ARES_GETHOSTBYADDR
Section: C Library Functions (3)
Updated: 24 July 1998
Page Index
NAME
ares_gethostbyaddr - Initiate a host query by address
SYNOPSIS
#include <ares.h>
typedef void (*ares_host_callback)(void *arg, int status,
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_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.
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.