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;
025import org.apache.commons.net.util.NetConstants;
026
027/**
028 * The EchoUDPClient class is a UDP implementation of a client for the
029 * Echo protocol described in RFC 862.  To use the class,
030 * just open a local UDP port
031 * with {@link org.apache.commons.net.DatagramSocketClient#open  open }
032 * and call {@link #send  send } to send datagrams to the server,
033 * then call {@link #receive  receive } to receive echoes.
034 * After you're done echoing data, call
035 * {@link org.apache.commons.net.DatagramSocketClient#close  close() }
036 * to clean up properly.
037 *
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(NetConstants.EMPTY_BTYE_ARRAY, 0);
048
049    /**
050     * Sends the specified data to the specified server at the default echo
051     * port.
052     *
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     * @throws IOException If an error occurs during the datagram send
058     *     operation.
059     */
060    @Override
061    public void send(final byte[] data, final int length, final 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(final byte[] data, final 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     * @param  data the buffer to receive the input
082     * @param length  of the buffer
083     *
084     * @return  Length of actual data received.
085     * @throws IOException If an error occurs while receiving the data.
086     */
087    public int receive(final byte[] data, final int length) throws IOException
088    {
089        receivePacket.setData(data);
090        receivePacket.setLength(length);
091        _socket_.receive(receivePacket);
092        return receivePacket.getLength();
093    }
094
095    /** Same as <code> receive(data, data.length)</code>
096     * @param data the buffer to receive the input
097     * @return the number of bytes
098     * @throws IOException on error
099     */
100    public int receive(final byte[] data) throws IOException
101    {
102        return receive(data, data.length);
103    }
104
105}
106