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ARES_QUERY(3)									    ARES_QUERY(3)

NAME
       ares_query - Initiate a single-question DNS query

SYNOPSIS
       #include <ares.h>

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

       void ares_query(ares_channel channel, const char *name,
	    int dnsclass, int type, ares_callback callback,
       void *arg)

DESCRIPTION
       The  ares_query function initiates a single-question DNS query on the name service channel
       identified by channel.  The parameter name gives the query  name  as  a	NUL-terminated	C
       string of period-separated labels optionally ending with a period; periods and backslashes
       within a label must be escaped with a backslash.  The parameters dnsclass  and  type  give
       the  class  and	type of the query using the values defined in <arpa/nameser.h>.  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_query 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 successfully.

       ARES_ENODATA	  The query completed but contains no answers.

       ARES_EFORMERR	  The query completed but the server claims that the query was malformat-
			  ted.

       ARES_ESERVFAIL	  The  query  completed but the server claims to have experienced a fail-
			  ure.	(This code can only occur if the ARES_FLAG_NOCHECKRESP	flag  was
			  specified at channel initialization time; otherwise, such responses are
			  ignored at the ares_send(3) level.)

       ARES_ENOTFOUND	  The query completed but the queried-for domain name was not found.

       ARES_ENOTIMP	  The query completed but the server does  not	implement  the	operation
			  requested   by   the	 query.    (This  code	can  only  occur  if  the
			  ARES_FLAG_NOCHECKRESP flag  was  specified  at  channel  initialization
			  time; otherwise, such responses are ignored at the ares_send(3) level.)

       ARES_EREFUSED	  The  query  completed but the server refused the query.  (This code can
			  only occur if the ARES_FLAG_NOCHECKRESP flag was specified  at  channel
			  initialization  time;  otherwise,  such  responses  are  ignored at the
			  ares_send(3) level.)

       ARES_EBADNAME	  The query name name could not be  encoded  as  a  domain  name,  either
			  because  it  contained  a  zero-length  label or because it contained a
			  label of more than 63 characters.

       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 (even if there was something wrong with it, as indicated by some of
       the  above  error  codes),  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.

SEE ALSO
       ares_process(3)

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

					   24 July 1998 			    ARES_QUERY(3)
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