#!/usr/bin/perl
            
use 5.010;
         
use strict;
use warnings;
use autodie;
        
use IO::Socket;
        
my $server       = '192.168.0.1';
my $client       = '192.168.0.12';
         
my @server_ports = ( 8020,  8019,  8008,  8003);
my @client_ports = (53036, 53037, 53038, 53039);
            
my $INTERVAL     =    10;
my $MAX_BUFSIZE  =   512;
            
my @sockets;
         
for (my $i = 0; $i < @server_ports; $i ++) {
    $sockets[$i] = IO::Socket::INET::->new(
        LocalPort  => $client_ports[$i],
        LocalAddr  => $client,
        PeerPort   => $server_ports[$i],
        PeerAddr   => $server,
        Proto      => 'udp',
    ) or die $!;
}
 
my $Rbits = "";
my $Ebits = "";
vec($Rbits, fileno($_), 1) = 1 for @sockets;
vec($Ebits, fileno($_), 1) = 1 for @sockets;
 
 
#
# Now loop. If there's data to read, read it. If it's time to send a
# heartbeat, do so.
#
my @heartbeats = (0) x @sockets;
while (1) {
    for (my $i = 0; $i < @sockets; $i++) {
        if (time >= $heartbeats[$i] + $INTERVAL - 1) {
            #
            # Initialize contact, or keep alive
            #
            say "Send HB on channel $i";
            $sockets[$i]->send("HB");
            $heartbeats[$i] = time;
        }
    }
    select(my $rbits = $Rbits, undef, my $ebits = $Ebits, 1);
    for (my $i = 0; $i < @sockets; $i++) {
        my $socket = $sockets[$i];
        my $fileno = fileno($socket);
        if (vec($ebits, $fileno, 1)) {
            say "Got an error on channel $i. I'm out of here";
            exit 1;
        }
        if (vec($rbits, $fileno, 1)) {
            #
            # Read messages, if any
            #
            $socket->recv(my $buffer, $MAX_BUFSIZE);
            next unless length $buffer;
            say "Received packet $buffer on channel $i";
        }
    }
}
 
__END__