#
# NetPacket::ARP - Decode and endode ARP (Address Resolution Protocol)
# packets.
#
# Comments/suggestions to tpot@samba.org
#
# $Id: ARP.pm,v 1.11 2001/07/29 23:45:00 tpot Exp $
#
package NetPacket::ARP;
#
# Copyright (c) 2001 Tim Potter.
#
# This package is free software and is provided "as is" without express
# or implied warranty. It may be used, redistributed and/or modified
# under the terms of the Perl Artistic License (see
# http://www.perl.com/perl/misc/Artistic.html)
#
# Copyright (c) 1995,1996,1997,1998,1999 ANU and CSIRO on behalf of
# the participants in the CRC for Advanced Computational Systems
# ('ACSys').
#
# ACSys makes this software and all associated data and documentation
# ('Software') available free of charge. You may make copies of the
# Software but you must include all of this notice on any copy.
#
# The Software was developed for research purposes and ACSys does not
# warrant that it is error free or fit for any purpose. ACSys
# disclaims any liability for all claims, expenses, losses, damages
# and costs any user may incur as a result of using, copying or
# modifying the Software.
#
use strict;
use vars qw($VERSION @ISA @EXPORT @EXPORT_OK %EXPORT_TAGS);
my $myclass;
BEGIN {
$myclass = __PACKAGE__;
$VERSION = "0.04";
}
sub Version () { "$myclass v$VERSION" }
BEGIN {
@ISA = qw(Exporter NetPacket);
# Items to export into callers namespace by default
# (move infrequently used names to @EXPORT_OK below)
@EXPORT = qw(
);
# Other items we are prepared to export if requested
@EXPORT_OK = qw(arp_strip
ARP_OPCODE_REQUEST ARP_OPCODE_REPLY RARP_OPCODE_REQUEST
RARP_OPCODE_REPLY
);
# Tags:
%EXPORT_TAGS = (
ALL => [@EXPORT, @EXPORT_OK],
opcodes => [qw(ARP_OPCODE_REQUEST ARP_OPCODE_REPLY RARP_OPCODE_REQUEST
RARP_OPCODE_REPLY)],
strip => [qw(arp_strip)],
);
}
#
# List of opcode values
#
use constant ARP_OPCODE_REQUEST => 1;
use constant ARP_OPCODE_REPLY => 2;
use constant RARP_OPCODE_REQUEST => 3;
use constant RARP_OPCODE_REPLY => 4;
#
# Decode the packet
#
sub decode {
my $class = shift;
my($pkt, $parent, @rest) = @_;
my $self = {};
# Class fields
$self->{_parent} = $parent;
$self->{_frame} = $pkt;
# Decode ARP packet
if (defined($pkt)) {
($self->{htype}, $self->{proto}, $self->{hlen}, $self->{plen},
$self->{opcode}, $self->{sha}, $self->{spa}, $self->{tha},
$self->{tpa}) =
unpack('nnCCnH12H8H12H8' , $pkt);
$self->{data} = undef;
}
# Return a blessed object
bless($self, $class);
return $self;
}
#
# Strip header from packet and return the data contained in it. ARP
# packets contain no encapsulated data.
#
undef &arp_strip;
*arp_strip = \&strip;
sub strip {
return undef;
}
#
# Encode a packet
#
sub encode {
die("Not implemented");
}
# Module return value
1;
# autoloaded methods go after the END token (&& pod) below
__END__
=head1 NAME
C<NetPacket::ARP> - Assemble and disassemble ARP (Address Resolution
Protocol) packets.
=head1 SYNOPSIS
use NetPacket::ARP;
$tcp_obj = NetPacket::ARP->decode($raw_pkt);
$tcp_pkt = NetPacket::ARP->encode(params...); # Not implemented
=head1 DESCRIPTION
C<NetPacket::ARP> provides a set of routines for assembling and
disassembling packets using ARP (Address Resolution Protocol).
=head2 Methods
=over
=item C<NetPacket::ARP-E<gt>decode([RAW PACKET])>
Decode the raw packet data given and return an object containing
instance data. This method will quite happily decode garbage input.
It is the responsibility of the programmer to ensure valid packet data
is passed to this method.
=item C<NetPacket::ARP-E<gt>encode(param =E<gt> value)>
Return a ARP packet encoded with the instance data specified. Not
implemented.
=back
=head2 Functions
=over
=item C<NetPacket::ARP::strip([RAW PACKET])>
Return the encapsulated data (or payload) contained in the TCP packet.
Since no payload data is encapulated in an ARP packet (only instance
data), this function returns undef.
=back
=head2 Instance data
The instance data for the C<NetPacket::ARP> object consists of
the following fields.
=over
=item htype
Hardware type.
=item proto
Protocol type.
=item hlen
Header length.
=item plen
Protocol length.
=item opcode
One of the following constants:
=over
=item * ARP_OPCODE_REQUEST
=item * ARP_OPCODE_REPLY
=item * RARP_OPCODE_REQUEST
=item * RARP_OPCODE_REPLY
=back
=item sha
Source hardware address.
=item spa
Source protocol address.
=item tha
Target hardware address.
=item tpa
Target protocol address.
=back
=head2 Exports
=over
=item default
none
=item exportable
none
=item tags
The following tags group together related exportable items.
=over
=item C<:ALL>
All the above exportable items.
=back
=back
=head1 EXAMPLE
Print out arp requests on the local network.
#!/usr/bin/perl -w
use Net::PcapUtils;
use NetPacket::Ethernet qw(:types);
use NetPacket::ARP;
sub process_pkt {
my ($arg, $hdr, $pkt) = @_;
my $eth_obj = NetPacket::Ethernet->decode($pkt);
if ($eth_obj->{type} == ETH_TYPE_ARP) {
my $arp_obj = NetPacket::ARP->decode($eth_obj->{data}, $eth_obj);
print("source hw addr=$arp_obj->{sha}, " .
"dest hw addr=$arp_obj->{tha}\n");
}
}
Net::PcapUtils::loop(\&process_pkt);
=head1 TODO
=over
=item Implement encode() function
=item Does this work for protocols other than IP? Need to read RFC.
=item Example is a bit silly
=back
=head1 COPYRIGHT
Copyright (c) 2001 Tim Potter.
This package is free software and is provided "as is" without express
or implied warranty. It may be used, redistributed and/or modified
under the terms of the Perl Artistic License (see
http://www.perl.com/perl/misc/Artistic.html)
Copyright (c) 1995,1996,1997,1998,1999 ANU and CSIRO on behalf of
the participants in the CRC for Advanced Computational Systems
('ACSys').
ACSys makes this software and all associated data and documentation
('Software') available free of charge. You may make copies of the
Software but you must include all of this notice on any copy.
The Software was developed for research purposes and ACSys does not
warrant that it is error free or fit for any purpose. ACSys
disclaims any liability for all claims, expenses, losses, damages
and costs any user may incur as a result of using, copying or
modifying the Software.
=head1 AUTHOR
Tim Potter E<lt>tpot@samba.orgE<gt>
=cut
# any real autoloaded methods go after this line