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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  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  package org.apache.commons.net.discard;
19  
20  import java.io.IOException;
21  import java.net.DatagramPacket;
22  import java.net.InetAddress;
23  
24  import org.apache.commons.net.DatagramSocketClient;
25  import org.apache.commons.net.util.NetConstants;
26  
27  /**
28   * The DiscardUDPClient class is a UDP implementation of a client for the Discard protocol described in RFC 863. To use the class, just open a local UDP port
29   * with {@link org.apache.commons.net.DatagramSocketClient#open open } and call {@link #send send } to send datagrams to the server After you're done sending
30   * discard data, call {@link org.apache.commons.net.DatagramSocketClient#close close() } to clean up properly.
31   *
32   * @see DiscardTCPClient
33   */
34  
35  public class DiscardUDPClient extends DatagramSocketClient {
36      /** The default discard port. It is set to 9 according to RFC 863. */
37      public static final int DEFAULT_PORT = 9;
38  
39      private final DatagramPacket sendPacket;
40  
41      public DiscardUDPClient() {
42          sendPacket = new DatagramPacket(NetConstants.EMPTY_BTYE_ARRAY, 0);
43      }
44  
45      /**
46       * Same as <code>send(data, data.length, host. DiscardUDPClient.DEFAULT_PORT)</code>.
47       *
48       * @param data the buffer to send
49       * @param host the target host
50       * @see #send(byte[], int, InetAddress, int)
51       * @throws IOException if an error occurs
52       */
53      public void send(final byte[] data, final InetAddress host) throws IOException {
54          send(data, data.length, host, DEFAULT_PORT);
55      }
56  
57      /**
58       * Same as <code>send(data, length, host. DiscardUDPClient.DEFAULT_PORT)</code>.
59       *
60       * @param data   the buffer to send
61       * @param length the length of the data in the buffer
62       * @param host   the target host
63       * @see #send(byte[], int, InetAddress, int)
64       * @throws IOException if an error occurs
65       */
66      public void send(final byte[] data, final int length, final InetAddress host) throws IOException {
67          send(data, length, host, DEFAULT_PORT);
68      }
69  
70      /**
71       * Sends the specified data to the specified server at the specified port.
72       *
73       * @param data   The discard data to send.
74       * @param length The length of the data to send. Should be less than or equal to the length of the data byte array.
75       * @param host   The address of the server.
76       * @param port   The service port.
77       * @throws IOException If an error occurs during the datagram send operation.
78       */
79      public void send(final byte[] data, final int length, final InetAddress host, final int port) throws IOException {
80          sendPacket.setData(data);
81          sendPacket.setLength(length);
82          sendPacket.setAddress(host);
83          sendPacket.setPort(port);
84          checkOpen().send(sendPacket);
85      }
86  
87  }