gio/gunixresolver.c - third_party/glib - Git at Google

 /* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */

 /* GIO - GLib Input, Output and Streaming Library
  *
  * Copyright (C) 2008 Red Hat, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General
  * Public License along with this library; if not, write to the
  * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  * Boston, MA 02111-1307, USA.
  */

 #include "config.h"
 #include <glib.h>
 #include "glibintl.h"

 #include <resolv.h>
 #include <stdio.h>
 #include <string.h>

 #include "gunixresolver.h"
 #include "gnetworkingprivate.h"

 #include "gcancellable.h"
 #include "gsimpleasyncresult.h"
 #include "gsocketaddress.h"

 #include "gioalias.h"

 G_DEFINE_TYPE (GUnixResolver, g_unix_resolver, G_TYPE_THREADED_RESOLVER)

 static gboolean g_unix_resolver_watch (GIOChannel   *iochannel,
                                        GIOCondition  condition,
                                        gpointer      user_data);

 static void
 g_unix_resolver_init (GUnixResolver *gur)
 {
   gint fd;
   GIOChannel *io;

   /* FIXME: how many workers? */
   gur->asyncns = _g_asyncns_new (2);

   fd = _g_asyncns_fd (gur->asyncns);
   io = g_io_channel_unix_new (fd);
   gur->watch = g_io_add_watch (io, G_IO_IN | G_IO_HUP | G_IO_ERR,
                                g_unix_resolver_watch, gur);
   g_io_channel_unref (io);
 }

 static void
 g_unix_resolver_finalize (GObject *object)
 {
   GUnixResolver *gur = G_UNIX_RESOLVER (object);

   if (gur->watch)
     g_source_remove (gur->watch);
   _g_asyncns_free (gur->asyncns);

   G_OBJECT_CLASS (g_unix_resolver_parent_class)->finalize (object);
 }

 /* The various request possibilities:
  *
  * 1. Synchronous: handed off to the base class (GThreadedResolver);
  *    since it's never possible to cancel a synchronous request in a
  *    single-threaded program, the request is done in the calling
  *    thread.
  *
  * 2. Asynchronous: An appropriate _g_asyncns_query_t is created, and
  *    then a GUnixResolverRequest is created with that query and a
  *    GSimpleAsyncResult. Two sub-possibilities:
  *
  *      a. The resolution completes: g_unix_resolver_watch() sees that
  *         the request has completed, and calls
  *         g_unix_resolver_request_complete(), which detaches the
  *         "cancelled" signal handler (if it was present) and then
  *         immediately completes the async_result (since
  *         g_unix_resolver_watch() is already run from main-loop
  *         time.) After completing the async_result, it unrefs it,
  *         causing the req to be freed as well.
  *
  *      b. The resolution is cancelled: request_cancelled() calls
  *         _g_asyncns_cancel() to cancel the resolution. Then it calls
  *         g_unix_resolver_request_complete(), which detaches the
  *         signal handler, and queues async_result to complete in an
  *         idle handler. It then unrefs the async_result to ensure
  *         that after its callback runs, it will be destroyed, in turn
  *         causing the req to be freed. Because the asyncns resolution
  *         was cancelled, g_unix_resolver_watch() will never be
  *         triggered for this req.
  *
  *    Since there's only a single thread, it's not possible for the
  *    request to both complete and be cancelled "at the same time",
  *    and each of the two possibilities takes steps to block the other
  *    from being able to happen later, so it's always safe to free req
  *    after the async_result completes.
  */

 typedef struct _GUnixResolverRequest GUnixResolverRequest;
 typedef void (*GUnixResolverFreeFunc) (GUnixResolverRequest *);

 struct _GUnixResolverRequest {
   GUnixResolver *gur;

   _g_asyncns_query_t *qy;
   union {
     gchar *hostname;
     GInetAddress *address;
     gchar *service;
   } u;
   GUnixResolverFreeFunc free_func;

   GCancellable *cancellable;
   GSimpleAsyncResult *async_result;

 };

 static void g_unix_resolver_request_free (GUnixResolverRequest *req);
 static void request_cancelled (GCancellable *cancellable,
                                gpointer      user_data);

 static GUnixResolverRequest *
 g_unix_resolver_request_new (GUnixResolver         *gur,
                              _g_asyncns_query_t    *qy,
                              GUnixResolverFreeFunc  free_func,
                              GCancellable          *cancellable,
                              GSimpleAsyncResult    *async_result)
 {
   GUnixResolverRequest *req;

   req = g_slice_new0 (GUnixResolverRequest);
   req->gur = g_object_ref (gur);
   req->qy = qy;
   req->free_func = free_func;

   if (cancellable)
     {
       req->cancellable = g_object_ref (cancellable);
       g_signal_connect (cancellable, "cancelled",
                         G_CALLBACK (request_cancelled), req);
     }

   req->async_result = g_object_ref (async_result);

   g_simple_async_result_set_op_res_gpointer (req->async_result, req, (GDestroyNotify)g_unix_resolver_request_free);

   return req;
 }

 static void
 g_unix_resolver_request_free (GUnixResolverRequest *req)
 {
   /* If the user didn't call _finish the qy will still be around. */
   if (req->qy)
     _g_asyncns_cancel (req->gur->asyncns, req->qy);

   /* We don't have to free req->cancellable and req->async_result,
    * since they must already have been freed if we're here.
    */

   g_slice_free (GUnixResolverRequest, req);
 }

 static void
 g_unix_resolver_request_complete (GUnixResolverRequest *req,
                                   gboolean              need_idle)
 {
   if (req->cancellable)
     {
       g_signal_handlers_disconnect_by_func (req->cancellable, request_cancelled, req);
       g_object_unref (req->cancellable);
       req->cancellable = NULL;
     }

   if (need_idle)
     g_simple_async_result_complete_in_idle (req->async_result);
   else
     g_simple_async_result_complete (req->async_result);

   /* If we completed_in_idle, that will have taken an extra ref on
    * req->async_result; if not, then we're already done. Either way we
    * need to unref the async_result to make sure it eventually is
    * destroyed, causing req to be freed.
    */
   g_object_unref (req->async_result);
 }

 static void
 request_cancelled (GCancellable *cancellable,
                    gpointer      user_data)
 {
   GUnixResolverRequest *req = user_data;
   GError *error = NULL;

   _g_asyncns_cancel (req->gur->asyncns, req->qy);
   req->qy = NULL;

   g_cancellable_set_error_if_cancelled (cancellable, &error);
   g_simple_async_result_set_from_error (req->async_result, error);
   g_error_free (error);

   g_unix_resolver_request_complete (req, TRUE);
 }

 static gboolean
 g_unix_resolver_watch (GIOChannel   *iochannel,
                        GIOCondition  condition,
                        gpointer      user_data)
 {
   GUnixResolver *gur = user_data;
   _g_asyncns_query_t *qy;
   GUnixResolverRequest *req;

   if (condition & (G_IO_HUP | G_IO_ERR))
     {
       /* Shouldn't happen. Should we create a new asyncns? FIXME */
       g_warning ("asyncns died");
       gur->watch = 0;
       return FALSE;
     }

   while (_g_asyncns_wait (gur->asyncns, FALSE) == 0 &&
          (qy = _g_asyncns_getnext (gur->asyncns)) != NULL)
     {
       req = _g_asyncns_getuserdata (gur->asyncns, qy);
       g_unix_resolver_request_complete (req, FALSE);
     }

   return TRUE;
 }

 static GUnixResolverRequest *
 resolve_async (GUnixResolver         *gur,
                _g_asyncns_query_t    *qy,
                GUnixResolverFreeFunc  free_func,
                GCancellable          *cancellable,
                GAsyncReadyCallback    callback,
                gpointer               user_data,
                gpointer               tag)
 {
   GSimpleAsyncResult *result;
   GUnixResolverRequest *req;

   result = g_simple_async_result_new (G_OBJECT (gur), callback, user_data, tag);
   req = g_unix_resolver_request_new (gur, qy, free_func, cancellable, result);
   g_object_unref (result);
   _g_asyncns_setuserdata (gur->asyncns, qy, req);

   return req;
 }

 static void
 lookup_by_name_free (GUnixResolverRequest *req)
 {
   g_free (req->u.hostname);
 }

 static void
 lookup_by_name_async (GResolver           *resolver,
                       const gchar         *hostname,
                       GCancellable        *cancellable,
                       GAsyncReadyCallback  callback,
                       gpointer             user_data)
 {
   GUnixResolver *gur = G_UNIX_RESOLVER (resolver);
   GUnixResolverRequest *req;
   _g_asyncns_query_t *qy;

   qy = _g_asyncns_getaddrinfo (gur->asyncns, hostname, NULL,
                                &_g_resolver_addrinfo_hints);
   req = resolve_async (gur, qy, lookup_by_name_free, cancellable,
                        callback, user_data, lookup_by_name_async);
   req->u.hostname = g_strdup (hostname);
 }

 static GList *
 lookup_by_name_finish (GResolver     *resolver,
                        GAsyncResult  *result,
                        GError       **error)
 {
   GSimpleAsyncResult *simple;
   GUnixResolverRequest *req;
   struct addrinfo *res;
   gint retval;
   GList *addresses;

   g_return_val_if_fail (g_simple_async_result_is_valid (result, G_OBJECT (resolver), lookup_by_name_async), FALSE);
   simple = G_SIMPLE_ASYNC_RESULT (result);

   req = g_simple_async_result_get_op_res_gpointer (simple);
   retval = _g_asyncns_getaddrinfo_done (req->gur->asyncns, req->qy, &res);
   req->qy = NULL;
   addresses = _g_resolver_addresses_from_addrinfo (req->u.hostname, res, retval, error);
   if (res)
     freeaddrinfo (res);

   return addresses;
 }


 static void
 lookup_by_address_free (GUnixResolverRequest *req)
 {
   g_object_unref (req->u.address);
 }

 static void
 lookup_by_address_async (GResolver           *resolver,
                          GInetAddress        *address,
                          GCancellable        *cancellable,
                          GAsyncReadyCallback  callback,
                          gpointer             user_data)
 {
   GUnixResolver *gur = G_UNIX_RESOLVER (resolver);
   GUnixResolverRequest *req;
   _g_asyncns_query_t *qy;
   struct sockaddr_storage sockaddr;
   gsize sockaddr_size;

   _g_resolver_address_to_sockaddr (address, &sockaddr, &sockaddr_size);
   qy = _g_asyncns_getnameinfo (gur->asyncns,
                                (struct sockaddr *)&sockaddr, sockaddr_size,
                                NI_NAMEREQD, TRUE, FALSE);
   req = resolve_async (gur, qy, lookup_by_address_free, cancellable,
                        callback, user_data, lookup_by_address_async);
   req->u.address = g_object_ref (address);
 }

 static gchar *
 lookup_by_address_finish (GResolver     *resolver,
                           GAsyncResult  *result,
                           GError       **error)
 {
   GSimpleAsyncResult *simple;
   GUnixResolverRequest *req;
   gchar host[NI_MAXHOST], *name;
   gint retval;

   g_return_val_if_fail (g_simple_async_result_is_valid (result, G_OBJECT (resolver), lookup_by_address_async), FALSE);
   simple = G_SIMPLE_ASYNC_RESULT (result);

   req = g_simple_async_result_get_op_res_gpointer (simple);
   retval = _g_asyncns_getnameinfo_done (req->gur->asyncns, req->qy,
                                         host, sizeof (host), NULL, 0);
   req->qy = NULL;
   name = _g_resolver_name_from_nameinfo (req->u.address, host, retval, error);

   return name;
 }


 static void
 lookup_service_free (GUnixResolverRequest *req)
 {
   g_free (req->u.service);
 }

 static void
 lookup_service_async (GResolver           *resolver,
                       const char          *rrname,
 		      GCancellable        *cancellable,
                       GAsyncReadyCallback  callback,
 		      gpointer             user_data)
 {
   GUnixResolver *gur = G_UNIX_RESOLVER (resolver);
   GUnixResolverRequest *req;
   _g_asyncns_query_t *qy;

   qy = _g_asyncns_res_query (gur->asyncns, rrname, C_IN, T_SRV);
   req = resolve_async (gur, qy, lookup_service_free, cancellable,
                        callback, user_data, lookup_service_async);
   req->u.service = g_strdup (rrname);
 }

 static GList *
 lookup_service_finish (GResolver     *resolver,
                        GAsyncResult  *result,
 		       GError       **error)
 {
   GSimpleAsyncResult *simple;
   GUnixResolverRequest *req;
   guchar *answer;
   gint len, herr;
   GList *targets;

   g_return_val_if_fail (g_simple_async_result_is_valid (result, G_OBJECT (resolver), lookup_service_async), FALSE);
   simple = G_SIMPLE_ASYNC_RESULT (result);

   req = g_simple_async_result_get_op_res_gpointer (simple);
   len = _g_asyncns_res_done (req->gur->asyncns, req->qy, &answer);
   req->qy = NULL;
   if (len < 0)
     herr = h_errno;
   else
     herr = 0;

   targets = _g_resolver_targets_from_res_query (req->u.service, answer, len, herr, error);
   _g_asyncns_freeanswer (answer);

   return targets;
 }


 static void
 g_unix_resolver_class_init (GUnixResolverClass *unix_class)
 {
   GResolverClass *resolver_class = G_RESOLVER_CLASS (unix_class);
   GObjectClass *object_class = G_OBJECT_CLASS (unix_class);

   resolver_class->lookup_by_name_async     = lookup_by_name_async;
   resolver_class->lookup_by_name_finish    = lookup_by_name_finish;
   resolver_class->lookup_by_address_async  = lookup_by_address_async;
   resolver_class->lookup_by_address_finish = lookup_by_address_finish;
   resolver_class->lookup_service_async     = lookup_service_async;
   resolver_class->lookup_service_finish    = lookup_service_finish;

   object_class->finalize = g_unix_resolver_finalize;
 }

 #define __G_UNIX_RESOLVER_C__
 #include "gioaliasdef.c"
	/* -- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -- */

	/* GIO - GLib Input, Output and Streaming Library
	*
	* Copyright (C) 2008 Red Hat, Inc.
	*
	* This library is free software; you can redistribute it and/or
	* modify it under the terms of the GNU Lesser General Public
	* License as published by the Free Software Foundation; either
	* version 2 of the License, or (at your option) any later version.
	*
	* This library is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* Lesser General Public License for more details.
	*
	* You should have received a copy of the GNU Lesser General
	* Public License along with this library; if not, write to the
	* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
	* Boston, MA 02111-1307, USA.
	*/

	#include "config.h"
	#include <glib.h>
	#include "glibintl.h"

	#include <resolv.h>
	#include <stdio.h>
	#include <string.h>

	#include "gunixresolver.h"
	#include "gnetworkingprivate.h"

	#include "gcancellable.h"
	#include "gsimpleasyncresult.h"
	#include "gsocketaddress.h"

	#include "gioalias.h"

	G_DEFINE_TYPE (GUnixResolver, g_unix_resolver, G_TYPE_THREADED_RESOLVER)

	static gboolean g_unix_resolver_watch (GIOChannel *iochannel,
	GIOCondition condition,
	gpointer user_data);

	static void
	g_unix_resolver_init (GUnixResolver *gur)
	{
	gint fd;
	GIOChannel *io;

	/* FIXME: how many workers? */
	gur->asyncns = _g_asyncns_new (2);

	fd = _g_asyncns_fd (gur->asyncns);
	io = g_io_channel_unix_new (fd);
	gur->watch = g_io_add_watch (io, G_IO_IN \| G_IO_HUP \| G_IO_ERR,
	g_unix_resolver_watch, gur);
	g_io_channel_unref (io);
	}

	static void
	g_unix_resolver_finalize (GObject *object)
	{
	GUnixResolver *gur = G_UNIX_RESOLVER (object);

	if (gur->watch)
	g_source_remove (gur->watch);
	_g_asyncns_free (gur->asyncns);

	G_OBJECT_CLASS (g_unix_resolver_parent_class)->finalize (object);
	}

	/* The various request possibilities:
	*
	* 1. Synchronous: handed off to the base class (GThreadedResolver);
	* since it's never possible to cancel a synchronous request in a
	* single-threaded program, the request is done in the calling
	* thread.
	*
	* 2. Asynchronous: An appropriate _g_asyncns_query_t is created, and
	* then a GUnixResolverRequest is created with that query and a
	* GSimpleAsyncResult. Two sub-possibilities:
	*
	* a. The resolution completes: g_unix_resolver_watch() sees that
	* the request has completed, and calls
	* g_unix_resolver_request_complete(), which detaches the
	* "cancelled" signal handler (if it was present) and then
	* immediately completes the async_result (since
	* g_unix_resolver_watch() is already run from main-loop
	* time.) After completing the async_result, it unrefs it,
	* causing the req to be freed as well.
	*
	* b. The resolution is cancelled: request_cancelled() calls
	* _g_asyncns_cancel() to cancel the resolution. Then it calls
	* g_unix_resolver_request_complete(), which detaches the
	* signal handler, and queues async_result to complete in an
	* idle handler. It then unrefs the async_result to ensure
	* that after its callback runs, it will be destroyed, in turn
	* causing the req to be freed. Because the asyncns resolution
	* was cancelled, g_unix_resolver_watch() will never be
	* triggered for this req.
	*
	* Since there's only a single thread, it's not possible for the
	* request to both complete and be cancelled "at the same time",
	* and each of the two possibilities takes steps to block the other
	* from being able to happen later, so it's always safe to free req
	* after the async_result completes.
	*/

	typedef struct _GUnixResolverRequest GUnixResolverRequest;
	typedef void (GUnixResolverFreeFunc) (GUnixResolverRequest );

	struct _GUnixResolverRequest {
	GUnixResolver *gur;

	_g_asyncns_query_t *qy;
	union {
	gchar *hostname;
	GInetAddress *address;
	gchar *service;
	} u;
	GUnixResolverFreeFunc free_func;

	GCancellable *cancellable;
	GSimpleAsyncResult *async_result;

	};

	static void g_unix_resolver_request_free (GUnixResolverRequest *req);
	static void request_cancelled (GCancellable *cancellable,
	gpointer user_data);

	static GUnixResolverRequest *
	g_unix_resolver_request_new (GUnixResolver *gur,
	_g_asyncns_query_t *qy,
	GUnixResolverFreeFunc free_func,
	GCancellable *cancellable,
	GSimpleAsyncResult *async_result)
	{
	GUnixResolverRequest *req;

	req = g_slice_new0 (GUnixResolverRequest);
	req->gur = g_object_ref (gur);
	req->qy = qy;
	req->free_func = free_func;

	if (cancellable)
	{
	req->cancellable = g_object_ref (cancellable);
	g_signal_connect (cancellable, "cancelled",
	G_CALLBACK (request_cancelled), req);
	}

	req->async_result = g_object_ref (async_result);

	g_simple_async_result_set_op_res_gpointer (req->async_result, req, (GDestroyNotify)g_unix_resolver_request_free);

	return req;
	}

	static void
	g_unix_resolver_request_free (GUnixResolverRequest *req)
	{
	/* If the user didn't call _finish the qy will still be around. */
	if (req->qy)
	_g_asyncns_cancel (req->gur->asyncns, req->qy);

	/* We don't have to free req->cancellable and req->async_result,
	* since they must already have been freed if we're here.
	*/

	g_slice_free (GUnixResolverRequest, req);
	}

	static void
	g_unix_resolver_request_complete (GUnixResolverRequest *req,
	gboolean need_idle)
	{
	if (req->cancellable)
	{
	g_signal_handlers_disconnect_by_func (req->cancellable, request_cancelled, req);
	g_object_unref (req->cancellable);
	req->cancellable = NULL;
	}

	if (need_idle)
	g_simple_async_result_complete_in_idle (req->async_result);
	else
	g_simple_async_result_complete (req->async_result);

	/* If we completed_in_idle, that will have taken an extra ref on
	* req->async_result; if not, then we're already done. Either way we
	* need to unref the async_result to make sure it eventually is
	* destroyed, causing req to be freed.
	*/
	g_object_unref (req->async_result);
	}

	static void
	request_cancelled (GCancellable *cancellable,
	gpointer user_data)
	{
	GUnixResolverRequest *req = user_data;
	GError *error = NULL;

	_g_asyncns_cancel (req->gur->asyncns, req->qy);
	req->qy = NULL;

	g_cancellable_set_error_if_cancelled (cancellable, &error);
	g_simple_async_result_set_from_error (req->async_result, error);
	g_error_free (error);

	g_unix_resolver_request_complete (req, TRUE);
	}

	static gboolean
	g_unix_resolver_watch (GIOChannel *iochannel,
	GIOCondition condition,
	gpointer user_data)
	{
	GUnixResolver *gur = user_data;
	_g_asyncns_query_t *qy;
	GUnixResolverRequest *req;

	if (condition & (G_IO_HUP \| G_IO_ERR))
	{
	/* Shouldn't happen. Should we create a new asyncns? FIXME */
	g_warning ("asyncns died");
	gur->watch = 0;
	return FALSE;
	}

	while (_g_asyncns_wait (gur->asyncns, FALSE) == 0 &&
	(qy = _g_asyncns_getnext (gur->asyncns)) != NULL)
	{
	req = _g_asyncns_getuserdata (gur->asyncns, qy);
	g_unix_resolver_request_complete (req, FALSE);
	}

	return TRUE;
	}

	static GUnixResolverRequest *
	resolve_async (GUnixResolver *gur,
	_g_asyncns_query_t *qy,
	GUnixResolverFreeFunc free_func,
	GCancellable *cancellable,
	GAsyncReadyCallback callback,
	gpointer user_data,
	gpointer tag)
	{
	GSimpleAsyncResult *result;
	GUnixResolverRequest *req;

	result = g_simple_async_result_new (G_OBJECT (gur), callback, user_data, tag);
	req = g_unix_resolver_request_new (gur, qy, free_func, cancellable, result);
	g_object_unref (result);
	_g_asyncns_setuserdata (gur->asyncns, qy, req);

	return req;
	}

	static void
	lookup_by_name_free (GUnixResolverRequest *req)
	{
	g_free (req->u.hostname);
	}

	static void
	lookup_by_name_async (GResolver *resolver,
	const gchar *hostname,
	GCancellable *cancellable,
	GAsyncReadyCallback callback,
	gpointer user_data)
	{
	GUnixResolver *gur = G_UNIX_RESOLVER (resolver);
	GUnixResolverRequest *req;
	_g_asyncns_query_t *qy;

	qy = _g_asyncns_getaddrinfo (gur->asyncns, hostname, NULL,
	&_g_resolver_addrinfo_hints);
	req = resolve_async (gur, qy, lookup_by_name_free, cancellable,
	callback, user_data, lookup_by_name_async);
	req->u.hostname = g_strdup (hostname);
	}

	static GList *
	lookup_by_name_finish (GResolver *resolver,
	GAsyncResult *result,
	GError **error)
	{
	GSimpleAsyncResult *simple;
	GUnixResolverRequest *req;
	struct addrinfo *res;
	gint retval;
	GList *addresses;

	g_return_val_if_fail (g_simple_async_result_is_valid (result, G_OBJECT (resolver), lookup_by_name_async), FALSE);
	simple = G_SIMPLE_ASYNC_RESULT (result);

	req = g_simple_async_result_get_op_res_gpointer (simple);
	retval = _g_asyncns_getaddrinfo_done (req->gur->asyncns, req->qy, &res);
	req->qy = NULL;
	addresses = _g_resolver_addresses_from_addrinfo (req->u.hostname, res, retval, error);
	if (res)
	freeaddrinfo (res);

	return addresses;
	}


	static void
	lookup_by_address_free (GUnixResolverRequest *req)
	{
	g_object_unref (req->u.address);
	}

	static void
	lookup_by_address_async (GResolver *resolver,
	GInetAddress *address,
	GCancellable *cancellable,
	GAsyncReadyCallback callback,
	gpointer user_data)
	{
	GUnixResolver *gur = G_UNIX_RESOLVER (resolver);
	GUnixResolverRequest *req;
	_g_asyncns_query_t *qy;
	struct sockaddr_storage sockaddr;
	gsize sockaddr_size;

	_g_resolver_address_to_sockaddr (address, &sockaddr, &sockaddr_size);
	qy = _g_asyncns_getnameinfo (gur->asyncns,
	(struct sockaddr *)&sockaddr, sockaddr_size,
	NI_NAMEREQD, TRUE, FALSE);
	req = resolve_async (gur, qy, lookup_by_address_free, cancellable,
	callback, user_data, lookup_by_address_async);
	req->u.address = g_object_ref (address);
	}

	static gchar *
	lookup_by_address_finish (GResolver *resolver,
	GAsyncResult *result,
	GError **error)
	{
	GSimpleAsyncResult *simple;
	GUnixResolverRequest *req;
	gchar host[NI_MAXHOST], *name;
	gint retval;

	g_return_val_if_fail (g_simple_async_result_is_valid (result, G_OBJECT (resolver), lookup_by_address_async), FALSE);
	simple = G_SIMPLE_ASYNC_RESULT (result);

	req = g_simple_async_result_get_op_res_gpointer (simple);
	retval = _g_asyncns_getnameinfo_done (req->gur->asyncns, req->qy,
	host, sizeof (host), NULL, 0);
	req->qy = NULL;
	name = _g_resolver_name_from_nameinfo (req->u.address, host, retval, error);

	return name;
	}


	static void
	lookup_service_free (GUnixResolverRequest *req)
	{
	g_free (req->u.service);
	}

	static void
	lookup_service_async (GResolver *resolver,
	const char *rrname,
	GCancellable *cancellable,
	GAsyncReadyCallback callback,
	gpointer user_data)
	{
	GUnixResolver *gur = G_UNIX_RESOLVER (resolver);
	GUnixResolverRequest *req;
	_g_asyncns_query_t *qy;

	qy = _g_asyncns_res_query (gur->asyncns, rrname, C_IN, T_SRV);
	req = resolve_async (gur, qy, lookup_service_free, cancellable,
	callback, user_data, lookup_service_async);
	req->u.service = g_strdup (rrname);
	}

	static GList *
	lookup_service_finish (GResolver *resolver,
	GAsyncResult *result,
	GError **error)
	{
	GSimpleAsyncResult *simple;
	GUnixResolverRequest *req;
	guchar *answer;
	gint len, herr;
	GList *targets;

	g_return_val_if_fail (g_simple_async_result_is_valid (result, G_OBJECT (resolver), lookup_service_async), FALSE);
	simple = G_SIMPLE_ASYNC_RESULT (result);

	req = g_simple_async_result_get_op_res_gpointer (simple);
	len = _g_asyncns_res_done (req->gur->asyncns, req->qy, &answer);
	req->qy = NULL;
	if (len < 0)
	herr = h_errno;
	else
	herr = 0;

	targets = _g_resolver_targets_from_res_query (req->u.service, answer, len, herr, error);
	_g_asyncns_freeanswer (answer);

	return targets;
	}


	static void
	g_unix_resolver_class_init (GUnixResolverClass *unix_class)
	{
	GResolverClass *resolver_class = G_RESOLVER_CLASS (unix_class);
	GObjectClass *object_class = G_OBJECT_CLASS (unix_class);

	resolver_class->lookup_by_name_async = lookup_by_name_async;
	resolver_class->lookup_by_name_finish = lookup_by_name_finish;
	resolver_class->lookup_by_address_async = lookup_by_address_async;
	resolver_class->lookup_by_address_finish = lookup_by_address_finish;
	resolver_class->lookup_service_async = lookup_service_async;
	resolver_class->lookup_service_finish = lookup_service_finish;

	object_class->finalize = g_unix_resolver_finalize;
	}

	#define __G_UNIX_RESOLVER_C__
	#include "gioaliasdef.c"