1 /* 2 * Copyright (c) 2003, 2004, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 */ 23 24 /* 25 * 26 * 27 * An "echo" service designed to be used with inetd. It can be configured in 28 * inetd.conf to be used by any of the following types of services :- 29 * 30 * stream tcp nowait 31 * stream tcp6 nowait 32 * stream tcp wait 33 * stream tcp6 wait 34 * dgram udp wait 35 * dgram udp6 wait 36 * 37 * If configured as a "tcp nowait" service then inetd will launch a 38 * VM to run the EchoService each time that a client connects to 39 * the TCP port. The EchoService simply echos any messages it 40 * receives from the client and shuts if the client closes the 41 * connection. 42 * 43 * If configured as a "tcp wait" service then inetd will launch a VM 44 * to run the EchoService when a client connects to the port. When 45 * launched the EchoService takes over the listener socket. It 46 * terminates when all clients have disconnected and the service 47 * is idle for a few seconds. 48 * 49 * If configured as a "udp wait" service then a VM will be launched for 50 * each UDP packet to the configured port. System.inheritedChannel() 51 * will return a DatagramChannel. The echo service here will terminate after 52 * echoing the UDP packet back to the client. 53 * 54 * The service closes the inherited network channel when complete. To 55 * facilate testing that the channel is closed the "tcp nowait" service 56 * can close the connection after a given number of bytes. 57 */ 58 import java.nio.*; 59 import java.nio.channels.*; 60 import java.io.IOException; 61 import java.net.*; 62 63 public class EchoService { 64 doIt(SocketChannel sc, int closeAfter, int delay)65 private static void doIt(SocketChannel sc, int closeAfter, int delay) throws IOException { 66 ByteBuffer bb = ByteBuffer.allocate(1024); 67 int total = 0; 68 for (;;) { 69 bb.clear(); 70 int n = sc.read(bb); 71 if (n < 0) { 72 break; 73 } 74 total += n; 75 76 // echo 77 bb.flip(); 78 sc.write(bb); 79 80 // close after X bytes? 81 if (closeAfter > 0 && total >= closeAfter) { 82 break; 83 } 84 } 85 86 sc.close(); 87 if (delay > 0) { 88 try { 89 Thread.currentThread().sleep(delay); 90 } catch (InterruptedException x) { } 91 } 92 } 93 doIt(DatagramChannel dc)94 private static void doIt(DatagramChannel dc) throws IOException { 95 ByteBuffer bb = ByteBuffer.allocate(1024); 96 SocketAddress sa = dc.receive(bb); 97 bb.flip(); 98 dc.send(bb, sa); 99 dc.close(); 100 } 101 102 103 // A worker thread to service a single connection 104 // The class maintains a count of the number of worker threads so 105 // can the service can terminate then all clients disconnect. 106 107 static class Worker implements Runnable { 108 private static int count = 0; 109 private static Object lock = new Object(); 110 count()111 public static int count() { 112 synchronized (lock) { 113 return count; 114 } 115 } 116 117 private SocketChannel sc; 118 Worker(SocketChannel sc)119 Worker(SocketChannel sc) { 120 this.sc = sc; 121 synchronized (lock) { 122 count++; 123 } 124 } 125 run()126 public void run() { 127 try { 128 doIt(sc, -1, -1); 129 } catch (IOException x) { 130 } finally { 131 synchronized (lock) { 132 count--; 133 } 134 } 135 136 } 137 } 138 main(String args[])139 public static void main(String args[]) throws IOException { 140 Channel c = System.inheritedChannel(); 141 if (c == null) { 142 return; 143 } 144 145 // tcp nowait 146 if (c instanceof SocketChannel) { 147 int closeAfter = 0; 148 int delay = 0; 149 if (args.length > 0) { 150 closeAfter = Integer.parseInt(args[0]); 151 } 152 if (args.length > 1) { 153 delay = Integer.parseInt(args[1]); 154 } 155 doIt((SocketChannel)c, closeAfter, delay); 156 } 157 158 // tcp wait - in this case we take over the listener socket 159 // In this test case we create a thread to service each connection 160 // and terminate after all clients are gone. 161 // 162 if (c instanceof ServerSocketChannel) { 163 ServerSocketChannel ssc = (ServerSocketChannel)c; 164 165 ssc.configureBlocking(false); 166 Selector sel = ssc.provider().openSelector(); 167 SelectionKey sk = ssc.register(sel, SelectionKey.OP_ACCEPT); 168 SocketChannel sc; 169 int count = 0; 170 for (;;) { 171 sel.select(5000); 172 if (sk.isAcceptable() && ((sc = ssc.accept()) != null)) { 173 Worker w = new Worker(sc); 174 (new Thread(w)).start(); 175 } else { 176 // if all clients have disconnected then we die as well. 177 if (Worker.count() == 0) { 178 break; 179 } 180 } 181 } 182 ssc.close(); 183 } 184 185 // udp wait 186 if (c instanceof DatagramChannel) { 187 doIt((DatagramChannel)c); 188 } 189 190 // linger? 191 if (args.length > 0) { 192 int delay = Integer.parseInt(args[0]); 193 try { 194 Thread.currentThread().sleep(delay); 195 } catch (InterruptedException x) { } 196 } 197 198 } 199 200 } 201