#! /usr/bin/perl
use warnings;
use strict;

use Socket qw(:all);

$|++; # no suffering from buffering

my $udp_port = 9999;

socket( UDPSOCK, PF_INET, SOCK_DGRAM, getprotobyname('udp') ) or die "socket: $!";

select( ( select(UDPSOCK), $|=1 )[0] ); # no suffering from buffering

setsockopt( UDPSOCK, SOL_SOCKET, SO_REUSEADDR, 1 )
    or die "setsockopt SO_REUSEADDR: $!";
setsockopt( UDPSOCK, SOL_SOCKET, SO_BROADCAST, 1 )
    or die "setsockopt SO_BROADCAST: $!";

my $broadcastAddr = sockaddr_in( $udp_port, INADDR_ANY );
bind( UDPSOCK, $broadcastAddr ) or die "bind failed: $!\n";

my $input;
while( my $addr = recv( UDPSOCK, $input, 4096, 0 ) ) {
    print "$addr => $input\n";
}


##</code><code>##


use warnings;
use strict;

use Socket qw(:all);
use POSIX ":sys_wait_h";

socket( SOCKET, PF_INET, SOCK_DGRAM, getprotobyname("udp") )
    or die "Error: can't create an udp socket: $!\n";

select( ( select(SOCKET), $|=1 )[0] ); # no suffering from buffering

my $broadcastAddr = sockaddr_in( 9999, INADDR_BROADCAST );
setsockopt( SOCKET, SOL_SOCKET, SO_BROADCAST, 1 );

send( SOCKET, "I'm here", 0,  $broadcastAddr )
    or die "Error at sendding: $!\n";

close SOCKET;