#SERVER:

use strict;
use warnings;
use 5.010;

use IO::Socket;
use IO::Select;

my $LISTEN_SOCK = IO::Socket::INET->new(
    LocalPort => 12555,
    Listen => 5,
    Reuse => 1,
)  or die "Couldn't create socket: $@";

my $sock_group = IO::Select->new() 
    or die "Couldn't create select";

$sock_group->add($LISTEN_SOCK);


warn "listening for connections...\n";

while (1) {
    my @ready_to_read = $sock_group->can_read;

    for my $READABLE_SOCK (@ready_to_read) {

        if ($READABLE_SOCK eq $LISTEN_SOCK) {
            my $NEW_CONNECTION = $LISTEN_SOCK->accept()
                or warn "Couldn't connect: $!";

            if($NEW_CONNECTION)
            {
                $sock_group->add($NEW_CONNECTION);
            }
        }
        else {
            my $status = $READABLE_SOCK->sysread( my($available_data), 8096 );

            if ($status > 0) { #read some data
                STDOUT->syswrite($available_data);
            }
            elsif ($status == 0) { #read eof=>client closed socket
                $sock_group->remove($READABLE_SOCK);
                close $READABLE_SOCK;
            }
            else { #undef=>IO error
                warn "IO error while reading socket: $READABLE_SOCK";
            }
        }
    }
}