package Net::DNS::Update;
use base Net::DNS::Packet;

#
# $Id: Update.pm 979 2012-01-27 08:43:38Z willem $
#
use vars qw($VERSION @ISA);
$VERSION = (qw$LastChangedRevision: 979 $)[1];


=head1 NAME

Net::DNS::Update - Create a DNS update packet

=head1 SYNOPSIS

    use Net::DNS::Update;

    $update = Net::DNS::Update->new;
    $update = Net::DNS::Update->new('example.com', 'IN');

    $update->push(prerequisite => nxrrset('foo.example.com. A'));
    $update->push(update => rr_add('foo.example.com. 86400 A 192.168.1.2'));

=head1 DESCRIPTION

C<Net::DNS::Update> is a subclass of C<Net::DNS::Packet>, to be
used for making DNS dynamic updates.  Programmers should refer
to RFC 2136 for the semantics of dynamic updates.

=cut


use strict;
use Net::DNS;


=head1 METHODS

=head2 new

    $update = Net::DNS::Update->new;
    $update = Net::DNS::Update->new('example.com');
    $update = Net::DNS::Update->new('example.com', 'HS');

Returns a C<Net::DNS::Update> object used to perform a DNS dynamic
update operation.  Specifically, it creates a packet with the header
opcode set to UPDATE and zone qtype to SOA (per RFC 2136, 2.3).

Programs must use the C<push> method to add RRs to the prerequisite,
update, and additional sections before performing the update.

Arguments are the zone name and the class.  If the zone is omitted,
the default domain will be taken from the resolver configuration.
If the class is omitted, it defaults to IN.

Future versions of C<Net::DNS> may provide a simpler interface
for making dynamic updates.

=cut

sub new {
	my ( $class, $zone, $zclass ) = @_;
	$zclass ||= 'IN';

	unless ($zone) {
		my $resolver = new Net::DNS::Resolver;
		($zone) = $resolver->searchlist;
		return undef unless $zone;
	}

	my $self = $class->SUPER::new( $zone, 'SOA', $zclass ) || return;

	$self->header->opcode('UPDATE');
	$self->header->rd(0);

	return $self;
}


1;
__END__


=head1 EXAMPLES

The first example below shows a complete program; subsequent examples
show only the creation of the update packet.

=head2 Add a new host

    #!/usr/bin/perl -w

    use strict;
    use Net::DNS;

    # Create the update packet.
    my $update = Net::DNS::Update->new('example.com');

    # Prerequisite is that no A records exist for the name.
    $update->push(prerequisite => nxrrset('foo.example.com. A'));

    # Add two A records for the name.
    $update->push(update => rr_add('foo.example.com. 86400 A 192.168.1.2'));
    $update->push(update => rr_add('foo.example.com. 86400 A 172.16.3.4'));

    # Send the update to the zone's primary master.
    my $res = Net::DNS::Resolver->new;
    $res->nameservers('primary-master.example.com');

    my $reply = $res->send($update);

    # Did it work?
    if ($reply) {
        my $rcode = $reply->header->rcode;
        print 'Update ', $rcode eq 'NOERROR' ? "succeeded\n" : "failed: $rcode\n";
    } else {
        print 'Update failed: ', $res->errorstring, "\n";
    }

=head2 Add an MX record for a name that already exists

    my $update = Net::DNS::Update->new('example.com');
    $update->push(prerequisite => yxdomain('example.com'));
    $update->push(update       => rr_add('example.com MX 10 mailhost.example.com'));

=head2 Add a TXT record for a name that doesn't exist

    my $update = Net::DNS::Update->new('example.com');
    $update->push(prerequisite => nxdomain('info.example.com'));
    $update->push(update       => rr_add('info.example.com TXT "yabba dabba doo"'));

=head2 Delete all A records for a name

    my $update = Net::DNS::Update->new('example.com');
    $update->push(prerequisite => yxrrset('foo.example.com A'));
    $update->push(update       => rr_del('foo.example.com A'));

=head2 Delete all RRs for a name

    my $update = Net::DNS::Update->new('example.com');
    $update->push(prerequisite => yxdomain('byebye.example.com'));
    $update->push(update       => rr_del('byebye.example.com'));

=head2 Perform a signed update

    my $key_name = 'tsig-key';
    my $key_data = 'awwLOtRfpGE+rRKF2+DEiw==';

    my $update = Net::DNS::Update->new('example.com');
    $update->push(update => rr_add('foo.example.com A 10.1.2.3'));
    $update->push(update => rr_add('bar.example.com A 10.4.5.6'));
    $update->sign_tsig($key_name, $key_data);

=head2 Another way to perform a signed update

    my $key_name = 'tsig-key';
    my $key_data = 'awwLOtRfpGE+rRKF2+DEiw==';

    my $update = Net::DNS::Update->new('example.com');
    $update->push(update     => rr_add('foo.example.com A 10.1.2.3'));
    $update->push(update     => rr_add('bar.example.com A 10.4.5.6'));
    $update->push(additional => Net::DNS::RR->new("$key_name TSIG $key_data"));

=head2 Perform a signed update with a customized TSIG record

    my $key_name = 'tsig-key';
    my $key_data = 'awwLOtRfpGE+rRKF2+DEiw==';

    my $tsig = Net::DNS::RR->new("$key_name TSIG $key_data");
    $tsig->fudge(60);

    my $update = Net::DNS::Update->new('example.com');
    $update->push(update     => rr_add('foo.example.com A 10.1.2.3'));
    $update->push(update     => rr_add('bar.example.com A 10.4.5.6'));
    $update->push(additional => $tsig);


=head1 BUGS

WARNING:  This code is still under development.
Please use with caution on production nameservers.


=head1 COPYRIGHT

Copyright (c)1997-2002 Michael Fuhr.

Portions Copyright (c)2002-2004 Chris Reinhardt.

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::Resolver>, L<Net::DNS::Header>,
L<Net::DNS::Packet>, L<Net::DNS::Question>, L<Net::DNS::RR>, RFC 2136,
RFC 2845

=cut