Example usage for org.apache.commons.net.ntp NtpV3Packet setDatagramPacket

Introduction

In this page you can find the example usage for org.apache.commons.net.ntp NtpV3Packet setDatagramPacket.

Prototype

public void setDatagramPacket(DatagramPacket dp);

Source Link

Document

Set the contents of this object from the datagram packet

Usage

From source file:examples.ntp.SimpleNTPServer.java

/**
 * Handle incoming packet. If NTP packet is client-mode then respond
 * to that host with a NTP response packet otherwise ignore.
 *
 * @param request incoming DatagramPacket
 * @param rcvTime time packet received//  w  ww . j  av a2  s . c  om
 *
 * @throws IOException  if an I/O error occurs.
 */
protected void handlePacket(DatagramPacket request, long rcvTime) throws IOException {
    NtpV3Packet message = new NtpV3Impl();
    message.setDatagramPacket(request);
    System.out.printf("NTP packet from %s mode=%s%n", request.getAddress().getHostAddress(),
            NtpUtils.getModeName(message.getMode()));
    if (message.getMode() == NtpV3Packet.MODE_CLIENT) {
        NtpV3Packet response = new NtpV3Impl();

        response.setStratum(1);
        response.setMode(NtpV3Packet.MODE_SERVER);
        response.setVersion(NtpV3Packet.VERSION_3);
        response.setPrecision(-20);
        response.setPoll(0);
        response.setRootDelay(62);
        response.setRootDispersion((int) (16.51 * 65.536));

        // originate time as defined in RFC-1305 (t1)
        response.setOriginateTimeStamp(message.getTransmitTimeStamp());
        // Receive Time is time request received by server (t2)
        response.setReceiveTimeStamp(TimeStamp.getNtpTime(rcvTime));
        response.setReferenceTime(response.getReceiveTimeStamp());
        response.setReferenceId(0x4C434C00); // LCL (Undisciplined Local Clock)

        // Transmit time is time reply sent by server (t3)
        response.setTransmitTime(TimeStamp.getNtpTime(System.currentTimeMillis()));

        DatagramPacket dp = response.getDatagramPacket();
        dp.setPort(request.getPort());
        dp.setAddress(request.getAddress());
        socket.send(dp);
    }
    // otherwise if received packet is other than CLIENT mode then ignore it
}

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