/*

 * Copyright (c) 1996, 2013, 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

 * questions.

 */

package sun.rmi.server;

import java.io.ByteArrayOutputStream;

import java.io.IOException;

import java.io.DataOutputStream;

import java.lang.reflect.Constructor;

import java.lang.reflect.InvocationHandler;

import java.lang.reflect.InvocationTargetException;

import java.lang.reflect.Proxy;

import java.lang.reflect.Method;

import java.rmi.Remote;

import java.rmi.RemoteException;

import java.rmi.StubNotFoundException;

import java.rmi.registry.Registry;

import java.rmi.server.LogStream;

import java.rmi.server.ObjID;

import java.rmi.server.RMIClientSocketFactory;

import java.rmi.server.RemoteObjectInvocationHandler;

import java.rmi.server.RemoteRef;

import java.rmi.server.RemoteStub;

import java.rmi.server.Skeleton;

import java.rmi.server.SkeletonNotFoundException;

import java.security.AccessController;

import java.security.MessageDigest;

import java.security.DigestOutputStream;

import java.security.NoSuchAlgorithmException;

import java.security.PrivilegedAction;

import java.util.ArrayList;

import java.util.Collections;

import java.util.Map;

import java.util.WeakHashMap;

import sun.rmi.registry.RegistryImpl;

import sun.rmi.runtime.Log;

import sun.rmi.transport.LiveRef;

import sun.rmi.transport.tcp.TCPEndpoint;

/**

 * A utility class with static methods for creating stubs/proxies and

 * skeletons for remote objects.

 */

@SuppressWarnings("deprecation")

public final class Util {

    /** "server" package log level */

    static final int logLevel = LogStream.parseLevel(

        AccessController.doPrivileged(

    /** server reference log */

    public static final Log serverRefLog =

        Log.getLog("sun.rmi.server.ref", "transport", Util.logLevel);

    /** cached value of property java.rmi.server.ignoreStubClasses */

    private static final boolean ignoreStubClasses =

        AccessController.doPrivileged(

    /** cache of  impl classes that have no corresponding stub class */

    private static final Map<Class<?>, Void> withoutStubs =

        Collections.synchronizedMap(new WeakHashMap<Class<?>, Void>(11));

    /** parameter types for stub constructor */

    private static final Class<?>[] stubConsParamTypes = { RemoteRef.class };

    private Util() {

    }

    /**

     * Returns a proxy for the specified implClass.

     *

     * If both of the following criteria is satisfied, a dynamic proxy for

     * the specified implClass is returned (otherwise a RemoteStub instance

     * for the specified implClass is returned):

     *

     *    a) either the property java.rmi.server.ignoreStubClasses is true or

     *       a pregenerated stub class does not exist for the impl class, and

     *    b) forceStubUse is false.

     *

     * If the above criteria are satisfied, this method constructs a

     * dynamic proxy instance (that implements the remote interfaces of

     * implClass) constructed with a RemoteObjectInvocationHandler instance

     * constructed with the clientRef.

     *

     * Otherwise, this method loads the pregenerated stub class (which

     * extends RemoteStub and implements the remote interfaces of

     * implClass) and constructs an instance of the pregenerated stub

     * class with the clientRef.

     *

     * @param implClass the class to obtain remote interfaces from

     * @param clientRef the remote ref to use in the invocation handler

     * @param forceStubUse if true, forces creation of a RemoteStub

     * @throws IllegalArgumentException if implClass implements illegal

     * remote interfaces

     * @throws StubNotFoundException if problem locating/creating stub or

     * creating the dynamic proxy instance

     **/

    public static Remote createProxy(Class<?> implClass,

                                     RemoteRef clientRef,

                                     boolean forceStubUse)

        throws StubNotFoundException

    {

        Class<?> remoteClass;

        try {

            remoteClass = getRemoteClass(implClass);

        } catch (ClassNotFoundException ex ) {

            throw new StubNotFoundException(

                "object does not implement a remote interface: " +

                implClass.getName());

        }

        if (forceStubUse ||

            !(ignoreStubClasses || !stubClassExists(remoteClass)))

        {

            return createStub(remoteClass, clientRef);

        }

        final ClassLoader loader = implClass.getClassLoader();

        final Class<?>[] interfaces = getRemoteInterfaces(implClass);

        final InvocationHandler handler =

            new RemoteObjectInvocationHandler(clientRef);

        /* REMIND: private remote interfaces? */

        try {

            return AccessController.doPrivileged(new PrivilegedAction<Remote>() {

                public Remote run() {

                    return (Remote) Proxy.newProxyInstance(loader,

                                                           interfaces,

                                                           handler);

                }});

        } catch (IllegalArgumentException e) {

            throw new StubNotFoundException("unable to create proxy", e);

        }

    }

    /**

     * Returns true if a stub class for the given impl class can be loaded,

     * otherwise returns false.

     *

     * @param remoteClass the class to obtain remote interfaces from

     */

    private static boolean stubClassExists(Class<?> remoteClass) {

        if (!withoutStubs.containsKey(remoteClass)) {

            try {

                Class.forName(remoteClass.getName() + "_Stub",

                              false,

                              remoteClass.getClassLoader());

                return true;

            } catch (ClassNotFoundException cnfe) {

                withoutStubs.put(remoteClass, null);

            }

        }

        return false;

    }

    /*

     * Returns the class/superclass that implements the remote interface.

     * @throws ClassNotFoundException if no class is found to have a

     * remote interface

     */

    private static Class<?> getRemoteClass(Class<?> cl)

        throws ClassNotFoundException

    {

        while (cl != null) {

            Class<?>[] interfaces = cl.getInterfaces();

            for (int i = interfaces.length -1; i >= 0; i--) {

                if (Remote.class.isAssignableFrom(interfaces[i]))

                    return cl;          // this class implements remote object

            }

            cl = cl.getSuperclass();

        }

        throw new ClassNotFoundException(

                "class does not implement java.rmi.Remote");

    }

    /**

     * Returns an array containing the remote interfaces implemented

     * by the given class.

     *

     * @param   remoteClass the class to obtain remote interfaces from

     * @throws  IllegalArgumentException if remoteClass implements

     *          any illegal remote interfaces

     * @throws  NullPointerException if remoteClass is null

     */

    private static Class<?>[] getRemoteInterfaces(Class<?> remoteClass) {

        ArrayList<Class<?>> list = new ArrayList<>();

        getRemoteInterfaces(list, remoteClass);

        return list.toArray(new Class<?>[list.size()]);

    }

    /**

     * Fills the given array list with the remote interfaces implemented

     * by the given class.

     *

     * @throws  IllegalArgumentException if the specified class implements

     *          any illegal remote interfaces

     * @throws  NullPointerException if the specified class or list is null

     */

    private static void getRemoteInterfaces(ArrayList<Class<?>> list, Class<?> cl) {

        Class<?> superclass = cl.getSuperclass();

        if (superclass != null) {

            getRemoteInterfaces(list, superclass);

        }

        Class<?>[] interfaces = cl.getInterfaces();

        for (int i = 0; i < interfaces.length; i++) {

            Class<?> intf = interfaces[i];

            /*

             * If it is a remote interface (if it extends from

             * java.rmi.Remote) and is not already in the list,

             * then add the interface to the list.

             */

            if (Remote.class.isAssignableFrom(intf)) {

                if (!(list.contains(intf))) {

                    Method[] methods = intf.getMethods();

                    for (int j = 0; j < methods.length; j++) {

                        checkMethod(methods[j]);

                    }

                    list.add(intf);

                }

            }

        }

    }

    /**

     * Verifies that the supplied method has at least one declared exception

     * type that is RemoteException or one of its superclasses.  If not,

     * then this method throws IllegalArgumentException.

     *

     * @throws IllegalArgumentException if m is an illegal remote method

     */

    private static void checkMethod(Method m) {

        Class<?>[] ex = m.getExceptionTypes();

        for (int i = 0; i < ex.length; i++) {

            if (ex[i].isAssignableFrom(RemoteException.class))

                return;

        }

        throw new IllegalArgumentException(

            "illegal remote method encountered: " + m);

    }

    /**

     * Creates a RemoteStub instance for the specified class, constructed

     * with the specified RemoteRef.  The supplied class must be the most

     * derived class in the remote object's superclass chain that

     * implements a remote interface.  The stub class name is the name of

     * the specified remoteClass with the suffix "_Stub".  The loading of

     * the stub class is initiated from class loader of the specified class

     * (which may be the bootstrap class loader).

     **/

    private static RemoteStub createStub(Class<?> remoteClass, RemoteRef ref)

        throws StubNotFoundException

    {

        String stubname = remoteClass.getName() + "_Stub";

        /* Make sure to use the local stub loader for the stub classes.

         * When loaded by the local loader the load path can be

         * propagated to remote clients, by the MarshalOutputStream/InStream

         * pickle methods

         */

        try {

            Class<?> stubcl =

                Class.forName(stubname, false, remoteClass.getClassLoader());

            Constructor<?> cons = stubcl.getConstructor(stubConsParamTypes);

            return (RemoteStub) cons.newInstance(new Object[] { ref });

        } catch (ClassNotFoundException e) {

            throw new StubNotFoundException(

                "Stub class not found: " + stubname, e);

        } catch (NoSuchMethodException e) {

            throw new StubNotFoundException(

                "Stub class missing constructor: " + stubname, e);

        } catch (InstantiationException e) {

            throw new StubNotFoundException(

                "Can't create instance of stub class: " + stubname, e);

        } catch (IllegalAccessException e) {

            throw new StubNotFoundException(

                "Stub class constructor not public: " + stubname, e);

        } catch (InvocationTargetException e) {

            throw new StubNotFoundException(

                "Exception creating instance of stub class: " + stubname, e);

        } catch (ClassCastException e) {

            throw new StubNotFoundException(

                "Stub class not instance of RemoteStub: " + stubname, e);

        }

    }

    /**

     * Locate and return the Skeleton for the specified remote object

     */

    static Skeleton createSkeleton(Remote object)

        throws SkeletonNotFoundException

    {

        Class<?> cl;

        try {

            cl = getRemoteClass(object.getClass());

        } catch (ClassNotFoundException ex ) {

            throw new SkeletonNotFoundException(

                "object does not implement a remote interface: " +

                object.getClass().getName());

        }

        // now try to load the skeleton based ont he name of the class

        String skelname = cl.getName() + "_Skel";

        try {

            Class<?> skelcl = Class.forName(skelname, false, cl.getClassLoader());

            return (Skeleton)skelcl.newInstance();

        } catch (ClassNotFoundException ex) {

            throw new SkeletonNotFoundException("Skeleton class not found: " +

                                                skelname, ex);

        } catch (InstantiationException ex) {

            throw new SkeletonNotFoundException("Can't create skeleton: " +

                                                skelname, ex);

        } catch (IllegalAccessException ex) {

            throw new SkeletonNotFoundException("No public constructor: " +

                                                skelname, ex);

        } catch (ClassCastException ex) {

            throw new SkeletonNotFoundException(

                "Skeleton not of correct class: " + skelname, ex);

        }

    }

    /**

     * Compute the "method hash" of a remote method.  The method hash

     * is a long containing the first 64 bits of the SHA digest from

     * the UTF encoded string of the method name and descriptor.

     */

    public static long computeMethodHash(Method m) {

        long hash = 0;

        ByteArrayOutputStream sink = new ByteArrayOutputStream(127);

        try {

            MessageDigest md = MessageDigest.getInstance("SHA");

            DataOutputStream out = new DataOutputStream(

                new DigestOutputStream(sink, md));

            String s = getMethodNameAndDescriptor(m);

            if (serverRefLog.isLoggable(Log.VERBOSE)) {

                serverRefLog.log(Log.VERBOSE,

                    "string used for method hash: \"" + s + "\"");

            }

            out.writeUTF(s);

            // use only the first 64 bits of the digest for the hash

            out.flush();

            byte hasharray[] = md.digest();

            for (int i = 0; i < Math.min(8, hasharray.length); i++) {

                hash += ((long) (hasharray[i] & 0xFF)) << (i * 8);

            }

        } catch (IOException ignore) {

            /* can't happen, but be deterministic anyway. */

            hash = -1;

        } catch (NoSuchAlgorithmException complain) {

            throw new SecurityException(complain.getMessage());

        }

        return hash;

    }

    /**

     * Return a string consisting of the given method's name followed by

     * its "method descriptor", as appropriate for use in the computation

     * of the "method hash".

     *

     * See section 4.3.3 of The Java Virtual Machine Specification for

     * the definition of a "method descriptor".

     */

    private static String getMethodNameAndDescriptor(Method m) {

        StringBuffer desc = new StringBuffer(m.getName());

        desc.append('(');

        Class<?>[] paramTypes = m.getParameterTypes();

        for (int i = 0; i < paramTypes.length; i++) {

            desc.append(getTypeDescriptor(paramTypes[i]));

        }

        desc.append(')');

        Class<?> returnType = m.getReturnType();

        if (returnType == void.class) { // optimization: handle void here

            desc.append('V');

        } else {

            desc.append(getTypeDescriptor(returnType));

        }

        return desc.toString();

    }

    /**

     * Get the descriptor of a particular type, as appropriate for either

     * a parameter or return type in a method descriptor.

     */

    private static String getTypeDescriptor(Class<?> type) {

        if (type.isPrimitive()) {

            if (type == int.class) {

                return "I";

            } else if (type == boolean.class) {

                return "Z";

            } else if (type == byte.class) {

                return "B";

            } else if (type == char.class) {

                return "C";

            } else if (type == short.class) {

                return "S";

            } else if (type == long.class) {

                return "J";

            } else if (type == float.class) {

                return "F";

            } else if (type == double.class) {

                return "D";

            } else if (type == void.class) {

                return "V";

            } else {

                throw new Error("unrecognized primitive type: " + type);

            }

        } else if (type.isArray()) {

            /*

             * According to JLS 20.3.2, the getName() method on Class does

             * return the VM type descriptor format for array classes (only);

             * using that should be quicker than the otherwise obvious code:

             *

             *     return "[" + getTypeDescriptor(type.getComponentType());

             */

            return type.getName().replace('.', '/');

        } else {

            return "L" + type.getName().replace('.', '/') + ";";

        }

    }

    /**

     * Returns the binary name of the given type without package

     * qualification.  Nested types are treated no differently from

     * top-level types, so for a nested type, the returned name will

     * still be qualified with the simple name of its enclosing

     * top-level type (and perhaps other enclosing types), the

     * separator will be '$', etc.

     **/

    public static String getUnqualifiedName(Class<?> c) {

        String binaryName = c.getName();

        return binaryName.substring(binaryName.lastIndexOf('.') + 1);

    }

}