#!/usr/bin/perl
use strict;
use warnings;
#use diagnostics;
use Data::Dumper;
use IO::Socket::INET;
use POSIX qw( CLOCKS_PER_SEC );
use Time::HiRes qw( gettimeofday CLOCK_REALTIME clock_getres );

use constant TRUE      => scalar 1;
use constant ARGUMENTS => scalar 1;
use constant MAXBYTES  => scalar 512;
use constant MAX_PORT  => scalar 65536;
use constant MIN_PORT  => scalar 1;

my $dot = ".";
my $rcvSntpPacket;

if ( @ARGV > ARGUMENTS ) {
    print "\nPlease no more than ".ARGUMENTS." argument input!\n";
    print "\nCorrect Syntax: perl $0 IP:PORT (e.g. 127.0.0.1:12345)\n";
    exit(0);
}
elsif ( @ARGV < ARGUMENTS ) {
    print "\nPlease no less than ".ARGUMENTS." argument input!\n";
    print "\nCorrect Syntax: perl $0 IP:PORT (e.g. 127.0.0.1:12345)\n";
    exit(0);
}
else {

    my $info = $ARGV[0]; # User input IP:PORT;

    my $string = index($info, ':');

    if ($string == '-1') {
	die "Please include ':' in between the IP and Port - ".$info."\n";
    }

    my @input = split( ':' , $info );

    die "\nPlease use PORT number between ".MIN_PORT." - ".MAX_PORT."\n\n" 
	if ( ( $input[1] > MAX_PORT ) || ( $input[1] < MIN_PORT ) );

    my $client_socket = new IO::Socket::INET (
	PeerHost => $input[0],
	Type     => SOCK_DGRAM,
	PeerPort => $input[1], # Default NTP port 123, due to permission denied switch to client set
	Proto    => 'udp'
	) or die "ERROR in Socket Creation: $@\n";

    my $Peer_Port = $client_socket->peerport();

    my $client_li_vm_mode = '00100011'; # 8 bit
    my $client_stratum = '0'; # 8 bit
    my $client_poll = '0'; # 8 bit
    my $client_precision = '0'; # 8 bit
    my $client_root_delay = '0'; # 32 bit
    my $client_dispersion = '0'; # 32 bit
    my $client_reference_identifier = '0'; # 32 bit
    my $client_reference_timestamp_sec = '0'; # 32 bit
    my $client_reference_timestamp_microsec = '0'; # 32 bit
    my $client_receive_timestamp_sec = '0'; # 32 bit
    my $client_receive_timestamp_microsec = '0'; # 32 bit

    my ( $client_transmit_sec , $client_transmit_microsec ) = gettimeofday(); # 64 bit

    my $client_originate_timestamp_sec = $client_transmit_sec;
    my $client_originate_timestamp_microsec = $client_transmit_microsec;

    my @arraySendSntpPacket = ($client_li_vm_mode , $client_stratum , $client_poll , $client_precision , $client_root_delay , $client_dispersion , $client_reference_identifier , $client_reference_timestamp_sec , $client_reference_timestamp_microsec , $client_originate_timestamp_sec , $client_originate_timestamp_microsec , $client_receive_timestamp_sec , $client_receive_timestamp_microsec , $client_transmit_sec , $client_transmit_microsec );

    warn Dumper \@arraySendSntpPacket;

    my $sendSntpPacket = pack "B8 C3 N11", @arraySendSntpPacket;

    $client_socket->send( $sendSntpPacket ) 
	or die "Client error while send: $!\n";

    $client_socket->recv( $rcvSntpPacket , MAXBYTES )
	or die "Client error while received: $!\n";

    my ( $client_rcv_sec , $client_rcv_microsec ) = gettimeofday();

    $client_socket->close(); # Close socket()

    my @arrayRcvSntpPacket = unpack("B8 C3 N11" , $rcvSntpPacket);

    my ( $server_li_vm_mode , $server_stratum , $server_poll_interval , $server_precision , $server_root_delay , $server_dispersion , $server_reference_identifier , $server_reference_timestamp_sec , $server_reference_timestamp_microsec , $server_originate_timestamp_sec , $server_originate_timestamp_microsec , $server_rcv_timestamp_sec , $server_rcv_timestamp_microsec , $server_transmit_timestamp_sec , $server_transmit_timestamp_microsec ) = @arrayRcvSntpPacket;

    warn Dumper \@arrayRcvSntpPacket;

} # End of else ARGV provided