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 * @author Daniel F. Savarese
039 * @see EchoTCPClient
040 * @see DiscardUDPClient
041 ***/
042
043public final class EchoUDPClient extends DiscardUDPClient
044{
045    /*** The default echo port.  It is set to 7 according to RFC 862. ***/
046    public static final int DEFAULT_PORT = 7;
047
048    private DatagramPacket __receivePacket = new DatagramPacket(new byte[0], 0);
049
050    /***
051     * Sends the specified data to the specified server at the default echo
052     * port.
053     * <p>
054     * @param data  The echo data to send.
055     * @param length  The length of the data to send.  Should be less than
056     *    or equal to the length of the data byte array.
057     * @param host  The address of the server.
058     * @exception IOException If an error occurs during the datagram send
059     *     operation.
060     ***/
061    @Override
062    public void send(byte[] data, int length, InetAddress host)
063    throws IOException
064    {
065        send(data, length, host, DEFAULT_PORT);
066    }
067
068
069    /*** Same as <code> send(data, data.length, host) </code> ***/
070    @Override
071    public void send(byte[] data, InetAddress host) throws IOException
072    {
073        send(data, data.length, host, DEFAULT_PORT);
074    }
075
076
077    /***
078     * Receives echoed data and returns its length.  The data may be divided
079     * up among multiple datagrams, requiring multiple calls to receive.
080     * Also, the UDP packets will not necessarily arrive in the same order
081     * they were sent.
082     * <p>
083     * @return  Length of actual data received.
084     * @exception IOException If an error occurs while receiving the data.
085     ***/
086    public int receive(byte[] data, int length) throws IOException
087    {
088        __receivePacket.setData(data);
089        __receivePacket.setLength(length);
090        _socket_.receive(__receivePacket);
091        return __receivePacket.getLength();
092    }
093
094    /*** Same as <code> receive(data, data.length)</code> ***/
095    public int receive(byte[] data) throws IOException
096    {
097        return receive(data, data.length);
098    }
099
100}
101