package Net::DNS::RR::DS;

#
# $Id: DS.pm 1307 2015-02-02 09:30:57Z willem $
#
use vars qw($VERSION);
$VERSION = (qw$LastChangedRevision: 1307 $)[1];


use strict;
use base qw(Net::DNS::RR);

=head1 NAME

Net::DNS::RR::DS - DNS DS resource record

=cut


use integer;

use warnings;
use Carp;

use constant BABBLE => eval { require Digest::BubbleBabble; };

eval { require Digest::SHA };		## optional for simple Net::DNS RR
eval { require Digest::GOST };
eval { require Digest::GOST::CryptoPro };

my %digest = (
	'1' => ['Digest::SHA', 1],
	'2' => ['Digest::SHA', 256],
	'3' => ['Digest::GOST::CryptoPro'],
	'4' => ['Digest::SHA', 384],
	);

#
# source: http://www.iana.org/assignments/dns-sec-alg-numbers
#
{
	my @algbyname = (		## Reserved	=> 0,	# [RFC4034][RFC4398]
		'RSAMD5'	     => 1,			# [RFC3110][RFC4034]
		'DH'		     => 2,			# [RFC2539]
		'DSA'		     => 3,			# [RFC3755][RFC2536]
					## Reserved	=> 4,	# [RFC6725]
		'RSASHA1'	     => 5,			# [RFC3110][RFC4034]
		'DSA-NSEC3-SHA1'     => 6,			# [RFC5155]
		'RSASHA1-NSEC3-SHA1' => 7,			# [RFC5155]
		'RSASHA256'	     => 8,			# [RFC5702]
					## Reserved	=> 9,	# [RFC6725]
		'RSASHA512'	     => 10,			# [RFC5702]
					## Reserved	=> 11,	# [RFC6725]
		'ECC-GOST'	     => 12,			# [RFC5933]
		'ECDSAP256SHA256'    => 13,			# [RFC6605]
		'ECDSAP384SHA384'    => 14,			# [RFC6605]

		'INDIRECT'   => 252,				# [RFC4034]
		'PRIVATEDNS' => 253,				# [RFC4034]
		'PRIVATEOID' => 254,				# [RFC4034]
					## Reserved	=> 255,	# [RFC4034]
		);

	my %algbyval = reverse @algbyname;

	my @algbynum = map { ( $_, 0 + $_ ) } ( 1 .. 250, keys %algbyval );

	my %algbyname = map { s/[^A-Za-z0-9]//g; $_ } @algbyname, @algbynum;

	sub algbyname {
		my $name = shift;
		my $key	 = uc $name;				# synthetic key
		$key =~ s/[^A-Z0-9]//g;				# strip non-alphanumerics
		return $algbyname{$key} || croak "unknown algorithm $name";
	}

	sub algbyval {
		my $value = shift;
		return $algbyval{$value} || $value;
	}
}

#
# source: http://www.iana.org/assignments/ds-rr-types
#
{
	my @digestbyname = (
		'SHA-1'	  => 1,					# RFC3658
		'SHA-256' => 2,					# RFC4509
		'GOST'	  => 3,					# RFC5933
		'SHA-384' => 4,					# RFC6605
		);

	my @digestbyalias = ( 'SHA' => 1 );

	my %digestbyval = reverse @digestbyname;

	my @digestbynum = map { ( $_, 0 + $_ ) } keys %digestbyval;    # accept algorithm number

	my %digestbyname = map { s /[^A-Za-z0-9]//g; $_ } @digestbyalias, @digestbyname, @digestbynum;


	sub digestbyname {
		my $name = shift;
		my $key	 = uc $name;				# synthetic key
		$key =~ s /[^A-Z0-9]//g;			# strip non-alphanumerics
		return $digestbyname{$key} || croak "unknown digest type $name";
	}

	sub digestbyval {
		my $value = shift;
		return $digestbyval{$value} || $value;
	}
}


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

	my $length = $self->{rdlength} - 4;
	@{$self}{qw(keytag algorithm digtype digestbin)} = unpack "\@$offset n C2 a$length", $$data;
}


sub encode_rdata {			## encode rdata as wire-format octet string
	my $self = shift;

	return '' unless $self->{digtype};
	pack 'n C2 a*', @{$self}{qw(keytag algorithm digtype digestbin)};
}


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

	return '' unless $self->{digtype};
	my @babble = BABBLE ? ( "\n;", $self->babble ) : ();
	my $digest = $self->digest;
	$digest = join( "\n", '(', split /(\S{64})/, $digest ) . ' )' if length $digest > 40;
	join ' ', @{$self}{qw(keytag algorithm digtype)}, $digest, @babble;
}


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

	$self->$_(shift) for qw(keytag algorithm digtype);
	$self->digest(@_);
}


sub keytag {
	my $self = shift;

	$self->{keytag} = 0 + shift if scalar @_;
	return $self->{keytag} || 0;
}


sub algorithm {
	my ( $self, $arg ) = @_;

	unless ( ref($self) ) {		## class method or simple function
		my $argn = pop || croak 'undefined argument';
		return $argn =~ /[^0-9]/ ? algbyname($argn) : algbyval($argn);
	}

	return $self->{algorithm} unless defined $arg;
	return algbyval( $self->{algorithm} ) if $arg =~ /MNEMONIC/i;
	return $self->{algorithm} = algbyname($arg);
}


sub digtype {
	my ( $self, $arg ) = @_;

	unless ( ref($self) ) {		## class method or simple function
		my $argn = pop || croak 'undefined argument';
		return $argn =~ /[^0-9]/ ? digestbyname($argn) : digestbyval($argn);
	}

	return $self->{digtype} unless defined $arg;
	return digestbyval( $self->{digtype} ) if $arg =~ /MNEMONIC/i;
	return $self->{digtype} = digestbyname($arg);
}


sub digest {
	my $self = shift;

	$self->digestbin( pack "H*", map { die "!hex!" if m/[^0-9A-Fa-f]/; $_ } join "", @_ ) if scalar @_;
	unpack "H*", $self->digestbin() if defined wantarray;
}


sub digestbin {
	my $self = shift;

	$self->{digestbin} = shift if scalar @_;
	$self->{digestbin} || "";
}


sub babble {
	return BABBLE ? Digest::BubbleBabble::bubblebabble( Digest => shift->digestbin ) : '';
}


sub create {
	my $class = shift;
	my $keyrr = shift;
	my %args  = $keyrr->ttl ? ( ttl => $keyrr->ttl, @_ ) : (@_);

	my ($type) = reverse split '::', $class;

	my $kname = $keyrr->name;
	my $flags = $keyrr->flags;
	croak "Unable to create $kname $type record for non-DNSSEC key" unless $keyrr->protocol == 3;
	croak "Unable to create $kname $type record for NULL key" if ( $flags & 0xc000 ) == 0xc000;
	croak "Unable to create $kname $type record for key with flag bit7 clear" unless $flags & 0x0100;
	croak "Unable to create $kname $type record for key with flag bit6 set" if $flags & 0x0200;
	croak "Unable to create $kname $type record for key with flag bit0 set" if $flags & 0x8000;

	my $self = new Net::DNS::RR(
		name	  => $kname,				# per definition, same as keyrr
		type	  => $type,
		class	  => $keyrr->class,
		keytag	  => $keyrr->keytag,
		algorithm => $keyrr->algorithm,
		digtype	  => 1,					# SHA1 by default
		%args
		);

	my $owner = $self->{owner}->encode();
	my $data = pack 'a* a*', $owner, $keyrr->encode_rdata;

	my $arglist = $digest{$self->digtype} || croak 'unsupported digest type';
	my ( $object, @argument ) = @$arglist;
	my $hash = $object->new(@argument);
	$hash->add($data);
	$self->digestbin( $hash->digest );

	return $self;
}


sub verify {
	my ( $self, $key ) = @_;
	my $verify = create Net::DNS::RR::DS( $key, ( digtype => $self->digtype ) );
	return $verify->digestbin eq $self->digestbin;
}

1;
__END__


=head1 SYNOPSIS

    use Net::DNS;
    $rr = new Net::DNS::RR('name DS keytag algorithm digtype digest');

=head1 DESCRIPTION

Class for DNS Delegation Signer (DS) 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 keytag

    $keytag = $rr->keytag;
    $rr->keytag( $keytag );

The 16-bit numerical key tag of the key. (RFC2535 4.1.6)

=head2 algorithm

    $algorithm = $rr->algorithm;
    $rr->algorithm( $algorithm );

Decimal representation of the 8-bit algorithm field.

algorithm() may also be invoked as a class method or simple function
to perform mnemonic and numeric code translation.

=head2 digtype

    $digtype = $rr->digtype;
    $rr->digtype( $digtype );

Decimal representation of the 8-bit digest type field.

digtype() may also be invoked as a class method or simple function
to perform mnemonic and numeric code translation.

=head2 digest

    $digest = $rr->digest;
    $rr->digest( $digest );

Hexadecimal representation of the digest over the label and key.

=head2 digestbin

    $digestbin = $rr->digestbin;
    $rr->digestbin( $digestbin );

Binary representation of the digest over the label and key.

=head2 babble

    print $rr->babble;

The babble() method returns the 'BubbleBabble' representation of the
The babble() method returns the 'BubbleBabble' representation of the
digest if the Digest::BubbleBabble package is available, otherwise
an empty string is returned.

BubbleBabble represents a message digest as a string of plausible
words, to make the digest easier to verify.  The "words" are not
necessarily real words, but they look more like words than a string
of hex characters.

The 'BubbleBabble' string is appended as a comment to the RDATA when
the string method is called.

=head2 create

    use Net::DNS::SEC;

    $dsrr = create Net::DNS::RR::DS($keyrr, digtype => 'SHA-256' );
    $keyrr->print;
    $dsrr->print;

This constructor takes a key object as argument and will return the
corresponding DS RR object.

The digest type defaults to SHA-1.

=head2 verify

    $verify = $dsrr->verify($keyrr);

The boolean verify method will return true if the hash over the key
RR provided as the argument conforms to the data in the DS itself
i.e. the DS points to the DNSKEY from the argument.


=head1 COPYRIGHT

Copyright (c)2001-2005 RIPE NCC.  Author Olaf M. Kolkman <olaf@net-dns.org>

Portions Copyright (c)2013 Dick Franks.

All Rights Reserved

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 the author not be used
in advertising or publicity pertaining to distribution of the software
without specific prior written permission.

THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS; IN NO
EVENT SHALL AUTHOR BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL
DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
THIS SOFTWARE.

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


=head1 SEE ALSO

L<perl>, L<Net::DNS>, L<Net::DNS::RR>, RFC4034, RFC3658

L<Algorithm Numbers|http://www.iana.org/assignments/dns-sec-alg-numbers>,
L<Digest Types|http://www.iana.org/assignments/ds-rr-types>

=cut
