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
61 /****
62 * The DaytimeUDPClient class is a UDP implementation of a client for the
63 * Daytime protocol described in RFC 867. To use the class, merely
64 * open a local datagram socket with
65 * <a href="org.apache.commons.net.DatagramSocketClient.html#open"> open </a>
66 * and call <a href="#getTime"> getTime </a> to retrieve the daytime
67 * string, then
68 * call <a href="org.apache.commons.net.DatagramSocketClient.html#close"> close </a>
69 * to close the connection properly. Unlike
70 * <a href="org.apache.commons.net.DaytimeTCPClient.html"> DaytimeTCPClient </a>,
71 * successive calls to <a href="#getTime"> getTime </a> are permitted
72 * without re-establishing a connection. That is because UDP is a
73 * connectionless protocol and the Daytime protocol is stateless.
74 * <p>
75 * <p>
76 * @author Daniel F. Savarese
77 * @see DaytimeTCPClient
78 ***/
79
80 public final class DaytimeUDPClient extends DatagramSocketClient
81 {
82 /**** The default daytime port. It is set to 13 according to RFC 867. ***/
83 public static final int DEFAULT_PORT = 13;
84
85 private byte[] __dummyData = new byte[1];
86 // Received dates should be less than 256 bytes
87 private byte[] __timeData = new byte[256];
88
89 /****
90 * Retrieves the time string from the specified server and port and
91 * returns it.
92 * <p>
93 * @param host The address of the server.
94 * @param port The port of the service.
95 * @return The time string.
96 * @exception IOException If an error occurs while retrieving the time.
97 ***/
98 public String getTime(InetAddress host, int port) throws IOException
99 {
100 DatagramPacket sendPacket, receivePacket;
101
102 sendPacket =
103 new DatagramPacket(__dummyData, __dummyData.length, host, port);
104 receivePacket = new DatagramPacket(__timeData, __timeData.length);
105
106 _socket_.send(sendPacket);
107 _socket_.receive(receivePacket);
108
109 return new String(receivePacket.getData(), 0, receivePacket.getLength());
110 }
111
112 /**** Same as <code>getTime(host, DaytimeUDPClient.DEFAULT_PORT);</code> ***/
113 public String getTime(InetAddress host) throws IOException
114 {
115 return getTime(host, DEFAULT_PORT);
116 }
117
118 }
119
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