/*

 * Copyright (c) 2007, 2018, 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 java.net;

import java.io.IOException;

import java.io.FileDescriptor;

import sun.net.ResourceManager;

/**

 * This class defines the plain DatagramSocketImpl that is used for all

 * Windows versions lower than Vista. It adds support for IPv6 on

 * these platforms where available.

 *

 * For backward compatibility windows platforms that do not have IPv6

 * support also use this implementation, and fd1 gets set to null

 * during socket creation.

 *

 * @author Chris Hegarty

 */

final class TwoStacksPlainDatagramSocketImpl extends AbstractPlainDatagramSocketImpl

{

    /* Used for IPv6 on Windows only */

    private FileDescriptor fd1;

    /*

     * Needed for ipv6 on windows because we need to know

     * if the socket was bound to ::0 or 0.0.0.0, when a caller

     * asks for it. In this case, both sockets are used, but we

     * don't know whether the caller requested ::0 or 0.0.0.0

     * and need to remember it here.

     */

    private InetAddress anyLocalBoundAddr=null;

    private int fduse=-1; /* saved between peek() and receive() calls */

    /* saved between successive calls to receive, if data is detected

     * on both sockets at same time. To ensure that one socket is not

     * starved, they rotate using this field

     */

    private int lastfd=-1;

    static {

        init();

    }

    // true if this socket is exclusively bound

    private final boolean exclusiveBind;

    /*

     * Set to true if SO_REUSEADDR is set after the socket is bound to

     * indicate SO_REUSEADDR is being emulated

     */

    private boolean reuseAddressEmulated;

    // emulates SO_REUSEADDR when exclusiveBind is true and socket is bound

    private boolean isReuseAddress;

    TwoStacksPlainDatagramSocketImpl(boolean exclBind) {

        exclusiveBind = exclBind;

    }

    protected synchronized void create() throws SocketException {

        fd1 = new FileDescriptor();

        try {

            super.create();

            SocketCleanable.register(fd1);

        } catch (SocketException e) {

            fd1 = null;

            throw e;

        }

    }

    protected synchronized void bind(int lport, InetAddress laddr)

        throws SocketException {

        super.bind(lport, laddr);

        if (laddr.isAnyLocalAddress()) {

            anyLocalBoundAddr = laddr;

        }

    }

    @Override

    protected synchronized void bind0(int lport, InetAddress laddr)

        throws SocketException

    {

        // The native bind0 may close one or both of the underlying file

        // descriptors, and even create new sockets, so the safest course of

        // action is to unregister the socket cleaners, and register afterwards.

        SocketCleanable.unregister(fd);

        SocketCleanable.unregister(fd1);

        bind0(lport, laddr, exclusiveBind);

        SocketCleanable.register(fd);

        SocketCleanable.register(fd1);

    }

    protected synchronized void receive(DatagramPacket p)

        throws IOException {

        try {

            receive0(p);

        } finally {

            fduse = -1;

        }

    }

    public Object getOption(int optID) throws SocketException {

        if (isClosed()) {

            throw new SocketException("Socket Closed");

        }

        if (optID == SO_BINDADDR) {

            if ((fd != null && fd1 != null) && !connected) {

                return anyLocalBoundAddr;

            }

            int family = connectedAddress == null ? -1 : connectedAddress.holder().getFamily();

            return socketLocalAddress(family);

        } else if (optID == SO_REUSEADDR && reuseAddressEmulated) {

            return isReuseAddress;

        } else if (optID == SO_REUSEPORT) {

            // SO_REUSEPORT is not supported on Windows.

            throw new UnsupportedOperationException("unsupported option");

        } else {

            return super.getOption(optID);

        }

    }

    protected void socketSetOption(int opt, Object val)

        throws SocketException

    {

        if (opt == SO_REUSEADDR && exclusiveBind && localPort != 0)  {

            // socket already bound, emulate

            reuseAddressEmulated = true;

            isReuseAddress = (Boolean)val;

        } else if (opt == SO_REUSEPORT) {

            // SO_REUSEPORT is not supported on Windows.

            throw new UnsupportedOperationException("unsupported option");

        } else {

            socketNativeSetOption(opt, val);

        }

    }

    protected boolean isClosed() {

        return (fd == null && fd1 == null) ? true : false;

    }

    protected void close() {

        if (fd != null || fd1 != null) {

            SocketCleanable.unregister(fd);

            SocketCleanable.unregister(fd1);

            datagramSocketClose();

            ResourceManager.afterUdpClose();

            fd = null;

            fd1 = null;

        }

    }

    /* Native methods */

    protected synchronized native void bind0(int lport, InetAddress laddr,

                                             boolean exclBind)

        throws SocketException;

    protected synchronized native int peek(InetAddress i) throws IOException;

    protected synchronized native int peekData(DatagramPacket p) throws IOException;

    protected synchronized native void receive0(DatagramPacket p)

        throws IOException;

    protected native void setTimeToLive(int ttl) throws IOException;

    protected native int getTimeToLive() throws IOException;

    @Deprecated

    protected native void setTTL(byte ttl) throws IOException;

    @Deprecated

    protected native byte getTTL() throws IOException;

    protected native void join(InetAddress inetaddr, NetworkInterface netIf)

        throws IOException;

    protected native void leave(InetAddress inetaddr, NetworkInterface netIf)

        throws IOException;

    protected native void datagramSocketCreate() throws SocketException;

    protected native void datagramSocketClose();

    protected native void socketNativeSetOption(int opt, Object val)

        throws SocketException;

    protected native Object socketGetOption(int opt) throws SocketException;

    protected native void connect0(InetAddress address, int port) throws SocketException;

    protected native Object socketLocalAddress(int family) throws SocketException;

    protected native void disconnect0(int family);

    native int dataAvailable();

    /**

     * Perform class load-time initializations.

     */

    private static native void init();

}