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1 package org.apache.commons.net; 2 3 /* ==================================================================== 4 * The Apache Software License, Version 1.1 5 * 6 * Copyright (c) 2001 The Apache Software Foundation. All rights 7 * reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in 18 * the documentation and/or other materials provided with the 19 * distribution. 20 * 21 * 3. The end-user documentation included with the redistribution, 22 * if any, must include the following acknowledgment: 23 * "This product includes software developed by the 24 * Apache Software Foundation (http://www.apache.org/)." 25 * Alternately, this acknowledgment may appear in the software itself, 26 * if and wherever such third-party acknowledgments normally appear. 27 * 28 * 4. The names "Apache" and "Apache Software Foundation" and 29 * "Apache Commons" must not be used to endorse or promote products 30 * derived from this software without prior written permission. For 31 * written permission, please contact apache@apache.org. 32 * 33 * 5. Products derived from this software may not be called "Apache", 34 * nor may "Apache" appear in their name, without 35 * prior written permission of the Apache Software Foundation. 36 * 37 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED 38 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 39 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 40 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR 41 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 42 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 43 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF 44 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 45 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 46 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 47 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 48 * SUCH DAMAGE. 49 * ==================================================================== 50 * 51 * This software consists of voluntary contributions made by many 52 * individuals on behalf of the Apache Software Foundation. For more 53 * information on the Apache Software Foundation, please see 54 * <http://www.apache.org/>;. 55 */ 56 57 import java.io.IOException; 58 import java.net.DatagramPacket; 59 import java.net.InetAddress; 60 import java.util.Date; 61 62 /**** 63 * The TimeUDPClient class is a UDP implementation of a client for the 64 * Time protocol described in RFC 868. To use the class, merely 65 * open a local datagram socket with 66 * <a href="org.apache.commons.net.DatagramSocketClient.html#open"> open </a> 67 * and call <a href="#getTime"> getTime </a> or 68 * <a href="#getTime"> getDate </a> to retrieve the time. Then call 69 * <a href="org.apache.commons.net.DatagramSocketClient.html#close"> close </a> 70 * to close the connection properly. Unlike 71 * <a href="org.apache.commons.net.TimeTCPClient.html"> TimeTCPClient </a>, 72 * successive calls to <a href="#getTime"> getTime </a> or 73 * <a href="#getDate"> getDate </a> are permitted 74 * without re-establishing a connection. That is because UDP is a 75 * connectionless protocol and the Time protocol is stateless. 76 * <p> 77 * <p> 78 * @author Daniel F. Savarese 79 * @see TimeTCPClient 80 ***/ 81 82 public final class TimeUDPClient extends DatagramSocketClient 83 { 84 /**** The default time port. It is set to 37 according to RFC 868. ***/ 85 public static final int DEFAULT_PORT = 37; 86 87 /**** 88 * The number of seconds between 00:00 1 January 1900 and 89 * 00:00 1 January 1970. This value can be useful for converting 90 * time values to other formats. 91 ***/ 92 public static final long SECONDS_1900_TO_1970 = 2208988800L; 93 94 private byte[] __dummyData = new byte[1]; 95 private byte[] __timeData = new byte[4]; 96 97 /**** 98 * Retrieves the time from the specified server and port and 99 * returns it. The time is the number of seconds since 100 * 00:00 (midnight) 1 January 1900 GMT, as specified by RFC 868. 101 * This method reads the raw 32-bit big-endian 102 * unsigned integer from the server, converts it to a Java long, and 103 * returns the value. 104 * <p> 105 * @param host The address of the server. 106 * @param port The port of the service. 107 * @return The time value retrieved from the server. 108 * @exception IOException If an error occurs while retrieving the time. 109 ***/ 110 public long getTime(InetAddress host, int port) throws IOException 111 { 112 long time; 113 DatagramPacket sendPacket, receivePacket; 114 115 sendPacket = 116 new DatagramPacket(__dummyData, __dummyData.length, host, port); 117 receivePacket = new DatagramPacket(__timeData, __timeData.length); 118 119 _socket_.send(sendPacket); 120 _socket_.receive(receivePacket); 121 122 time = 0L; 123 time |= (((__timeData[0] & 0xff) << 24) & 0xffffffffL); 124 time |= (((__timeData[1] & 0xff) << 16) & 0xffffffffL); 125 time |= (((__timeData[2] & 0xff) << 8) & 0xffffffffL); 126 time |= ((__timeData[3] & 0xff) & 0xffffffffL); 127 128 return time; 129 } 130 131 /**** Same as <code> getTime(host, DEFAULT_PORT); </code> ***/ 132 public long getTime(InetAddress host) throws IOException 133 { 134 return getTime(host, DEFAULT_PORT); 135 } 136 137 138 /**** 139 * Retrieves the time from the server and returns a Java Date 140 * containing the time converted to the local timezone. 141 * <p> 142 * @param host The address of the server. 143 * @param port The port of the service. 144 * @return A Date value containing the time retrieved from the server 145 * converted to the local timezone. 146 * @exception IOException If an error occurs while fetching the time. 147 ***/ 148 public Date getDate(InetAddress host, int port) throws IOException 149 { 150 return new Date((getTime(host, port) - SECONDS_1900_TO_1970)*1000L); 151 } 152 153 154 /**** Same as <code> getTime(host, DEFAULT_PORT); </code> ***/ 155 public Date getDate(InetAddress host) throws IOException 156 { 157 return new Date((getTime(host, DEFAULT_PORT) - 158 SECONDS_1900_TO_1970)*1000L); 159 } 160 161 } 162

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