#!/usr/bin/perl -X
if($#ARGV<0){
	print '
PROGRAM udprx
Call: perl udprx PORT [FILENAME]
where
  perl call the perl program. (\'./\' works also.)
  PORT is the desired port, e.g. 5555
  FILENAME (optional) defines a file where collected data are stored.

Example:
  perl udprx 5555 /tmp/prpdata.txt
or
  perl udprx 5555 		-> to display data only.

   THIS PROGRAM WAITS FOR DATA FROM UDP CLIENT.
';
	exit 1;
};

use lib $ENV{DAQLIB};
use perltools::MRtime;
use perltools::MRutilities;
use IO::Socket;

my $serverport=$ARGV[0];

# SAVE TO FILE
my $recordflag=0;
if ($#ARGV >= 1){
	my $datfile = $ARGV[1];
	$recordflag=1;
	print"record data to $datfile\n";
}

##########################
#  we call IO::Socket::INET->new() to create the UDP Socket and bound 
# to specific port number mentioned in LocalPort and there is no need to provide 
#########################
my $sock = IO::Socket::INET->new (
	LocalPort => $serverport,
	Proto => 'udp',
) or die "[!!] Could not create socket: $!\n";
print"Waiting on port $serverport for UDP message: \n";

my ($received_data);
my ($peer_address,$peer_port);
while ($sock->recv($received_data, 1024)) {
    my($port, $ipaddr) = sockaddr_in($sock->peername);
    $peer_address = $sock->peerhost();
    print "$peer_address $serverport => $received_data";
} 
die "recv: $!";

close($sock);