/*

 * Copyright (c) 2003, 2019, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

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package jdk.internal.agent;

import java.io.BufferedInputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.IOException;

import java.io.InputStream;

import java.lang.management.ManagementFactory;

import java.lang.reflect.Method;

import java.net.InetAddress;

import java.net.MalformedURLException;

import java.net.UnknownHostException;

import java.security.AccessController;

import java.security.PrivilegedAction;

import java.text.MessageFormat;

import java.util.HashMap;

import java.util.Map;

import java.util.MissingResourceException;

import java.util.Properties;

import java.util.ResourceBundle;

import java.util.ServiceLoader;

import java.util.function.Function;

import java.util.function.Predicate;

import javax.management.remote.JMXConnectorServer;

import javax.management.remote.JMXServiceURL;

import static jdk.internal.agent.AgentConfigurationError.*;

import jdk.internal.agent.spi.AgentProvider;

import jdk.internal.vm.VMSupport;

import sun.management.jdp.JdpController;

import sun.management.jdp.JdpException;

import sun.management.jmxremote.ConnectorBootstrap;

/**

 * This class provides the methods to start the management agent.

 * 1. {@link #startAgent} method is invoked by the VM if {@code -Dcom.sun.management.*} is set

 * 2. {@link #startLocalManagementAgent} or {@link #startRemoteManagementAgent}

 *    is invoked to start the management agent after the VM starts

 *    via jcmd ManagementAgent.start and start_local command.

 */

public class Agent {

    /**

     * Agent status collector strategy class

     */

    private static abstract class StatusCollector {

        protected static final Map<String, String> DEFAULT_PROPS = new HashMap<>();

        static {

            DEFAULT_PROPS.put(ConnectorBootstrap.PropertyNames.PORT,

                              ConnectorBootstrap.DefaultValues.PORT);

            DEFAULT_PROPS.put(ConnectorBootstrap.PropertyNames.USE_LOCAL_ONLY,

                              ConnectorBootstrap.DefaultValues.USE_LOCAL_ONLY);

            DEFAULT_PROPS.put(ConnectorBootstrap.PropertyNames.USE_AUTHENTICATION,

                              ConnectorBootstrap.DefaultValues.USE_AUTHENTICATION);

            DEFAULT_PROPS.put(ConnectorBootstrap.PropertyNames.USE_SSL,

                              ConnectorBootstrap.DefaultValues.USE_SSL);

            DEFAULT_PROPS.put(ConnectorBootstrap.PropertyNames.USE_REGISTRY_SSL,

                              ConnectorBootstrap.DefaultValues.USE_REGISTRY_SSL);

            DEFAULT_PROPS.put(ConnectorBootstrap.PropertyNames.SSL_NEED_CLIENT_AUTH,

                              ConnectorBootstrap.DefaultValues.SSL_NEED_CLIENT_AUTH);

            DEFAULT_PROPS.put(ConnectorBootstrap.PropertyNames.CONFIG_FILE_NAME,

                              ConnectorBootstrap.DefaultValues.CONFIG_FILE_NAME);

            DEFAULT_PROPS.put(ConnectorBootstrap.PropertyNames.PASSWORD_FILE_NAME,

                              ConnectorBootstrap.DefaultValues.PASSWORD_FILE_NAME);

            DEFAULT_PROPS.put(ConnectorBootstrap.PropertyNames.ACCESS_FILE_NAME,

                              ConnectorBootstrap.DefaultValues.ACCESS_FILE_NAME);

        }

        final protected StringBuilder sb = new StringBuilder();

        final public String collect() {

            Properties agentProps = VMSupport.getAgentProperties();

            String localConnAddr = (String)agentProps.get(LOCAL_CONNECTOR_ADDRESS_PROP);

            if (localConnAddr != null || jmxServer != null) {

                addAgentStatus(true);

                appendConnections(localConnAddr);

            } else {

                addAgentStatus(false);

            }

            return sb.toString();

        }

        private void appendConnections(String localConnAddr) {

            appendConnectionsHeader();

            if (localConnAddr != null) {

                try {

                    JMXServiceURL u = new JMXServiceURL(localConnAddr);

                    addConnection(false, u);

                } catch (MalformedURLException e) {

                    // will never happen

                }

            }

            if (jmxServer != null) {

                addConnection(true, jmxServer.getAddress());

            }

            appendConnectionsFooter();

        }

        private void addConnection(boolean remote, JMXServiceURL u) {

            appendConnectionHeader(remote);

            addConnectionDetails(u);

            addConfigProperties();

            appendConnectionFooter(remote);

        }

        private void addConfigProperties() {

            appendConfigPropsHeader();

            Properties remoteProps = configProps != null ?

                                        configProps : getManagementProperties();

            Map<Object, Object> props = new HashMap<>(DEFAULT_PROPS);

            if (remoteProps == null) {

                // local connector only

                String loc_only = System.getProperty(

                    ConnectorBootstrap.PropertyNames.USE_LOCAL_ONLY

                );

                if (loc_only != null &&

                    !ConnectorBootstrap.DefaultValues.USE_LOCAL_ONLY.equals(loc_only)) {

                    props.put(

                        ConnectorBootstrap.PropertyNames.USE_LOCAL_ONLY,

                        loc_only

                    );

                }

            } else {

                props.putAll(remoteProps);

            }

            props.entrySet().stream()

                .filter(preprocess(Map.Entry::getKey, StatusCollector::isManagementProp))

                .forEach(this::addConfigProp);

            appendConfigPropsFooter();

        }

        private static boolean isManagementProp(Object pName) {

            return pName != null && pName.toString().startsWith("com.sun.management.");

        }

        private static <T, V> Predicate<T> preprocess(Function<T, V> f, Predicate<V> p) {

            return (T t) -> p.test(f.apply(t));

        }

        abstract protected void addAgentStatus(boolean enabled);

        abstract protected void appendConnectionsHeader();

        abstract protected void appendConnectionsFooter();

        abstract protected void addConnectionDetails(JMXServiceURL u);

        abstract protected void appendConnectionHeader(boolean remote);

        abstract protected void appendConnectionFooter(boolean remote);

        abstract protected void appendConfigPropsHeader();

        abstract protected void appendConfigPropsFooter();

        abstract protected void addConfigProp(Map.Entry<?, ?> prop);

    }

    /**

     * Free-text status collector strategy implementation

     */

    final private static class TextStatusCollector extends StatusCollector {

        @Override

        protected void addAgentStatus(boolean enabled) {

            sb.append("Agent: ").append(enabled ? "enabled" : "disabled").append('\n');

        }

        @Override

        protected void appendConnectionsHeader() {

            sb.append('\n');

        }

        @Override

        protected void addConnectionDetails(JMXServiceURL u) {

            sb.append("Protocol       : ").append(u.getProtocol()).append('\n')

              .append("Host           : ").append(u.getHost()).append('\n')

              .append("URL            : ").append(u).append('\n');

        }

        @Override

        protected void appendConnectionHeader(boolean remote) {

            sb.append("Connection Type: ").append(remote ? "remote" : "local").append('\n');

        }

        @Override

        protected void appendConfigPropsHeader() {

            sb.append("Properties     :\n");

        }

        @Override

        protected void addConfigProp(Map.Entry<?, ?> prop) {

            sb.append("  ").append(prop.getKey()).append(" = ")

              .append(prop.getValue());

            Object defVal = DEFAULT_PROPS.get(prop.getKey());

            if (defVal != null && defVal.equals(prop.getValue())) {

                sb.append(" [default]");

            }

            sb.append("\n");

        }

        @Override

        protected void appendConnectionsFooter() {}

        @Override

        protected void appendConnectionFooter(boolean remote) {

            sb.append('\n');

        }

        @Override

        protected void appendConfigPropsFooter() {}

    }

    // management properties

    private static Properties mgmtProps;

    private static ResourceBundle messageRB;

    private static final String CONFIG_FILE =

            "com.sun.management.config.file";

    private static final String JMXREMOTE =

            "com.sun.management.jmxremote";

    private static final String JMXREMOTE_PORT =

            "com.sun.management.jmxremote.port";

    private static final String RMI_PORT =

            "com.sun.management.jmxremote.rmi.port";

    private static final String ENABLE_THREAD_CONTENTION_MONITORING =

            "com.sun.management.enableThreadContentionMonitoring";

    private static final String LOCAL_CONNECTOR_ADDRESS_PROP =

            "com.sun.management.jmxremote.localConnectorAddress";

    private static final String JDP_DEFAULT_ADDRESS = "224.0.23.178";

    private static final int JDP_DEFAULT_PORT = 7095;

    // The only active agent allowed

    private static JMXConnectorServer jmxServer = null;

    // The properties used to configure the server

    private static Properties configProps = null;

    // Parse string com.sun.management.prop=xxx,com.sun.management.prop=yyyy

    // and return property set if args is null or empty

    // return empty property set

    private static Properties parseString(String args) {

        Properties argProps = new Properties();

        if (args != null && !args.trim().isEmpty()) {

            for (String option : args.split(",")) {

                String s[] = option.split("=", 2);

                String name = s[0].trim();

                String value = (s.length > 1) ? s[1].trim() : "";

                if (!name.startsWith("com.sun.management.")) {

                    error(INVALID_OPTION, name);

                }

                argProps.setProperty(name, value);

            }

        }

        return argProps;

    }

    // invoked by -javaagent or -Dcom.sun.management.agent.class

    public static void premain(String args) throws Exception {

        agentmain(args);

    }

    // invoked by attach mechanism

    public static void agentmain(String args) throws Exception {

        if (args == null || args.length() == 0) {

            args = JMXREMOTE;           // default to local management

        }

        Properties arg_props = parseString(args);

        // Read properties from the config file

        Properties config_props = new Properties();

        String fname = arg_props.getProperty(CONFIG_FILE);

        readConfiguration(fname, config_props);

        // Arguments override config file

        config_props.putAll(arg_props);

        startAgent(config_props);

    }

    /*

     * Starts the local management agent.

     * This method is invoked by either startAgent method or

     * by the VM directly via jcmd ManagementAgent.start_local command.

     */

    private static synchronized void startLocalManagementAgent() {

        Properties agentProps = VMSupport.getAgentProperties();

        // start local connector if not started

        if (agentProps.get(LOCAL_CONNECTOR_ADDRESS_PROP) == null) {

            JMXConnectorServer cs = ConnectorBootstrap.startLocalConnectorServer();

            String address = cs.getAddress().toString();

            // Add the local connector address to the agent properties

            agentProps.put(LOCAL_CONNECTOR_ADDRESS_PROP, address);

            try {

                // export the address to the instrumentation buffer

                ConnectorAddressLink.export(address);

            } catch (Exception x) {

                // Connector server started but unable to export address

                // to instrumentation buffer - non-fatal error.

                warning(EXPORT_ADDRESS_FAILED, x.getMessage());

            }

        }

    }

    /*

     * This method is invoked by the VM to start the remote management agent

     * via jcmd ManagementAgent.start command.

     */

    private static synchronized void startRemoteManagementAgent(String args) throws Exception {

        if (jmxServer != null) {

            throw new RuntimeException(getText(INVALID_STATE, "Agent already started"));

        }

        try {

            Properties argProps = parseString(args);

            configProps = new Properties();

            // Load the management properties from the config file

            // if config file is not specified readConfiguration implicitly

            // reads <java.home>/conf/management/management.properties

            String fname = System.getProperty(CONFIG_FILE);

            readConfiguration(fname, configProps);

            // management properties can be overridden by system properties

            // which take precedence

            Properties sysProps = System.getProperties();

            synchronized (sysProps) {

                configProps.putAll(sysProps);

            }

            // if user specifies config file into command line for either

            // jcmd utilities or attach command it overrides properties set in

            // command line at the time of VM start

            String fnameUser = argProps.getProperty(CONFIG_FILE);

            if (fnameUser != null) {

                readConfiguration(fnameUser, configProps);

            }

            // arguments specified in command line of jcmd utilities

            // override both system properties and one set by config file

            // specified in jcmd command line

            configProps.putAll(argProps);

            // jcmd doesn't allow to change ThreadContentionMonitoring, but user

            // can specify this property inside config file, so enable optional

            // monitoring functionality if this property is set

            final String enableThreadContentionMonitoring =

                    configProps.getProperty(ENABLE_THREAD_CONTENTION_MONITORING);

            if (enableThreadContentionMonitoring != null) {

                ManagementFactory.getThreadMXBean().

                        setThreadContentionMonitoringEnabled(true);

            }

            String jmxremotePort = configProps.getProperty(JMXREMOTE_PORT);

            if (jmxremotePort != null) {

                jmxServer = ConnectorBootstrap.

                        startRemoteConnectorServer(jmxremotePort, configProps);

                startDiscoveryService(configProps);

            } else {

                throw new AgentConfigurationError(INVALID_JMXREMOTE_PORT, "No port specified");

            }

        } catch (JdpException e) {

            error(e);

        } catch (AgentConfigurationError err) {

            error(err);

        }

    }

    private static synchronized void stopRemoteManagementAgent() throws Exception {

        JdpController.stopDiscoveryService();

        if (jmxServer != null) {

            ConnectorBootstrap.unexportRegistry();

            ConnectorAddressLink.unexportRemote();

            // Attempt to stop already stopped agent

            // Don't cause any errors.

            jmxServer.stop();

            jmxServer = null;

            configProps = null;

        }

    }

    private static synchronized String getManagementAgentStatus() throws Exception {

        return new TextStatusCollector().collect();

    }

    private static void startAgent(Properties props) throws Exception {

        String jmxremote = props.getProperty(JMXREMOTE);

        String jmxremotePort = props.getProperty(JMXREMOTE_PORT);

        // Enable optional monitoring functionality if requested

        final String enableThreadContentionMonitoring =

                props.getProperty(ENABLE_THREAD_CONTENTION_MONITORING);

        if (enableThreadContentionMonitoring != null) {

            ManagementFactory.getThreadMXBean().

                    setThreadContentionMonitoringEnabled(true);

        }

        try {

            /*

             * If the jmxremote.port property is set then we start the

             * RMIConnectorServer for remote M&M.

             *

             * If the jmxremote or jmxremote.port properties are set then

             * we start a RMIConnectorServer for local M&M. The address

             * of this "local" server is exported as a counter to the jstat

             * instrumentation buffer.

             */

            if (jmxremote != null || jmxremotePort != null) {

                if (jmxremotePort != null) {

                    jmxServer = ConnectorBootstrap.

                            startRemoteConnectorServer(jmxremotePort, props);

                    startDiscoveryService(props);

                }

                startLocalManagementAgent();

            }

        } catch (AgentConfigurationError e) {

            error(e);

        } catch (Exception e) {

            error(e);

        }

    }

    private static void startDiscoveryService(Properties props)

            throws IOException, JdpException {

        // Start discovery service if requested

        String discoveryPort = props.getProperty("com.sun.management.jdp.port");

        String discoveryAddress = props.getProperty("com.sun.management.jdp.address");

        String discoveryShouldStart = props.getProperty("com.sun.management.jmxremote.autodiscovery");

        // Decide whether we should start autodicovery service.

        // To start autodiscovery following conditions should be met:

        // autodiscovery==true OR (autodicovery==null AND jdp.port != NULL)

        boolean shouldStart = false;

        if (discoveryShouldStart == null){

            shouldStart = (discoveryPort != null);

        }

        else{

            try{

               shouldStart = Boolean.parseBoolean(discoveryShouldStart);

            } catch (NumberFormatException e) {

                throw new AgentConfigurationError(AGENT_EXCEPTION, "Couldn't parse autodiscovery argument");

            }

        }

        if (shouldStart) {

            // port and address are required arguments and have no default values

            InetAddress address;

            try {

                address = (discoveryAddress == null) ?

                        InetAddress.getByName(JDP_DEFAULT_ADDRESS) : InetAddress.getByName(discoveryAddress);

            } catch (UnknownHostException e) {

                throw new AgentConfigurationError(AGENT_EXCEPTION, e, "Unable to broadcast to requested address");

            }