#!/usr/bin/perl -w
$|++;
use strict;
use IO::Socket;
use IO::Select;

my $response = IO::Socket::INET->new(Proto=>"udp",LocalPort=>5000)
  or die "Can't make UDP server: $@";

my $sel = new IO::Select( $response );

my ($datagram,$flags);

binmode($response);

while(my @ready = $sel->can_read) #Make sure socket has something to give us
{
  $datagram = '';
  $flags = '';
  $response->recv($datagram,1500,$flags);
  my $length = length($datagram);
  print "Length : $length\n";
  if($datagram =~ /^(\C\C\C\C)(.*)$/s)
  {
    #Do some stuff
  }
  else
  {
    #Didn't match for some reason
    print "Did not match!\n";
  }
}