#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11152468
use warnings;
$SIG{__WARN__} = sub { die $@ };

use feature 'say';

use IO::Socket qw(AF_INET AF_UNIX SOCK_STREAM SHUT_WR);
use Data::Dumper;

my $server = IO::Socket::INET->new(
    LocalPort => 3333,
    ReusePort => 1,
    Listen => 5,
) or die "Can't open socket: $IO::Socket::errstr";

while (1) 
  {
  say "Waiting on 3333";
  my $client = $server->accept() or die "accept failed on $!";
  my $client_address = $client->peerhost();
  my $client_port = $client->peerport();
  say "Connection from $client_address:$client_port";

  while( defined $client->recv(my $data, 1024) )
    {
    say "received data: $data";
    length $data or last;

    if ($data =~ m/99/)    
      {
      $data = "We've received a string starting with 99\n";
      }
    if ($data =~ m/63/) 
      {
      $data = "We've received a string starting with 63\n";
      }
    $client->send($data);
    }
  }