/*
 * Copyright (c) 1996, 2017, 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.IOException;
import java.io.ObjectInput;
import java.io.ObjectInputStream;
import java.io.ObjectOutput;
import java.lang.reflect.Method;
import java.rmi.MarshalException;
import java.rmi.Remote;
import java.rmi.RemoteException;
import java.rmi.UnmarshalException;
import java.rmi.server.Operation;
import java.rmi.server.RemoteCall;
import java.rmi.server.RemoteObject;
import java.rmi.server.RemoteRef;
import java.security.AccessController;
import java.security.PrivilegedAction;

import jdk.internal.misc.SharedSecrets;
import sun.rmi.runtime.Log;
import sun.rmi.transport.Connection;
import sun.rmi.transport.LiveRef;
import sun.rmi.transport.StreamRemoteCall;

NOTE: There is a JDK-internal dependency on the existence of this
class's getLiveRef method (as it is inherited by UnicastRef2) in
the implementation of javax.management.remote.rmi.RMIConnector.
/**
 * NOTE: There is a JDK-internal dependency on the existence of this
 * class's getLiveRef method (as it is inherited by UnicastRef2) in
 * the implementation of javax.management.remote.rmi.RMIConnector.
 */
@SuppressWarnings("deprecation")
public class UnicastRef implements RemoteRef {

    
Client-side transport log.
/**
     * Client-side transport log.
     */
    public static final Log clientRefLog =
        Log.getLog("sun.rmi.client.ref", "transport",  Util.logLevel);

    
Client-side call log.
/**
     * Client-side call log.
     */
    public static final Log clientCallLog =
        Log.getLog("sun.rmi.client.call", "RMI",
                   AccessController.doPrivileged((PrivilegedAction<Boolean>) () ->
                       Boolean.getBoolean("sun.rmi.client.logCalls")));
    private static final long serialVersionUID = 8258372400816541186L;

    protected LiveRef ref;

    
Create a new (empty) Unicast remote reference.
/**
     * Create a new (empty) Unicast remote reference.
     */
    public UnicastRef() {
    }

    
Create a new Unicast RemoteRef.
/**
     * Create a new Unicast RemoteRef.
     */
    public UnicastRef(LiveRef liveRef) {
        ref = liveRef;
    }

    
Returns the current value of this UnicastRef's underlying
LiveRef.
NOTE: There is a JDK-internal dependency on the existence of
this method (as it is inherited by UnicastRef) in the
implementation of javax.management.remote.rmi.RMIConnector.
/**
     * Returns the current value of this UnicastRef's underlying
     * LiveRef.
     *
     * NOTE: There is a JDK-internal dependency on the existence of
     * this method (as it is inherited by UnicastRef) in the
     * implementation of javax.management.remote.rmi.RMIConnector.
     **/
    public LiveRef getLiveRef() {
        return ref;
    }

    
Invoke a method. This form of delegating method invocation
to the reference allows the reference to take care of
setting up the connection to the remote host, marshalling
some representation for the method and parameters, then
communicating the method invocation to the remote host.
This method either returns the result of a method invocation
on the remote object which resides on the remote host or
throws a RemoteException if the call failed or an
application-level exception if the remote invocation throws
an exception.
Params:
obj – the proxy for the remote object
method – the method to be invoked
params – the parameter list
opnum –  a hash that may be used to represent the method
Since:
1.2/**
     * Invoke a method. This form of delegating method invocation
     * to the reference allows the reference to take care of
     * setting up the connection to the remote host, marshalling
     * some representation for the method and parameters, then
     * communicating the method invocation to the remote host.
     * This method either returns the result of a method invocation
     * on the remote object which resides on the remote host or
     * throws a RemoteException if the call failed or an
     * application-level exception if the remote invocation throws
     * an exception.
     *
     * @param obj the proxy for the remote object
     * @param method the method to be invoked
     * @param params the parameter list
     * @param opnum  a hash that may be used to represent the method
     * @since 1.2
     */
    public Object invoke(Remote obj,
                         Method method,
                         Object[] params,
                         long opnum)
        throws Exception
    {
        if (clientRefLog.isLoggable(Log.VERBOSE)) {
            clientRefLog.log(Log.VERBOSE, "method: " + method);
        }

        if (clientCallLog.isLoggable(Log.VERBOSE)) {
            logClientCall(obj, method);
        }

        Connection conn = ref.getChannel().newConnection();
        RemoteCall call = null;
        boolean reuse = true;

        /* If the call connection is "reused" early, remember not to
         * reuse again.
         */
        boolean alreadyFreed = false;

        try {
            if (clientRefLog.isLoggable(Log.VERBOSE)) {
                clientRefLog.log(Log.VERBOSE, "opnum = " + opnum);
            }

            // create call context
            call = new StreamRemoteCall(conn, ref.getObjID(), -1, opnum);

            // marshal parameters
            try {
                ObjectOutput out = call.getOutputStream();
                marshalCustomCallData(out);
                Class<?>[] types = method.getParameterTypes();
                for (int i = 0; i < types.length; i++) {
                    marshalValue(types[i], params[i], out);
                }
            } catch (IOException e) {
                clientRefLog.log(Log.BRIEF,
                    "IOException marshalling arguments: ", e);
                throw new MarshalException("error marshalling arguments", e);
            }

            // unmarshal return
            call.executeCall();

            try {
                Class<?> rtype = method.getReturnType();
                if (rtype == void.class)
                    return null;
                ObjectInput in = call.getInputStream();

                /* StreamRemoteCall.done() does not actually make use
                 * of conn, therefore it is safe to reuse this
                 * connection before the dirty call is sent for
                 * registered refs.
                 */
                Object returnValue = unmarshalValue(rtype, in);

                /* we are freeing the connection now, do not free
                 * again or reuse.
                 */
                alreadyFreed = true;

                /* if we got to this point, reuse must have been true. */
                clientRefLog.log(Log.BRIEF, "free connection (reuse = true)");

                /* Free the call's connection early. */
                ref.getChannel().free(conn, true);

                return returnValue;

            } catch (IOException | ClassNotFoundException e) {
                // disable saving any refs in the inputStream for GC
                ((StreamRemoteCall)call).discardPendingRefs();
                clientRefLog.log(Log.BRIEF,
                                 e.getClass().getName() + " unmarshalling return: ", e);
                throw new UnmarshalException("error unmarshalling return", e);
            } finally {
                try {
                    call.done();
                } catch (IOException e) {
                    /* WARNING: If the conn has been reused early,
                     * then it is too late to recover from thrown
                     * IOExceptions caught here. This code is relying
                     * on StreamRemoteCall.done() not actually
                     * throwing IOExceptions.
                     */
                    reuse = false;
                }
            }

        } catch (RuntimeException e) {
            /*
             * Need to distinguish between client (generated by the
             * invoke method itself) and server RuntimeExceptions.
             * Client side RuntimeExceptions are likely to have
             * corrupted the call connection and those from the server
             * are not likely to have done so.  If the exception came
             * from the server the call connection should be reused.
             */
            if ((call == null) ||
                (((StreamRemoteCall) call).getServerException() != e))
            {
                reuse = false;
            }
            throw e;

        } catch (RemoteException e) {
            /*
             * Some failure during call; assume connection cannot
             * be reused.  Must assume failure even if ServerException
             * or ServerError occurs since these failures can happen
             * during parameter deserialization which would leave
             * the connection in a corrupted state.
             */
            reuse = false;
            throw e;

        } catch (Error e) {
            /* If errors occurred, the connection is most likely not
             *  reusable.
             */
            reuse = false;
            throw e;

        } finally {

            /* alreadyFreed ensures that we do not log a reuse that
             * may have already happened.
             */
            if (!alreadyFreed) {
                if (clientRefLog.isLoggable(Log.BRIEF)) {
                    clientRefLog.log(Log.BRIEF, "free connection (reuse = " +
                                           reuse + ")");
                }
                ref.getChannel().free(conn, reuse);
            }
        }
    }

    protected void marshalCustomCallData(ObjectOutput out) throws IOException
    {}

    
Marshal value to an ObjectOutput sink using RMI's serialization
format for parameters or return values.
/**
     * Marshal value to an ObjectOutput sink using RMI's serialization
     * format for parameters or return values.
     */
    protected static void marshalValue(Class<?> type, Object value,
                                       ObjectOutput out)
        throws IOException
    {
        if (type.isPrimitive()) {
            if (type == int.class) {
                out.writeInt(((Integer) value).intValue());
            } else if (type == boolean.class) {
                out.writeBoolean(((Boolean) value).booleanValue());
            } else if (type == byte.class) {
                out.writeByte(((Byte) value).byteValue());
            } else if (type == char.class) {
                out.writeChar(((Character) value).charValue());
            } else if (type == short.class) {
                out.writeShort(((Short) value).shortValue());
            } else if (type == long.class) {
                out.writeLong(((Long) value).longValue());
            } else if (type == float.class) {
                out.writeFloat(((Float) value).floatValue());
            } else if (type == double.class) {
                out.writeDouble(((Double) value).doubleValue());
            } else {
                throw new Error("Unrecognized primitive type: " + type);
            }
        } else {
            out.writeObject(value);
        }
    }

    
Unmarshal value from an ObjectInput source using RMI's serialization
format for parameters or return values.
/**
     * Unmarshal value from an ObjectInput source using RMI's serialization
     * format for parameters or return values.
     */
    protected static Object unmarshalValue(Class<?> type, ObjectInput in)
        throws IOException, ClassNotFoundException
    {
        if (type.isPrimitive()) {
            if (type == int.class) {
                return Integer.valueOf(in.readInt());
            } else if (type == boolean.class) {
                return Boolean.valueOf(in.readBoolean());
            } else if (type == byte.class) {
                return Byte.valueOf(in.readByte());
            } else if (type == char.class) {
                return Character.valueOf(in.readChar());
            } else if (type == short.class) {
                return Short.valueOf(in.readShort());
            } else if (type == long.class) {
                return Long.valueOf(in.readLong());
            } else if (type == float.class) {
                return Float.valueOf(in.readFloat());
            } else if (type == double.class) {
                return Double.valueOf(in.readDouble());
            } else {
                throw new Error("Unrecognized primitive type: " + type);
            }
        } else if (type == String.class && in instanceof ObjectInputStream) {
            return SharedSecrets.getJavaObjectInputStreamReadString().readString((ObjectInputStream)in);
        } else {
            return in.readObject();
        }
    }

    
Create an appropriate call object for a new call on this object.
Passing operation array and index, allows the stubs generator to
assign the operation indexes and interpret them. The RemoteRef
may need the operation to encode in for the call.
/**
     * Create an appropriate call object for a new call on this object.
     * Passing operation array and index, allows the stubs generator to
     * assign the operation indexes and interpret them. The RemoteRef
     * may need the operation to encode in for the call.
     */
    public RemoteCall newCall(RemoteObject obj, Operation[] ops, int opnum,
                              long hash)
        throws RemoteException
    {
        clientRefLog.log(Log.BRIEF, "get connection");

        Connection conn = ref.getChannel().newConnection();
        try {
            clientRefLog.log(Log.VERBOSE, "create call context");

            /* log information about the outgoing call */
            if (clientCallLog.isLoggable(Log.VERBOSE)) {
                logClientCall(obj, ops[opnum]);
            }

            RemoteCall call =
                new StreamRemoteCall(conn, ref.getObjID(), opnum, hash);
            try {
                marshalCustomCallData(call.getOutputStream());
            } catch (IOException e) {
                throw new MarshalException("error marshaling " +
                                           "custom call data");
            }
            return call;
        } catch (RemoteException e) {
            ref.getChannel().free(conn, false);
            throw e;
        }
    }

    
Invoke makes the remote call present in the RemoteCall object.
Invoke will raise any "user" exceptions which
should pass through and not be caught by the stub.  If any
exception is raised during the remote invocation, invoke should
take care of cleaning up the connection before raising the
"user" or remote exception.
/**
     * Invoke makes the remote call present in the RemoteCall object.
     *
     * Invoke will raise any "user" exceptions which
     * should pass through and not be caught by the stub.  If any
     * exception is raised during the remote invocation, invoke should
     * take care of cleaning up the connection before raising the
     * "user" or remote exception.
     */
    public void invoke(RemoteCall call) throws Exception {
        try {
            clientRefLog.log(Log.VERBOSE, "execute call");

            call.executeCall();

        } catch (RemoteException e) {
            /*
             * Call did not complete; connection can't be reused.
             */
            clientRefLog.log(Log.BRIEF, "exception: ", e);
            free(call, false);
            throw e;

        } catch (Error e) {
            /* If errors occurred, the connection is most likely not
             *  reusable.
             */
            clientRefLog.log(Log.BRIEF, "error: ", e);
            free(call, false);
            throw e;

        } catch (RuntimeException e) {
            /*
             * REMIND: Since runtime exceptions are no longer wrapped,
             * we can't assue that the connection was left in
             * a reusable state. Is this okay?
             */
            clientRefLog.log(Log.BRIEF, "exception: ", e);
            free(call, false);
            throw e;

        } catch (Exception e) {
            /*
             * Assume that these other exceptions are user exceptions
             * and leave the connection in a reusable state.
             */
            clientRefLog.log(Log.BRIEF, "exception: ", e);
            free(call, true);
            /* reraise user (and unknown) exceptions. */
            throw e;
        }

        /*
         * Don't free the connection if an exception did not
         * occur because the stub needs to unmarshal the
         * return value. The connection will be freed
         * by a call to the "done" method.
         */
    }

    
Private method to free a connection.
/**
     * Private method to free a connection.
     */
    private void free(RemoteCall call, boolean reuse) throws RemoteException {
        Connection conn = ((StreamRemoteCall)call).getConnection();
        ref.getChannel().free(conn, reuse);
    }

    
Done should only be called if the invoke returns successfully
(non-exceptionally) to the stub. It allows the remote reference to
clean up (or reuse) the connection.
/**
     * Done should only be called if the invoke returns successfully
     * (non-exceptionally) to the stub. It allows the remote reference to
     * clean up (or reuse) the connection.
     */
    public void done(RemoteCall call) throws RemoteException {

        /* Done only uses the connection inside the call to obtain the
         * channel the connection uses.  Once all information is read
         * from the connection, the connection may be freed.
         */
        clientRefLog.log(Log.BRIEF, "free connection (reuse = true)");

        /* Free the call connection early. */
        free(call, true);

        try {
            call.done();
        } catch (IOException e) {
            /* WARNING: If the conn has been reused early, then it is
             * too late to recover from thrown IOExceptions caught
             * here. This code is relying on StreamRemoteCall.done()
             * not actually throwing IOExceptions.
             */
        }
    }

    
Log the details of an outgoing call.  The method parameter is either of
type java.lang.reflect.Method or java.rmi.server.Operation.
/**
     * Log the details of an outgoing call.  The method parameter is either of
     * type java.lang.reflect.Method or java.rmi.server.Operation.
     */
    void logClientCall(Object obj, Object method) {
        clientCallLog.log(Log.VERBOSE, "outbound call: " +
            ref + " : " + obj.getClass().getName() +
            ref.getObjID().toString() + ": " + method);
    }

    
Returns the class of the ref type to be serialized
/**
     * Returns the class of the ref type to be serialized
     */
    public String getRefClass(ObjectOutput out) {
        return "UnicastRef";
    }

    
Write out external representation for remote ref.
/**
     * Write out external representation for remote ref.
     */
    public void writeExternal(ObjectOutput out) throws IOException {
        ref.write(out, false);
    }

    
Read in external representation for remote ref.
Throws:
ClassNotFoundException – If the class for an object
being restored cannot be found./**
     * Read in external representation for remote ref.
     * @exception ClassNotFoundException If the class for an object
     * being restored cannot be found.
     */
    public void readExternal(ObjectInput in)
        throws IOException, ClassNotFoundException
    {
        ref = LiveRef.read(in, false);
    }

    //----------------------------------------------------------------------;
    
Method from object, forward from RemoteObject
/**
     * Method from object, forward from RemoteObject
     */
    public String remoteToString() {
        return Util.getUnqualifiedName(getClass()) + " [liveRef: " + ref + "]";
    }

    
default implementation of hashCode for remote objects
/**
     * default implementation of hashCode for remote objects
     */
    public int remoteHashCode() {
        return ref.hashCode();
    }

    
default implementation of equals for remote objects
/** default implementation of equals for remote objects
     */
    public boolean remoteEquals(RemoteRef sub) {
        if (sub instanceof UnicastRef)
            return ref.remoteEquals(((UnicastRef)sub).ref);
        return false;
    }
}