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9a3d18d2a6
Higher-level wrappers around GResolver. GSocketConnectable provides an interface for synchronously or asynchronously iterating multiple socket addresses, with GNetworkAddress and GNetworkService providing interfaces based on hostname and SRV record resolution. Part of #548466.
338 lines
8.2 KiB
C
338 lines
8.2 KiB
C
/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
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/* GIO - GLib Input, Output and Streaming Library
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*
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* Copyright (C) 2008 Red Hat, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General
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* Public License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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#include "config.h"
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#include <glib.h>
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#include "glibintl.h"
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#include "gsrvtarget.h"
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#include <stdlib.h>
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#include <string.h>
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#include "gioalias.h"
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/**
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* SECTION:gsrvtarget
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* @short_description: DNS SRV record target
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* @include: gio/gio.h
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*
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* SRV (service) records are used by some network protocols to provide
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* service-specific aliasing and load-balancing. For example, XMPP
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* (Jabber) uses SRV records to locate the XMPP server for a domain;
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* rather than connecting directly to "example.com" or assuming a
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* specific server hostname like "xmpp.example.com", an XMPP client
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* would look up the "xmpp-client" SRV record for "example.com", and
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* then connect to whatever host was pointed to by that record.
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*
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* You can use g_resolver_lookup_service() or
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* g_resolver_lookup_service_async() to find the #GSrvTarget<!-- -->s
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* for a given service. However, if you are simply planning to connect
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* to the remote service, you can use #GNetworkService's
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* #GSocketConnectable interface and not need to worry about
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* #GSrvTarget at all.
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**/
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struct _GSrvTarget {
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gchar *hostname;
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guint16 port;
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guint16 priority;
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guint16 weight;
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};
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/**
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* GSrvTarget:
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*
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* A single target host/port that a network service is running on.
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*/
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GType
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g_srv_target_get_type (void)
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{
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static volatile gsize type_volatile = 0;
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if (g_once_init_enter (&type_volatile))
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{
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GType type = g_boxed_type_register_static (
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g_intern_static_string ("GSrvTarget"),
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(GBoxedCopyFunc) g_srv_target_copy,
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(GBoxedFreeFunc) g_srv_target_free);
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g_once_init_leave (&type_volatile, type);
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}
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return type_volatile;
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}
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/**
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* g_srv_target_new:
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* @hostname: the host that the service is running on
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* @port: the port that the service is running on
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* @priority: the target's priority
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* @weight: the target's weight
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*
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* Creates a new #GSrvTarget with the given parameters.
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*
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* You should not need to use this; normally #GSrvTarget<!-- -->s are
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* created by #GResolver.
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*
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* Return value: a new #GSrvTarget.
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*
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* Since: 2.22
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**/
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GSrvTarget *
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g_srv_target_new (const gchar *hostname,
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guint16 port,
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guint16 priority,
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guint16 weight)
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{
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GSrvTarget *target = g_slice_new0 (GSrvTarget);
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target->hostname = g_strdup (hostname);
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target->port = port;
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target->priority = priority;
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target->weight = weight;
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return target;
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}
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/**
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* g_srv_target_copy:
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* @target: a #GSrvTarget
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*
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* Copies @target
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*
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* Return value: a copy of @target
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*
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* Since: 2.22
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**/
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GSrvTarget *
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g_srv_target_copy (GSrvTarget *target)
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{
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return g_srv_target_new (target->hostname, target->port,
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target->priority, target->weight);
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}
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/**
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* g_srv_target_free:
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* @target: a #GSrvTarget
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*
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* Frees @target
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*
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* Since: 2.22
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**/
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void
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g_srv_target_free (GSrvTarget *target)
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{
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g_free (target->hostname);
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g_slice_free (GSrvTarget, target);
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}
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/**
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* g_srv_target_get_hostname:
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* @target: a #GSrvTarget
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*
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* Gets @target's hostname (in ASCII form; if you are going to present
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* this to the user, you should use g_hostname_is_ascii_encoded() to
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* check if it contains encoded Unicode segments, and use
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* g_hostname_to_unicode() to convert it if it does.)
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*
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* Return value: @target's hostname
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*
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* Since: 2.22
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**/
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const gchar *
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g_srv_target_get_hostname (GSrvTarget *target)
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{
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return target->hostname;
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}
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/**
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* g_srv_target_get_port:
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* @target: a #GSrvTarget
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*
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* Gets @target's port
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*
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* Return value: @target's port
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*
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* Since: 2.22
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**/
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guint16
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g_srv_target_get_port (GSrvTarget *target)
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{
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return target->port;
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}
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/**
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* g_srv_target_get_priority:
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* @target: a #GSrvTarget
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*
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* Gets @target's priority. You should not need to look at this;
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* #GResolver already sorts the targets according to the algorithm in
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* RFC 2782.
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*
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* Return value: @target's priority
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*
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* Since: 2.22
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**/
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guint16
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g_srv_target_get_priority (GSrvTarget *target)
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{
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return target->priority;
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}
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/**
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* g_srv_target_get_weight:
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* @target: a #GSrvTarget
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*
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* Gets @target's weight. You should not need to look at this;
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* #GResolver already sorts the targets according to the algorithm in
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* RFC 2782.
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*
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* Return value: @target's weight
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*
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* Since: 2.22
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**/
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guint16
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g_srv_target_get_weight (GSrvTarget *target)
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{
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return target->weight;
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}
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gint
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compare_target (gconstpointer a, gconstpointer b)
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{
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GSrvTarget *ta = (GSrvTarget *)a;
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GSrvTarget *tb = (GSrvTarget *)b;
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if (ta->priority == tb->priority)
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{
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/* Arrange targets of the same priority "in any order, except
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* that all those with weight 0 are placed at the beginning of
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* the list"
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*/
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if (ta->weight == 0)
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return -1;
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else if (tb->weight == 0)
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return 1;
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else
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return g_random_int_range (-1, 1);
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}
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else
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return ta->priority - tb->priority;
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}
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/**
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* g_srv_target_list_sort:
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* @targets: a #GList of #GSrvTarget
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*
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* Sorts @targets in place according to the algorithm in RFC 2782.
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*
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* Return value: the head of the sorted list.
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*
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* Since: 2.22
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**/
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GList *
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g_srv_target_list_sort (GList *targets)
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{
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gint sum, val, priority, weight;
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GList *first, *last, *n;
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GSrvTarget *target;
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gpointer tmp;
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if (!targets)
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return NULL;
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if (!targets->next)
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{
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target = targets->data;
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if (!strcmp (target->hostname, "."))
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{
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/* 'A Target of "." means that the service is decidedly not
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* available at this domain.'
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*/
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g_srv_target_free (target);
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g_list_free (targets);
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return NULL;
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}
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}
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/* Sort by priority, and partly by weight */
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targets = g_list_sort (targets, compare_target);
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/* For each group of targets with the same priority, rebalance them
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* according to weight.
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*/
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for (first = targets; first; first = last->next)
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{
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/* Skip @first to a non-0-weight target. */
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while (first && ((GSrvTarget *)first->data)->weight == 0)
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first = first->next;
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if (!first)
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break;
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/* Skip @last to the last target of the same priority. */
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priority = ((GSrvTarget *)first->data)->priority;
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last = first;
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while (last->next &&
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((GSrvTarget *)last->next->data)->priority == priority)
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last = last->next;
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/* If there's only one non-0 weight target at this priority,
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* we can move on to the next priority level.
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*/
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if (last == first)
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continue;
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/* Randomly reorder the non-0 weight targets, giving precedence
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* to the ones with higher weight. RFC 2782 describes this in
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* terms of assigning a running sum to each target and building
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* a new list. We do things slightly differently, but should get
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* the same result.
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*/
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for (n = first, sum = 0; n != last->next; n = n->next)
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sum += ((GSrvTarget *)n->data)->weight;
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while (first != last)
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{
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val = g_random_int_range (0, sum);
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for (n = first; n != last; n = n->next)
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{
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weight = ((GSrvTarget *)n->data)->weight;
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if (val < weight)
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break;
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val -= weight;
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}
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tmp = first->data;
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first->data = n->data;
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n->data = tmp;
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sum -= weight;
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first = first->next;
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}
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}
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return targets;
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}
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#define __G_SRV_TARGET_C__
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#include "gioaliasdef.c"
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