/*

 * 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.SocketTimeoutException;

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.IllegalBlockingModeException;

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

 */

abstract 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

    final FileDescriptor fd;

    private final int fdVal;

    // Lock held by current reading or connecting thread

    final ReentrantLock readLock = new ReentrantLock();

    // Lock held by current writing or connecting thread

    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!

    final Object stateLock = new Object();

    // Input/Output closed

    volatile boolean isInputClosed;

    volatile boolean isOutputClosed;

    // Connection reset protected by readLock

    private boolean connectionReset;

    // -- The following fields are protected by stateLock

    // State, increases monotonically

    static final int ST_UNCONNECTED = 0;

    static final int ST_CONNECTIONPENDING = 1;

    static final int ST_CONNECTED = 2;

    static final int ST_CLOSING = 3;

    static final int ST_CLOSED = 4;

    volatile int state;  // need stateLock to change

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

    private long readerThread;

    private long writerThread;

    // Binding

    SocketAddress localAddress;

    SocketAddress remoteAddress;

    // Socket adaptor, created on demand

    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)

        throws IOException

    {

        super(sp);

        this.fd = fd;

        this.fdVal = IOUtil.fdVal(fd);

    }

    /**

     * Checks that the channel is open.

     *

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

     */

    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();

        }

    }

    /**

     * 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;

                if (state == ST_CLOSING) {

                    tryFinishClose();

                }

            }

            // 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;

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

                if (blocking) {

                    while (IOStatus.okayToRetry(n) && isOpen()) {

                        park(Net.POLLIN);

                        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;

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

                if (blocking) {

                    while (IOStatus.okayToRetry(n) && isOpen()) {

                        park(Net.POLLIN);

                        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

     */

    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.

     */

    void endWrite(boolean blocking, boolean completed)

        throws AsynchronousCloseException

    {

        if (blocking) {

            synchronized (stateLock) {

                writerThread = 0;

                if (state == ST_CLOSING) {

                    tryFinishClose();

                }

            }

            // 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);

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

                if (blocking) {

                    while (IOStatus.okayToRetry(n) && isOpen()) {

                        park(Net.POLLOUT);

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

                    }

                }

            } finally {

                endWrite(blocking, n > 0);

                if (n <= 0 && isOutputClosed)

                    throw new AsynchronousCloseException();

            }

            return IOStatus.normalize(n);

        } finally {

            writeLock.unlock();

        }

    }

    @Override

    public long write(ByteBuffer[] srcs, int offset, int length)

        throws IOException

    {

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

        writeLock.lock();

        try {

            boolean blocking = isBlocking();

            long n = 0;

            try {

                beginWrite(blocking);

                n = IOUtil.write(fd, srcs, offset, length, nd);

                if (blocking) {

                    while (IOStatus.okayToRetry(n) && isOpen()) {

                        park(Net.POLLOUT);

                        n = IOUtil.write(fd, srcs, offset, length, nd);

                    }

                }

            } finally {

                endWrite(blocking, n > 0);

                if (n <= 0 && isOutputClosed)

                    throw new AsynchronousCloseException();

            }

            return IOStatus.normalize(n);

        } finally {

            writeLock.unlock();

        }

    }

    @Override

    protected void implConfigureBlocking(boolean block) throws IOException {

        readLock.lock();

        try {

            writeLock.lock();

            try {

                lockedConfigureBlocking(block);

            } finally {

                writeLock.unlock();

            }

        } finally {

            readLock.unlock();

        }

    }

    /**

     * Adjusts the blocking mode. readLock or writeLock must already be held.

     */

    private void lockedConfigureBlocking(boolean block) throws IOException {

        assert readLock.isHeldByCurrentThread() || writeLock.isHeldByCurrentThread();

        synchronized (stateLock) {

            ensureOpen();

            IOUtil.configureBlocking(fd, block);

        }

    }

    /**

     * Adjusts the blocking mode if the channel is open. readLock or writeLock

     * must already be held.

     *

     * @return {@code true} if the blocking mode was adjusted, {@code false} if

     *         the blocking mode was not adjusted because the channel is closed

     */

    private boolean tryLockedConfigureBlocking(boolean block) throws IOException {

        assert readLock.isHeldByCurrentThread() || writeLock.isHeldByCurrentThread();

        synchronized (stateLock) {

            if (isOpen()) {

                IOUtil.configureBlocking(fd, block);

                return true;

            } else {

                return false;

            }

        }

    }

    /**

     * Returns the local address, or null if not bound

     */

    SocketAddress localAddress() {

        synchronized (stateLock) {

            return localAddress;

        }

    }

    /**

     * Returns the remote address, or null if not connected

     */

    SocketAddress remoteAddress() {

        synchronized (stateLock) {

            return remoteAddress;

        }

    }

    @Override

    public boolean isConnected() {

        return (state == ST_CONNECTED);

    }

    @Override

    public boolean isConnectionPending() {

        return (state == ST_CONNECTIONPENDING);

    }

    /**

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

     * @param blocking true if configured blocking

     * @param isa the remote address

     * @throws ClosedChannelException if the channel is closed

     * @throws AlreadyConnectedException if already connected

     * @throws ConnectionPendingException is a connection is pending

     * @throws IOException if the pre-connect hook fails

     */

    private void beginConnect(boolean blocking, SocketAddress sa)

        throws IOException

    {

        if (blocking) {

            // set hook for Thread.interrupt

            begin();

        }

        synchronized (stateLock) {

            ensureOpen();

            int state = this.state;

            if (state == ST_CONNECTED)

                throw new AlreadyConnectedException();

            if (state == ST_CONNECTIONPENDING)

                throw new ConnectionPendingException();