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 *
037 * @see EchoTCPClient
038 * @see DiscardUDPClient
039 ***/
040
041public final class EchoUDPClient extends DiscardUDPClient
042{
043    /*** The default echo port.  It is set to 7 according to RFC 862. ***/
044    public static final int DEFAULT_PORT = 7;
045
046    private final DatagramPacket __receivePacket = new DatagramPacket(new byte[0], 0);
047
048    /***
049     * Sends the specified data to the specified server at the default echo
050     * port.
051     *
052     * @param data  The echo data to send.
053     * @param length  The length of the data to send.  Should be less than
054     *    or equal to the length of the data byte array.
055     * @param host  The address of the server.
056     * @throws IOException If an error occurs during the datagram send
057     *     operation.
058     ***/
059    @Override
060    public void send(byte[] data, int length, InetAddress host)
061    throws IOException
062    {
063        send(data, length, host, DEFAULT_PORT);
064    }
065
066
067    /*** Same as <code> send(data, data.length, host) </code> ***/
068    @Override
069    public void send(byte[] data, InetAddress host) throws IOException
070    {
071        send(data, data.length, host, DEFAULT_PORT);
072    }
073
074
075    /***
076     * Receives echoed data and returns its length.  The data may be divided
077     * up among multiple datagrams, requiring multiple calls to receive.
078     * Also, the UDP packets will not necessarily arrive in the same order
079     * they were sent.
080     * @param  data the buffer to receive the input
081     * @param length  of the buffer
082     *
083     * @return  Length of actual data received.
084     * @throws 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     * @param data the buffer to receive the input
096     * @return the number of bytes
097     * @throws IOException on error
098     ***/
099    public int receive(byte[] data) throws IOException
100    {
101        return receive(data, data.length);
102    }
103
104}
105