001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.commons.net.echo;
019
020import java.io.IOException;
021import java.net.DatagramPacket;
022import java.net.InetAddress;
023
024import org.apache.commons.net.discard.DiscardUDPClient;
025
026/***
027 * The EchoUDPClient class is a UDP implementation of a client for the
028 * Echo protocol described in RFC 862.  To use the class,
029 * just open a local UDP port
030 * with {@link org.apache.commons.net.DatagramSocketClient#open  open }
031 * and call {@link #send  send } to send datagrams to the server,
032 * then call {@link #receive  receive } to receive echoes.
033 * After you're done echoing data, call
034 * {@link org.apache.commons.net.DatagramSocketClient#close  close() }
035 * to clean up properly.
036 * <p>
037 * <p>
038 * @see EchoTCPClient
039 * @see DiscardUDPClient
040 ***/
041
042public final class EchoUDPClient extends DiscardUDPClient
043{
044    /*** The default echo port.  It is set to 7 according to RFC 862. ***/
045    public static final int DEFAULT_PORT = 7;
046
047    private final DatagramPacket __receivePacket = new DatagramPacket(new byte[0], 0);
048
049    /***
050     * Sends the specified data to the specified server at the default echo
051     * port.
052     * <p>
053     * @param data  The echo data to send.
054     * @param length  The length of the data to send.  Should be less than
055     *    or equal to the length of the data byte array.
056     * @param host  The address of the server.
057     * @exception IOException If an error occurs during the datagram send
058     *     operation.
059     ***/
060    @Override
061    public void send(byte[] data, int length, InetAddress host)
062    throws IOException
063    {
064        send(data, length, host, DEFAULT_PORT);
065    }
066
067
068    /*** Same as <code> send(data, data.length, host) </code> ***/
069    @Override
070    public void send(byte[] data, InetAddress host) throws IOException
071    {
072        send(data, data.length, host, DEFAULT_PORT);
073    }
074
075
076    /***
077     * Receives echoed data and returns its length.  The data may be divided
078     * up among multiple datagrams, requiring multiple calls to receive.
079     * Also, the UDP packets will not necessarily arrive in the same order
080     * they were sent.
081     * <p>
082     * @return  Length of actual data received.
083     * @exception IOException If an error occurs while receiving the data.
084     ***/
085    public int receive(byte[] data, int length) throws IOException
086    {
087        __receivePacket.setData(data);
088        __receivePacket.setLength(length);
089        _socket_.receive(__receivePacket);
090        return __receivePacket.getLength();
091    }
092
093    /*** Same as <code> receive(data, data.length)</code> ***/
094    public int receive(byte[] data) throws IOException
095    {
096        return receive(data, data.length);
097    }
098
099}
100