/*

 * Copyright (c) 2008, 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.nio.ByteBuffer;

import java.nio.channels.*;

import java.net.SocketOption;

import java.net.StandardSocketOptions;

import java.net.SocketAddress;

import java.net.InetSocketAddress;

import java.io.IOException;

import java.io.FileDescriptor;

import java.util.Set;

import java.util.HashSet;

import java.util.Collections;

import java.util.concurrent.*;

import java.util.concurrent.locks.*;

import sun.net.NetHooks;

import sun.net.ext.ExtendedSocketOptions;

/**

 * Base implementation of AsynchronousSocketChannel

 */

abstract class AsynchronousSocketChannelImpl

    extends AsynchronousSocketChannel

    implements Cancellable, Groupable

{

    protected final FileDescriptor fd;

    // protects state, localAddress, and remoteAddress

    protected final Object stateLock = new Object();

    protected volatile InetSocketAddress localAddress;

    protected volatile InetSocketAddress remoteAddress;

    // State, increases monotonically

    static final int ST_UNINITIALIZED = -1;

    static final int ST_UNCONNECTED = 0;

    static final int ST_PENDING = 1;

    static final int ST_CONNECTED = 2;

    protected volatile int state = ST_UNINITIALIZED;

    // reading state

    private final Object readLock = new Object();

    private boolean reading;

    private boolean readShutdown;

    private boolean readKilled;     // further reading disallowed due to timeout

    // writing state

    private final Object writeLock = new Object();

    private boolean writing;

    private boolean writeShutdown;

    private boolean writeKilled;    // further writing disallowed due to timeout

    // close support

    private final ReadWriteLock closeLock = new ReentrantReadWriteLock();

    private volatile boolean closed;

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

    private boolean isReuseAddress;

    AsynchronousSocketChannelImpl(AsynchronousChannelGroupImpl group)

        throws IOException

    {

        super(group.provider());

        this.fd = Net.socket(true);

        this.state = ST_UNCONNECTED;

    }

    // Constructor for sockets obtained from AsynchronousServerSocketChannelImpl

    AsynchronousSocketChannelImpl(AsynchronousChannelGroupImpl group,

                                  FileDescriptor fd,

                                  InetSocketAddress remote)

        throws IOException

    {

        super(group.provider());

        this.fd = fd;

        this.state = ST_CONNECTED;

        this.localAddress = Net.localAddress(fd);

        this.remoteAddress = remote;

    }

    @Override

    public final boolean isOpen() {

        return !closed;

    }

    /**

     * Marks beginning of access to file descriptor/handle

     */

    final void begin() throws IOException {

        closeLock.readLock().lock();

        if (!isOpen())

            throw new ClosedChannelException();

    }

    /**

     * Marks end of access to file descriptor/handle

     */

    final void end() {

        closeLock.readLock().unlock();

    }

    /**

     * Invoked to close socket and release other resources.

     */

    abstract void implClose() throws IOException;

    @Override

    public final void close() throws IOException {

        // synchronize with any threads initiating asynchronous operations

        closeLock.writeLock().lock();

        try {

            if (closed)

                return;     // already closed

            closed = true;

        } finally {

            closeLock.writeLock().unlock();

        }

        implClose();

    }

    final void enableReading(boolean killed) {

        synchronized (readLock) {

            reading = false;

            if (killed)

                readKilled = true;

        }

    }

    final void enableReading() {

        enableReading(false);

    }

    final void enableWriting(boolean killed) {

        synchronized (writeLock) {

            writing = false;

            if (killed)

                writeKilled = true;

        }

    }

    final void enableWriting() {

        enableWriting(false);

    }

    final void killReading() {

        synchronized (readLock) {

            readKilled = true;

        }

    }

    final void killWriting() {

        synchronized (writeLock) {

            writeKilled = true;

        }

    }

    final void killConnect() {

        // when a connect is cancelled then the connection may have been

        // established so prevent reading or writing.

        killReading();

        killWriting();

    }

    /**

     * Invoked by connect to initiate the connect operation.

     */

    abstract <A> Future<Void> implConnect(SocketAddress remote,

                                          A attachment,

                                          CompletionHandler<Void,? super A> handler);

    @Override

    public final Future<Void> connect(SocketAddress remote) {

        return implConnect(remote, null, null);

    }

    @Override

    public final <A> void connect(SocketAddress remote,

                                  A attachment,

                                  CompletionHandler<Void,? super A> handler)

    {

        if (handler == null)

            throw new NullPointerException("'handler' is null");

        implConnect(remote, attachment, handler);

    }

    /**

     * Invoked by read to initiate the I/O operation.

     */

    abstract <V extends Number,A> Future<V> implRead(boolean isScatteringRead,

                                                     ByteBuffer dst,

                                                     ByteBuffer[] dsts,

                                                     long timeout,

                                                     TimeUnit unit,

                                                     A attachment,

                                                     CompletionHandler<V,? super A> handler);

    @SuppressWarnings("unchecked")

    private <V extends Number,A> Future<V> read(boolean isScatteringRead,

                                                ByteBuffer dst,

                                                ByteBuffer[] dsts,

                                                long timeout,

                                                TimeUnit unit,

                                                A att,

                                                CompletionHandler<V,? super A> handler)

    {

        if (!isOpen()) {

            Throwable e = new ClosedChannelException();

            if (handler == null)

                return CompletedFuture.withFailure(e);

            Invoker.invoke(this, handler, att, null, e);

            return null;

        }

        if (remoteAddress == null)

            throw new NotYetConnectedException();

        boolean hasSpaceToRead = isScatteringRead || dst.hasRemaining();

        boolean shutdown = false;

        // check and update state

        synchronized (readLock) {

            if (readKilled)

                throw new IllegalStateException("Reading not allowed due to timeout or cancellation");

            if (reading)

                throw new ReadPendingException();

            if (readShutdown) {

                shutdown = true;

            } else {

                if (hasSpaceToRead) {

                    reading = true;

                }

            }

        }

        // immediately complete with -1 if shutdown for read

        // immediately complete with 0 if no space remaining

        if (shutdown || !hasSpaceToRead) {

            Number result;

            if (isScatteringRead) {

                result = (shutdown) ? Long.valueOf(-1L) : Long.valueOf(0L);

            } else {

                result = (shutdown) ? -1 : 0;

            }

            if (handler == null)

                return CompletedFuture.withResult((V)result);

            Invoker.invoke(this, handler, att, (V)result, null);

            return null;

        }

        return implRead(isScatteringRead, dst, dsts, timeout, unit, att, handler);

    }

    @Override

    public final Future<Integer> read(ByteBuffer dst) {

        if (dst.isReadOnly())

            throw new IllegalArgumentException("Read-only buffer");

        return read(false, dst, null, 0L, TimeUnit.MILLISECONDS, null, null);

    }

    @Override

    public final <A> void read(ByteBuffer dst,

                               long timeout,

                               TimeUnit unit,

                               A attachment,

                               CompletionHandler<Integer,? super A> handler)

    {

        if (handler == null)

            throw new NullPointerException("'handler' is null");

        if (dst.isReadOnly())

            throw new IllegalArgumentException("Read-only buffer");

        read(false, dst, null, timeout, unit, attachment, handler);

    }

    @Override

    public final <A> void read(ByteBuffer[] dsts,

                               int offset,

                               int length,

                               long timeout,

                               TimeUnit unit,

                               A attachment,

                               CompletionHandler<Long,? super A> handler)

    {

        if (handler == null)

            throw new NullPointerException("'handler' is null");

        if ((offset < 0) || (length < 0) || (offset > dsts.length - length))

            throw new IndexOutOfBoundsException();

        ByteBuffer[] bufs = Util.subsequence(dsts, offset, length);

        for (int i=0; i<bufs.length; i++) {

            if (bufs[i].isReadOnly())

                throw new IllegalArgumentException("Read-only buffer");

        }

        read(true, null, bufs, timeout, unit, attachment, handler);

    }

    /**

     * Invoked by write to initiate the I/O operation.

     */

    abstract <V extends Number,A> Future<V> implWrite(boolean isGatheringWrite,

                                                      ByteBuffer src,

                                                      ByteBuffer[] srcs,

                                                      long timeout,

                                                      TimeUnit unit,

                                                      A attachment,

                                                      CompletionHandler<V,? super A> handler);

    @SuppressWarnings("unchecked")

    private <V extends Number,A> Future<V> write(boolean isGatheringWrite,

                                                 ByteBuffer src,

                                                 ByteBuffer[] srcs,

                                                 long timeout,

                                                 TimeUnit unit,

                                                 A att,

                                                 CompletionHandler<V,? super A> handler)

    {

        boolean hasDataToWrite = isGatheringWrite || src.hasRemaining();

        boolean closed = false;

        if (isOpen()) {

            if (remoteAddress == null)

                throw new NotYetConnectedException();

            // check and update state

            synchronized (writeLock) {

                if (writeKilled)

                    throw new IllegalStateException("Writing not allowed due to timeout or cancellation");

                if (writing)

                    throw new WritePendingException();

                if (writeShutdown) {

                    closed = true;

                } else {

                    if (hasDataToWrite)

                        writing = true;

                }

            }

        } else {

            closed = true;

        }

        // channel is closed or shutdown for write

        if (closed) {

            Throwable e = new ClosedChannelException();

            if (handler == null)

                return CompletedFuture.withFailure(e);

            Invoker.invoke(this, handler, att, null, e);

            return null;

        }

        // nothing to write so complete immediately

        if (!hasDataToWrite) {

            Number result = (isGatheringWrite) ? (Number)0L : (Number)0;

            if (handler == null)

                return CompletedFuture.withResult((V)result);

            Invoker.invoke(this, handler, att, (V)result, null);

            return null;

        }

        return implWrite(isGatheringWrite, src, srcs, timeout, unit, att, handler);

    }

    @Override

    public final Future<Integer> write(ByteBuffer src) {

        return write(false, src, null, 0L, TimeUnit.MILLISECONDS, null, null);

    }

    @Override

    public final <A> void write(ByteBuffer src,

                                long timeout,

                                TimeUnit unit,

                                A attachment,

                                CompletionHandler<Integer,? super A> handler)

    {

        if (handler == null)

            throw new NullPointerException("'handler' is null");

        write(false, src, null, timeout, unit, attachment, handler);

    }

    @Override

    public final <A> void  write(ByteBuffer[] srcs,

                                 int offset,

                                 int length,

                                 long timeout,

                                 TimeUnit unit,

                                 A attachment,

                                 CompletionHandler<Long,? super A> handler)

    {

        if (handler == null)

            throw new NullPointerException("'handler' is null");

        if ((offset < 0) || (length < 0) || (offset > srcs.length - length))

            throw new IndexOutOfBoundsException();

        srcs = Util.subsequence(srcs, offset, length);

        write(true, null, srcs, timeout, unit, attachment, handler);

    }

    @Override

    public final AsynchronousSocketChannel bind(SocketAddress local)

        throws IOException

    {

        try {

            begin();

            synchronized (stateLock) {

                if (state == ST_PENDING)

                    throw new ConnectionPendingException();

                if (localAddress != null)

                    throw new AlreadyBoundException();

                InetSocketAddress isa = (local == null) ?

                    new InetSocketAddress(0) : Net.checkAddress(local);

                SecurityManager sm = System.getSecurityManager();

                if (sm != null) {

                    sm.checkListen(isa.getPort());

                }

                NetHooks.beforeTcpBind(fd, isa.getAddress(), isa.getPort());

                Net.bind(fd, isa.getAddress(), isa.getPort());

                localAddress = Net.localAddress(fd);

            }

        } finally {

            end();

        }

        return this;

    }

    @Override

    public final SocketAddress getLocalAddress() throws IOException {

        if (!isOpen())

            throw new ClosedChannelException();

         return Net.getRevealedLocalAddress(localAddress);

    }

    @Override

    public final <T> AsynchronousSocketChannel setOption(SocketOption<T> name, T value)

        throws IOException

    {

        if (name == null)

            throw new NullPointerException();

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

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

        try {

            begin();

            if (writeShutdown)

                throw new IOException("Connection has been shutdown for writing");

            if (name == StandardSocketOptions.SO_REUSEADDR &&

                    Net.useExclusiveBind())

            {

                // SO_REUSEADDR emulated when using exclusive bind

                isReuseAddress = (Boolean)value;

            } else {

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

            }

            return this;

        } finally {

            end();

        }

    }

    @Override

    @SuppressWarnings("unchecked")

    public final <T> T getOption(SocketOption<T> name) throws IOException {

        if (name == null)

            throw new NullPointerException();

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

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

        try {

            begin();

            if (name == StandardSocketOptions.SO_REUSEADDR &&

                    Net.useExclusiveBind())

            {

                // SO_REUSEADDR emulated when using exclusive bind

                return (T)Boolean.valueOf(isReuseAddress);

            }

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

        } finally {

            end();

        }

    }

    private static class DefaultOptionsHolder {

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

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

            HashSet<SocketOption<?>> set = new HashSet<>(5);

            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);