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_setup.h"
29
30 #include "ares.h"
31 #include "ares_private.h"
32
ares_fds(ares_channel_t * channel,fd_set * read_fds,fd_set * write_fds)33 int ares_fds(ares_channel_t *channel, fd_set *read_fds, fd_set *write_fds)
34 {
35 ares_socket_t nfds;
36 ares__slist_node_t *snode;
37 /* Are there any active queries? */
38 size_t active_queries;
39
40 if (channel == NULL || read_fds == NULL || write_fds == NULL) {
41 return 0;
42 }
43
44 ares__channel_lock(channel);
45
46 active_queries = ares__llist_len(channel->all_queries);
47
48 nfds = 0;
49 for (snode = ares__slist_node_first(channel->servers); snode != NULL;
50 snode = ares__slist_node_next(snode)) {
51 struct server_state *server = ares__slist_node_val(snode);
52 ares__llist_node_t *node;
53
54 for (node = ares__llist_node_first(server->connections); node != NULL;
55 node = ares__llist_node_next(node)) {
56 const struct server_connection *conn = ares__llist_node_val(node);
57
58 if (!active_queries && !conn->is_tcp) {
59 continue;
60 }
61
62 /* Silence coverity, shouldn't be possible */
63 if (conn->fd == ARES_SOCKET_BAD) {
64 continue;
65 }
66
67 /* Always wait on read */
68 FD_SET(conn->fd, read_fds);
69
70 if (conn->fd >= nfds) {
71 nfds = conn->fd + 1;
72 }
73
74 /* TCP only wait on write if we have buffered data */
75 if (conn->is_tcp && ares__buf_len(server->tcp_send)) {
76 FD_SET(conn->fd, write_fds);
77 }
78 }
79 }
80
81 ares__channel_unlock(channel);
82 return (int)nfds;
83 }
84