ARES_SEND(3)           FreeBSD Library Functions Manual           ARES_SEND(3)

NAME
       ares_send - Initiate a DNS query

SYNOPSIS
       #include <ares.h>

       typedef void (*ares_callback)(void *arg, int status,
       int timeouts, unsigned char *abuf, int alen)

       void ares_send(ares_channel channel, const unsigned char *qbuf,
            int qlen, ares_callback callback, void *arg)

DESCRIPTION
       The ares_send function initiates a DNS query on the name service
       channel identified by channel.  The parameters qbuf and qlen give the
       DNS query, which should already have been formatted according to the
       DNS protocol.  When the query is complete or has failed, the ares
       library will invoke callback.  Completion or failure of the query may
       happen immediately, or may happen during a later call to
       ares_process(3) or ares_destroy(3).

       The callback argument arg is copied from the ares_send argument arg.
       The callback argument status indicates whether the query succeeded and,
       if not, how it failed.  It may have any of the following values:

       ARES_SUCCESS       The query completed.

       ARES_EBADQUERY     The query buffer was poorly formed (was not long
                          enough for a DNS header or was too long for TCP
                          transmission).

       ARES_ETIMEOUT      No name servers responded within the timeout period.

       ARES_ECONNREFUSED  No name servers could be contacted.

       ARES_ENOMEM        Memory was exhausted.

       ARES_ECANCELLED    The query was cancelled.

       ARES_EDESTRUCTION  The name service channel channel is being destroyed;
                          the query will not be completed.

       The callback argument timeouts reports how many times a query timed out
       during the execution of the given request.

       If the query completed, the callback argument abuf points to a result
       buffer of length alen.  If the query did not complete, abuf will be
       NULL and alen will be 0.

       Unless the flag ARES_FLAG_NOCHECKRESP was set at channel initialization
       time, ares_send will normally ignore responses whose questions do not
       match the questions in qbuf, as well as responses with reply codes of
       SERVFAIL, NOTIMP, and REFUSED.  Unlike other query functions in the
       ares library, however, ares_send does not inspect the header of the
       reply packet to determine the error status, so a callback status of
       ARES_SUCCESS does not reflect as much about the response as for other
       query functions.

SEE ALSO
       ares_process(3)

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

                                 25 July 1998                     ARES_SEND(3)