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 */
38void 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
91done:
92  ares__channel_unlock(channel);
93}
94