    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