1 /* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
3 /* GIO - GLib Input, Output and Streaming Library
5 * Copyright (C) 2008 Red Hat, Inc.
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.
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.
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.
27 #include "gsrvtarget.h"
35 * @short_description: DNS SRV record target
38 * SRV (service) records are used by some network protocols to provide
39 * service-specific aliasing and load-balancing. For example, XMPP
40 * (Jabber) uses SRV records to locate the XMPP server for a domain;
41 * rather than connecting directly to "example.com" or assuming a
42 * specific server hostname like "xmpp.example.com", an XMPP client
43 * would look up the "xmpp-client" SRV record for "example.com", and
44 * then connect to whatever host was pointed to by that record.
46 * You can use g_resolver_lookup_service() or
47 * g_resolver_lookup_service_async() to find the #GSrvTarget<!-- -->s
48 * for a given service. However, if you are simply planning to connect
49 * to the remote service, you can use #GNetworkService's
50 * #GSocketConnectable interface and not need to worry about
65 * A single target host/port that a network service is running on.
68 G_DEFINE_BOXED_TYPE (GSrvTarget
, g_srv_target
,
69 g_srv_target_copy
, g_srv_target_free
)
73 * @hostname: the host that the service is running on
74 * @port: the port that the service is running on
75 * @priority: the target's priority
76 * @weight: the target's weight
78 * Creates a new #GSrvTarget with the given parameters.
80 * You should not need to use this; normally #GSrvTarget<!-- -->s are
81 * created by #GResolver.
83 * Return value: a new #GSrvTarget.
88 g_srv_target_new (const gchar
*hostname
,
93 GSrvTarget
*target
= g_slice_new0 (GSrvTarget
);
95 target
->hostname
= g_strdup (hostname
);
97 target
->priority
= priority
;
98 target
->weight
= weight
;
105 * @target: a #GSrvTarget
109 * Return value: a copy of @target
114 g_srv_target_copy (GSrvTarget
*target
)
116 return g_srv_target_new (target
->hostname
, target
->port
,
117 target
->priority
, target
->weight
);
122 * @target: a #GSrvTarget
129 g_srv_target_free (GSrvTarget
*target
)
131 g_free (target
->hostname
);
132 g_slice_free (GSrvTarget
, target
);
136 * g_srv_target_get_hostname:
137 * @target: a #GSrvTarget
139 * Gets @target's hostname (in ASCII form; if you are going to present
140 * this to the user, you should use g_hostname_is_ascii_encoded() to
141 * check if it contains encoded Unicode segments, and use
142 * g_hostname_to_unicode() to convert it if it does.)
144 * Return value: @target's hostname
149 g_srv_target_get_hostname (GSrvTarget
*target
)
151 return target
->hostname
;
155 * g_srv_target_get_port:
156 * @target: a #GSrvTarget
158 * Gets @target's port
160 * Return value: @target's port
165 g_srv_target_get_port (GSrvTarget
*target
)
171 * g_srv_target_get_priority:
172 * @target: a #GSrvTarget
174 * Gets @target's priority. You should not need to look at this;
175 * #GResolver already sorts the targets according to the algorithm in
178 * Return value: @target's priority
183 g_srv_target_get_priority (GSrvTarget
*target
)
185 return target
->priority
;
189 * g_srv_target_get_weight:
190 * @target: a #GSrvTarget
192 * Gets @target's weight. You should not need to look at this;
193 * #GResolver already sorts the targets according to the algorithm in
196 * Return value: @target's weight
201 g_srv_target_get_weight (GSrvTarget
*target
)
203 return target
->weight
;
207 compare_target (gconstpointer a
, gconstpointer b
)
209 GSrvTarget
*ta
= (GSrvTarget
*)a
;
210 GSrvTarget
*tb
= (GSrvTarget
*)b
;
212 if (ta
->priority
== tb
->priority
)
214 /* Arrange targets of the same priority "in any order, except
215 * that all those with weight 0 are placed at the beginning of
218 return ta
->weight
- tb
->weight
;
221 return ta
->priority
- tb
->priority
;
225 * g_srv_target_list_sort: (skip)
226 * @targets: a #GList of #GSrvTarget
228 * Sorts @targets in place according to the algorithm in RFC 2782.
230 * Return value: (transfer full): the head of the sorted list.
235 g_srv_target_list_sort (GList
*targets
)
237 gint sum
, num
, val
, priority
, weight
;
238 GList
*t
, *out
, *tail
;
246 target
= targets
->data
;
247 if (!strcmp (target
->hostname
, "."))
249 /* 'A Target of "." means that the service is decidedly not
250 * available at this domain.'
252 g_srv_target_free (target
);
253 g_list_free (targets
);
258 /* Sort input list by priority, and put the 0-weight targets first
259 * in each priority group. Initialize output list to %NULL.
261 targets
= g_list_sort (targets
, compare_target
);
264 /* For each group of targets with the same priority, remove them
265 * from @targets and append them to @out in a valid order.
269 priority
= ((GSrvTarget
*)targets
->data
)->priority
;
271 /* Count the number of targets at this priority level, and
272 * compute the sum of their weights.
275 for (t
= targets
; t
; t
= t
->next
)
277 target
= (GSrvTarget
*)t
->data
;
278 if (target
->priority
!= priority
)
280 sum
+= target
->weight
;
284 /* While there are still targets at this priority level... */
287 /* Randomly select from the targets at this priority level,
288 * giving precedence to the ones with higher weight,
289 * according to the rules from RFC 2782.
291 val
= g_random_int_range (0, sum
+ 1);
292 for (t
= targets
; ; t
= t
->next
)
294 weight
= ((GSrvTarget
*)t
->data
)->weight
;
300 targets
= g_list_remove_link (targets
, t
);