#! perl -slw
use strict;
use threads;
use threads::shared;
use IO::Socket;

use constant CRLF => chr( 13 ) . chr( 10 );

my $server = IO::Socket::INET->new(
    LocalHost => 'localhost',
    LocalPort => '7070',
    Proto => 'tcp',
    Listen => 5,
    Reuse => 1,
) or die "Couldn't create listening socket";

my $running :shared = 0;

$/ = $\ = CRLF;

while( 1 ) {
    my $client = $server->accept;
    print "running: $running";
    close( $client ), next if $running >= 5;
    print "Accepted connection from $client";
    async {
        { lock $running; ++$running;}
        print "$client running";
        while( ( my $input = <$client> ) ne 'quit' . CRLF ) {
            chomp $input;
            if( $input eq 'printhelp' ) {
                print $client 'Some help' . CRLF;
            }
            elsif( $input eq 'cmd1' ) {
                print $client 'CMD1 stuff' . CRLF;
            }
            elsif( $input eq 'cmd2' ) {
                print $client 'CMD2 stuff' . CRLF;
            }
            elsif( $input eq 'cmd3' ) {
                print $client 'CMD3 stuff' . CRLF;
            }
            else {
                print $client "Unrecognised command; '$input'" . CRLF;
            }
        }
        lock $running; --$running;
        print "$client done";
    }->detach;
}

close $server;