001 /*
002 * Copyright 2001-2005 The Apache Software Foundation
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016 package org.apache.commons.net;
017
018 import java.io.IOException;
019 import java.net.DatagramPacket;
020 import java.net.InetAddress;
021
022 /***
023 * The EchoUDPClient class is a UDP implementation of a client for the
024 * Echo protocol described in RFC 862. To use the class,
025 * just open a local UDP port
026 * with {@link org.apache.commons.net.DatagramSocketClient#open open }
027 * and call {@link #send send } to send datagrams to the server,
028 * then call {@link #receive receive } to receive echoes.
029 * After you're done echoing data, call
030 * {@link org.apache.commons.net.DatagramSocketClient#close close() }
031 * to clean up properly.
032 * <p>
033 * <p>
034 * @author Daniel F. Savarese
035 * @see EchoTCPClient
036 * @see DiscardUDPClient
037 ***/
038
039 public final class EchoUDPClient extends DiscardUDPClient
040 {
041 /*** The default echo port. It is set to 7 according to RFC 862. ***/
042 public static final int DEFAULT_PORT = 7;
043
044 private DatagramPacket __receivePacket = new DatagramPacket(new byte[0], 0);
045
046 /***
047 * Sends the specified data to the specified server at the default echo
048 * port.
049 * <p>
050 * @param data The echo data to send.
051 * @param length The length of the data to send. Should be less than
052 * or equal to the length of the data byte array.
053 * @param host The address of the server.
054 * @exception IOException If an error occurs during the datagram send
055 * operation.
056 ***/
057 public void send(byte[] data, int length, InetAddress host)
058 throws IOException
059 {
060 send(data, length, host, DEFAULT_PORT);
061 }
062
063
064 /*** Same as <code> send(data, data.length, host) </code> ***/
065 public void send(byte[] data, InetAddress host) throws IOException
066 {
067 send(data, data.length, host, DEFAULT_PORT);
068 }
069
070
071 /***
072 * Receives echoed data and returns its length. The data may be divided
073 * up among multiple datagrams, requiring multiple calls to receive.
074 * Also, the UDP packets will not necessarily arrive in the same order
075 * they were sent.
076 * <p>
077 * @return Length of actual data received.
078 * @exception IOException If an error occurs while receiving the data.
079 ***/
080 public int receive(byte[] data, int length) throws IOException
081 {
082 __receivePacket.setData(data);
083 __receivePacket.setLength(length);
084 _socket_.receive(__receivePacket);
085 return __receivePacket.getLength();
086 }
087
088 /*** Same as <code> receive(data, data.length)</code> ***/
089 public int receive(byte[] data) throws IOException
090 {
091 return receive(data, data.length);
092 }
093
094 }
095