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ARES_SEND(3)									     ARES_SEND(3)

       ares_send - Initiate a DNS query

       #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)

       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  immedi-
       ately, 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 argu-
       ment 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 execu-
       tion 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 func-
       tions 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.


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

					   25 July 1998 			     ARES_SEND(3)
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