package Net::DNS::RR::MX;

#
# $Id: MX.pm 1096 2012-12-28 13:35:15Z willem $
#
use vars qw($VERSION);
$VERSION = (qw$LastChangedRevision: 1096 $)[1]; # Unchanged since 1037

use base Net::DNS::RR;

=head1 NAME

Net::DNS::RR::MX - DNS MX resource record

=cut


use strict;
use integer;

use Net::DNS::DomainName;


sub decode_rdata {			## decode rdata from wire-format octet string
	my $self = shift;
	my ( $data, $offset, @opaque ) = @_;

	$self->{preference} = unpack( "\@$offset n", $$data );
	$self->{exchange} = decode Net::DNS::DomainName1035($data,$offset+2,@opaque );
}


sub encode_rdata {			## encode rdata as wire-format octet string
	my $self = shift;
	my ( $offset, @opaque ) = @_;

	return '' unless $self->{exchange};
	my $rdata = pack 'n', $self->preference;
	$rdata .= $self->{exchange}->encode( $offset + length($rdata), @opaque );
}


sub format_rdata {			## format rdata portion of RR string.
	my $self = shift;

	return '' unless $self->{exchange};
	join ' ', $self->preference, $self->{exchange}->string;
}


sub parse_rdata {			## populate RR from rdata in argument list
	my $self = shift;

	$self->$_(shift) for qw(preference exchange);
}


sub preference {
	my $self = shift;

	$self->{preference} = shift if @_;
	return 0 + ( $self->{preference} || 0 );
}

sub exchange {
	my $self = shift;

	$self->{exchange} = new Net::DNS::DomainName1035(shift) if @_;
	$self->{exchange}->name if defined wantarray;
}

# sort RRs in numerically ascending order.
__PACKAGE__->set_rrsort_func(
	'preference',
	sub {
		my ( $a, $b ) = ( $Net::DNS::a, $Net::DNS::b );
		$a->{preference} <=> $b->{preference};
	} );


__PACKAGE__->set_rrsort_func(
	'default_sort',
	__PACKAGE__->get_rrsort_func('preference')

	);

1;
__END__


=head1 SYNOPSIS

    use Net::DNS;
    $rr = new Net::DNS::RR('name MX preference exchange');

=head1 DESCRIPTION

DNS Mail Exchanger (MX) resource record

=head1 METHODS

The available methods are those inherited from the base class augmented
by the type-specific methods defined in this package.

Use of undocumented package features or direct access to internal data
structures is discouraged and could result in program termination or
other unpredictable behaviour.


=head2 preference

    $preference = $rr->preference;

A 16 bit integer which specifies the preference
given to this RR among others at the same owner.
Lower values are preferred.

=head2 exchange

    $exchange = $rr->exchange;

A domain name which specifies a host willing
to act as a mail exchange for the owner name.


=head1 COPYRIGHT

Copyright (c)1997-2002 Michael Fuhr. 

Portions Copyright (c)2005 Olaf Kolkman, NLnet Labs.

Package template (c)2009,2012 O.M.Kolkman and R.W.Franks.

All rights reserved.

This program is free software; you may redistribute it and/or
modify it under the same terms as Perl itself.


=head1 SEE ALSO

L<perl>, L<Net::DNS>, L<Net::DNS::RR>, RFC1035 Section 3.3.9

=cut