glib/gio/gunixresolver.c
Dan Winship c94d3f9288 Add GResolver, a glib-ish interface to DNS
GResolver provides asynchronous (and synchronous-but-cancellable) APIs
for resolving hostnames, reverse-resolving IP addresses back to
hostnames, and resolving SRV records. Part of #548466.
2009-04-22 08:36:32 -04:00

434 lines
14 KiB
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"