1
2 /* Copyright 1998 by the Massachusetts Institute of Technology.
3 *
4 * Permission to use, copy, modify, and distribute this
5 * software and its documentation for any purpose and without
6 * fee is hereby granted, provided that the above copyright
7 * notice appear in all copies and that both that copyright
8 * notice and this permission notice appear in supporting
9 * documentation, and that the name of M.I.T. not be used in
10 * advertising or publicity pertaining to distribution of the
11 * software without specific, written prior permission.
12 * M.I.T. makes no representations about the suitability of
13 * this software for any purpose. It is provided "as is"
14 * without express or implied warranty.
15 */
16
17 #include "ares_setup.h"
18
19 #ifdef HAVE_SYS_TIME_H
20 #include <sys/time.h>
21 #endif
22
23 #include "ares.h"
24 #include "ares_nowarn.h"
25 #include "ares_private.h"
26
ares_fds(ares_channel channel,fd_set * read_fds,fd_set * write_fds)27 int ares_fds(ares_channel channel, fd_set *read_fds, fd_set *write_fds)
28 {
29 struct server_state *server;
30 ares_socket_t nfds;
31 int i;
32
33 /* Are there any active queries? */
34 int active_queries = !ares__is_list_empty(&(channel->all_queries));
35
36 nfds = 0;
37 for (i = 0; i < channel->nservers; i++)
38 {
39 server = &channel->servers[i];
40 /* We only need to register interest in UDP sockets if we have
41 * outstanding queries.
42 */
43 if (active_queries && server->udp_socket != ARES_SOCKET_BAD)
44 {
45 FD_SET(server->udp_socket, read_fds);
46 if (server->udp_socket >= nfds)
47 nfds = server->udp_socket + 1;
48 }
49 /* We always register for TCP events, because we want to know
50 * when the other side closes the connection, so we don't waste
51 * time trying to use a broken connection.
52 */
53 if (server->tcp_socket != ARES_SOCKET_BAD)
54 {
55 FD_SET(server->tcp_socket, read_fds);
56 if (server->qhead)
57 FD_SET(server->tcp_socket, write_fds);
58 if (server->tcp_socket >= nfds)
59 nfds = server->tcp_socket + 1;
60 }
61 }
62 return (int)nfds;
63 }
64