1 /* MIT License
2 *
3 * Copyright (c) 1998 Massachusetts Institute of Technology
4 * Copyright (c) The c-ares project and its contributors
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice (including the next
14 * paragraph) shall be included in all copies or substantial portions of the
15 * Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
20 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
23 * SOFTWARE.
24 *
25 * SPDX-License-Identifier: MIT
26 */
27
28 #include "ares_private.h"
29
ares_fds(const ares_channel_t * channel,fd_set * read_fds,fd_set * write_fds)30 int ares_fds(const ares_channel_t *channel, fd_set *read_fds, fd_set *write_fds)
31 {
32 ares_socket_t nfds;
33 ares_slist_node_t *snode;
34 /* Are there any active queries? */
35 size_t active_queries;
36
37 if (channel == NULL || read_fds == NULL || write_fds == NULL) {
38 return 0;
39 }
40
41 ares_channel_lock(channel);
42
43 active_queries = ares_llist_len(channel->all_queries);
44
45 nfds = 0;
46 for (snode = ares_slist_node_first(channel->servers); snode != NULL;
47 snode = ares_slist_node_next(snode)) {
48 ares_server_t *server = ares_slist_node_val(snode);
49 ares_llist_node_t *node;
50
51 for (node = ares_llist_node_first(server->connections); node != NULL;
52 node = ares_llist_node_next(node)) {
53 const ares_conn_t *conn = ares_llist_node_val(node);
54
55 if (!active_queries && !(conn->flags & ARES_CONN_FLAG_TCP)) {
56 continue;
57 }
58
59 /* Silence coverity, shouldn't be possible */
60 if (conn->fd == ARES_SOCKET_BAD) {
61 continue;
62 }
63
64 /* Always wait on read */
65 FD_SET(conn->fd, read_fds);
66
67 if (conn->fd >= nfds) {
68 nfds = conn->fd + 1;
69 }
70
71 /* TCP only wait on write if we have the flag set */
72 if (conn->state_flags & ARES_CONN_STATE_WRITE) {
73 FD_SET(conn->fd, write_fds);
74 }
75 }
76 }
77
78 ares_channel_unlock(channel);
79 return (int)nfds;
80 }
81