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 "ginetsocketaddress.h"
  32 #include "gsimpleasyncresult.h"
  33 #include "gsrvtarget.h"
  34
  35 #ifdef G_OS_UNIX
  36 #include "gunixresolver.h"
  37 #include <sys/stat.h>
  38 #endif
  39 #ifdef G_OS_WIN32
  40 #include "gwin32resolver.h"
  41 #endif
  42
  43 #include <stdlib.h>
  44
  45
  46 /**
  47  * SECTION:gresolver
  48  * @short_description: Asynchronous and cancellable DNS resolver
  49  * @include: gio/gio.h
  50  *
  51  * #GResolver provides cancellable synchronous and asynchronous DNS
  52  * resolution, for hostnames (g_resolver_lookup_by_address(),
  53  * g_resolver_lookup_by_name() and their async variants) and SRV
  54  * (service) records (g_resolver_lookup_service()).
  55  *
  56  * #GNetworkAddress and #GNetworkService provide wrappers around
  57  * #GResolver functionality that also implement #GSocketConnectable,
  58  * making it easy to connect to a remote host/service.
  59  */
  60
  61 enum {
  62   RELOAD,
  63   LAST_SIGNAL
  64 };
  65
  66 static guint signals[LAST_SIGNAL] = { 0 };
  67
  68 struct _GResolverPrivate {
  69 #ifdef G_OS_UNIX
  70   time_t resolv_conf_timestamp;
  71 #else
  72   int dummy;
  73 #endif
  74 };
  75
  76 /**
  77  * GResolver:
  78  *
  79  * The object that handles DNS resolution. Use g_resolver_get_default()
  80  * to get the default resolver.
  81  */
  82 G_DEFINE_TYPE (GResolver, g_resolver, G_TYPE_OBJECT)
  83
  84 static void
  85 g_resolver_class_init (GResolverClass *resolver_class)
  86 {
  87   volatile GType type;
  88
  89   g_type_class_add_private (resolver_class, sizeof (GResolverPrivate));
  90
  91   /* Make sure _g_networking_init() has been called */
  92   type = g_inet_address_get_type ();
  93
  94   /* Initialize _g_resolver_addrinfo_hints */
  95 #ifdef AI_ADDRCONFIG
  96   _g_resolver_addrinfo_hints.ai_flags |= AI_ADDRCONFIG;
  97 #endif
  98   /* These two don't actually matter, they just get copied into the
  99    * returned addrinfo structures (and then we ignore them). But if
 100    * we leave them unset, we'll get back duplicate answers.
 101    */
 102   _g_resolver_addrinfo_hints.ai_socktype = SOCK_STREAM;
 103   _g_resolver_addrinfo_hints.ai_protocol = IPPROTO_TCP;
 104
 105   /**
 106    * GResolver::reload:
 107    * @resolver: a #GResolver
 108    *
 109    * Emitted when the resolver notices that the system resolver
 110    * configuration has changed.
 111    **/
 112   signals[RELOAD] =
 113     g_signal_new (I_("reload"),
 114                   G_TYPE_RESOLVER,
 115                   G_SIGNAL_RUN_LAST,
 116                   G_STRUCT_OFFSET (GResolverClass, reload),
 117                   NULL, NULL,
 118                   g_cclosure_marshal_VOID__VOID,
 119                   G_TYPE_NONE, 0);
 120 }
 121
 122 static void
 123 g_resolver_init (GResolver *resolver)
 124 {
 125 #ifdef G_OS_UNIX
 126   struct stat st;
 127 #endif
 128
 129   resolver->priv = G_TYPE_INSTANCE_GET_PRIVATE (resolver, G_TYPE_RESOLVER, GResolverPrivate);
 130
 131 #ifdef G_OS_UNIX
 132   if (stat (_PATH_RESCONF, &st) == 0)
 133     resolver->priv->resolv_conf_timestamp = st.st_mtime;
 134 #endif
 135 }
 136
 137 static GResolver *default_resolver;
 138
 139 /**
 140  * g_resolver_get_default:
 141  *
 142  * Gets the default #GResolver. You should unref it when you are done
 143  * with it. #GResolver may use its reference count as a hint about how
 144  * many threads/processes, etc it should allocate for concurrent DNS
 145  * resolutions.
 146  *
 147  * Return value: (transfer full): the default #GResolver.
 148  *
 149  * Since: 2.22
 150  */
 151 GResolver *
 152 g_resolver_get_default (void)
 153 {
 154   if (!default_resolver)
 155     {
 156       if (g_thread_supported ())
 157         default_resolver = g_object_new (G_TYPE_THREADED_RESOLVER, NULL);
 158       else
 159         {
 160 #if defined(G_OS_UNIX)
 161           default_resolver = g_object_new (G_TYPE_UNIX_RESOLVER, NULL);
 162 #elif defined(G_OS_WIN32)
 163           default_resolver = g_object_new (G_TYPE_WIN32_RESOLVER, NULL);
 164 #endif
 165         }
 166     }
 167
 168   return g_object_ref (default_resolver);
 169 }
 170
 171 /**
 172  * g_resolver_set_default:
 173  * @resolver: the new default #GResolver
 174  *
 175  * Sets @resolver to be the application's default resolver (reffing
 176  * @resolver, and unreffing the previous default resolver, if any).
 177  * Future calls to g_resolver_get_default() will return this resolver.
 178  *
 179  * This can be used if an application wants to perform any sort of DNS
 180  * caching or "pinning"; it can implement its own #GResolver that
 181  * calls the original default resolver for DNS operations, and
 182  * implements its own cache policies on top of that, and then set
 183  * itself as the default resolver for all later code to use.
 184  *
 185  * Since: 2.22
 186  */
 187 void
 188 g_resolver_set_default (GResolver *resolver)
 189 {
 190   if (default_resolver)
 191     g_object_unref (default_resolver);
 192   default_resolver = g_object_ref (resolver);
 193 }
 194
 195
 196 static void
 197 g_resolver_maybe_reload (GResolver *resolver)
 198 {
 199 #ifdef G_OS_UNIX
 200   struct stat st;
 201
 202   if (stat (_PATH_RESCONF, &st) == 0)
 203     {
 204       if (st.st_mtime != resolver->priv->resolv_conf_timestamp)
 205         {
 206           resolver->priv->resolv_conf_timestamp = st.st_mtime;
 207           res_init ();
 208           g_signal_emit (resolver, signals[RELOAD], 0);
 209         }
 210     }
 211 #endif
 212 }
 213
 214 /**
 215  * g_resolver_lookup_by_name:
 216  * @resolver: a #GResolver
 217  * @hostname: the hostname to look up
 218  * @cancellable: a #GCancellable, or %NULL
 219  * @error: return location for a #GError, or %NULL
 220  *
 221  * Synchronously resolves @hostname to determine its associated IP
 222  * address(es). @hostname may be an ASCII-only or UTF-8 hostname, or
 223  * the textual form of an IP address (in which case this just becomes
 224  * a wrapper around g_inet_address_new_from_string()).
 225  *
 226  * On success, g_resolver_lookup_by_name() will return a #GList of
 227  * #GInetAddress, sorted in order of preference. (That is, you should
 228  * attempt to connect to the first address first, then the second if
 229  * the first fails, etc.)
 230  *
 231  * If the DNS resolution fails, @error (if non-%NULL) will be set to a
 232  * value from #GResolverError.
 233  *
 234  * If @cancellable is non-%NULL, it can be used to cancel the
 235  * operation, in which case @error (if non-%NULL) will be set to
 236  * %G_IO_ERROR_CANCELLED.
 237  *
 238  * If you are planning to connect to a socket on the resolved IP
 239  * address, it may be easier to create a #GNetworkAddress and use its
 240  * #GSocketConnectable interface.
 241  *
 242  * Return value: (element-type GInetAddress) (transfer full): a #GList
 243  * of #GInetAddress, or %NULL on error. You
 244  * must unref each of the addresses and free the list when you are
 245  * done with it. (You can use g_resolver_free_addresses() to do this.)
 246  *
 247  * Since: 2.22
 248  */
 249 GList *
 250 g_resolver_lookup_by_name (GResolver     *resolver,
 251                            const gchar   *hostname,
 252                            GCancellable  *cancellable,
 253                            GError       **error)
 254 {
 255   GInetAddress *addr;
 256   GList *addrs;
 257   gchar *ascii_hostname = NULL;
 258
 259   g_return_val_if_fail (G_IS_RESOLVER (resolver), NULL);
 260   g_return_val_if_fail (hostname != NULL, NULL);
 261
 262   /* Check if @hostname is just an IP address */
 263   addr = g_inet_address_new_from_string (hostname);
 264   if (addr)
 265     return g_list_append (NULL, addr);
 266
 267   if (g_hostname_is_non_ascii (hostname))
 268     hostname = ascii_hostname = g_hostname_to_ascii (hostname);
 269
 270   g_resolver_maybe_reload (resolver);
 271   addrs = G_RESOLVER_GET_CLASS (resolver)->
 272     lookup_by_name (resolver, hostname, cancellable, error);
 273
 274   g_free (ascii_hostname);
 275   return addrs;
 276 }
 277
 278 /**
 279  * g_resolver_lookup_by_name_async:
 280  * @resolver: a #GResolver
 281  * @hostname: the hostname to look up the address of
 282  * @cancellable: a #GCancellable, or %NULL
 283  * @callback: callback to call after resolution completes
 284  * @user_data: data for @callback
 285  *
 286  * Begins asynchronously resolving @hostname to determine its
 287  * associated IP address(es), and eventually calls @callback, which
 288  * must call g_resolver_lookup_by_name_finish() to get the result.
 289  * See g_resolver_lookup_by_name() for more details.
 290  *
 291  * Since: 2.22
 292  */
 293 void
 294 g_resolver_lookup_by_name_async (GResolver           *resolver,
 295                                  const gchar         *hostname,
 296                                  GCancellable        *cancellable,
 297                                  GAsyncReadyCallback  callback,
 298                                  gpointer             user_data)
 299 {
 300   GInetAddress *addr;
 301   gchar *ascii_hostname = NULL;
 302
 303   g_return_if_fail (G_IS_RESOLVER (resolver));
 304   g_return_if_fail (hostname != NULL);
 305
 306   /* Check if @hostname is just an IP address */
 307   addr = g_inet_address_new_from_string (hostname);
 308   if (addr)
 309     {
 310       GSimpleAsyncResult *simple;
 311
 312       simple = g_simple_async_result_new (G_OBJECT (resolver),
 313                                           callback, user_data,
 314                                           g_resolver_lookup_by_name_async);
 315
 316       g_simple_async_result_set_op_res_gpointer (simple, addr, g_object_unref);
 317       g_simple_async_result_complete_in_idle (simple);
 318       g_object_unref (simple);
 319       return;
 320     }
 321
 322   if (g_hostname_is_non_ascii (hostname))
 323     hostname = ascii_hostname = g_hostname_to_ascii (hostname);
 324
 325   g_resolver_maybe_reload (resolver);
 326   G_RESOLVER_GET_CLASS (resolver)->
 327     lookup_by_name_async (resolver, hostname, cancellable, callback, user_data);
 328
 329   g_free (ascii_hostname);
 330 }
 331
 332 /**
 333  * g_resolver_lookup_by_name_finish:
 334  * @resolver: a #GResolver
 335  * @result: the result passed to your #GAsyncReadyCallback
 336  * @error: return location for a #GError, or %NULL
 337  *
 338  * Retrieves the result of a call to
 339  * g_resolver_lookup_by_name_async().
 340  *
 341  * If the DNS resolution failed, @error (if non-%NULL) will be set to
 342  * a value from #GResolverError. If the operation was cancelled,
 343  * @error will be set to %G_IO_ERROR_CANCELLED.
 344  *
 345  * Return value: (element-type GInetAddress) (transfer full): a #GList
 346  * of #GInetAddress, or %NULL on error. See g_resolver_lookup_by_name()
 347  * for more details.
 348  *
 349  * Since: 2.22
 350  */
 351 GList *
 352 g_resolver_lookup_by_name_finish (GResolver     *resolver,
 353                                   GAsyncResult  *result,
 354                                   GError       **error)
 355 {
 356   g_return_val_if_fail (G_IS_RESOLVER (resolver), NULL);
 357
 358   if (G_IS_SIMPLE_ASYNC_RESULT (result))
 359     {
 360       GSimpleAsyncResult *simple = G_SIMPLE_ASYNC_RESULT (result);
 361
 362       if (g_simple_async_result_propagate_error (simple, error))
 363         return NULL;
 364
 365       /* Handle the stringified-IP-addr case */
 366       if (g_simple_async_result_get_source_tag (simple) == g_resolver_lookup_by_name_async)
 367         {
 368           GInetAddress *addr;
 369
 370           addr = g_simple_async_result_get_op_res_gpointer (simple);
 371           return g_list_append (NULL, g_object_ref (addr));
 372         }
 373     }
 374
 375   return G_RESOLVER_GET_CLASS (resolver)->
 376     lookup_by_name_finish (resolver, result, error);
 377 }
 378
 379 /**
 380  * g_resolver_free_addresses: (skip)
 381  * @addresses: a #GList of #GInetAddress
 382  *
 383  * Frees @addresses (which should be the return value from
 384  * g_resolver_lookup_by_name() or g_resolver_lookup_by_name_finish()).
 385  * (This is a convenience method; you can also simply free the results
 386  * by hand.)
 387  *
 388  * Since: 2.22
 389  */
 390 void
 391 g_resolver_free_addresses (GList *addresses)
 392 {
 393   GList *a;
 394
 395   for (a = addresses; a; a = a->next)
 396     g_object_unref (a->data);
 397   g_list_free (addresses);
 398 }
 399
 400 /**
 401  * g_resolver_lookup_by_address:
 402  * @resolver: a #GResolver
 403  * @address: the address to reverse-resolve
 404  * @cancellable: a #GCancellable, or %NULL
 405  * @error: return location for a #GError, or %NULL
 406  *
 407  * Synchronously reverse-resolves @address to determine its
 408  * associated hostname.
 409  *
 410  * If the DNS resolution fails, @error (if non-%NULL) will be set to
 411  * a value from #GResolverError.
 412  *
 413  * If @cancellable is non-%NULL, it can be used to cancel the
 414  * operation, in which case @error (if non-%NULL) will be set to
 415  * %G_IO_ERROR_CANCELLED.
 416  *
 417  * Return value: a hostname (either ASCII-only, or in ASCII-encoded
 418  *     form), or %NULL on error.
 419  *
 420  * Since: 2.22
 421  */
 422 gchar *
 423 g_resolver_lookup_by_address (GResolver     *resolver,
 424                               GInetAddress  *address,
 425                               GCancellable  *cancellable,
 426                               GError       **error)
 427 {
 428   g_return_val_if_fail (G_IS_RESOLVER (resolver), NULL);
 429   g_return_val_if_fail (G_IS_INET_ADDRESS (address), NULL);
 430
 431   g_resolver_maybe_reload (resolver);
 432   return G_RESOLVER_GET_CLASS (resolver)->
 433     lookup_by_address (resolver, address, cancellable, error);
 434 }
 435
 436 /**
 437  * g_resolver_lookup_by_address_async:
 438  * @resolver: a #GResolver
 439  * @address: the address to reverse-resolve
 440  * @cancellable: a #GCancellable, or %NULL
 441  * @callback: callback to call after resolution completes
 442  * @user_data: data for @callback
 443  *
 444  * Begins asynchronously reverse-resolving @address to determine its
 445  * associated hostname, and eventually calls @callback, which must
 446  * call g_resolver_lookup_by_address_finish() to get the final result.
 447  *
 448  * Since: 2.22
 449  */
 450 void
 451 g_resolver_lookup_by_address_async (GResolver           *resolver,
 452                                     GInetAddress        *address,
 453                                     GCancellable        *cancellable,
 454                                     GAsyncReadyCallback  callback,
 455                                     gpointer             user_data)
 456 {
 457   g_return_if_fail (G_IS_RESOLVER (resolver));
 458   g_return_if_fail (G_IS_INET_ADDRESS (address));
 459
 460   g_resolver_maybe_reload (resolver);
 461   G_RESOLVER_GET_CLASS (resolver)->
 462     lookup_by_address_async (resolver, address, cancellable, callback, user_data);
 463 }
 464
 465 /**
 466  * g_resolver_lookup_by_address_finish:
 467  * @resolver: a #GResolver
 468  * @result: the result passed to your #GAsyncReadyCallback
 469  * @error: return location for a #GError, or %NULL
 470  *
 471  * Retrieves the result of a previous call to
 472  * g_resolver_lookup_by_address_async().
 473  *
 474  * If the DNS resolution failed, @error (if non-%NULL) will be set to
 475  * a value from #GResolverError. If the operation was cancelled,
 476  * @error will be set to %G_IO_ERROR_CANCELLED.
 477  *
 478  * Return value: a hostname (either ASCII-only, or in ASCII-encoded
 479  * form), or %NULL on error.
 480  *
 481  * Since: 2.22
 482  */
 483 gchar *
 484 g_resolver_lookup_by_address_finish (GResolver     *resolver,
 485                                      GAsyncResult  *result,
 486                                      GError       **error)
 487 {
 488   g_return_val_if_fail (G_IS_RESOLVER (resolver), NULL);
 489
 490   if (G_IS_SIMPLE_ASYNC_RESULT (result))
 491     {
 492       GSimpleAsyncResult *simple = G_SIMPLE_ASYNC_RESULT (result);
 493
 494       if (g_simple_async_result_propagate_error (simple, error))
 495         return NULL;
 496     }
 497
 498   return G_RESOLVER_GET_CLASS (resolver)->
 499     lookup_by_address_finish (resolver, result, error);
 500 }
 501
 502 static gchar *
 503 g_resolver_get_service_rrname (const char *service,
 504                                const char *protocol,
 505                                const char *domain)
 506 {
 507   gchar *rrname, *ascii_domain = NULL;
 508
 509   if (g_hostname_is_non_ascii (domain))
 510     domain = ascii_domain = g_hostname_to_ascii (domain);
 511
 512   rrname = g_strdup_printf ("_%s._%s.%s", service, protocol, domain);
 513
 514   g_free (ascii_domain);
 515   return rrname;
 516 }
 517
 518 /**
 519  * g_resolver_lookup_service:
 520  * @resolver: a #GResolver
 521  * @service: the service type to look up (eg, "ldap")
 522  * @protocol: the networking protocol to use for @service (eg, "tcp")
 523  * @domain: the DNS domain to look up the service in
 524  * @cancellable: a #GCancellable, or %NULL
 525  * @error: return location for a #GError, or %NULL
 526  *
 527  * Synchronously performs a DNS SRV lookup for the given @service and
 528  * @protocol in the given @domain and returns an array of #GSrvTarget.
 529  * @domain may be an ASCII-only or UTF-8 hostname. Note also that the
 530  * @service and @protocol arguments <emphasis>do not</emphasis>
 531  * include the leading underscore that appears in the actual DNS
 532  * entry.
 533  *
 534  * On success, g_resolver_lookup_service() will return a #GList of
 535  * #GSrvTarget, sorted in order of preference. (That is, you should
 536  * attempt to connect to the first target first, then the second if
 537  * the first fails, etc.)
 538  *
 539  * If the DNS resolution fails, @error (if non-%NULL) will be set to
 540  * a value from #GResolverError.
 541  *
 542  * If @cancellable is non-%NULL, it can be used to cancel the
 543  * operation, in which case @error (if non-%NULL) will be set to
 544  * %G_IO_ERROR_CANCELLED.
 545  *
 546  * If you are planning to connect to the service, it is usually easier
 547  * to create a #GNetworkService and use its #GSocketConnectable
 548  * interface.
 549  *
 550  * Return value: (element-type GSrvTarget) (transfer full): a #GList of #GSrvTarget,
 551  * or %NULL on error. You must free each of the targets and the list when you are
 552  * done with it. (You can use g_resolver_free_targets() to do this.)
 553  *
 554  * Since: 2.22
 555  */
 556 GList *
 557 g_resolver_lookup_service (GResolver     *resolver,
 558                            const gchar   *service,
 559                            const gchar   *protocol,
 560                            const gchar   *domain,
 561                            GCancellable  *cancellable,
 562                            GError       **error)
 563 {
 564   GList *targets;
 565   gchar *rrname;
 566
 567   g_return_val_if_fail (G_IS_RESOLVER (resolver), NULL);
 568   g_return_val_if_fail (service != NULL, NULL);
 569   g_return_val_if_fail (protocol != NULL, NULL);
 570   g_return_val_if_fail (domain != NULL, NULL);
 571
 572   rrname = g_resolver_get_service_rrname (service, protocol, domain);
 573
 574   g_resolver_maybe_reload (resolver);
 575   targets = G_RESOLVER_GET_CLASS (resolver)->
 576     lookup_service (resolver, rrname, cancellable, error);
 577
 578   g_free (rrname);
 579   return targets;
 580 }
 581
 582 /**
 583  * g_resolver_lookup_service_async:
 584  * @resolver: a #GResolver
 585  * @service: the service type to look up (eg, "ldap")
 586  * @protocol: the networking protocol to use for @service (eg, "tcp")
 587  * @domain: the DNS domain to look up the service in
 588  * @cancellable: a #GCancellable, or %NULL
 589  * @callback: callback to call after resolution completes
 590  * @user_data: data for @callback
 591  *
 592  * Begins asynchronously performing a DNS SRV lookup for the given
 593  * @service and @protocol in the given @domain, and eventually calls
 594  * @callback, which must call g_resolver_lookup_service_finish() to
 595  * get the final result. See g_resolver_lookup_service() for more
 596  * details.
 597  *
 598  * Since: 2.22
 599  */
 600 void
 601 g_resolver_lookup_service_async (GResolver           *resolver,
 602                                  const gchar         *service,
 603                                  const gchar         *protocol,
 604                                  const gchar         *domain,
 605                                  GCancellable        *cancellable,
 606                                  GAsyncReadyCallback  callback,
 607                                  gpointer             user_data)
 608 {
 609   gchar *rrname;
 610
 611   g_return_if_fail (G_IS_RESOLVER (resolver));
 612   g_return_if_fail (service != NULL);
 613   g_return_if_fail (protocol != NULL);
 614   g_return_if_fail (domain != NULL);
 615
 616   rrname = g_resolver_get_service_rrname (service, protocol, domain);
 617
 618   g_resolver_maybe_reload (resolver);
 619   G_RESOLVER_GET_CLASS (resolver)->
 620     lookup_service_async (resolver, rrname, cancellable, callback, user_data);
 621
 622   g_free (rrname);
 623 }
 624
 625 /**
 626  * g_resolver_lookup_service_finish:
 627  * @resolver: a #GResolver
 628  * @result: the result passed to your #GAsyncReadyCallback
 629  * @error: return location for a #GError, or %NULL
 630  *
 631  * Retrieves the result of a previous call to
 632  * g_resolver_lookup_service_async().
 633  *
 634  * If the DNS resolution failed, @error (if non-%NULL) will be set to
 635  * a value from #GResolverError. If the operation was cancelled,
 636  * @error will be set to %G_IO_ERROR_CANCELLED.
 637  *
 638  * Return value: (element-type GSrvTarget) (transfer full): a #GList of #GSrvTarget,
 639  * or %NULL on error. See g_resolver_lookup_service() for more details.
 640  *
 641  * Since: 2.22
 642  */
 643 GList *
 644 g_resolver_lookup_service_finish (GResolver     *resolver,
 645                                   GAsyncResult  *result,
 646                                   GError       **error)
 647 {
 648   g_return_val_if_fail (G_IS_RESOLVER (resolver), NULL);
 649
 650   if (G_IS_SIMPLE_ASYNC_RESULT (result))
 651     {
 652       GSimpleAsyncResult *simple = G_SIMPLE_ASYNC_RESULT (result);
 653
 654       if (g_simple_async_result_propagate_error (simple, error))
 655         return NULL;
 656     }
 657
 658   return G_RESOLVER_GET_CLASS (resolver)->
 659     lookup_service_finish (resolver, result, error);
 660 }
 661
 662 /**
 663  * g_resolver_free_targets: (skip)
 664  * @targets: a #GList of #GSrvTarget
 665  *
 666  * Frees @targets (which should be the return value from
 667  * g_resolver_lookup_service() or g_resolver_lookup_service_finish()).
 668  * (This is a convenience method; you can also simply free the
 669  * results by hand.)
 670  *
 671  * Since: 2.22
 672  */
 673 void
 674 g_resolver_free_targets (GList *targets)
 675 {
 676   GList *t;
 677
 678   for (t = targets; t; t = t->next)
 679     g_srv_target_free (t->data);
 680   g_list_free (targets);
 681 }
 682
 683 /**
 684  * g_resolver_error_quark:
 685  *
 686  * Gets the #GResolver Error Quark.
 687  *
 688  * Return value: a #GQuark.
 689  *
 690  * Since: 2.22
 691  */
 692 GQuark
 693 g_resolver_error_quark (void)
 694 {
 695   return g_quark_from_static_string ("g-resolver-error-quark");
 696 }
 697
 698
 699 static GResolverError
 700 g_resolver_error_from_addrinfo_error (gint err)
 701 {
 702   switch (err)
 703     {
 704     case EAI_FAIL:
 705 #if defined(EAI_NODATA) && (EAI_NODATA != EAI_NONAME)
 706     case EAI_NODATA:
 707 #endif
 708     case EAI_NONAME:
 709       return G_RESOLVER_ERROR_NOT_FOUND;
 710
 711     case EAI_AGAIN:
 712       return G_RESOLVER_ERROR_TEMPORARY_FAILURE;
 713
 714     default:
 715       return G_RESOLVER_ERROR_INTERNAL;
 716     }
 717 }
 718
 719 struct addrinfo _g_resolver_addrinfo_hints;
 720
 721 /* Private method to process a getaddrinfo() response. */
 722 GList *
 723 _g_resolver_addresses_from_addrinfo (const char       *hostname,
 724                                      struct addrinfo  *res,
 725                                      gint              gai_retval,
 726                                      GError          **error)
 727 {
 728   struct addrinfo *ai;
 729   GSocketAddress *sockaddr;
 730   GInetAddress *addr;
 731   GList *addrs;
 732
 733   if (gai_retval != 0)
 734     {
 735       g_set_error (error, G_RESOLVER_ERROR,
 736                    g_resolver_error_from_addrinfo_error (gai_retval),
 737                    _("Error resolving '%s': %s"),
 738                    hostname, gai_strerror (gai_retval));
 739       return NULL;
 740     }
 741
 742   g_return_val_if_fail (res != NULL, NULL);
 743
 744   addrs = NULL;
 745   for (ai = res; ai; ai = ai->ai_next)
 746     {
 747       sockaddr = g_socket_address_new_from_native (ai->ai_addr, ai->ai_addrlen);
 748       if (!sockaddr || !G_IS_INET_SOCKET_ADDRESS (sockaddr))
 749         continue;
 750
 751       addr = g_object_ref (g_inet_socket_address_get_address ((GInetSocketAddress *)sockaddr));
 752       addrs = g_list_prepend (addrs, addr);
 753       g_object_unref (sockaddr);
 754     }
 755
 756   return g_list_reverse (addrs);
 757 }
 758
 759 /* Private method to set up a getnameinfo() request */
 760 void
 761 _g_resolver_address_to_sockaddr (GInetAddress            *address,
 762                                  struct sockaddr_storage *sa,
 763                                  gsize                   *len)
 764 {
 765   GSocketAddress *sockaddr;
 766
 767   sockaddr = g_inet_socket_address_new (address, 0);
 768   g_socket_address_to_native (sockaddr, (struct sockaddr *)sa, sizeof (*sa), NULL);
 769   *len = g_socket_address_get_native_size (sockaddr);
 770   g_object_unref (sockaddr);
 771 }
 772
 773 /* Private method to process a getnameinfo() response. */
 774 char *
 775 _g_resolver_name_from_nameinfo (GInetAddress  *address,
 776                                 const gchar   *name,
 777                                 gint           gni_retval,
 778                                 GError       **error)
 779 {
 780   if (gni_retval != 0)
 781     {
 782       gchar *phys;
 783
 784       phys = g_inet_address_to_string (address);
 785       g_set_error (error, G_RESOLVER_ERROR,
 786                    g_resolver_error_from_addrinfo_error (gni_retval),
 787                    _("Error reverse-resolving '%s': %s"),
 788                    phys ? phys : "(unknown)", gai_strerror (gni_retval));
 789       g_free (phys);
 790       return NULL;
 791     }
 792
 793   return g_strdup (name);
 794 }
 795
 796 #if defined(G_OS_UNIX)
 797 /* Private method to process a res_query response into GSrvTargets */
 798 GList *
 799 _g_resolver_targets_from_res_query (const gchar      *rrname,
 800                                     guchar           *answer,
 801                                     gint              len,
 802                                     gint              herr,
 803                                     GError          **error)
 804 {
 805   gint count;
 806   gchar namebuf[1024];
 807   guchar *end, *p;
 808   guint16 type, qclass, rdlength, priority, weight, port;
 809   guint32 ttl;
 810   HEADER *header;
 811   GSrvTarget *target;
 812   GList *targets;
 813
 814   if (len <= 0)
 815     {
 816       GResolverError errnum;
 817       const gchar *format;
 818
 819       if (len == 0 || herr == HOST_NOT_FOUND || herr == NO_DATA)
 820         {
 821           errnum = G_RESOLVER_ERROR_NOT_FOUND;
 822           format = _("No service record for '%s'");
 823         }
 824       else if (herr == TRY_AGAIN)
 825         {
 826           errnum = G_RESOLVER_ERROR_TEMPORARY_FAILURE;
 827           format = _("Temporarily unable to resolve '%s'");
 828         }
 829       else
 830         {
 831           errnum = G_RESOLVER_ERROR_INTERNAL;
 832           format = _("Error resolving '%s'");
 833         }
 834
 835       g_set_error (error, G_RESOLVER_ERROR, errnum, format, rrname);
 836       return NULL;
 837     }
 838
 839   targets = NULL;
 840
 841   header = (HEADER *)answer;
 842   p = answer + sizeof (HEADER);
 843   end = answer + len;
 844
 845   /* Skip query */
 846   count = ntohs (header->qdcount);
 847   while (count-- && p < end)
 848     {
 849       p += dn_expand (answer, end, p, namebuf, sizeof (namebuf));
 850       p += 4;
 851     }
 852
 853   /* Read answers */
 854   count = ntohs (header->ancount);
 855   while (count-- && p < end)
 856     {
 857       p += dn_expand (answer, end, p, namebuf, sizeof (namebuf));
 858       GETSHORT (type, p);
 859       GETSHORT (qclass, p);
 860       GETLONG  (ttl, p);
 861       GETSHORT (rdlength, p);
 862
 863       if (type != T_SRV || qclass != C_IN)
 864         {
 865           p += rdlength;
 866           continue;
 867         }
 868
 869       GETSHORT (priority, p);
 870       GETSHORT (weight, p);
 871       GETSHORT (port, p);
 872       p += dn_expand (answer, end, p, namebuf, sizeof (namebuf));
 873
 874       target = g_srv_target_new (namebuf, port, priority, weight);
 875       targets = g_list_prepend (targets, target);
 876     }
 877
 878   return g_srv_target_list_sort (targets);
 879 }
 880 #elif defined(G_OS_WIN32)
 881 /* Private method to process a DnsQuery response into GSrvTargets */
 882 GList *
 883 _g_resolver_targets_from_DnsQuery (const gchar  *rrname,
 884                                    DNS_STATUS    status,
 885                                    DNS_RECORD   *results,
 886                                    GError      **error)
 887 {
 888   DNS_RECORD *rec;
 889   GSrvTarget *target;
 890   GList *targets;
 891
 892   if (status != ERROR_SUCCESS)
 893     {
 894       GResolverError errnum;
 895       const gchar *format;
 896
 897       if (status == DNS_ERROR_RCODE_NAME_ERROR)
 898         {
 899           errnum = G_RESOLVER_ERROR_NOT_FOUND;
 900           format = _("No service record for '%s'");
 901         }
 902       else if (status == DNS_ERROR_RCODE_SERVER_FAILURE)
 903         {
 904           errnum = G_RESOLVER_ERROR_TEMPORARY_FAILURE;
 905           format = _("Temporarily unable to resolve '%s'");
 906         }
 907       else
 908         {
 909           errnum = G_RESOLVER_ERROR_INTERNAL;
 910           format = _("Error resolving '%s'");
 911         }
 912
 913       g_set_error (error, G_RESOLVER_ERROR, errnum, format, rrname);
 914       return NULL;
 915     }
 916
 917   targets = NULL;
 918   for (rec = results; rec; rec = rec->pNext)
 919     {
 920       if (rec->wType != DNS_TYPE_SRV)
 921         continue;
 922
 923       target = g_srv_target_new (rec->Data.SRV.pNameTarget,
 924                                  rec->Data.SRV.wPort,
 925                                  rec->Data.SRV.wPriority,
 926                                  rec->Data.SRV.wWeight);
 927       targets = g_list_prepend (targets, target);
 928     }
 929
 930   return g_srv_target_list_sort (targets);
 931 }
 932
 933 #endif