1 /*
   2  * Copyright (c) 2013, 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.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 package sun.management.jdp;
  26 
  27 import java.io.IOException;
  28 import java.net.InetAddress;
  29 import java.net.UnknownHostException;
  30 import java.util.UUID;
  31 
  32 import java.lang.management.ManagementFactory;
  33 import java.lang.management.RuntimeMXBean;
  34 import java.lang.reflect.Field;
  35 import java.lang.reflect.Method;
  36 import sun.management.VMManagement;
  37 
  38 /**
  39  * JdpController is responsible to create and manage a broadcast loop.
  40  *
  41  * <p> Other part of code has no access to broadcast loop and have to use
  42  * provided static methods
  43  * {@link #startDiscoveryService(InetAddress,int,String,String) startDiscoveryService}
  44  * and {@link #stopDiscoveryService() stopDiscoveryService}
  45  * <p>{@link #startDiscoveryService(InetAddress,int,String,String) startDiscoveryService} could be called multiple
  46  * times as it stops the running service if it is necessary.
  47  * Call to {@link #stopDiscoveryService() stopDiscoveryService}
  48  * ignored if service isn't run.
  49  *
  50  *
  51  * <p> System properties below could be used to control broadcast loop behavior.
  52  * Property below have to be set explicitly in command line. It's not possible to
  53  * set it in management.config file.  Careless changes of these properties could
  54  * lead to security or network issues.
  55  * <ul>
  56  *     <li>com.sun.management.jdp.ttl         - set ttl for broadcast packet</li>
  57  *     <li>com.sun.management.jdp.pause       - set broadcast interval in seconds</li>
  58  *     <li>com.sun.management.jdp.source_addr - an address of interface to use for broadcast</li>
  59  * </ul>
  60  *
  61  * <p>null parameters values are filtered out on {@link JdpPacketWriter} level and
  62  * corresponding keys are not placed to packet.
  63  */
  64 public final class JdpController {
  65 
  66     private static class JDPControllerRunner implements Runnable {
  67 
  68         private final JdpJmxPacket packet;
  69         private final JdpBroadcaster bcast;
  70         private final int pause;
  71         private volatile boolean shutdown = false;
  72 
  73         private JDPControllerRunner(JdpBroadcaster bcast, JdpJmxPacket packet, int pause) {
  74             this.bcast = bcast;
  75             this.packet = packet;
  76             this.pause = pause;
  77         }
  78 
  79         @Override
  80         public void run() {
  81             try {
  82                 while (!shutdown) {
  83                     bcast.sendPacket(packet);
  84                     try {
  85                         Thread.sleep(this.pause);
  86                     } catch (InterruptedException e) {
  87                         // pass
  88                     }
  89                 }
  90 
  91             } catch (IOException e) {
  92               // pass;
  93             }
  94 
  95             // It's not possible to re-use controller,
  96             // nevertheless reset shutdown variable
  97             try {
  98                 stop();
  99                 bcast.shutdown();
 100             } catch (IOException ex) {
 101                 // pass - ignore IOException during shutdown
 102             }
 103         }
 104 
 105         public void stop() {
 106             shutdown = true;
 107         }
 108     }
 109     private static JDPControllerRunner controller = null;
 110 
 111     private JdpController(){
 112         // Don't allow to instantiate this class.
 113     }
 114 
 115     // Utility to handle optional system properties
 116     // Parse an integer from string or return default if provided string is null
 117     private static int getInteger(String val, int dflt, String msg) throws JdpException {
 118         try {
 119             return (val == null) ? dflt : Integer.parseInt(val);
 120         } catch (NumberFormatException ex) {
 121             throw new JdpException(msg);
 122         }
 123     }
 124 
 125     // Parse an inet address from string or return default if provided string is null
 126     private static InetAddress getInetAddress(String val, InetAddress dflt, String msg) throws JdpException {
 127         try {
 128             return (val == null) ? dflt : InetAddress.getByName(val);
 129         } catch (UnknownHostException ex) {
 130             throw new JdpException(msg);
 131         }
 132     }
 133 
 134     // Get the process id of the current running Java process
 135     private static Integer getProcessId() {
 136         try {
 137             // Get the current process id using a reflection hack
 138             RuntimeMXBean runtime = ManagementFactory.getRuntimeMXBean();
 139             Field jvm = runtime.getClass().getDeclaredField("jvm");
 140             jvm.setAccessible(true);
 141 
 142             VMManagement mgmt = (sun.management.VMManagement) jvm.get(runtime);
 143             Method pid_method = mgmt.getClass().getDeclaredMethod("getProcessId");
 144             pid_method.setAccessible(true);
 145             Integer pid = (Integer) pid_method.invoke(mgmt);
 146             return pid;
 147         } catch(Exception ex) {
 148             return null;
 149         }
 150     }
 151 
 152 
 153     /**
 154      * Starts discovery service
 155      *
 156      * @param address - multicast group address
 157      * @param port - udp port to use
 158      * @param instanceName - name of running JVM instance
 159      * @param url - JMX service url
 160      * @throws IOException
 161      */
 162     public static synchronized void startDiscoveryService(InetAddress address, int port, String instanceName, String url)
 163             throws IOException, JdpException {
 164 
 165         // Limit packet to local subnet by default
 166         int ttl = getInteger(
 167                 System.getProperty("com.sun.management.jdp.ttl"), 1,
 168                 "Invalid jdp packet ttl");
 169 
 170         // Broadcast once a 5 seconds by default
 171         int pause = getInteger(
 172                 System.getProperty("com.sun.management.jdp.pause"), 5,
 173                 "Invalid jdp pause");
 174 
 175         // Converting seconds to milliseconds
 176         pause = pause * 1000;
 177 
 178         // Allow OS to choose broadcast source
 179         InetAddress sourceAddress = getInetAddress(
 180                 System.getProperty("com.sun.management.jdp.source_addr"), null,
 181                 "Invalid source address provided");
 182 
 183         // Generate session id
 184         UUID id = UUID.randomUUID();
 185 
 186         JdpJmxPacket packet = new JdpJmxPacket(id, url);
 187 
 188         // Don't broadcast whole command line for security reason.
 189         // Strip everything after first space
 190         String javaCommand = System.getProperty("sun.java.command");
 191         if (javaCommand != null) {
 192             String[] arr = javaCommand.split(" ", 2);
 193             packet.setMainClass(arr[0]);
 194         }
 195 
 196         // Put optional explicit java instance name to packet, if user doesn't specify
 197         // it the key is skipped. PacketWriter is responsible to skip keys having null value.
 198         packet.setInstanceName(instanceName);
 199 
 200         // Set rmi server hostname if it explicitly specified by user with
 201         // java.rmi.server.hostname
 202         String rmiHostname = System.getProperty("java.rmi.server.hostname");
 203         packet.setRmiHostname(rmiHostname);
 204 
 205         // Set broadcast interval
 206         packet.setBroadcastInterval(Integer.toString(pause));
 207 
 208         // Set process id
 209         Integer pid = getProcessId();
 210         if (pid != null) {
 211            packet.setProcessId(pid.toString());
 212         }
 213 
 214         JdpBroadcaster bcast = new JdpBroadcaster(address, sourceAddress, port, ttl);
 215 
 216         // Stop discovery service if it's already running
 217         stopDiscoveryService();
 218 
 219         controller = new JDPControllerRunner(bcast, packet, pause);
 220 
 221         Thread t = new Thread(null, controller, "JDP broadcaster", 0, false);
 222         t.setDaemon(true);
 223         t.start();
 224     }
 225 
 226     /**
 227      * Stop running discovery service,
 228      * it's safe to attempt to stop not started service
 229      */
 230     public static synchronized void stopDiscoveryService() {
 231         if ( controller != null ){
 232              controller.stop();
 233              controller = null;
 234         }
 235     }
 236 }