.\"

.\" Copyright 2005 by Dominick Meglio.

.\"

.\" Permission to use, copy, modify, and distribute this

.\" software and its documentation for any purpose and without

.\" fee is hereby granted, provided that the above copyright

.\" notice appear in all copies and that both that copyright

.\" notice and this permission notice appear in supporting

.\" documentation, and that the name of M.I.T. not be used in

.\" advertising or publicity pertaining to distribution of the

.\" software without specific, written prior permission.

.\" M.I.T. makes no representations about the suitability of

.\" this software for any purpose.  It is provided "as is"

.\" without express or implied warranty.

.\"

.TH ARES_GETNAMEINFO 3 "1 May 2009"

.SH NAME

ares_getnameinfo \- Address-to-nodename translation in protocol-independent manner

.SH SYNOPSIS

.nf

.B #include <ares.h>

.PP

.B typedef void (*ares_nameinfo_callback)(void *\fIarg\fP, int \fIstatus\fP,

.B	int \fItimeouts\fP, char *\fInode\fP, char *\fIservice\fP)

.PP

.B void ares_getnameinfo(ares_channel \fIchannel\fP, const struct sockaddr *\fIsa\fP,

.B 	ares_socklen_t \fIsalen\fP, int \fIflags\fP, ares_nameinfo_callback \fIcallback\fP,

.B 	void *\fIarg\fP)

.fi

.SH DESCRIPTION

The

.B ares_getnameinfo

function is defined for protocol-independent address translation. The function

is a combination of \fIares_gethostbyaddr(3)\fP and \fIgetservbyport(3)\fP. The function will

translate the address either by executing a host query on the name service channel

identified by

.IR channel 

or it will attempt to resolve it locally if possible.

The parameters

.I sa

and

.I len

give the address as a sockaddr structure, and

.I flags

gives the options that the function will use.  Valid flags are listed below:

.TP 19

.B ARES_NI_NOFQDN

Only the nodename portion of the FQDN is returned for local hosts.

.TP 19

.B ARES_NI_NUMERICHOST

The numeric form of the hostname is returned rather than the name.

.TP 19

.B ARES_NI_NAMEREQD

An error is returned if the hostname cannot be found in the DNS.

.TP 19

.B ARES_NI_NUMERICSERV

The numeric form of the service is returned rather than the name.

.TP 19

.B ARES_NI_TCP

The service name is to be looked up for the TCP protocol.

.TP 19

.B ARES_NI_UDP

The service name is to be looked up for the UDP protocol.

.TP 19

.B ARES_NI_SCTP

The service name is to be looked up for the SCTP protocol.

.TP 19

.B ARES_NI_DCCP

The service name is to be looked up for the DCCP protocol.

.TP 19

.B ARES_NI_NUMERICSCOPE

The numeric form of the scope ID is returned rather than the name.

.TP 19

.B ARES_NI_LOOKUPHOST

A hostname lookup is being requested.

.TP 19

.B ARES_NI_LOOKUPSERVICE

A service name lookup is being requested.

.PP

When the query

is complete or has 

failed, the ares library will invoke \fIcallback\fP.  Completion or failure of 

the query may happen immediately, or may happen during a later call to

\fIares_process(3)\fP, \fIares_destroy(3)\fP or \fIares_cancel(3)\fP.

.PP

The callback argument

.I arg

is copied from the

.B ares_getnameinfo

argument

.IR arg .

The callback argument

.I status

indicates whether the query succeeded and, if not, how it failed.  It

may have any of the following values:

.TP 19

.B ARES_SUCCESS

The host lookup completed successfully.

.TP 19

.B ARES_ENOTIMP

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

.IR family .

.TP 19

.B ARES_ENOTFOUND

The address

.I addr

was not found.

.TP 19

.B ARES_ENOMEM

Memory was exhausted.

.TP 19

.B ARES_ECANCELLED

The query was cancelled.

.TP 19

.B ARES_EDESTRUCTION

The name service channel

.I channel

is being destroyed; the query will not be completed.

.TP 19

.B ARES_EBADFLAGS

The

.I flags

parameter contains an illegal value.

.PP

The callback argument

.I timeouts

reports how many times a query timed out during the execution of the

given request.

.PP

On successful completion of the query, the callback argument

.I node

contains a string representing the hostname (assuming 

.B ARES_NI_LOOKUPHOST

was specified). Additionally, 

.I service

contains a string representing the service name (assuming

.B ARES_NI_LOOKUPSERVICE

was specified).

If the query did not complete successfully, or one of the values

was not requested, 

.I node

or

.I service

will be 

.BR NULL .

.SH SEE ALSO

.BR ares_process (3),

.SH AUTHOR

Dominick Meglio

.br

Copyright 2005 by Dominick Meglio.