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/*
 * 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.

/**
 * 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 
/** "server" package log level */
    static final int logLevel = LogStream.parseLevel(
        AccessController.doPrivileged(
            (PrivilegedAction<String>) () -> System.getProperty("sun.rmi.server.logLevel")));

    
server reference log 
/** 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 
/** cached value of property java.rmi.server.ignoreStubClasses */
    private static final boolean ignoreStubClasses =
        AccessController.doPrivileged(
            (PrivilegedAction<Boolean>) () -> Boolean.getBoolean("java.rmi.server.ignoreStubClasses"));

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

Params:
  • implClass – the class to obtain remote interfaces from
  • clientRef – the remote ref to use in the invocation handler
  • forceStubUse – if true, forces creation of a RemoteStub
Throws:
/**
     * 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.

Params:
  • remoteClass – the class to obtain remote interfaces from
/**
     * 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.

Params:
  • remoteClass – the class to obtain remote interfaces from
Throws:
/**
     * 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
  • NullPointerException – if the specified class or list is null
/**
     * 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
/**
     * 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).

/**
     * 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

/**
     * 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.

/**
     * 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".

/**
     * 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) {
        StringBuilder desc = new StringBuilder(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.

/**
     * 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.

/**
     * 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);
    }
}