/*

 * Copyright (c) 2000, 2019, 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.nio.ch;

import java.io.FileDescriptor;

import java.io.IOException;

import java.net.InetAddress;

import java.net.InetSocketAddress;

import java.net.ProtocolFamily;

import java.net.Socket;

import java.net.SocketAddress;

import java.net.SocketException;

import java.net.SocketOption;

import java.net.StandardProtocolFamily;

import java.net.StandardSocketOptions;

import java.nio.ByteBuffer;

import java.nio.channels.AlreadyBoundException;

import java.nio.channels.AlreadyConnectedException;

import java.nio.channels.AsynchronousCloseException;

import java.nio.channels.ClosedChannelException;

import java.nio.channels.ConnectionPendingException;

import java.nio.channels.NoConnectionPendingException;

import java.nio.channels.NotYetConnectedException;

import java.nio.channels.SelectionKey;

import java.nio.channels.SocketChannel;

import java.nio.channels.spi.SelectorProvider;

import java.util.Collections;

import java.util.HashSet;

import java.util.Objects;

import java.util.Set;

import java.util.concurrent.locks.ReentrantLock;

import sun.net.ConnectionResetException;

import sun.net.NetHooks;

import sun.net.ext.ExtendedSocketOptions;

import sun.net.util.SocketExceptions;

/**

 * An implementation of SocketChannels

 */

class SocketChannelImpl

    extends SocketChannel

    implements SelChImpl

{

    // Used to make native read and write calls

    private static final NativeDispatcher nd = new SocketDispatcher();

    // Our file descriptor object

    private final FileDescriptor fd;

    private final int fdVal;

    // Lock held by current reading or connecting thread

    private final ReentrantLock readLock = new ReentrantLock();

    // Lock held by current writing or connecting thread

    private final ReentrantLock writeLock = new ReentrantLock();

    // Lock held by any thread that modifies the state fields declared below

    // DO NOT invoke a blocking I/O operation while holding this lock!

    private final Object stateLock = new Object();

    // Input/Output closed

    private volatile boolean isInputClosed;

    private volatile boolean isOutputClosed;

    // Connection reset protected by readLock

    private boolean connectionReset;

    // -- The following fields are protected by stateLock

    // set true when exclusive binding is on and SO_REUSEADDR is emulated

    private boolean isReuseAddress;

    // State, increases monotonically

    private static final int ST_UNCONNECTED = 0;

    private static final int ST_CONNECTIONPENDING = 1;

    private static final int ST_CONNECTED = 2;

    private static final int ST_CLOSING = 3;

    private static final int ST_KILLPENDING = 4;

    private static final int ST_KILLED = 5;

    private volatile int state;  // need stateLock to change

    // IDs of native threads doing reads and writes, for signalling

    private long readerThread;

    private long writerThread;

    // Binding

    private InetSocketAddress localAddress;

    private InetSocketAddress remoteAddress;

    // Socket adaptor, created on demand

    private Socket socket;

    // -- End of fields protected by stateLock

    // Constructor for normal connecting sockets

    //

    SocketChannelImpl(SelectorProvider sp) throws IOException {

        super(sp);

        this.fd = Net.socket(true);

        this.fdVal = IOUtil.fdVal(fd);

    }

    SocketChannelImpl(SelectorProvider sp, FileDescriptor fd, boolean bound)

        throws IOException

    {

        super(sp);

        this.fd = fd;

        this.fdVal = IOUtil.fdVal(fd);

        if (bound) {

            synchronized (stateLock) {

                this.localAddress = Net.localAddress(fd);

            }

        }

    }

    // Constructor for sockets obtained from server sockets

    //

    SocketChannelImpl(SelectorProvider sp, FileDescriptor fd, InetSocketAddress isa)

        throws IOException

    {

        super(sp);

        this.fd = fd;

        this.fdVal = IOUtil.fdVal(fd);

        synchronized (stateLock) {

            this.localAddress = Net.localAddress(fd);

            this.remoteAddress = isa;

            this.state = ST_CONNECTED;

        }

    }

    /**

     * Checks that the channel is open.

     *

     * @throws ClosedChannelException if channel is closed (or closing)

     */

    private void ensureOpen() throws ClosedChannelException {

        if (!isOpen())

            throw new ClosedChannelException();

    }

    /**

     * Checks that the channel is open and connected.

     *

     * @apiNote This method uses the "state" field to check if the channel is

     * open. It should never be used in conjuncion with isOpen or ensureOpen

     * as these methods check AbstractInterruptibleChannel's closed field - that

     * field is set before implCloseSelectableChannel is called and so before

     * the state is changed.

     *

     * @throws ClosedChannelException if channel is closed (or closing)

     * @throws NotYetConnectedException if open and not connected

     */

    private void ensureOpenAndConnected() throws ClosedChannelException {

        int state = this.state;

        if (state < ST_CONNECTED) {

            throw new NotYetConnectedException();

        } else if (state > ST_CONNECTED) {

            throw new ClosedChannelException();

        }

    }

    @Override

    public Socket socket() {

        synchronized (stateLock) {

            if (socket == null)

                socket = SocketAdaptor.create(this);

            return socket;

        }

    }

    @Override

    public SocketAddress getLocalAddress() throws IOException {

        synchronized (stateLock) {

            ensureOpen();

            return Net.getRevealedLocalAddress(localAddress);

        }

    }

    @Override

    public SocketAddress getRemoteAddress() throws IOException {

        synchronized (stateLock) {

            ensureOpen();

            return remoteAddress;

        }

    }

    @Override

    public <T> SocketChannel setOption(SocketOption<T> name, T value)

        throws IOException

    {

        Objects.requireNonNull(name);

        if (!supportedOptions().contains(name))

            throw new UnsupportedOperationException("'" + name + "' not supported");

        synchronized (stateLock) {

            ensureOpen();

            if (name == StandardSocketOptions.IP_TOS) {

                ProtocolFamily family = Net.isIPv6Available() ?

                    StandardProtocolFamily.INET6 : StandardProtocolFamily.INET;

                Net.setSocketOption(fd, family, name, value);

                return this;

            }

            if (name == StandardSocketOptions.SO_REUSEADDR && Net.useExclusiveBind()) {

                // SO_REUSEADDR emulated when using exclusive bind

                isReuseAddress = (Boolean)value;

                return this;

            }

            // no options that require special handling

            Net.setSocketOption(fd, name, value);

            return this;

        }

    }

    @Override

    @SuppressWarnings("unchecked")

    public <T> T getOption(SocketOption<T> name)

        throws IOException

    {

        Objects.requireNonNull(name);

        if (!supportedOptions().contains(name))

            throw new UnsupportedOperationException("'" + name + "' not supported");

        synchronized (stateLock) {

            ensureOpen();

            if (name == StandardSocketOptions.SO_REUSEADDR && Net.useExclusiveBind()) {

                // SO_REUSEADDR emulated when using exclusive bind

                return (T)Boolean.valueOf(isReuseAddress);

            }

            // special handling for IP_TOS: always return 0 when IPv6

            if (name == StandardSocketOptions.IP_TOS) {

                ProtocolFamily family = Net.isIPv6Available() ?

                    StandardProtocolFamily.INET6 : StandardProtocolFamily.INET;

                return (T) Net.getSocketOption(fd, family, name);

            }

            // no options that require special handling

            return (T) Net.getSocketOption(fd, name);

        }

    }

    private static class DefaultOptionsHolder {

        static final Set<SocketOption<?>> defaultOptions = defaultOptions();

        private static Set<SocketOption<?>> defaultOptions() {

            HashSet<SocketOption<?>> set = new HashSet<>();

            set.add(StandardSocketOptions.SO_SNDBUF);

            set.add(StandardSocketOptions.SO_RCVBUF);

            set.add(StandardSocketOptions.SO_KEEPALIVE);

            set.add(StandardSocketOptions.SO_REUSEADDR);

            if (Net.isReusePortAvailable()) {

                set.add(StandardSocketOptions.SO_REUSEPORT);

            }

            set.add(StandardSocketOptions.SO_LINGER);

            set.add(StandardSocketOptions.TCP_NODELAY);

            // additional options required by socket adaptor

            set.add(StandardSocketOptions.IP_TOS);

            set.add(ExtendedSocketOption.SO_OOBINLINE);

            set.addAll(ExtendedSocketOptions.clientSocketOptions());

            return Collections.unmodifiableSet(set);

        }

    }

    @Override

    public final Set<SocketOption<?>> supportedOptions() {

        return DefaultOptionsHolder.defaultOptions;

    }

    /**

     * Marks the beginning of a read operation that might block.

     *

     * @throws ClosedChannelException if the channel is closed

     * @throws NotYetConnectedException if the channel is not yet connected

     */

    private void beginRead(boolean blocking) throws ClosedChannelException {

        if (blocking) {

            // set hook for Thread.interrupt

            begin();

            synchronized (stateLock) {

                ensureOpenAndConnected();

                // record thread so it can be signalled if needed

                readerThread = NativeThread.current();

            }

        } else {

            ensureOpenAndConnected();

        }

    }

    /**

     * Marks the end of a read operation that may have blocked.

     *

     * @throws AsynchronousCloseException if the channel was closed due to this

     * thread being interrupted on a blocking read operation.

     */

    private void endRead(boolean blocking, boolean completed)

        throws AsynchronousCloseException

    {

        if (blocking) {

            synchronized (stateLock) {

                readerThread = 0;

                // notify any thread waiting in implCloseSelectableChannel

                if (state == ST_CLOSING) {

                    stateLock.notifyAll();

                }

            }

            // remove hook for Thread.interrupt

            end(completed);

        }

    }

    private void throwConnectionReset() throws SocketException {

        throw new SocketException("Connection reset");

    }

    @Override

    public int read(ByteBuffer buf) throws IOException {

        Objects.requireNonNull(buf);

        readLock.lock();

        try {

            boolean blocking = isBlocking();

            int n = 0;

            try {

                beginRead(blocking);

                // check if connection has been reset

                if (connectionReset)

                    throwConnectionReset();

                // check if input is shutdown

                if (isInputClosed)

                    return IOStatus.EOF;

                if (blocking) {

                    do {

                        n = IOUtil.read(fd, buf, -1, nd);

                    } while (n == IOStatus.INTERRUPTED && isOpen());

                } else {

                    n = IOUtil.read(fd, buf, -1, nd);

                }

            } catch (ConnectionResetException e) {

                connectionReset = true;

                throwConnectionReset();

            } finally {

                endRead(blocking, n > 0);

                if (n <= 0 && isInputClosed)

                    return IOStatus.EOF;

            }

            return IOStatus.normalize(n);

        } finally {

            readLock.unlock();

        }

    }

    @Override

    public long read(ByteBuffer[] dsts, int offset, int length)

        throws IOException

    {

        Objects.checkFromIndexSize(offset, length, dsts.length);

        readLock.lock();

        try {

            boolean blocking = isBlocking();

            long n = 0;

            try {

                beginRead(blocking);

                // check if connection has been reset

                if (connectionReset)

                    throwConnectionReset();

                // check if input is shutdown

                if (isInputClosed)

                    return IOStatus.EOF;

                if (blocking) {

                    do {

                        n = IOUtil.read(fd, dsts, offset, length, nd);

                    } while (n == IOStatus.INTERRUPTED && isOpen());

                } else {

                    n = IOUtil.read(fd, dsts, offset, length, nd);

                }

            } catch (ConnectionResetException e) {

                connectionReset = true;

                throwConnectionReset();

            } finally {

                endRead(blocking, n > 0);

                if (n <= 0 && isInputClosed)

                    return IOStatus.EOF;

            }

            return IOStatus.normalize(n);

        } finally {

            readLock.unlock();

        }

    }

    /**

     * Marks the beginning of a write operation that might block.

     *

     * @throws ClosedChannelException if the channel is closed or output shutdown

     * @throws NotYetConnectedException if the channel is not yet connected

     */

    private void beginWrite(boolean blocking) throws ClosedChannelException {

        if (blocking) {

            // set hook for Thread.interrupt

            begin();

            synchronized (stateLock) {

                ensureOpenAndConnected();

                if (isOutputClosed)

                    throw new ClosedChannelException();

                // record thread so it can be signalled if needed

                writerThread = NativeThread.current();

            }

        } else {

            ensureOpenAndConnected();

        }

    }

    /**

     * Marks the end of a write operation that may have blocked.

     *

     * @throws AsynchronousCloseException if the channel was closed due to this

     * thread being interrupted on a blocking write operation.

     */

    private void endWrite(boolean blocking, boolean completed)

        throws AsynchronousCloseException

    {

        if (blocking) {

            synchronized (stateLock) {

                writerThread = 0;

                // notify any thread waiting in implCloseSelectableChannel

                if (state == ST_CLOSING) {

                    stateLock.notifyAll();

                }

            }

            // remove hook for Thread.interrupt

            end(completed);

        }

    }

    @Override

    public int write(ByteBuffer buf) throws IOException {

        Objects.requireNonNull(buf);

        writeLock.lock();

        try {

            boolean blocking = isBlocking();

            int n = 0;

            try {

                beginWrite(blocking);

                if (blocking) {

                    do {

                        n = IOUtil.write(fd, buf, -1, nd);

                    } while (n == IOStatus.INTERRUPTED && isOpen());

                } else {

                    n = IOUtil.write(fd, buf, -1, nd);

                }

            } finally {

                endWrite(blocking, n > 0);

                if (n <= 0 && isOutputClosed)

                    throw new AsynchronousCloseException();