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    1   /*
    2    * Copyright 2001-2005 The Apache Software Foundation
    3    *
    4    * Licensed under the Apache License, Version 2.0 (the "License");
    5    * you may not use this file except in compliance with the License.
    6    * You may obtain a copy of the License at
    7    *
    8    *     http://www.apache.org/licenses/LICENSE-2.0
    9    *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS,
    12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   * See the License for the specific language governing permissions and
    14   * limitations under the License.
    15   */
    16  package org.apache.commons.net;
    17
    18  import java.io.IOException;
    19  import java.net.DatagramPacket;
    20  import java.net.InetAddress;
    21
    22  /****
    23   * The EchoUDPClient class is a UDP implementation of a client for the
    24   * Echo protocol described in RFC 862.  To use the class,
    25   * just open a local UDP port
    26   * with {@link org.apache.commons.net.DatagramSocketClient#open  open }
    27   * and call {@link #send  send } to send datagrams to the server,
    28   * then call {@link #receive  receive } to receive echoes.
    29   * After you're done echoing data, call
    30   * {@link org.apache.commons.net.DatagramSocketClient#close  close() }
    31   * to clean up properly.
    32   * <p>
    33   * <p>
    34   * @author Daniel F. Savarese
    35   * @see EchoTCPClient
    36   * @see DiscardUDPClient
    37   ***/
    38
    39  public final class EchoUDPClient extends DiscardUDPClient
    40  {
    41      /**** The default echo port.  It is set to 7 according to RFC 862. ***/
    42      public static final int DEFAULT_PORT = 7;
    43
    44      private DatagramPacket __receivePacket = new DatagramPacket(new byte[0], 0);
    45
    46      /****
    47       * Sends the specified data to the specified server at the default echo
    48       * port.
    49       * <p>
    50       * @param data  The echo data to send.
    51       * @param length  The length of the data to send.  Should be less than
    52       *    or equal to the length of the data byte array.
    53       * @param host  The address of the server.
    54       * @exception IOException If an error occurs during the datagram send
    55       *     operation.
    56       ***/
    57      public void send(byte[] data, int length, InetAddress host)
    58      throws IOException
    59      {
    60          send(data, length, host, DEFAULT_PORT);
    61      }
    62
    63
    64      /**** Same as <code> send(data, data.length, host) </code> ***/
    65      public void send(byte[] data, InetAddress host) throws IOException
    66      {
    67          send(data, data.length, host, DEFAULT_PORT);
    68      }
    69
    70
    71      /****
    72       * Receives echoed data and returns its length.  The data may be divided
    73       * up among multiple datagrams, requiring multiple calls to receive.
    74       * Also, the UDP packets will not necessarily arrive in the same order
    75       * they were sent.
    76       * <p>
    77       * @return  Length of actual data received.
    78       * @exception IOException If an error occurs while receiving the data.
    79       ***/
    80      public int receive(byte[] data, int length) throws IOException
    81      {
    82          __receivePacket.setData(data);
    83          __receivePacket.setLength(length);
    84          _socket_.receive(__receivePacket);
    85          return __receivePacket.getLength();
    86      }
    87
    88      /**** Same as <code> receive(data, data.length)</code> ***/
    89      public int receive(byte[] data) throws IOException
    90      {
    91          return receive(data, data.length);
    92      }
    93
    94  }
    95