#
# $Id: UDP.pm 360 2015-01-20 18:36:06Z gomor $
#
package Net::Frame::Layer::UDP;
use strict;
use warnings;
use Net::Frame::Layer qw(:consts :subs);
require Exporter;
our @ISA = qw(Net::Frame::Layer Exporter);
our %EXPORT_TAGS = (
consts => [qw(
NF_UDP_HDR_LEN
)],
);
our @EXPORT_OK = (
@{$EXPORT_TAGS{consts}},
);
use constant NF_UDP_HDR_LEN => 8;
our @AS = qw(
src
dst
length
checksum
);
__PACKAGE__->cgBuildIndices;
__PACKAGE__->cgBuildAccessorsScalar(\@AS);
no strict 'vars';
sub new {
my $self = shift->SUPER::new(
src => getRandomHighPort(),
dst => 0,
length => 0,
checksum => 0,
@_,
);
return $self;
}
sub pack {
my $self = shift;
$self->[$__raw] = $self->SUPER::pack('nnnn',
$self->[$__src],
$self->[$__dst],
$self->[$__length],
$self->[$__checksum],
) or return;
return $self->[$__raw];
}
sub unpack {
my $self = shift;
# Pad it if less than the required length
if (length($self->[$__raw]) < NF_UDP_HDR_LEN) {
$self->[$__raw] .= ("\x00" x (NF_UDP_HDR_LEN - length($self->[$__raw])));
}
my ($src, $dst, $len, $checksum, $payload) =
$self->SUPER::unpack('nnnn a*', $self->[$__raw])
or return;
$self->[$__src] = $src;
$self->[$__dst] = $dst;
$self->[$__length] = $len;
$self->[$__checksum] = $checksum;
$self->[$__payload] = $payload;
return $self;
}
sub getLength {
return NF_UDP_HDR_LEN;
}
sub computeLengths {
my $self = shift;
my ($layers) = @_;
my $len = $self->getLength;
my $start = 0;
my $last = $self;
for my $l (@$layers) {
$last = $l;
if (! $start) {
$start++ if $l->layer eq 'UDP';
next;
}
$len += $l->getLength;
}
if (defined($last->payload) && length($last->payload)) {
$len += length($last->payload);
}
$self->[$__length] = $len;
return 1;
}
sub computeChecksums {
my $self = shift;
my ($layers) = @_;
my $phpkt;
for my $l (@$layers) {
if ($l->layer eq 'IPv4') {
$phpkt = $self->SUPER::pack('a4a4CCn',
inetAton($l->src), inetAton($l->dst), 0, 17, $self->[$__length]);
}
elsif ($l->layer eq 'IPv6') {
$phpkt = $self->SUPER::pack('a*a*NnCC',
inet6Aton($l->src), inet6Aton($l->dst), $self->[$__length],
0, 0, 17);
}
}
$phpkt .= $self->SUPER::pack('nnnn',
$self->[$__src], $self->[$__dst], $self->[$__length], 0)
or return;
my $start = 0;
my $last = $self;
my $payload = '';
for my $l (@$layers) {
$last = $l;
if (! $start) {
$start++ if $l->layer eq 'UDP';
next;
}
$payload .= $l->pack;
}
if (defined($last->payload) && length($last->payload)) {
$payload .= $last->payload;
}
if (length($payload)) {
$phpkt .= $self->SUPER::pack('a*', $payload)
or return;
}
$self->[$__checksum] = inetChecksum($phpkt);
return 1;
}
our $Next = {
};
sub encapsulate {
my $self = shift;
return $Next->{$self->[$__dst]} || $Next->{$self->[$__src]}
|| $self->[$__nextLayer];
}
sub getKey {
my $self = shift;
return $self->layer.':'.$self->[$__src].'-'.$self->[$__dst];
}
sub getKeyReverse {
my $self = shift;
return $self->layer.':'.$self->[$__dst].'-'.$self->[$__src];
}
sub match {
my $self = shift;
my ($with) = @_;
return 1;
}
sub print {
my $self = shift;
my $l = $self->layer;
return sprintf
"$l: src:%d dst:%d length:%d checksum:0x%02x",
$self->[$__src], $self->[$__dst], $self->[$__length],
$self->[$__checksum];
}
1;
__END__
=head1 NAME
Net::Frame::Layer::UDP - User Datagram Protocol layer object
=head1 SYNOPSIS
use Net::Frame::Layer::UDP qw(:consts);
# Build a layer
my $layer = Net::Frame::Layer::UDP->new(
src => getRandomHighPort(),
dst => 0,
length => 0,
checksum => 0,
);
$layer->pack;
print 'RAW: '.$layer->dump."\n";
# Read a raw layer
my $layer = Net::Frame::Layer::UDP->new(raw = $raw);
print $layer->print."\n";
print 'PAYLOAD: '.unpack('H*', $layer->payload)."\n"
if $layer->payload;
=head1 DESCRIPTION
This modules implements the encoding and decoding of the UDP layer.
RFC: ftp://ftp.rfc-editor.org/in-notes/rfc768.txt
See also B<Net::Frame::Layer> for other attributes and methods.
=head1 ATTRIBUTES
=over 4
=item B<src>
=item B<dst>
Source and destination ports.
=item B<length>
The length in bytes of the datagram, including layer 7 payload (that is, layer 4 + layer 7).
=item B<checksum>
Checksum of the datagram.
=back
The following are inherited attributes. See B<Net::Frame::Layer> for more information.
=over 4
=item B<raw>
=item B<payload>
=item B<nextLayer>
=back
=head1 METHODS
=over 4
=item B<new>
=item B<new> (hash)
Object constructor. You can pass attributes that will overwrite default ones. See B<SYNOPSIS> for default values.
=item B<computeLengths>
Computes various lengths contained within this layer.
=item B<computeChecksums> ({ type => PROTO, src => IP, dst => IP })
In order to compute checksums of TCP, you need to pass the protocol type (IPv4, IPv6), the source and destination IP addresses (IPv4 for IPv4, IPv6 for IPv6).
=item B<getKey>
=item B<getKeyReverse>
These two methods are basically used to increase the speed when using B<recv> method from B<Net::Frame::Simple>. Usually, you write them when you need to write B<match> method.
=item B<match> (Net::Frame::Layer::UDP object)
This method is mostly used internally. You pass a B<Net::Frame::Layer::UDP> layer as a parameter, and it returns true if this is a response corresponding for the request, or returns false if not.
=back
The following are inherited methods. Some of them may be overridden in this layer, and some others may not be meaningful in this layer. See B<Net::Frame::Layer> for more information.
=over 4
=item B<layer>
=item B<computeLengths>
=item B<computeChecksums>
=item B<pack>
=item B<unpack>
=item B<encapsulate>
=item B<getLength>
=item B<getPayloadLength>
=item B<print>
=item B<dump>
=back
=head1 CONSTANTS
No constants here.
=head1 SEE ALSO
L<Net::Frame::Layer>
=head1 AUTHOR
Patrice E<lt>GomoRE<gt> Auffret
=head1 COPYRIGHT AND LICENSE
Copyright (c) 2006-2015, Patrice E<lt>GomoRE<gt> Auffret
You may distribute this module under the terms of the Artistic license.
See LICENSE.Artistic file in the source distribution archive.
=cut