    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