1 /* 2 * Copyright (c) 2003, 2017, 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.io.IOException; 59 import java.net.SocketAddress; 60 import java.nio.ByteBuffer; 61 import java.nio.channels.Channel; 62 import java.nio.channels.DatagramChannel; 63 import java.nio.channels.SelectionKey; 64 import java.nio.channels.Selector; 65 import java.nio.channels.ServerSocketChannel; 66 import java.nio.channels.SocketChannel; 67 68 public class EchoService { 69 70 private static void doIt(SocketChannel sc, int closeAfter, int delay) throws IOException { 71 ByteBuffer bb = ByteBuffer.allocate(1024); 72 int total = 0; 73 for (;;) { 74 bb.clear(); 75 int n = sc.read(bb); 76 if (n < 0) { 77 break; 78 } 79 total += n; 80 81 // echo 82 bb.flip(); 83 sc.write(bb); 84 85 // close after X bytes? 86 if (closeAfter > 0 && total >= closeAfter) { 87 break; 88 } 89 } 90 91 sc.close(); 92 if (delay > 0) { 93 try { 94 Thread.currentThread().sleep(delay); 95 } catch (InterruptedException x) { } 96 } 97 } 98 99 private static void doIt(DatagramChannel dc) throws IOException { 100 ByteBuffer bb = ByteBuffer.allocate(1024); 101 SocketAddress sa = dc.receive(bb); 102 bb.flip(); 103 dc.send(bb, sa); 104 dc.close(); 105 } 106 107 108 // A worker thread to service a single connection 109 // The class maintains a count of the number of worker threads so 110 // can the service can terminate then all clients disconnect. 111 112 static class Worker implements Runnable { 113 private static int count = 0; 114 private static Object lock = new Object(); 115 116 public static int count() { 117 synchronized (lock) { 118 return count; 119 } 120 } 121 122 private SocketChannel sc; 123 124 Worker(SocketChannel sc) { 125 this.sc = sc; 126 synchronized (lock) { 127 count++; 128 } 129 } 130 131 public void run() { 132 try { 133 doIt(sc, -1, -1); 134 } catch (IOException x) { 135 } finally { 136 synchronized (lock) { 137 count--; 138 } 139 } 140 141 } 142 } 143 144 public static void main(String args[]) throws IOException { 145 Channel c = System.inheritedChannel(); 146 if (c == null) { 147 return; 148 } 149 150 // tcp nowait 151 if (c instanceof SocketChannel) { 152 int closeAfter = 0; 153 int delay = 0; 154 if (args.length > 0) { 155 closeAfter = Integer.parseInt(args[0]); 156 } 157 if (args.length > 1) { 158 delay = Integer.parseInt(args[1]); 159 } 160 doIt((SocketChannel)c, closeAfter, delay); 161 } 162 163 // tcp wait - in this case we take over the listener socket 164 // In this test case we create a thread to service each connection 165 // and terminate after all clients are gone. 166 // 167 if (c instanceof ServerSocketChannel) { 168 ServerSocketChannel ssc = (ServerSocketChannel)c; 169 170 ssc.configureBlocking(false); 171 Selector sel = ssc.provider().openSelector(); 172 SelectionKey sk = ssc.register(sel, SelectionKey.OP_ACCEPT); 173 SocketChannel sc; 174 int count = 0; 175 for (;;) { 176 sel.select(5000); 177 if (sk.isAcceptable() && ((sc = ssc.accept()) != null)) { 178 Worker w = new Worker(sc); 179 (new Thread(w)).start(); 180 } else { 181 // if all clients have disconnected then we die as well. 182 if (Worker.count() == 0) { 183 break; 184 } 185 } 186 } 187 ssc.close(); 188 } 189 190 // udp wait 191 if (c instanceof DatagramChannel) { 192 doIt((DatagramChannel)c); 193 } 194 195 // linger? 196 if (args.length > 0) { 197 int delay = Integer.parseInt(args[0]); 198 try { 199 Thread.currentThread().sleep(delay); 200 } catch (InterruptedException x) { } 201 } 202 203 } 204 205 }