//
//  ========================================================================
//  Copyright (c) 1995-2019 Mort Bay Consulting Pty. Ltd.
//  ------------------------------------------------------------------------
//  All rights reserved. This program and the accompanying materials
//  are made available under the terms of the Eclipse Public License v1.0
//  and Apache License v2.0 which accompanies this distribution.
//
//      The Eclipse Public License is available at
//      http://www.eclipse.org/legal/epl-v10.html
//
//      The Apache License v2.0 is available at
//      http://www.opensource.org/licenses/apache2.0.php
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//  You may elect to redistribute this code under either of these licenses.
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package org.eclipse.jetty.jmx;

import java.io.IOException;
import java.lang.management.ManagementFactory;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.UnknownHostException;
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
import java.rmi.server.RMIClientSocketFactory;
import java.rmi.server.RMIServerSocketFactory;
import java.rmi.server.UnicastRemoteObject;
import java.util.HashMap;
import java.util.Map;
import java.util.Objects;
import java.util.function.IntConsumer;
import javax.management.MBeanServer;
import javax.management.ObjectName;
import javax.management.remote.JMXConnectorServer;
import javax.management.remote.JMXConnectorServerFactory;
import javax.management.remote.JMXServiceURL;
import javax.management.remote.rmi.RMIConnectorServer;
import javax.rmi.ssl.SslRMIClientSocketFactory;

import org.eclipse.jetty.util.HostPort;
import org.eclipse.jetty.util.component.AbstractLifeCycle;
import org.eclipse.jetty.util.log.Log;
import org.eclipse.jetty.util.log.Logger;
import org.eclipse.jetty.util.ssl.SslContextFactory;
import org.eclipse.jetty.util.thread.ShutdownThread;

LifeCycle wrapper for JMXConnectorServer.
This class provides the following facilities:

participates in the Server lifecycle
starts the RMI registry if not there already
allows to bind the RMI registry and the RMI server to the loopback interface
makes it easy to use TLS for the JMX communication

/**
 * <p>LifeCycle wrapper for JMXConnectorServer.</p>
 * <p>This class provides the following facilities:</p>
 * <ul>
 * <li>participates in the {@code Server} lifecycle</li>
 * <li>starts the RMI registry if not there already</li>
 * <li>allows to bind the RMI registry and the RMI server to the loopback interface</li>
 * <li>makes it easy to use TLS for the JMX communication</li>
 * </ul>
 */
public class ConnectorServer extends AbstractLifeCycle
{
    public static final String RMI_REGISTRY_CLIENT_SOCKET_FACTORY_ATTRIBUTE = "com.sun.jndi.rmi.factory.socket";
    private static final Logger LOG = Log.getLogger(ConnectorServer.class);

    private JMXServiceURL _jmxURL;
    private final Map<String, Object> _environment;
    private final String _objectName;
    private final SslContextFactory _sslContextFactory;
    private int _registryPort;
    private int _rmiPort;
    private JMXConnectorServer _connectorServer;
    private Registry _registry;

    
Constructs a ConnectorServer
Params:
serviceURL – the address of the new ConnectorServer
name – object name string to be assigned to ConnectorServer bean/**
     * Constructs a ConnectorServer
     *
     * @param serviceURL the address of the new ConnectorServer
     * @param name object name string to be assigned to ConnectorServer bean
     */
    public ConnectorServer(JMXServiceURL serviceURL, String name)
    {
        this(serviceURL, null, name);
    }

    
Constructs a ConnectorServer
Params:
svcUrl – the address of the new ConnectorServer
environment – a set of attributes to control the new ConnectorServer's behavior.
This parameter can be null. Keys in this map must
be Strings. The appropriate type of each associated value depends on
the attribute. The contents of environment are not changed by this call.
name – object name string to be assigned to ConnectorServer bean/**
     * Constructs a ConnectorServer
     *
     * @param svcUrl the address of the new ConnectorServer
     * @param environment a set of attributes to control the new ConnectorServer's behavior.
     * This parameter can be null. Keys in this map must
     * be Strings. The appropriate type of each associated value depends on
     * the attribute. The contents of environment are not changed by this call.
     * @param name object name string to be assigned to ConnectorServer bean
     */
    public ConnectorServer(JMXServiceURL svcUrl, Map<String, ?> environment, String name)
    {
        this(svcUrl, environment, name, null);
    }

    public ConnectorServer(JMXServiceURL svcUrl, Map<String, ?> environment, String name, SslContextFactory sslContextFactory)
    {
        this._jmxURL = svcUrl;
        this._environment = environment == null ? new HashMap<>() : new HashMap<>(environment);
        this._objectName = name;
        this._sslContextFactory = sslContextFactory;
    }

    public JMXServiceURL getAddress()
    {
        return _jmxURL;
    }

    @Override
    public void doStart() throws Exception
    {
        boolean rmi = "rmi".equals(_jmxURL.getProtocol());
        if (rmi)
        {
            if (!_environment.containsKey(RMIConnectorServer.RMI_SERVER_SOCKET_FACTORY_ATTRIBUTE))
                _environment.put(RMIConnectorServer.RMI_SERVER_SOCKET_FACTORY_ATTRIBUTE, new JMXRMIServerSocketFactory(_jmxURL.getHost(), port -> _rmiPort = port));
            if (_sslContextFactory != null)
            {
                SslRMIClientSocketFactory csf = new SslRMIClientSocketFactory();
                if (!_environment.containsKey(RMIConnectorServer.RMI_CLIENT_SOCKET_FACTORY_ATTRIBUTE))
                    _environment.put(RMIConnectorServer.RMI_CLIENT_SOCKET_FACTORY_ATTRIBUTE, csf);
                if (!_environment.containsKey(RMI_REGISTRY_CLIENT_SOCKET_FACTORY_ATTRIBUTE))
                    _environment.put(RMI_REGISTRY_CLIENT_SOCKET_FACTORY_ATTRIBUTE, csf);
            }
        }

        String urlPath = _jmxURL.getURLPath();
        String jndiRMI = "/jndi/rmi://";
        if (urlPath.startsWith(jndiRMI))
        {
            int startIndex = jndiRMI.length();
            int endIndex = urlPath.indexOf('/', startIndex);
            HostPort hostPort = new HostPort(urlPath.substring(startIndex, endIndex));
            String registryHost = startRegistry(hostPort);
            // If the RMI registry was already started, use the existing port.
            if (_registryPort == 0)
                _registryPort = hostPort.getPort();
            urlPath = jndiRMI + registryHost + ":" + _registryPort + urlPath.substring(endIndex);
            // Rebuild JMXServiceURL to use it for the creation of the JMXConnectorServer.
            _jmxURL = new JMXServiceURL(_jmxURL.getProtocol(), _jmxURL.getHost(), _jmxURL.getPort(), urlPath);
        }

        MBeanServer mbeanServer = ManagementFactory.getPlatformMBeanServer();
        _connectorServer = JMXConnectorServerFactory.newJMXConnectorServer(_jmxURL, _environment, mbeanServer);
        mbeanServer.registerMBean(_connectorServer, new ObjectName(_objectName));
        _connectorServer.start();
        String rmiHost = normalizeHost(_jmxURL.getHost());
        // If _rmiPort is still zero, it's using the same port as the RMI registry.
        if (_rmiPort == 0)
            _rmiPort = _registryPort;
        _jmxURL = new JMXServiceURL(_jmxURL.getProtocol(), rmiHost, _rmiPort, urlPath);

        ShutdownThread.register(0, this);

        LOG.info("JMX URL: {}", _jmxURL);
    }

    @Override
    public void doStop() throws Exception
    {
        ShutdownThread.deregister(this);
        _connectorServer.stop();
        MBeanServer mbeanServer = ManagementFactory.getPlatformMBeanServer();
        mbeanServer.unregisterMBean(new ObjectName(_objectName));
        stopRegistry();
    }

    private String startRegistry(HostPort hostPort) throws Exception
    {
        String host = hostPort.getHost();
        int port = hostPort.getPort(1099);

        try
        {
            // Check if a local registry is already running.
            LocateRegistry.getRegistry(host, port).list();
            return normalizeHost(host);
        }
        catch (Throwable ex)
        {
            LOG.ignore(ex);
        }

        RMIClientSocketFactory csf = _sslContextFactory == null ? null : new SslRMIClientSocketFactory();
        RMIServerSocketFactory ssf = new JMXRMIServerSocketFactory(host, p -> _registryPort = p);
        _registry = LocateRegistry.createRegistry(port, csf, ssf);

        return normalizeHost(host);
    }

    private String normalizeHost(String host) throws UnknownHostException
    {
        return host == null || host.isEmpty() ? InetAddress.getLocalHost().getHostName() : host;
    }

    private void stopRegistry()
    {
        if (_registry != null)
        {
            try
            {
                UnicastRemoteObject.unexportObject(_registry, true);
            }
            catch (Exception ex)
            {
                LOG.ignore(ex);
            }
            finally
            {
                _registry = null;
            }
        }
    }

    private class JMXRMIServerSocketFactory implements RMIServerSocketFactory
    {
        private final String _host;
        private final IntConsumer _portConsumer;

        private JMXRMIServerSocketFactory(String host, IntConsumer portConsumer)
        {
            this._host = host;
            this._portConsumer = portConsumer;
        }

        @Override
        public ServerSocket createServerSocket(int port) throws IOException
        {
            InetAddress address = _host == null || _host.isEmpty() ? InetAddress.getLocalHost() : InetAddress.getByName(_host);
            ServerSocket server = createServerSocket(address, port);
            _portConsumer.accept(server.getLocalPort());
            return server;
        }

        private ServerSocket createServerSocket(InetAddress address, int port) throws IOException
        {
            // A null address binds to the wildcard address.
            if (_sslContextFactory == null)
            {
                ServerSocket server = new ServerSocket();
                server.bind(new InetSocketAddress(address, port));
                return server;
            }
            else
            {
                return _sslContextFactory.newSslServerSocket(address == null ? null : address.getHostName(), port, 0);
            }
        }

        @Override
        public int hashCode()
        {
            return _host != null ? _host.hashCode() : 0;
        }

        @Override
        public boolean equals(Object obj)
        {
            if (this == obj)
                return true;
            if (obj == null || getClass() != obj.getClass())
                return false;
            JMXRMIServerSocketFactory that = (JMXRMIServerSocketFactory)obj;
            return Objects.equals(_host, that._host);
        }
    }
}