    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
    018    package org.apache.commons.net.echo;
    019
    020    import java.io.IOException;
    021    import java.net.DatagramPacket;
    022    import java.net.InetAddress;
    023
    024    import 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
    042    public 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