#SERVER:

use strict;
use warnings;
use 5.010;

use Socket;



my $protocol = getprotobyname 'tcp';
socket my $LISTEN_SOCK, AF_INET, SOCK_STREAM, $protocol 
    or die "Can't make socket: $!";
setsockopt $LISTEN_SOCK, SOL_SOCKET, SO_REUSEADDR, 1
    or die "Cant set SO_REUSADDR: $!";

my $port = 12555;
my $listen_addr = sockaddr_in $port, INADDR_ANY;
bind $LISTEN_SOCK, $listen_addr or die "bind failed: $!";
listen $LISTEN_SOCK, 5;

warn "processing sockets...\n";

my $rin = '';
my $rout;
vec($rin, fileno($LISTEN_SOCK), 1) = 1; 

my %open_sockets;
my ($remote_host, $remote_port);

while (1) {

    my $nfound = select ($rout=$rin, undef, undef, undef);

    if ($nfound) {
        if (vec $rout, fileno $LISTEN_SOCK, 1) {
            my $packed_remote_addr = accept my ($CONNECTION), $LISTEN_SOCK;

            if ($packed_remote_addr) {
                vec($rin, fileno $CONNECTION, 1) = 1;

                ($remote_port, my $packed_remote_host) =
                    unpack_sockaddr_in($packed_remote_addr);
                $remote_host = inet_ntoa $packed_remote_host;

                warn "adding new connection to hash...\n";
                $open_sockets{fileno $CONNECTION} = 
                    [$CONNECTION, "$remote_host : $remote_port"];
            }
            else {
                warn "couldn't connect";
            }
        }

        for my $filenum (keys %open_sockets) {
            my ($CONN, $remote_info) = @{$open_sockets{$filenum}};

            if (vec $rout, $filenum, 1) {
                my $available_data;
                my $result = sysread $CONN, $available_data, 8096;

                if ($result) { #data was read from socket
                    print "[$remote_info] says: $available_data";
                }
                elsif ($result == 0) { #eof=>socket closed 
                    delete $open_sockets{$filenum};
                    vec($rin, $filenum, 1) = 0;
                    close $CONN;
                    say "[$remote_info]: deleted from hash. Goodbye!";
                }
                else {#undef=>IO error on socket
                    warn "[$remote_info]: experienced an IO error: $!";
                }
            }   
        }  
    }
}