ares_query(3) [centos man page]

ARES_QUERY(3)						     Library Functions Manual						     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 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 successfully.

       ARES_ENODATA	  The query completed but contains no answers.

       ARES_EFORMERR	  The query completed but the server claims that the query was malformatted.

       ARES_ESERVFAIL	  The query completed but the  server  claims  to  have  experienced  a  failure.   (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 execution 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)

Check Out this Related Man Page

ARES_GETHOSTBYADDR(3)					     Library Functions Manual					     ARES_GETHOSTBYADDR(3)

NAME

       ares_gethostbyaddr - Initiate a host query by address

SYNOPSIS

       #include <ares.h>

       typedef void (*ares_host_callback)(void *arg, int status,
       int timeouts, struct hostent *hostent)

       void ares_gethostbyaddr(ares_channel channel, const void *addr,
	    int addrlen, int family, ares_host_callback callback,
	    void *arg)

DESCRIPTION

       The  ares_gethostbyaddr	function initiates a host query by address on the name service channel identified by channel.  The parameters addr
       and addrlen give the address as a series of bytes, and family gives the type of address.  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), ares_destroy(3) or ares_cancel(3).

       The callback argument arg is copied from the ares_gethostbyaddr 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 host lookup completed successfully.

       ARES_ENOTIMP	  The ares library does not know how to look up addresses of type family.

       ARES_ENOTFOUND	  The address addr was not found.

       ARES_ENOMEM	  Memory was exhausted.

       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.

       On successful completion of the query, the callback argument hostent points to a struct hostent containing the name of the host returned by
       the query.  The callback need not and should not attempt to free the memory pointed to by hostent; the ares library will free it  when  the
       callback returns.  If the query did not complete successfully, hostent will be NULL.

SEE ALSO

       ares_process(3), ares_gethostbyname(3)

AUTHOR

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

								   24 July 1998 					     ARES_GETHOSTBYADDR(3)

Linux and UNIX Man Pages

ares_query(3) [centos man page]

Check Out this Related Man Page