/*

 * Copyright (c) 2007, 2008, 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.management.jmxremote;

import java.io.IOException;

import java.net.InetAddress;

import java.net.NetworkInterface;

import java.net.ServerSocket;

import java.net.Socket;

import java.net.SocketException;

import java.rmi.server.RMIServerSocketFactory;

import java.util.Enumeration;

/**

 * This RMI server socket factory creates server sockets that

 * will only accept connection requests from clients running

 * on the host where the RMI remote objects have been exported.

 */

public final class LocalRMIServerSocketFactory implements RMIServerSocketFactory {

    /**

     * Creates a server socket that only accepts connection requests from

     * clients running on the host where the RMI remote objects have been

     * exported.

     */

    public ServerSocket createServerSocket(int port) throws IOException {

        return new ServerSocket(port) {

            @Override

            public Socket accept() throws IOException {

                final Socket socket = super.accept();

                final InetAddress remoteAddr = socket.getInetAddress();

                final String msg = "The server sockets created using the " +

                       "LocalRMIServerSocketFactory only accept connections " +

                       "from clients running on the host where the RMI " +

                       "remote objects have been exported.";

                if (remoteAddr == null) {

                    // Though unlikeky, the socket could be already

                    // closed... Send a more detailed message in

                    // this case. Also avoid throwing NullPointerExceptiion

                    //

                    String details = "";

                    if (socket.isClosed()) {

                        details = " Socket is closed.";

                    } else if (!socket.isConnected()) {

                        details = " Socket is not connected";

                    }

                    try {

                        socket.close();

                    } catch (Exception ok) {

                        // ok - this is just cleanup before throwing detailed

                        // exception.

                    }

                    throw new IOException(msg +

                            " Couldn't determine client address." +

                            details);

                } else if (remoteAddr.isLoopbackAddress()) {

                    // local address: accept the connection.

                    return socket;

                }

                // Retrieve all the network interfaces on this host.

                Enumeration<NetworkInterface> nis;

                try {

                    nis = NetworkInterface.getNetworkInterfaces();

                } catch (SocketException e) {

                    try {

                        socket.close();

                    } catch (IOException ioe) {

                        // Ignore...

                    }

                    throw new IOException(msg, e);

                }

                // Walk through the network interfaces to see

                // if any of them matches the client's address.

                // If true, then the client's address is local.

                while (nis.hasMoreElements()) {

                    NetworkInterface ni = nis.nextElement();

                    Enumeration<InetAddress> addrs = ni.getInetAddresses();

                    while (addrs.hasMoreElements()) {

                        InetAddress localAddr = addrs.nextElement();

                        if (localAddr.equals(remoteAddr)) {

                            return socket;

                        }

                    }

                }

                // The client's address is remote so refuse the connection.

                try {

                    socket.close();

                } catch (IOException ioe) {

                    // Ignore...

                }

                throw new IOException(msg);

            }

        };

    }

    /**

     * Two LocalRMIServerSocketFactory objects

     * are equal if they are of the same type.

     */

    @Override

    public boolean equals(Object obj) {

        return (obj instanceof LocalRMIServerSocketFactory);

    }

    /**

     * Returns a hash code value for this LocalRMIServerSocketFactory.

     */

    @Override

    public int hashCode() {

        return getClass().hashCode();

    }

}