Final follow up, bug is likely more of a desired feature/behavior and looks to have existed since the begining. Attached is a untested patch (did not test applying), changes in it have been tested against 1.3.3 on perl 5.14.2 to allow arbitrary packet creation. At present it appears that encode expects a packet to have been decoded by this module previously which does not allow packets to be generated by providing the L3, L4 and payload information.
On Thu May 16 22:01:26 2013,
http://openid-provider.appspot.com/koncept1 wrote:
Show quoted text> As a follow up to this, if it is called as NetPacket::UDP->encode($l4
> ,$l3) returns "Can't use string ("NetPacket::UDP") as a HASH ref
> while "strict refs" in use" however calling it as
> NetPacket::UDP::encode($l4, $l3); appears to work so one optioin
> would be updating the POD another would fixing the module to
> properly bless things into the class. I may take a shot at that
> and post a patch.
>
> On Thu May 16 18:21:14 2013, koncept1@gmail.com wrote:
> > There appears to be an issue in the NetPacket::UDP module where it
> is
> > looking in $self for the parameters but they are stored in $ip
> unless I am
> > calling this function incorrectly. The fix appears to be changing
> $self->
> > to $ip-> in the encode and checksum functions.
> >
> > Thanks
>
>
--- /usr/local/share/perl/5.14.2/NetPacket/UDP.pm 2013-05-16 22:45:39.517348883 -0400
+++ /tmp/UDP.pm 2013-05-15 23:36:38.000000000 -0400
@@ -83,21 +83,20 @@
#
sub encode {
- my $class = shift;
- my $self = {};
- bless($self, $class);
- my ($udp, $ip) = @_;
+
+ my $self = shift;
+ my ($ip) = @_;
my ($packet);
-
+
# Adjust the length accodingly
- $udp->{len} = 8 + length($udp->{data});
+ $self->{len} = 8 + length($self->{data});
# First of all, fix the checksum
$self->checksum($ip);
# Put the packet together
- $packet = pack("nnnna*", $udp->{src_port},$udp->{dest_port},
- $udp->{len}, $udp->{cksum}, $udp->{data});
+ $packet = pack("nnnna*", $self->{src_port},$self->{dest_port},
+ $self->{len}, $self->{cksum}, $self->{data});
return($packet);
}
@@ -152,7 +151,7 @@
use NetPacket::UDP;
$udp_obj = NetPacket::UDP->decode($raw_pkt);
- $udp_pkt = NetPacket::UDP->encode($l4_obj, $l3_obj);
+ $udp_pkt = NetPacket::UDP->encode($ip_obj);
$udp_data = NetPacket::UDP::strip($raw_pkt);
=head1 DESCRIPTION
@@ -171,12 +170,11 @@
It is the responsibility of the programmer to ensure valid packet data
is passed to this method.
-=item C<NetPacket::UDP-E<gt>encode($l4_obj, $l3_obj)>
+=item C<NetPacket::UDP-E<gt>encode($ip_obj)>
-Return a UDP packet encoded with the instance data specified in $l4_obj. Needs
-part of the IP header contained (src_ip and dest_ip specifically) in $l3_obj,
-in order to calculate the UDP checksum. The length field will also be set
-automatically based on values provided.
+Return a UDP packet encoded with the instance data specified. Needs parts
+of the IP header contained in $ip_obj, the IP object, in order to calculate
+the UDP checksum. The length field will also be set automatically.
=back
@@ -225,24 +223,6 @@
=back
-=head2 IP data
-
-The IP data for the $l3_obj object consists of the following fields.
-Additional items may be supplied as well as passing the whole
-object returned by NetPacket::IP->decode but are unnecessary.
-
-=over
-
-=item src_ip
-
-The source IP for the datagram
-
-=item dest_ip
-
-The destination IP for the datagram
-
-=back
-
=head2 Exports
=over
@@ -327,7 +307,7 @@
$udp_obj->{data} =~ s/foo/bar/g;
# reencode the packet
- $ip_obj->{data} = $udp_obj->encode($udp_obj, $ip_obj);
+ $ip_obj->{data} = $udp_obj->encode($ip_obj);
$data = $ip_obj->encode;
}
RT for rt.cpan.org