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.echo;
19
20 import java.io.IOException;
21 import java.net.DatagramPacket;
22 import java.net.InetAddress;
23
24 import org.apache.commons.net.discard.DiscardUDPClient;
25 import org.apache.commons.net.util.NetConstants;
26
27 /**
28 * The EchoUDPClient class is a UDP implementation of a client for the Echo protocol described in RFC 862. To use the class, just open a local UDP port with
29 * {@link org.apache.commons.net.DatagramSocketClient#open open } and call {@link #send send } to send datagrams to the server, then call {@link #receive
30 * receive } to receive echoes. After you're done echoing data, call {@link org.apache.commons.net.DatagramSocketClient#close close() } to clean up properly.
31 *
32 * @see EchoTCPClient
33 * @see DiscardUDPClient
34 */
35
36 public final class EchoUDPClient extends DiscardUDPClient {
37 /** The default echo port. It is set to 7 according to RFC 862. */
38 public static final int DEFAULT_PORT = 7;
39
40 private final DatagramPacket receivePacket = new DatagramPacket(NetConstants.EMPTY_BTYE_ARRAY, 0);
41
42 /**
43 * Same as <code>receive(data, data.length)</code>
44 *
45 * @param data the buffer to receive the input
46 * @return the number of bytes
47 * @throws IOException on error
48 */
49 public int receive(final byte[] data) throws IOException {
50 return receive(data, data.length);
51 }
52
53 /**
54 * Receives echoed data and returns its length. The data may be divided up among multiple datagrams, requiring multiple calls to receive. Also, the UDP
55 * packets will not necessarily arrive in the same order they were sent.
56 *
57 * @param data the buffer to receive the input
58 * @param length of the buffer
59 *
60 * @return Length of actual data received.
61 * @throws IOException If an error occurs while receiving the data.
62 */
63 public int receive(final byte[] data, final int length) throws IOException {
64 receivePacket.setData(data);
65 receivePacket.setLength(length);
66 checkOpen().receive(receivePacket);
67 return receivePacket.getLength();
68 }
69
70 /** Same as <code>send(data, data.length, host)</code> */
71 @Override
72 public void send(final byte[] data, final InetAddress host) throws IOException {
73 send(data, data.length, host, DEFAULT_PORT);
74 }
75
76 /**
77 * Sends the specified data to the specified server at the default echo port.
78 *
79 * @param data The echo data to send.
80 * @param length The length of the data to send. Should be less than or equal to the length of the data byte array.
81 * @param host The address of the server.
82 * @throws IOException If an error occurs during the datagram send operation.
83 */
84 @Override
85 public void send(final byte[] data, final int length, final InetAddress host) throws IOException {
86 send(data, length, host, DEFAULT_PORT);
87 }
88
89 }