#!/usr/bin/env perl

use strict;
use warnings;
use Socket qw/TCP_NODELAY/;
use IO::Socket::INET;

my @cmd = (qw(/bin/cat));

my $sock = IO::Socket::INET::->new(
   Listen    => 20,
   LocalAddr => '0.0.0.0',
   LocalPort => 20202,
   Proto     => 'tcp',
   Reuse     => 1,
);

die "Unable to create socket: $!" unless $sock;

$sock->sockopt(TCP_NODELAY, 1);

$SIG{CHLD} = 'IGNORE';

while (1) {      # Go on forever!
   my $client = $sock->accept();   # Blocking
   my $child = fork();
   next unless defined $child;     # Not enough resources to fork() - ignore silently
   if ($child) {
      # I'm the parent
      close($client);
      next;
   } else {
      # I'm the child, I serve this connection
      close($sock);
      open (STDIN, "<&".fileno($client)) 
         or die "Cannot dup STDIN to connection: $!";
      open (STDOUT,">&".fileno($client)) 
         or die "Cannot dup STDOUT to connection: $!";
      open (STDERR,">&".fileno($client)) 
         or die "Cannot dup STDERR to connection: $!";
      # Now leave the rest to CHILD process
      exec(@cmd);
   }
}