#!/usr/bin/perl -w
use IO::Socket;

	($server,$port1) = &rdt_listen($ARGV[0]);
  	
  	print"LISTENING ON PORT $port1\n";
	
	$serverhasdata = &select($server);
	
		
	($thehost,$request) = &rcv_from($serverhasdata);
	
	$thedata  = &statmachine_send($request);
	
	@payloadwoh = &statemachine_rcv($thedata);
	@payld = &rdt_recv(@payloadwoh);
	@payloadwoh = split(/\t/,$line);
				

	print"u have got a request from:$thehost and the request is:@payloadwoh\n\n";



sub rdt_listen{
	#takes necessary parameters creates a socket and listens on that port.
	my $port1 = $_[0];
	$protocol = 'udp';
	$socket1 =  IO::Socket::INET->new(LocalPort=>$port1,Proto=>$protocol)or die "Cannot Listen On The Socket $@";
		return $socket1,$port1;
	}
	
sub select{

	#it selects the socket(socket is given as a parameter) and receives data from that socket
	my ($rcvsocket) = @_;
	$_[0]->recv($buf,534);
	if ( length($buf) != 0 ){

	return $_[0];

	}
}

sub rcv_from{

	#takes data from the socket which is selected by the select function
	my $sock = @_;
    while($_[0]->recv($msg, 534)){
    my($port, $ipaddr) = sockaddr_in($_[0]->peername);
    $hishost = gethostbyaddr($ipaddr,AF_INET);
	return ($hishost,$msg);
}
}

sub statmachine_send {
		#takes data from rcv_from and returns it
		my $comingdata = @_;
		return $_[0];		
}	

sub statemachine_rcv {
	
	#it takes the packet from the statmachine_send function;
	my $packet = @_;
	#unpack the packet	
	my($r,$d,$t,$one,$point,$zero,$null1,$null2,$null3,$lengthpayload,$null4,$null5,$null6,$null7) = unpack('a3 C3 N3 n N3 n',$_[0]);
	$lengthpayload1 = $lengthpayload;
	@payload = unpack('a*',substr($_[0],34,$lengthpayload1+34));
	#check if payload contains data or its empty	
	if ( length(@payload) != 0){
		return @payload;
	}else { return ;}

}

sub rdt_recv{
	#it reads data from recive buffer.
	my @read = $_[0];
	while (@read){
	return "$_[0]";	
	}
}