1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 18 package org.apache.commons.net.chargen; 19 20 import java.io.IOException; 21 import java.net.DatagramPacket; 22 import java.net.InetAddress; 23 24 import org.apache.commons.net.DatagramSocketClient; 25 26 /*** 27 * The CharGenUDPClient class is a UDP implementation of a client for the 28 * character generator protocol described in RFC 864. It can also be 29 * used for Systat (RFC 866), Quote of the Day (RFC 865), and netstat 30 * (port 15). All of these protocols involve sending a datagram to the 31 * appropriate port, and reading data contained in one or more reply 32 * datagrams. The chargen and quote of the day protocols only send 33 * one reply datagram containing 512 bytes or less of data. The other 34 * protocols may reply with more than one datagram, in which case you 35 * must wait for a timeout to determine that all reply datagrams have 36 * been sent. 37 * <p> 38 * To use the CharGenUDPClient class, just open a local UDP port 39 * with {@link org.apache.commons.net.DatagramSocketClient#open open } 40 * and call {@link #send send } to send the datagram that will 41 * initiate the data reply. For chargen or quote of the day, just 42 * call {@link #receive receive }, and you're done. For netstat and 43 * systat, call receive in a while loop, and catch a SocketException and 44 * InterruptedIOException to detect a timeout (don't forget to set the 45 * timeout duration beforehand). Don't forget to call 46 * {@link org.apache.commons.net.DatagramSocketClient#close close() } 47 * to clean up properly. 48 * <p> 49 * <p> 50 * @author Daniel F. Savarese 51 * @see CharGenTCPClient 52 ***/ 53 54 public final class CharGenUDPClient extends DatagramSocketClient 55 { 56 /*** The systat port value of 11 according to RFC 866. ***/ 57 public static final int SYSTAT_PORT = 11; 58 /*** The netstat port value of 19. ***/ 59 public static final int NETSTAT_PORT = 15; 60 /*** The quote of the day port value of 17 according to RFC 865. ***/ 61 public static final int QUOTE_OF_DAY_PORT = 17; 62 /*** The character generator port value of 19 according to RFC 864. ***/ 63 public static final int CHARGEN_PORT = 19; 64 /*** The default chargen port. It is set to 19 according to RFC 864. ***/ 65 public static final int DEFAULT_PORT = 19; 66 67 private byte[] __receiveData; 68 private DatagramPacket __receivePacket; 69 private DatagramPacket __sendPacket; 70 71 /*** 72 * The default CharGenUDPClient constructor. It initializes some internal 73 * data structures for sending and receiving the necessary datagrams for 74 * the chargen and related protocols. 75 ***/ 76 public CharGenUDPClient() 77 { 78 // CharGen return packets have a maximum length of 512 79 __receiveData = new byte[512]; 80 __receivePacket = new DatagramPacket(__receiveData, 512); 81 __sendPacket = new DatagramPacket(new byte[0], 0); 82 } 83 84 85 /*** 86 * Sends the data initiation datagram. This data in the packet is ignored 87 * by the server, and merely serves to signal that the server should send 88 * its reply. 89 * <p> 90 * @param host The address of the server. 91 * @param port The port of the service. 92 * @exception IOException If an error occurs while sending the datagram. 93 ***/ 94 public void send(InetAddress host, int port) throws IOException 95 { 96 __sendPacket.setAddress(host); 97 __sendPacket.setPort(port); 98 _socket_.send(__sendPacket); 99 } 100 101 /*** Same as <code>send(host, CharGenUDPClient.DEFAULT_PORT);</code> ***/ 102 public void send(InetAddress host) throws IOException 103 { 104 send(host, DEFAULT_PORT); 105 } 106 107 /*** 108 * Receive the reply data from the server. This will always be 512 bytes 109 * or less. Chargen and quote of the day only return one packet. Netstat 110 * and systat require multiple calls to receive() with timeout detection. 111 * <p> 112 * @return The reply data from the server. 113 * @exception IOException If an error occurs while receiving the datagram. 114 ***/ 115 public byte[] receive() throws IOException 116 { 117 int length; 118 byte[] result; 119 120 _socket_.receive(__receivePacket); 121 122 result = new byte[length = __receivePacket.getLength()]; 123 System.arraycopy(__receiveData, 0, result, 0, length); 124 125 return result; 126 } 127 128 } 129