Time Fetcher

import java.net.ServerSocket;
import java.net.Socket;
import java.nio.charset.StandardCharsets;
import java.time.Instant;
import java.util.*;
import java.io.InputStream;
import java.util.Date;
import java.time.ZoneId;

public class script
{

static String[] timeServers = { "pool.ntp.org",
"us.pool.ntp.org",
"north-america.pool.ntp.org",
"time.google.com",
"time.cloudflare.com",
"time.windows.com",
"time.nist.gov",
"time-a-g.nist.gov",
"time-b-g.nist.gov",
"time-a-b.nist.gov",
"time-b-b.nist.gov",
"time.apple.com",
"time.asia.apple.com",
"time.euro.apple.com",
"tock.usno.navy.mil",
"tick.usno.navy.mil",
"ntp.ubuntu.com",
"0.amazon.pool.ntp.org",
"1.amazon.pool.ntp.org",
"2.amazon.pool.ntp.org",
"3.amazon.pool.ntp.org",
"0.debian.pool.ntp.org",
"1.debian.pool.ntp.org",
"2.debian.pool.ntp.org",
"3.debian.pool.ntp.org",
"0.fedora.pool.ntp.org",
"1.fedora.pool.ntp.org",
"2.fedora.pool.ntp.org",
"3.fedora.pool.ntp.org",
"0.arch.pool.ntp.org",
"1.arch.pool.ntp.org",
"2.arch.pool.ntp.org",
"3.arch.pool.ntp.org",
"time1.google.com",
"time2.google.com",
"time3.google.com",
"time4.google.com",
"time.android.com",
"time.aws.com",
"time.facebook.com",
"time1.facebook.com",
"time2.facebook.com",
"time3.facebook.com",
"time4.facebook.com",
"time5.facebook.com",
"time-macos.apple.com",
"time-ios.apple.com",
"time-c-g.nist.gov",
"time-d-g.nist.gov",
"time-e-g.nist.gov",
"time-f-g.nist.gov",
"time-a-wwv.nist.gov",
"time-b-wwv.nist.gov",
"time-c-wwv.nist.gov",
"time-d-wwv.nist.gov",
"time-e-wwv.nist.gov",
"time-c-b.nist.gov",
"time-d-b.nist.gov",
"time-e-b.nist.gov",
"time-nw.nist.gov",
"utcnist.colorado.edu",
"utcnist2.colorado.edu",
"clock.sjc.he.net",
"clock.fmt.he.net",
"clock.nyc.he.net",
"clock.isc.org",
"ntp.ripe.net",
"ntp.gsu.edu",
"ntp1.net.berkeley.edu",
"ntp2.net.berkeley.edu",
"ntp-01.caltech.edu",
"ntp-02.caltech.edu",
"ntp-03.caltech.edu",
"tick.usask.ca",
"tock.usask.ca",
"ntp.se",
"ntp.time.nl",
"ntp1.time.nl",
"ntp.nict.jp",
"ntp1.jst.mfeed.ad.jp",
"ntp2.jst.mfeed.ad.jp",
"ntp3.jst.mfeed.ad.jp",
"ntp.ntsc.ac.cn",
"ntp1.hetzner.de",
"ntp2.hetzner.de",
"ntp3.hetzner.de",
"ca.pool.ntp.org",
"uk.pool.ntp.org",
"de.pool.ntp.org",
"fr.pool.ntp.org",
"br.pool.ntp.org" };

public static void main(String... args) throws Exception
{
String host = "pool.ntp.org"; // Default fallback time server

if (timeServers.length > 0)
{
// Safe random index calculation
int randomIndex = (int) (Math.random() * timeServers.length);
host = timeServers[randomIndex].trim();
}
int port = 123;

// Use DatagramSocket for UDP instead of standard TCP Socket
try (java.net.DatagramSocket socket = new java.net.DatagramSocket())
{
socket.setSoTimeout(2000); // 4-second timeout so it won't hang.
java.net.InetAddress address = java.net.InetAddress.getByName(host);

byte[] buffer = new byte[48];
buffer[0] = 0x1B; // NTP Client request configuration

java.net.DatagramPacket packet = new java.net.DatagramPacket(buffer, buffer.length, address, port);
socket.send(packet);

packet = new java.net.DatagramPacket(buffer, buffer.length);
socket.receive(packet);

// Extract Transmit Timestamp (bytes 40-43)
long secondsSince1900 = 0;
for (int i = 40; i <= 43; i++)
{
secondsSince1900 = (secondsSince1900 << 8) | (buffer[i] & 0xff);
}

long differenceBetween1900and1970 = 2208988800L;
long secondsSince1970 = secondsSince1900 - differenceBetween1900and1970;
long msSince1970 = secondsSince1970 * 1000;

// Calculate seconds since specified time-zone, or UTC if not specified.
String tz = (args.length > 1) ? args[0] + "/" + args[1] : "Etc/GMT";

ZoneId zoneId = ZoneId.of(tz);
java.time.ZonedDateTime serverDateTime = java.time.ZonedDateTime.ofInstant(java.time.Instant.ofEpochMilli(msSince1970), zoneId);
long secondsSinceMidnight = serverDateTime.toLocalTime().toSecondOfDay();

System.out.println(Long.toString(secondsSinceMidnight));
System.out.flush();
}
catch (Exception e)
{
System.out.println("Error: "+e.getMessage());
System.out.flush();
}
}
}