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1   /*
2    * Copyright 2001-2005 The Apache Software Foundation
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *     http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  package org.apache.commons.net;
17  
18  import java.io.IOException;
19  import java.net.DatagramPacket;
20  import java.net.InetAddress;
21  
22  /***
23   * The EchoUDPClient class is a UDP implementation of a client for the
24   * Echo protocol described in RFC 862.  To use the class,
25   * just open a local UDP port
26   * with {@link org.apache.commons.net.DatagramSocketClient#open  open }
27   * and call {@link #send  send } to send datagrams to the server,
28   * then call {@link #receive  receive } to receive echoes.
29   * After you're done echoing data, call
30   * {@link org.apache.commons.net.DatagramSocketClient#close  close() }
31   * to clean up properly.
32   * <p>
33   * <p>
34   * @author Daniel F. Savarese
35   * @see EchoTCPClient
36   * @see DiscardUDPClient
37   ***/
38  
39  public final class EchoUDPClient extends DiscardUDPClient
40  {
41      /*** The default echo port.  It is set to 7 according to RFC 862. ***/
42      public static final int DEFAULT_PORT = 7;
43  
44      private DatagramPacket __receivePacket = new DatagramPacket(new byte[0], 0);
45  
46      /***
47       * Sends the specified data to the specified server at the default echo
48       * port.
49       * <p>
50       * @param data  The echo data to send.
51       * @param length  The length of the data to send.  Should be less than
52       *    or equal to the length of the data byte array.
53       * @param host  The address of the server.
54       * @exception IOException If an error occurs during the datagram send
55       *     operation.
56       ***/
57      public void send(byte[] data, int length, InetAddress host)
58      throws IOException
59      {
60          send(data, length, host, DEFAULT_PORT);
61      }
62  
63  
64      /*** Same as <code> send(data, data.length, host) </code> ***/
65      public void send(byte[] data, InetAddress host) throws IOException
66      {
67          send(data, data.length, host, DEFAULT_PORT);
68      }
69  
70  
71      /***
72       * Receives echoed data and returns its length.  The data may be divided
73       * up among multiple datagrams, requiring multiple calls to receive.
74       * Also, the UDP packets will not necessarily arrive in the same order
75       * they were sent.
76       * <p>
77       * @return  Length of actual data received.
78       * @exception IOException If an error occurs while receiving the data.
79       ***/
80      public int receive(byte[] data, int length) throws IOException
81      {
82          __receivePacket.setData(data);
83          __receivePacket.setLength(length);
84          _socket_.receive(__receivePacket);
85          return __receivePacket.getLength();
86      }
87  
88      /*** Same as <code> receive(data, data.length)</code> ***/
89      public int receive(byte[] data) throws IOException
90      {
91          return receive(data, data.length);
92      }
93  
94  }
95