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 * 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,
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 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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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;
import jdk.internal.misc.JavaIOFileDescriptorAccess;
import jdk.internal.misc.SharedSecrets;

Defines extended socket options, beyond those defined in StandardSocketOptions. These options may be platform specific. 
Since:
1.8/**
 * 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 NetworkPermission ("setOption.SO_FLOW_SLA") or "getOption.SO_FLOW_SLA" respectively. /**
     * 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.
 This socket option can be used to reduce or disable delayed acknowledgments (ACKs). When 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 TCP_QUICKACK mode. Subsequent operations of the TCP protocol will once again disable/enable 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 setOption after each operation of TCP on a given socket. 
 The value of this socket option is a 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/**
     * 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.
 The value of this socket option is an 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. 
 When the 
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 TCP_KEEPIDLE option can be used to affect this value for a given socket. 
Since:
11/**
     * 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.
 The value of this socket option is an 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. 
 When the 
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 TCP_KEEPINTERVAL option can be used to affect this value for a given socket. 
Since:
11/**
     * 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.
 The value of this socket option is an 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. 
 When the 
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 TCP_KEEPCOUNT option can be used to affect this value for a given socket. 
Since:
11/**
     * 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, option.type());
                    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<?> 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");
        }
    }
}