #GResolverError.
 757  *
 758  * If @cancellable is non-%NULL, it can be used to cancel the
 759  * operation, in which case @error (if non-%NULL) will be set to
 760  * %G_IO_ERROR_CANCELLED.
 761  *
 762  * Return value: (element-type GVariant) (transfer full): a #GList of #GVariant,
 763  * or %NULL on error. You must free each of the records and the list when you are
 764  * done with it. (You can use g_list_free_full() with g_variant_unref() to do this.)
 765  *
 766  * Since: 2.34
 767  */
 768 GList *
 769 g_resolver_lookup_records (GResolver            *resolver,
 770                            const gchar          *rrname,
 771                            GResolverRecordType   record_type,
 772                            GCancellable         *cancellable,
 773                            GError              **error)
 774 {
 775   GList *records;
 776
 777   g_return_val_if_fail (G_IS_RESOLVER (resolver), NULL);
 778   g_return_val_if_fail (rrname != NULL, NULL);
 779
 780   g_resolver_maybe_reload (resolver);
 781   records = G_RESOLVER_GET_CLASS (resolver)->
 782     lookup_records (resolver, rrname, record_type, cancellable, error);
 783
 784   return records;
 785 }
 786
 787 /**
 788  * g_resolver_lookup_records_async:
 789  * @resolver: a #GResolver
 790  * @rrname: the DNS name to lookup the record for
 791  * @record_type: the type of DNS record to lookup
 792  * @cancellable: (allow-none): a #GCancellable, or %NULL
 793  * @callback: (scope async): callback to call after resolution completes
 794  * @user_data: (closure): data for @callback
 795  *
 796  * Begins asynchronously performing a DNS lookup for the given
 797  * @rrname, and eventually calls @callback, which must call
 798  * g_resolver_lookup_records_finish() to get the final result. See
 799  * g_resolver_lookup_records() for more details.
 800  *
 801  * Since: 2.34
 802  */
 803 void
 804 g_resolver_lookup_records_async (GResolver           *resolver,
 805                                  const gchar         *rrname,
 806                                  GResolverRecordType  record_type,
 807                                  GCancellable        *cancellable,
 808                                  GAsyncReadyCallback  callback,
 809                                  gpointer             user_data)
 810 {
 811   g_return_if_fail (G_IS_RESOLVER (resolver));
 812   g_return_if_fail (rrname != NULL);
 813
 814   g_resolver_maybe_reload (resolver);
 815   G_RESOLVER_GET_CLASS (resolver)->
 816     lookup_records_async (resolver, rrname, record_type, cancellable, callback, user_data);
 817 }
 818
 819 /**
 820  * g_resolver_lookup_records_finish:
 821  * @resolver: a #GResolver
 822  * @result: the result passed to your #GAsyncReadyCallback
 823  * @error: return location for a #GError, or %NULL
 824  *
 825  * Retrieves the result of a previous call to
 826  * g_resolver_lookup_records_async(). Returns a list of records as #GVariant
 827  * tuples. See #GResolverRecordType for information on what the records contain.
 828  *
 829  * If the DNS resolution failed, @error (if non-%NULL) will be set to
 830  * a value from #GResolverError. If the operation was cancelled,
 831  * @error will be set to %G_IO_ERROR_CANCELLED.
 832  *
 833  * Return value: (element-type GVariant) (transfer full): a #GList of #GVariant,
 834  * or %NULL on error. You must free each of the records and the list when you are
 835  * done with it. (You can use g_list_free_full() with g_variant_unref() to do this.)
 836  *
 837  * Since: 2.34
 838  */
 839 GList *
 840 g_resolver_lookup_records_finish (GResolver     *resolver,
 841                                   GAsyncResult  *result,
 842                                   GError       **error)
 843 {
 844   g_return_val_if_fail (G_IS_RESOLVER (resolver), NULL);
 845   return G_RESOLVER_GET_CLASS (resolver)->
 846     lookup_records_finish (resolver, result, error);
 847 }
 848
 849 /**
 850  * g_resolver_error_quark:
 851  *
 852  * Gets the #GResolver Error Quark.
 853  *
 854  * Return value: a #GQuark.
 855  *
 856  * Since: 2.22
 857  */
 858 G_DEFINE_QUARK (g-resolver-error-quark, g_resolver_error)