use IO::Socket::INET;
use warnings;
use strict;

# auto-flush on socket
$| = 1;

my $port_client = 9001; # Port fuer Client-Anfragen des MITM-Servers

# example data
# $data     = "\x00\x01\x12\x34\x5A\x86";
# $response = "\x00\x03\x05\x27";

# creating a listening socket
# => Wir sind der Server fuer den Anwender
my $socket_server = new IO::Socket::INET (
  LocalHost => '0.0.0.0',
  LocalPort => $port_client,
  Proto => 'tcp',
  Listen => 5,
  Reuse => 1
);
die "cannot create socket $!\n" unless $socket_server;
print "server waiting for client connection on port ".$port_client."\n";

while(1)
{
  print "\n\n\n";
  
  # waiting for a new client connection
  my $client_socket = $socket_server->accept();
  
  # get information about a newly connected client
  my $client_address = $client_socket->peerhost();
  my $client_port = $client_socket->peerport();
  print "connection from $client_address:$client_port\n";
  
  # read up to 1024 characters from the connected client
  my $data = "";
  $client_socket->recv($data, 1024);
  my $data_hex = $data;
  $data_hex =~ s/(.)/sprintf("\\x%02X",ord($1))/eg;
  print "mitm server received data: $data\n";
  print " hex: (".$data_hex.")\n";
  
  
  # write response data to the connected client
  print "mitm server is sending data to real client\n";
  $client_socket->send($data);
  print "mitm server has send data to real client\n";
  print " data: (".$data.")\n";
  print " hex: (".$data_hex.")\n";
  
  # notify client that response has been sent
  shutdown($client_socket, 1);
}

$socket_server->close();