ares_process (3) Linux Manual Page

ares_process – Process events for name resolution

Synopsis

#include <ares.h>

void ares_process(ares_channel channel, fd_set *read_fds,

void ares_process_fd(ares_channel channel, ares_socket_t read_fd,

Description

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 according 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 timeout no greater than the timeout given by ares_timeout(3) ).

The ares_process function will invoke callbacks for pending queries if they complete successfully 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.

Example

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;

while (1)

 {

 FD_ZERO(&readers);

 FD_ZERO(&writers);

 nfds = ares_fds(channel, &readers, &writers);

 if (nfds == 0)

 break;

 tvp = ares_timeout(channel, NULL, &tv);

 count = select(nfds, &readers, &writers, NULL, tvp);

 ares_process(channel, &readers, &writers);

 }

See Also

ares_fds(3), ares_timeout(3)

Author

Greg Hudson, MIT Information Systems
Copyright 1998 by the Massachusetts Institute of Technology.