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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