/*
 * Copyright (c) 1996, 2002, 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
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 */
package sun.rmi.transport.proxy;

import java.io.*;
import java.net.*;
import java.security.*;
import java.util.*;
import java.rmi.server.LogStream;
import java.rmi.server.RMISocketFactory;
import sun.rmi.runtime.Log;
import sun.rmi.runtime.NewThreadAction;
import sun.security.action.GetBooleanAction;
import sun.security.action.GetLongAction;

RMIMasterSocketFactory attempts to create a socket connection to the
specified host using successively less efficient mechanisms
until one succeeds.  If the host is successfully connected to,
the factory for the successful mechanism is stored in an internal
hash table keyed by the host name, so that future attempts to
connect to the same host will automatically use the same
mechanism.
/**
 * RMIMasterSocketFactory attempts to create a socket connection to the
 * specified host using successively less efficient mechanisms
 * until one succeeds.  If the host is successfully connected to,
 * the factory for the successful mechanism is stored in an internal
 * hash table keyed by the host name, so that future attempts to
 * connect to the same host will automatically use the same
 * mechanism.
 */
public class RMIMasterSocketFactory extends RMISocketFactory {

    
"proxy" package log level /** "proxy" package log level */
    static int logLevel = LogStream.parseLevel(getLogLevel());

    private static String getLogLevel() {
        return java.security.AccessController.doPrivileged(
            new sun.security.action.GetPropertyAction("sun.rmi.transport.proxy.logLevel"));
    }

    /* proxy package log */
    static final Log proxyLog =
        Log.getLog("sun.rmi.transport.tcp.proxy",
                   "transport", RMIMasterSocketFactory.logLevel);

    
timeout for attemping direct socket connections /** timeout for attemping direct socket connections */
    private static long connectTimeout = getConnectTimeout();

    private static long getConnectTimeout() {
        return java.security.AccessController.doPrivileged(
                new GetLongAction("sun.rmi.transport.proxy.connectTimeout",
                              15000)).longValue(); // default: 15 seconds
    }

    
whether to fallback to HTTP on general connect failures /** whether to fallback to HTTP on general connect failures */
    private static final boolean eagerHttpFallback =
        java.security.AccessController.doPrivileged(new GetBooleanAction(
            "sun.rmi.transport.proxy.eagerHttpFallback")).booleanValue();

    
table of hosts successfully connected to and the factory used /** table of hosts successfully connected to and the factory used */
    private Hashtable successTable = new Hashtable();

    
maximum number of hosts to remember successful connection to /** maximum number of hosts to remember successful connection to */
    private static final int MaxRememberedHosts = 64;

    
list of the hosts in successTable in initial connection order /** list of the hosts in successTable in initial connection order */
    private Vector hostList = new Vector(MaxRememberedHosts);

    
default factory to initally use for direct socket connection /** default factory to initally use for direct socket connection */
    protected RMISocketFactory initialFactory = new RMIDirectSocketFactory();

    
ordered list of factories to try as alternate connection
mechanisms if a direct socket connections fails /** ordered list of factories to try as alternate connection
      * mechanisms if a direct socket connections fails */
    protected Vector altFactoryList;

    
Create a RMIMasterSocketFactory object.  Establish order of
connection mechanisms to attempt on createSocket, if a direct
socket connection fails.
/**
     * Create a RMIMasterSocketFactory object.  Establish order of
     * connection mechanisms to attempt on createSocket, if a direct
     * socket connection fails.
     */
    public RMIMasterSocketFactory() {
        altFactoryList = new Vector(2);
        boolean setFactories = false;

        try {
            String proxyHost;
            proxyHost = java.security.AccessController.doPrivileged(
                new sun.security.action.GetPropertyAction("http.proxyHost"));

            if (proxyHost == null)
                proxyHost = java.security.AccessController.doPrivileged(
                    new sun.security.action.GetPropertyAction("proxyHost"));

            Boolean tmp = java.security.AccessController.doPrivileged(
                new sun.security.action.GetBooleanAction("java.rmi.server.disableHttp"));

            if (!tmp.booleanValue() &&
                (proxyHost != null && proxyHost.length() > 0)) {
                setFactories = true;
            }
        } catch (Exception e) {
            // unable to obtain the properties, so assume default behavior.
            setFactories = true;
        }

        if (setFactories) {
            altFactoryList.addElement(new RMIHttpToPortSocketFactory());
            altFactoryList.addElement(new RMIHttpToCGISocketFactory());
        }
    }

    
Create a new client socket.  If we remember connecting to this host
successfully before, then use the same factory again.  Otherwise,
try using a direct socket connection and then the alternate factories
in the order specified in altFactoryList.
/**
     * Create a new client socket.  If we remember connecting to this host
     * successfully before, then use the same factory again.  Otherwise,
     * try using a direct socket connection and then the alternate factories
     * in the order specified in altFactoryList.
     */
    public Socket createSocket(String host, int port)
        throws IOException
    {
        if (proxyLog.isLoggable(Log.BRIEF)) {
            proxyLog.log(Log.BRIEF, "host: " + host + ", port: " + port);
        }

        /*
         * If we don't have any alternate factories to consult, short circuit
         * the fallback procedure and delegate to the initial factory.
         */
        if (altFactoryList.size() == 0) {
            return initialFactory.createSocket(host, port);
        }

        RMISocketFactory factory;

        /*
         * If we remember successfully connecting to this host before,
         * use the same factory.
         */
        factory = (RMISocketFactory) successTable.get(host);
        if (factory != null) {
            if (proxyLog.isLoggable(Log.BRIEF)) {
                proxyLog.log(Log.BRIEF,
                    "previously successful factory found: " + factory);
            }
            return factory.createSocket(host, port);
        }

        /*
         * Next, try a direct socket connection.  Open socket in another
         * thread and only wait for specified timeout, in case the socket
         * would otherwise spend minutes trying an unreachable host.
         */
        Socket initialSocket = null;
        Socket fallbackSocket = null;
        final AsyncConnector connector =
            new AsyncConnector(initialFactory, host, port,
                AccessController.getContext());
                // connection must be attempted with
                // this thread's access control context
        IOException initialFailure = null;

        try {
            synchronized (connector) {

                Thread t = java.security.AccessController.doPrivileged(
                    new NewThreadAction(connector, "AsyncConnector", true));
                t.start();

                try {
                    long now = System.currentTimeMillis();
                    long deadline = now + connectTimeout;
                    do {
                        connector.wait(deadline - now);
                        initialSocket = checkConnector(connector);
                        if (initialSocket != null)
                            break;
                        now = System.currentTimeMillis();
                    } while (now < deadline);
                } catch (InterruptedException e) {
                    throw new InterruptedIOException(
                        "interrupted while waiting for connector");
                }
            }

            // assume no route to host (for now) if no connection yet
            if (initialSocket == null)
                throw new NoRouteToHostException(
                    "connect timed out: " + host);

            proxyLog.log(Log.BRIEF, "direct socket connection successful");

            return initialSocket;

        } catch (UnknownHostException e) {
            initialFailure = e;
        } catch (NoRouteToHostException e) {
            initialFailure = e;
        } catch (SocketException e) {
            if (eagerHttpFallback) {
                initialFailure = e;
            } else {
                throw e;
            }
        } finally {
            if (initialFailure != null) {

                if (proxyLog.isLoggable(Log.BRIEF)) {
                    proxyLog.log(Log.BRIEF,
                        "direct socket connection failed: ", initialFailure);
                }

                // Finally, try any alternate connection mechanisms.
                for (int i = 0; i < altFactoryList.size(); ++ i) {
                    factory = (RMISocketFactory) altFactoryList.elementAt(i);
                    try {
                        if (proxyLog.isLoggable(Log.BRIEF)) {
                            proxyLog.log(Log.BRIEF,
                                "trying with factory: " + factory);
                        }

                        // For HTTP connections, the output (POST request) must
                        // be sent before we verify a successful connection.
                        // So, sacrifice a socket for the sake of testing...
                        // The following sequence should verify a successful
                        // HTTP connection if no IOException is thrown.
                        Socket testSocket = factory.createSocket(host, port);
                        InputStream in = testSocket.getInputStream();
                        int b = in.read(); // probably -1 for EOF...
                        testSocket.close();
                    } catch (IOException ex) {
                        if (proxyLog.isLoggable(Log.BRIEF)) {
                            proxyLog.log(Log.BRIEF, "factory failed: ", ex);
                        }

                        continue;
                    }
                    proxyLog.log(Log.BRIEF, "factory succeeded");

                    // factory succeeded, open new socket for caller's use
                    try {
                        fallbackSocket = factory.createSocket(host, port);
                    } catch (IOException ex) {  // if it fails 2nd time,
                    }                           // just give up
                    break;
                }
            }
        }

        synchronized (successTable) {
            try {
                // check once again to see if direct connection succeeded
                synchronized (connector) {
                    initialSocket = checkConnector(connector);
                }
                if (initialSocket != null) {
                    // if we had made another one as well, clean it up...
                    if (fallbackSocket != null)
                        fallbackSocket.close();
                    return initialSocket;
                }
                // if connector ever does get socket, it won't be used
                connector.notUsed();
            } catch (UnknownHostException e) {
                initialFailure = e;
            } catch (NoRouteToHostException e) {
                initialFailure = e;
            } catch (SocketException e) {
                if (eagerHttpFallback) {
                    initialFailure = e;
                } else {
                    throw e;
                }
            }
            // if we had found an alternate mechanism, go and use it
            if (fallbackSocket != null) {
                // remember this successful host/factory pair
                rememberFactory(host, factory);
                return fallbackSocket;
            }
            throw initialFailure;
        }
    }

    
Remember a successful factory for connecting to host.
Currently, excess hosts are removed from the remembered list
using a Least Recently Created strategy.
/**
     * Remember a successful factory for connecting to host.
     * Currently, excess hosts are removed from the remembered list
     * using a Least Recently Created strategy.
     */
    void rememberFactory(String host, RMISocketFactory factory) {
        synchronized (successTable) {
            while (hostList.size() >= MaxRememberedHosts) {
                successTable.remove(hostList.elementAt(0));
                hostList.removeElementAt(0);
            }
            hostList.addElement(host);
            successTable.put(host, factory);
        }
    }

    
Check if an AsyncConnector succeeded.  If not, return socket
given to fall back to.
/**
     * Check if an AsyncConnector succeeded.  If not, return socket
     * given to fall back to.
     */
    Socket checkConnector(AsyncConnector connector)
        throws IOException
    {
        Exception e = connector.getException();
        if (e != null) {
            e.fillInStackTrace();
            /*
             * The AsyncConnector implementation guaranteed that the exception
             * will be either an IOException or a RuntimeException, and we can
             * only throw one of those, so convince that compiler that it must
             * be one of those.
             */
            if (e instanceof IOException) {
                throw (IOException) e;
            } else if (e instanceof RuntimeException) {
                throw (RuntimeException) e;
            } else {
                throw new Error("internal error: " +
                    "unexpected checked exception: " + e.toString());
            }
        }
        return connector.getSocket();
    }

    
Create a new server socket.
/**
     * Create a new server socket.
     */
    public ServerSocket createServerSocket(int port) throws IOException {
        //return new HttpAwareServerSocket(port);
        return initialFactory.createServerSocket(port);
    }


    
AsyncConnector is used by RMIMasterSocketFactory to attempt socket
connections on a separate thread.  This allows RMIMasterSocketFactory
to control how long it will wait for the connection to succeed.
/**
     * AsyncConnector is used by RMIMasterSocketFactory to attempt socket
     * connections on a separate thread.  This allows RMIMasterSocketFactory
     * to control how long it will wait for the connection to succeed.
     */
    private class AsyncConnector implements Runnable {

        
what factory to use to attempt connection /** what factory to use to attempt connection */
        private RMISocketFactory factory;

        
the host to connect to /** the host to connect to */
        private String host;

        
the port to connect to /** the port to connect to */
        private int port;

        
access control context to attempt connection within /** access control context to attempt connection within */
        private AccessControlContext acc;

        
exception that occurred during connection, if any /** exception that occurred during connection, if any */
        private Exception exception = null;

        
the connected socket, if successful /** the connected socket, if successful */
        private Socket socket = null;

        
socket should be closed after created, if ever /** socket should be closed after created, if ever */
        private boolean cleanUp = false;

        
Create a new asynchronous connector object.
/**
         * Create a new asynchronous connector object.
         */
        AsyncConnector(RMISocketFactory factory, String host, int port,
                       AccessControlContext acc)
        {
            this.factory = factory;
            this.host    = host;
            this.port    = port;
            this.acc     = acc;
            SecurityManager security = System.getSecurityManager();
            if (security != null) {
                security.checkConnect(host, port);
            }
        }

        
Attempt socket connection in separate thread.  If successful,
notify master waiting,
/**
         * Attempt socket connection in separate thread.  If successful,
         * notify master waiting,
         */
        public void run() {
            try {
                /*
                 * Using the privileges of the thread that wants to make the
                 * connection is tempting, but it will fail with applets with
                 * the current applet security manager because the applet
                 * network connection policy is not captured in the permission
                 * framework of the access control context we have.
                 *
                 * java.security.AccessController.beginPrivileged(acc);
                 */
                try {
                    Socket temp = factory.createSocket(host, port);
                    synchronized (this) {
                        socket = temp;
                        notify();
                    }
                    rememberFactory(host, factory);
                    synchronized (this) {
                        if (cleanUp)
                          try {
                              socket.close();
                          } catch (IOException e) {
                          }
                    }
                } catch (Exception e) {
                    /*
                     * Note that the only exceptions which could actually have
                     * occurred here are IOException or RuntimeException.
                     */
                    synchronized (this) {
                        exception = e;
                        notify();
                    }
                }
            } finally {
                /*
                 * See above comments for matching beginPrivileged() call that
                 * is also commented out.
                 *
                 * java.security.AccessController.endPrivileged();
                 */
            }
        }

        
Get exception that occurred during connection attempt, if any.
In the current implementation, this is guaranteed to be either
an IOException or a RuntimeException.
/**
         * Get exception that occurred during connection attempt, if any.
         * In the current implementation, this is guaranteed to be either
         * an IOException or a RuntimeException.
         */
        private synchronized Exception getException() {
            return exception;
        }

        
Get successful socket, if any.
/**
         * Get successful socket, if any.
         */
        private synchronized Socket getSocket() {
            return socket;
        }

        
Note that this connector's socket, if ever successfully created,
will not be used, so it should be cleaned up quickly
/**
         * Note that this connector's socket, if ever successfully created,
         * will not be used, so it should be cleaned up quickly
         */
        synchronized void notUsed() {
            if (socket != null) {
                try {
                    socket.close();
                } catch (IOException e) {
                }
            }
            cleanUp = true;
        }
    }
}