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 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
