[Nottingham] Perl - NetPacket modules

[Graeme Fowler]

On Thu, 2006-12-28 at 11:46 +0000, Michael Erskine (at home!) wrote:
> OK, how are you calling the encode method? From the docs on cpan 
> (http://search.cpan.org/~atrak/NetPacket-0.04/NetPacket/IP.pm) I see 
> that encode expects a scalar containing an object ref but you seem to be 
> passing something else (perhaps by mistake). Post a bit of code that 
> gives you the problem.

Slightly edited to remove the surrounding and contained cruft, we have:

print "entering loop...\n" if ($debug > 0);
while (1) {
  if (!defined($packet = $queue->get_message($timeout))) {
    if (IPTables::IPv4::IPQueue->errstr=~/Timeout/) {
      print "Timeout...\n" if ($debug > 1);
    } else {
      die "ERROR: ". IPTables::IPv4::IPQueue->errstr . "\n";
    }
  } else {
    print "packet!\n" if ($debug > 1);
    if(defined($ip = NetPacket::IP->decode($packet->payload()))) {

      # at this point, $ip is a scalar hashref

      #...various tests to determine where the packet came from, what
      # it's doing, etc etc and set various flags
      $src_ip_addr = $ip->{src_ip};
      $dst_ip_addr = $ip->{dst_ip};
      if ($ip->{proto}==6) {
        $tcp = NetPacket::TCP->decode($ip->{data});
        $dst_port = $tcp{dest_port};
        $proto="TCP";
      }
    } else {
      # something isn't right
      die "Exiting: decode failed\n";
    }
    $retpack = NetPacket::IP->encode($ip)
    print "Passing packet back to kernel...\n" if ($debug > 1);
    $queue->set_verdict($packet->packet_id(), NF_ACCEPT);
  }
}
 

The line defining $retpack is where it throws the error, every time. I
can call it with the scalar hashref or try to create an empty
constructor, the error is the same.

Graeme