ares_process - Process events for name resolution
void ares_process(ares_channel channel, fd_set *read_fds,
void ares_process_fd(ares_channel channel, ares_socket_t read_fd, ares_socket_t write_fd)
The ares_process(3) function handles input/output events and timeouts associated with
queries pending on the name service channel identified by channel. The file descriptor
sets pointed to by read_fds and write_fds should have file descriptors set in them accord-
ing to whether the file descriptors specified by ares_fds(3) are ready for reading and
writing. (The easiest way to determine this information is to invoke select with a time-
out no greater than the timeout given by ares_timeout(3) ).
The ares_process function will invoke callbacks for pending queries if they complete suc-
cessfully or fail.
ares_process_fd(3) works the same way but acts and operates only on the specific file
descriptors (sockets) you pass in to the function. Use ARES_SOCKET_BAD for "no action".
This function is of course provided to allow users of c-ares to void select() in their
applications and within c-ares.
The following code fragment waits for all pending queries on a channel to complete:
int nfds, count;
fd_set readers, writers;
struct timeval tv, *tvp;
nfds = ares_fds(channel, &readers, &writers);
if (nfds == 0)
tvp = ares_timeout(channel, NULL, &tv);
count = select(nfds, &readers, &writers, NULL, tvp);
ares_process(channel, &readers, &writers);
Greg Hudson, MIT Information Systems
Copyright 1998 by the Massachusetts Institute of Technology.
25 July 1998 ARES_PROCESS(3)