Coverage report

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org.apache.commons.net.ntp.NTPUDPClient
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 1  
 package org.apache.commons.net.ntp;
 2  
 /*
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  * Copyright 2001-2005 The Apache Software Foundation
 4  
  *
 5  
  * Licensed under the Apache License, Version 2.0 (the "License");
 6  
  * you may not use this file except in compliance with the License.
 7  
  * You may obtain a copy of the License at
 8  
  *
 9  
  *     http://www.apache.org/licenses/LICENSE-2.0
 10  
  *
 11  
  * Unless required by applicable law or agreed to in writing, software
 12  
  * distributed under the License is distributed on an "AS IS" BASIS,
 13  
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 14  
  * See the License for the specific language governing permissions and
 15  
  * limitations under the License.
 16  
  */
 17  
 
 18  
 import java.io.IOException;
 19  
 import java.net.DatagramPacket;
 20  
 import java.net.InetAddress;
 21  
 import org.apache.commons.net.DatagramSocketClient;
 22  
 
 23  
 /***
 24  
  * The NTPUDPClient class is a UDP implementation of a client for the
 25  
  * Network Time Protocol (NTP) described in RFC 1305 as well as the
 26  
  * Simple Network Time Protocol (SNTP) in RFC-2030. To use the class,
 27  
  * merely open a local datagram socket with <a href="#open"> open </a>
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  * and call <a href="#getTime"> getTime </a> to retrieve the time. Then call
 29  
  * <a href="org.apache.commons.net.DatagramSocketClient.html#close"> close </a>
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  * to close the connection properly.
 31  
  * Successive calls to <a href="#getTime"> getTime </a> are permitted
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  * without re-establishing a connection.  That is because UDP is a
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  * connectionless protocol and the Network Time Protocol is stateless.
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  *
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  * @author Jason Mathews, MITRE Corp
 36  
  * @version $Revision: 165675 $ $Date: 2005-05-02 15:09:55 -0500 (Mon, 02 May 2005) $
 37  
  ***/
 38  
 
 39  0
 public final class NTPUDPClient extends DatagramSocketClient
 40  
 {
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     /*** The default NTP port.  It is set to 123 according to RFC 1305. ***/
 42  
     public static final int DEFAULT_PORT = 123;
 43  
 
 44  0
     private int _version = NtpV3Packet.VERSION_3;
 45  
 
 46  
     /***
 47  
      * Retrieves the time information from the specified server and port and
 48  
      * returns it. The time is the number of miliiseconds since
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      * 00:00 (midnight) 1 January 1900 UTC, as specified by RFC 1305.
 50  
      * This method reads the raw NTP packet and constructs a <i>TimeInfo</i>
 51  
      * object that allows access to all the fields of the NTP message header.
 52  
      * <p>
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      * @param host The address of the server.
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      * @param port The port of the service.
 55  
      * @return The time value retrieved from the server.
 56  
      * @exception IOException If an error occurs while retrieving the time.
 57  
      ***/
 58  
     public TimeInfo getTime(InetAddress host, int port) throws IOException
 59  
     {
 60  
         // if not connected then open to next available UDP port
 61  0
         if (!isOpen())
 62  
         {
 63  0
             open();
 64  
         }
 65  
 
 66  0
         NtpV3Packet message = new NtpV3Impl();
 67  0
         message.setMode(NtpV3Packet.MODE_CLIENT);
 68  0
         message.setVersion(_version);
 69  0
         DatagramPacket sendPacket = message.getDatagramPacket();
 70  0
         sendPacket.setAddress(host);
 71  0
         sendPacket.setPort(port);
 72  
 
 73  0
         NtpV3Packet recMessage = new NtpV3Impl();
 74  0
         DatagramPacket receivePacket = recMessage.getDatagramPacket();
 75  
 
 76  
         /*
 77  
          * Must minimize the time between getting the current time,
 78  
          * timestamping the packet, and sending it out which
 79  
          * introduces an error in the delay time.
 80  
          * No extraneous logging and initializations here !!!
 81  
          */
 82  0
         TimeStamp now = TimeStamp.getCurrentTime();
 83  
 
 84  
         // Note that if you do not set the transmit time field then originating time
 85  
         // in server response is all 0's which is "Thu Feb 07 01:28:16 EST 2036".
 86  0
         message.setTransmitTime(now);
 87  
 
 88  0
         _socket_.send(sendPacket);
 89  0
         _socket_.receive(receivePacket);
 90  
 
 91  0
         long returnTime = System.currentTimeMillis();
 92  
         // create TimeInfo message container but don't pre-compute the details yet
 93  0
         TimeInfo info = new TimeInfo(recMessage, returnTime, false);
 94  
 
 95  0
         return info;
 96  
     }
 97  
 
 98  
     /***
 99  
      * Retrieves the time information from the specified server on the
 100  
      * default NTP port and returns it. The time is the number of miliiseconds
 101  
      * since 00:00 (midnight) 1 January 1900 UTC, as specified by RFC 1305.
 102  
      * This method reads the raw NTP packet and constructs a <i>TimeInfo</i>
 103  
      * object that allows access to all the fields of the NTP message header.
 104  
      * <p>
 105  
      * @param host The address of the server.
 106  
      * @return The time value retrieved from the server.
 107  
      * @exception IOException If an error occurs while retrieving the time.
 108  
      ***/
 109  
     public TimeInfo getTime(InetAddress host) throws IOException
 110  
     {
 111  0
         return getTime(host, NtpV3Packet.NTP_PORT);
 112  
     }
 113  
 
 114  
     /***
 115  
      * Returns the NTP protocol version number that client sets on request packet
 116  
      * that is sent to remote host (e.g. 3=NTP v3, 4=NTP v4, etc.)
 117  
      *
 118  
      * @return  the NTP protocol version number that client sets on request packet.
 119  
      * @see #setVersion(int)
 120  
      ***/
 121  
     public int getVersion()
 122  
     {
 123  0
         return _version;
 124  
     }
 125  
 
 126  
     /***
 127  
      * Sets the NTP protocol version number that client sets on request packet
 128  
      * communicate with remote host.
 129  
      *
 130  
      * @param version the NTP protocol version number
 131  
      ***/
 132  
     public void setVersion(int version)
 133  
     {
 134  0
         _version = version;
 135  0
     }
 136  
 
 137  
 }

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