1 /* MIT License
2 *
3 * Copyright (c) 2004 Daniel Stenberg
4 *
5 * Permission is hereby granted, free of charge, to any person obtaining a copy
6 * of this software and associated documentation files (the "Software"), to deal
7 * in the Software without restriction, including without limitation the rights
8 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
9 * copies of the Software, and to permit persons to whom the Software is
10 * furnished to do so, subject to the following conditions:
11 *
12 * The above copyright notice and this permission notice (including the next
13 * paragraph) shall be included in all copies or substantial portions of the
14 * Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22 * SOFTWARE.
23 *
24 * SPDX-License-Identifier: MIT
25 */
26
27 #include "ares_setup.h"
28 #include <assert.h>
29
30 #include "ares.h"
31 #include "ares_private.h"
32
33 /*
34 * ares_cancel() cancels all ongoing requests/resolves that might be going on
35 * on the given channel. It does NOT kill the channel, use ares_destroy() for
36 * that.
37 */
ares_cancel(ares_channel_t * channel)38 void ares_cancel(ares_channel_t *channel)
39 {
40 if (channel == NULL) {
41 return;
42 }
43
44 ares__channel_lock(channel);
45
46 if (ares__llist_len(channel->all_queries) > 0) {
47 ares__llist_node_t *node = NULL;
48 ares__llist_node_t *next = NULL;
49
50 /* Swap list heads, so that only those queries which were present on entry
51 * into this function are cancelled. New queries added by callbacks of
52 * queries being cancelled will not be cancelled themselves.
53 */
54 ares__llist_t *list_copy = channel->all_queries;
55 channel->all_queries = ares__llist_create(NULL);
56
57 /* Out of memory, this function doesn't return a result code though so we
58 * can't report to caller */
59 if (channel->all_queries == NULL) {
60 channel->all_queries = list_copy;
61 goto done;
62 }
63
64 node = ares__llist_node_first(list_copy);
65 while (node != NULL) {
66 struct query *query;
67 struct server_connection *conn;
68
69 /* Cache next since this node is being deleted */
70 next = ares__llist_node_next(node);
71
72 query = ares__llist_node_claim(node);
73 conn = query->conn;
74 query->node_all_queries = NULL;
75
76 /* NOTE: its possible this may enqueue new queries */
77 query->callback(query->arg, ARES_ECANCELLED, 0, NULL, 0);
78 ares__free_query(query);
79
80 /* See if the connection should be cleaned up */
81 ares__check_cleanup_conn(channel, conn);
82
83 node = next;
84 }
85
86 ares__llist_destroy(list_copy);
87 }
88
89 ares_queue_notify_empty(channel);
90
91 done:
92 ares__channel_unlock(channel);
93 }
94