Java tutorial
/** * Copyright (C) 2007 - 2008 Pingtel Corp., certain elements licensed under a Contributor Agreement. * Contributors retain copyright to elements licensed under a Contributor Agreement. * Licensed to the User under the LGPL license. */ package org.sipfoundry.preflight; import java.io.IOException; import java.net.InetAddress; import java.net.SocketException; import java.net.UnknownHostException; import java.text.NumberFormat; import org.apache.commons.net.ntp.*; import org.sipfoundry.commons.dhcp.NetworkResources; import org.sipfoundry.commons.util.JournalService; import static org.sipfoundry.preflight.ResultCode.*; /** * [Enter descriptive text here] * <p> * * @author Mardy Marshall */ public class NTP { private static final int bindPort = 0; private static final NumberFormat numberFormat = new java.text.DecimalFormat("0.00"); public ResultCode validate(int timeout, NetworkResources networkResources, JournalService journalService, InetAddress bindAddress) { ResultCode results = NONE; if (networkResources.ntpServers == null) { journalService.println("No NTP servers provided, skipping test."); results = NTP_SERVERS_MISSING; } else { journalService.println("Starting NTP servers test."); NTPUDPClient client = new NTPUDPClient(); client.setDefaultTimeout(timeout * 1000); try { client.open(bindPort, bindAddress); for (InetAddress ntpServer : networkResources.ntpServers) { journalService.println("NTP test for server: " + ntpServer.getCanonicalHostName()); try { TimeInfo info = client.getTime(ntpServer); journalService.println(new String(processResponse(info))); } catch (IOException e) { client.close(); if (e.getClass() == java.net.SocketTimeoutException.class) { journalService.println(" NTP request timed out."); results = NTP_SERVER_FAILURE; } else { journalService.println(" NTP request error: " + e.getMessage()); results = NTP_TEST_FAILURE; } } } } catch (SocketException e) { journalService.println("Unable to create NTP client: " + e.getMessage()); results = NTP_TEST_FAILURE; } } journalService.println(""); return results; } /** * Process <code>TimeInfo</code> object and return details. * * @param info * <code>TimeInfo</code> object. */ private String processResponse(TimeInfo info) { String response; NtpV3Packet message = info.getMessage(); int stratum = message.getStratum(); String refType; if (stratum <= 0) { refType = "(Unspecified or Unavailable)"; } else if (stratum == 1) { refType = "(Primary Reference; e.g., GPS)"; // GPS, radio clock, // etc. } else { refType = "(Secondary Reference; e.g. via NTP or SNTP)"; } // stratum should be 0..15... response = new String(" Stratum: " + stratum + " " + refType + "\n"); int version = message.getVersion(); int li = message.getLeapIndicator(); response += new String( " leap=" + li + ", version=" + version + ", precision=" + message.getPrecision() + "\n"); response += new String(" mode: " + message.getModeName() + " (" + message.getMode() + ")\n"); int poll = message.getPoll(); // poll value typically btwn MINPOLL (4) and MAXPOLL (14) response += new String( " poll: " + (poll <= 0 ? 1 : (int) Math.pow(2, poll)) + " seconds" + " (2 ** " + poll + ")\n"); double disp = message.getRootDispersionInMillisDouble(); response += new String(" rootdelay=" + numberFormat.format(message.getRootDelayInMillisDouble()) + ", rootdispersion(ms): " + numberFormat.format(disp) + "\n"); int refId = message.getReferenceId(); String refAddr = NtpUtils.getHostAddress(refId); String refName = null; if (refId != 0) { if (refAddr.equals("127.127.1.0")) { refName = "LOCAL"; // This is the ref address for the Local // Clock } else if (stratum >= 2) { // If reference id has 127.127 prefix then it uses its own // reference clock // defined in the form 127.127.clock-type.unit-num (e.g. // 127.127.8.0 mode 5 // for GENERIC DCF77 AM; see refclock.htm from the NTP software // distribution. if (!refAddr.startsWith("127.127")) { try { InetAddress addr = InetAddress.getByName(refAddr); String name = addr.getHostName(); if (name != null && !name.equals(refAddr)) { refName = name; } } catch (UnknownHostException e) { // some stratum-2 servers sync to ref clock device but // fudge stratum level higher... (e.g. 2) // ref not valid host maybe it's a reference clock name? // otherwise just show the ref IP address. refName = NtpUtils.getReferenceClock(message); } } } else if (version >= 3 && (stratum == 0 || stratum == 1)) { refName = NtpUtils.getReferenceClock(message); // refname usually have at least 3 characters (e.g. GPS, WWV, // LCL, etc.) } // otherwise give up on naming the beast... } if (refName != null && refName.length() > 1) { refAddr += " (" + refName + ")"; } response += new String(" Reference Identifier: " + refAddr + "\n"); TimeStamp refNtpTime = message.getReferenceTimeStamp(); response += new String(" Reference Timestamp: " + refNtpTime + " " + refNtpTime.toDateString() + "\n"); // Originate Time is time request sent by client (t1) TimeStamp origNtpTime = message.getOriginateTimeStamp(); response += new String( " Originate Timestamp: " + origNtpTime + " " + origNtpTime.toDateString() + "\n"); long destTime = info.getReturnTime(); // Receive Time is time request received by server (t2) TimeStamp rcvNtpTime = message.getReceiveTimeStamp(); response += new String(" Receive Timestamp: " + rcvNtpTime + " " + rcvNtpTime.toDateString() + "\n"); // Transmit time is time reply sent by server (t3) TimeStamp xmitNtpTime = message.getTransmitTimeStamp(); response += new String( " Transmit Timestamp: " + xmitNtpTime + " " + xmitNtpTime.toDateString() + "\n"); // Destination time is time reply received by client (t4) TimeStamp destNtpTime = TimeStamp.getNtpTime(destTime); response += new String( " Destination Timestamp: " + destNtpTime + " " + destNtpTime.toDateString() + "\n"); info.computeDetails(); // compute offset/delay if not already done Long offsetValue = info.getOffset(); Long delayValue = info.getDelay(); String delay = (delayValue == null) ? "N/A" : delayValue.toString(); String offset = (offsetValue == null) ? "N/A" : offsetValue.toString(); response += new String(" Roundtrip delay(ms)=" + delay + ", clock offset(ms)=" + offset + "\n"); // offset // in // ms return response; } }