/*

 * Copyright (c) 2014, 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 jdk.net;

import java.io.FileDescriptor;

import java.net.SocketException;

import java.net.SocketOption;

import java.security.AccessController;

import java.security.PrivilegedAction;

import java.util.Collections;

import java.util.HashSet;

import java.util.Set;

/**

 * Defines extended socket options, beyond those defined in

 * {@link java.net.StandardSocketOptions}. These options may be platform

 * specific.

 *

 * @since 1.8

 */

public final class ExtendedSocketOptions {

    private static class ExtSocketOption<T> implements SocketOption<T> {

        private final String name;

        private final Class<T> type;

        ExtSocketOption(String name, Class<T> type) {

            this.name = name;

            this.type = type;

        }

        @Override public String name() { return name; }

        @Override public Class<T> type() { return type; }

        @Override public String toString() { return name; }

    }

    private ExtendedSocketOptions() { }

    /**

     * Service level properties. When a security manager is installed,

     * setting or getting this option requires a {@link NetworkPermission}

     * {@code ("setOption.SO_FLOW_SLA")} or {@code "getOption.SO_FLOW_SLA"}

     * respectively.

     */

    public static final SocketOption<SocketFlow> SO_FLOW_SLA = new

        ExtSocketOption<SocketFlow>("SO_FLOW_SLA", SocketFlow.class);

    /**

     * Disable Delayed Acknowledgements.

     *

     * <p>

     * This socket option can be used to reduce or disable delayed

     * acknowledgments (ACKs). When {@code TCP_QUICKACK} is enabled, ACKs are

     * sent immediately, rather than delayed if needed in accordance to normal

     * TCP operation. This option is not permanent, it only enables a switch to

     * or from {@code TCP_QUICKACK} mode. Subsequent operations of the TCP

     * protocol will once again disable/enable {@code TCP_QUICKACK} mode

     * depending on internal protocol processing and factors such as delayed ACK

     * timeouts occurring and data transfer, therefore this option needs to be

     * set with {@code setOption} after each operation of TCP on a given socket.

     *

     * <p>

     * The value of this socket option is a {@code Boolean} that represents

     * whether the option is enabled or disabled. The socket option is specific

     * to stream-oriented sockets using the TCP/IP protocol. The exact semantics

     * of this socket option are socket type and system dependent.

     *

     * @since 10

     */

    public static final SocketOption<Boolean> TCP_QUICKACK =

            new ExtSocketOption<Boolean>("TCP_QUICKACK", Boolean.class);

    /**

     * Keep-Alive idle time.

     *

     * <p>

     * The value of this socket option is an {@code Integer} that is the number

     * of seconds of idle time before keep-alive initiates a probe. The socket

     * option is specific to stream-oriented sockets using the TCP/IP protocol.

     * The exact semantics of this socket option are system dependent.

     *

     * <p>

     * When the {@link java.net.StandardSocketOptions#SO_KEEPALIVE

     * SO_KEEPALIVE} option is enabled, TCP probes a connection that has been

     * idle for some amount of time. The default value for this idle period is

     * system dependent, but is typically 2 hours. The {@code TCP_KEEPIDLE}

     * option can be used to affect this value for a given socket.

     *

     * @since 11

     */

    public static final SocketOption<Integer> TCP_KEEPIDLE

            = new ExtSocketOption<Integer>("TCP_KEEPIDLE", Integer.class);

    /**

     * Keep-Alive retransmission interval time.

     *

     * <p>

     * The value of this socket option is an {@code Integer} that is the number

     * of seconds to wait before retransmitting a keep-alive probe. The socket

     * option is specific to stream-oriented sockets using the TCP/IP protocol.

     * The exact semantics of this socket option are system dependent.

     *

     * <p>

     * When the {@link java.net.StandardSocketOptions#SO_KEEPALIVE

     * SO_KEEPALIVE} option is enabled, TCP probes a connection that has been

     * idle for some amount of time. If the remote system does not respond to a

     * keep-alive probe, TCP retransmits the probe after some amount of time.

     * The default value for this retransmission interval is system dependent,

     * but is typically 75 seconds. The {@code TCP_KEEPINTERVAL} option can be

     * used to affect this value for a given socket.

     *

     * @since 11

     */

    public static final SocketOption<Integer> TCP_KEEPINTERVAL

            = new ExtSocketOption<Integer>("TCP_KEEPINTERVAL", Integer.class);

    /**

     * Keep-Alive retransmission maximum limit.

     *

     * <p>

     * The value of this socket option is an {@code Integer} that is the maximum

     * number of keep-alive probes to be sent. The socket option is specific to

     * stream-oriented sockets using the TCP/IP protocol. The exact semantics of

     * this socket option are system dependent.

     *

     * <p>

     * When the {@link java.net.StandardSocketOptions#SO_KEEPALIVE

     * SO_KEEPALIVE} option is enabled, TCP probes a connection that has been

     * idle for some amount of time. If the remote system does not respond to a

     * keep-alive probe, TCP retransmits the probe a certain number of times

     * before a connection is considered to be broken. The default value for

     * this keep-alive probe retransmit limit is system dependent, but is

     * typically 8. The {@code TCP_KEEPCOUNT} option can be used to affect this

     * value for a given socket.

     *

     * @since 11

     */

    public static final SocketOption<Integer> TCP_KEEPCOUNT

            = new ExtSocketOption<Integer>("TCP_KEEPCOUNT", Integer.class);

    private static final PlatformSocketOptions platformSocketOptions =

            PlatformSocketOptions.get();

    private static final boolean flowSupported =

            platformSocketOptions.flowSupported();

    private static final boolean quickAckSupported =

            platformSocketOptions.quickAckSupported();

    private static final boolean keepAliveOptSupported =

            platformSocketOptions.keepAliveOptionsSupported();

    private static final Set<SocketOption<?>> extendedOptions = options();

    static Set<SocketOption<?>> options() {

        Set<SocketOption<?>> options = new HashSet<>();

        if (flowSupported) {

            options.add(SO_FLOW_SLA);

        }

        if (quickAckSupported) {

            options.add(TCP_QUICKACK);

        }

        if (keepAliveOptSupported) {

            options.addAll(Set.of(TCP_KEEPCOUNT, TCP_KEEPIDLE, TCP_KEEPINTERVAL));

        }

        return Collections.unmodifiableSet(options);

    }

    static {

        // Registers the extended socket options with the base module.

        sun.net.ext.ExtendedSocketOptions.register(

                new sun.net.ext.ExtendedSocketOptions(extendedOptions) {

            @Override

            public void setOption(FileDescriptor fd,

                                  SocketOption<?> option,

                                  Object value)

                throws SocketException

            {

                SecurityManager sm = System.getSecurityManager();

                if (sm != null)

                    sm.checkPermission(new NetworkPermission("setOption." + option.name()));

                if (fd == null || !fd.valid())

                    throw new SocketException("socket closed");

                if (option == SO_FLOW_SLA) {

                    assert flowSupported;

                    SocketFlow flow = checkValueType(value, SocketFlow.class);

                    setFlowOption(fd, flow);

                } else if (option == TCP_QUICKACK) {

                    setQuickAckOption(fd, (boolean) value);

                } else if (option == TCP_KEEPCOUNT) {

                    setTcpkeepAliveProbes(fd, (Integer) value);

                } else if (option == TCP_KEEPIDLE) {

                    setTcpKeepAliveTime(fd, (Integer) value);

                } else if (option == TCP_KEEPINTERVAL) {

                    setTcpKeepAliveIntvl(fd, (Integer) value);

                } else {

                    throw new InternalError("Unexpected option " + option);

                }

            }

            @Override

            public Object getOption(FileDescriptor fd,

                                    SocketOption<?> option)

                throws SocketException

            {

                SecurityManager sm = System.getSecurityManager();

                if (sm != null)

                    sm.checkPermission(new NetworkPermission("getOption." + option.name()));

                if (fd == null || !fd.valid())

                    throw new SocketException("socket closed");

                if (option == SO_FLOW_SLA) {

                    assert flowSupported;

                    SocketFlow flow = SocketFlow.create();

                    getFlowOption(fd, flow);

                    return flow;

                } else if (option == TCP_QUICKACK) {

                    return getQuickAckOption(fd);

                } else if (option == TCP_KEEPCOUNT) {

                    return getTcpkeepAliveProbes(fd);

                } else if (option == TCP_KEEPIDLE) {

                    return getTcpKeepAliveTime(fd);

                } else if (option == TCP_KEEPINTERVAL) {

                    return getTcpKeepAliveIntvl(fd);

                } else {

                    throw new InternalError("Unexpected option " + option);

                }

            }

        });

    }

    @SuppressWarnings("unchecked")

    private static <T> T checkValueType(Object value, Class<T> type) {

        if (!type.isAssignableFrom(value.getClass())) {

            String s = "Found: " + value.getClass() + ", Expected: " + type;

            throw new IllegalArgumentException(s);

        }

        return (T) value;

    }

    private static final JavaIOFileDescriptorAccess fdAccess =

            SharedSecrets.getJavaIOFileDescriptorAccess();

    private static void setFlowOption(FileDescriptor fd, SocketFlow f)

        throws SocketException

    {

        int status = platformSocketOptions.setFlowOption(fdAccess.get(fd),

                                                         f.priority(),

                                                         f.bandwidth());

        f.status(status);  // augment the given flow with the status

    }

    private static void getFlowOption(FileDescriptor fd, SocketFlow f)

            throws SocketException {

        int status = platformSocketOptions.getFlowOption(fdAccess.get(fd), f);

        f.status(status);  // augment the given flow with the status

    }

    private static void setQuickAckOption(FileDescriptor fd, boolean enable)

            throws SocketException {

        platformSocketOptions.setQuickAck(fdAccess.get(fd), enable);

    }

    private static Object getQuickAckOption(FileDescriptor fd)

            throws SocketException {

        return platformSocketOptions.getQuickAck(fdAccess.get(fd));

    }

    private static void setTcpkeepAliveProbes(FileDescriptor fd, int value)

            throws SocketException {

        platformSocketOptions.setTcpkeepAliveProbes(fdAccess.get(fd), value);

    }

    private static void setTcpKeepAliveTime(FileDescriptor fd, int value)

            throws SocketException {

        platformSocketOptions.setTcpKeepAliveTime(fdAccess.get(fd), value);

    }

    private static void setTcpKeepAliveIntvl(FileDescriptor fd, int value)

            throws SocketException {

        platformSocketOptions.setTcpKeepAliveIntvl(fdAccess.get(fd), value);

    }

    private static int getTcpkeepAliveProbes(FileDescriptor fd) throws SocketException {

        return platformSocketOptions.getTcpkeepAliveProbes(fdAccess.get(fd));

    }

    private static int getTcpKeepAliveTime(FileDescriptor fd) throws SocketException {

        return platformSocketOptions.getTcpKeepAliveTime(fdAccess.get(fd));

    }

    private static int getTcpKeepAliveIntvl(FileDescriptor fd) throws SocketException {

        return platformSocketOptions.getTcpKeepAliveIntvl(fdAccess.get(fd));

    }

    static class PlatformSocketOptions {

        protected PlatformSocketOptions() {}

        @SuppressWarnings("unchecked")

        private static PlatformSocketOptions newInstance(String cn) {

            Class<PlatformSocketOptions> c;

            try {

                c = (Class<PlatformSocketOptions>)Class.forName(cn);

                return c.getConstructor(new Class<?>[] { }).newInstance();

            } catch (ReflectiveOperationException x) {

                throw new AssertionError(x);

            }

        }

        private static PlatformSocketOptions create() {

            String osname = AccessController.doPrivileged(

                    new PrivilegedAction<String>() {

                        public String run() {

                            return System.getProperty("os.name");

                        }

                    });

            if ("SunOS".equals(osname)) {

                return newInstance("jdk.net.SolarisSocketOptions");

            } else if ("Linux".equals(osname)) {

                return newInstance("jdk.net.LinuxSocketOptions");

            } else if (osname.startsWith("Mac")) {

                return newInstance("jdk.net.MacOSXSocketOptions");

            } else {

                return new PlatformSocketOptions();

            }

        }

        private static final PlatformSocketOptions instance = create();

        static PlatformSocketOptions get() {

            return instance;

        }

        int setFlowOption(int fd, int priority, long bandwidth)

            throws SocketException

        {

            throw new UnsupportedOperationException("unsupported socket option");

        }

        int getFlowOption(int fd, SocketFlow f) throws SocketException {

            throw new UnsupportedOperationException("unsupported socket option");

        }

        boolean flowSupported() {

            return false;

        }

        void setQuickAck(int fd, boolean on) throws SocketException {

            throw new UnsupportedOperationException("unsupported TCP_QUICKACK option");

        }

        boolean getQuickAck(int fd) throws SocketException {

            throw new UnsupportedOperationException("unsupported TCP_QUICKACK option");

        }

        boolean quickAckSupported() {

            return false;

        }

        boolean keepAliveOptionsSupported() {

            return false;

        }

        void setTcpkeepAliveProbes(int fd, final int value) throws SocketException {

            throw new UnsupportedOperationException("unsupported TCP_KEEPCNT option");

        }

        void setTcpKeepAliveTime(int fd, final int value) throws SocketException {

            throw new UnsupportedOperationException("unsupported TCP_KEEPIDLE option");

        }

        void setTcpKeepAliveIntvl(int fd, final int value) throws SocketException {

            throw new UnsupportedOperationException("unsupported TCP_KEEPINTVL option");

        }

        int getTcpkeepAliveProbes(int fd) throws SocketException {

            throw new UnsupportedOperationException("unsupported TCP_KEEPCNT option");

        }

        int getTcpKeepAliveTime(int fd) throws SocketException {

            throw new UnsupportedOperationException("unsupported TCP_KEEPIDLE option");

        }

        int getTcpKeepAliveIntvl(int fd) throws SocketException {

            throw new UnsupportedOperationException("unsupported TCP_KEEPINTVL option");

        }

    }

}