/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.tomcat.util.net;

import java.io.EOFException;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.AsynchronousSocketChannel;
import java.nio.channels.CompletionHandler;
import java.nio.channels.WritePendingException;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.atomic.AtomicInteger;

import javax.net.ssl.SSLEngine;
import javax.net.ssl.SSLEngineResult;
import javax.net.ssl.SSLEngineResult.HandshakeStatus;
import javax.net.ssl.SSLEngineResult.Status;
import javax.net.ssl.SSLException;
import javax.net.ssl.SSLSession;

import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;
import org.apache.tomcat.util.buf.ByteBufferUtils;
import org.apache.tomcat.util.net.TLSClientHelloExtractor.ExtractorResult;
import org.apache.tomcat.util.net.openssl.ciphers.Cipher;
import org.apache.tomcat.util.net.openssl.ciphers.Group;
import org.apache.tomcat.util.net.openssl.ciphers.SignatureScheme;
import org.apache.tomcat.util.res.StringManager;

/**
 * Implementation of a secure socket channel for NIO2.
 */
public class SecureNio2Channel extends Nio2Channel {

    private static final Log log = LogFactory.getLog(SecureNio2Channel.class);
    private static final StringManager sm = StringManager.getManager(SecureNio2Channel.class);

    // Value determined by observation of what the SSL Engine requested in various scenarios
    private static final int DEFAULT_NET_BUFFER_SIZE = 16921;

    // Much longer than it should ever need to be but short enough to trigger connection closure if something goes wrong
    private static final int HANDSHAKE_WRAP_QUEUE_LENGTH_LIMIT = 100;

    protected final Nio2Endpoint endpoint;

    protected ByteBuffer netInBuffer;
    protected ByteBuffer netOutBuffer;

    protected SSLEngine sslEngine;

    protected volatile boolean sniComplete = false;

    private volatile boolean handshakeComplete = false;
    private final AtomicInteger handshakeWrapQueueLength = new AtomicInteger();
    private volatile HandshakeStatus handshakeStatus; // gets set by handshake

    protected boolean closed;
    protected boolean closing;

    private final Map<String,List<String>> additionalTlsAttributes = new HashMap<>();

    private volatile boolean unwrapBeforeRead;
    private final CompletionHandler<Integer,SocketWrapperBase<Nio2Channel>> handshakeReadCompletionHandler;
    private final CompletionHandler<Integer,SocketWrapperBase<Nio2Channel>> handshakeWriteCompletionHandler;

    public SecureNio2Channel(SocketBufferHandler bufHandler, Nio2Endpoint endpoint) {
        super(bufHandler);
        this.endpoint = endpoint;
        if (endpoint.getSocketProperties().getDirectSslBuffer()) {
            netInBuffer = ByteBuffer.allocateDirect(DEFAULT_NET_BUFFER_SIZE);
            netOutBuffer = ByteBuffer.allocateDirect(DEFAULT_NET_BUFFER_SIZE);
        } else {
            netInBuffer = ByteBuffer.allocate(DEFAULT_NET_BUFFER_SIZE);
            netOutBuffer = ByteBuffer.allocate(DEFAULT_NET_BUFFER_SIZE);
        }
        handshakeReadCompletionHandler = new HandshakeReadCompletionHandler();
        handshakeWriteCompletionHandler = new HandshakeWriteCompletionHandler();
    }

    protected void createSSLEngine(String hostName, List<Cipher> clientRequestedCiphers,
            List<String> clientRequestedApplicationProtocols, List<String> clientRequestedProtocols,
            List<Group> clientSupportedGroups, List<SignatureScheme> clientSignatureSchemes) {
        sslEngine = endpoint.createSSLEngine(hostName, clientRequestedCiphers, clientRequestedApplicationProtocols,
                clientRequestedProtocols, clientSupportedGroups, clientSignatureSchemes);
    }


    private class HandshakeReadCompletionHandler implements CompletionHandler<Integer,SocketWrapperBase<Nio2Channel>> {
        @Override
        public void completed(Integer result, SocketWrapperBase<Nio2Channel> attachment) {
            if (result.intValue() < 0) {
                failed(new EOFException(), attachment);
            } else {
                endpoint.processSocket(attachment, SocketEvent.OPEN_READ, false);
            }
        }

        @Override
        public void failed(Throwable exc, SocketWrapperBase<Nio2Channel> attachment) {
            endpoint.processSocket(attachment, SocketEvent.ERROR, false);
        }
    }


    private class HandshakeWriteCompletionHandler implements CompletionHandler<Integer,SocketWrapperBase<Nio2Channel>> {
        @Override
        public void completed(Integer result, SocketWrapperBase<Nio2Channel> attachment) {
            if (result.intValue() < 0) {
                failed(new EOFException(), attachment);
            } else {
                endpoint.processSocket(attachment, SocketEvent.OPEN_WRITE, false);
            }
        }

        @Override
        public void failed(Throwable exc, SocketWrapperBase<Nio2Channel> attachment) {
            endpoint.processSocket(attachment, SocketEvent.ERROR, false);
        }
    }


    @Override
    public void reset(AsynchronousSocketChannel channel, SocketWrapperBase<Nio2Channel> socket) throws IOException {
        super.reset(channel, socket);
        sslEngine = null;
        sniComplete = false;
        handshakeComplete = false;
        handshakeWrapQueueLength.set(0);
        unwrapBeforeRead = true;
        closed = false;
        closing = false;
        netInBuffer.clear();
    }

    @Override
    public void free() {
        super.free();
        if (endpoint.getSocketProperties().getDirectSslBuffer()) {
            ByteBufferUtils.cleanDirectBuffer(netInBuffer);
            ByteBufferUtils.cleanDirectBuffer(netOutBuffer);
        }
    }

    private class FutureFlush implements Future<Boolean> {
        private Future<Integer> integer;
        private Exception e = null;

        protected FutureFlush() {
            try {
                integer = sc.write(netOutBuffer);
            } catch (IllegalStateException e) {
                this.e = e;
            }
        }

        @Override
        public boolean cancel(boolean mayInterruptIfRunning) {
            return e != null || integer.cancel(mayInterruptIfRunning);
        }

        @Override
        public boolean isCancelled() {
            return e != null || integer.isCancelled();
        }

        @Override
        public boolean isDone() {
            return e != null || integer.isDone();
        }

        @Override
        public Boolean get() throws InterruptedException, ExecutionException {
            if (e != null) {
                throw new ExecutionException(e);
            }
            return Boolean.valueOf(integer.get().intValue() >= 0);
        }

        @Override
        public Boolean get(long timeout, TimeUnit unit)
                throws InterruptedException, ExecutionException, TimeoutException {
            if (e != null) {
                throw new ExecutionException(e);
            }
            return Boolean.valueOf(integer.get(timeout, unit).intValue() >= 0);
        }
    }

    /**
     * Flush the channel.
     *
     * @return <code>true</code> if the network buffer has been flushed out and is empty else <code>false</code> (as a
     *             future)
     */
    @Override
    public Future<Boolean> flush() {
        return new FutureFlush();
    }

    /**
     * Performs SSL handshake, non-blocking, but performs NEED_TASK on the same thread. Hence, you should never call
     * this method using your Acceptor thread, as you would slow down your system significantly.
     * <p>
     * The return for this operation is 0 if the handshake is complete and a positive value if it is not complete. In
     * the event of a positive value coming back, the appropriate read/write will already have been called with an
     * appropriate CompletionHandler.
     *
     * @return 0 if hand shake is complete, negative if the socket needs to close and positive if the handshake is
     *             incomplete
     *
     * @throws IOException if an error occurs during the handshake
     */
    @Override
    public int handshake() throws IOException {
        return handshakeInternal(true);
    }

    protected int handshakeInternal(boolean async) throws IOException {
        if (handshakeComplete) {
            return 0; // we have done our initial handshake
        }

        if (!sniComplete) {
            int sniResult = processSNI();
            if (sniResult == 0) {
                sniComplete = true;
            } else {
                return sniResult;
            }
        }

        SSLEngineResult handshake;
        long timeout = endpoint.getConnectionTimeout();

        while (!handshakeComplete) {
            switch (handshakeStatus) {
                case NOT_HANDSHAKING: {
                    // should never happen
                    throw new IOException(sm.getString("channel.nio.ssl.notHandshaking"));
                }
                case FINISHED: {
                    if (endpoint.hasNegotiableProtocols()) {
                        if (sslEngine instanceof SSLUtil.ProtocolInfo) {
                            socketWrapper
                                    .setNegotiatedProtocol(((SSLUtil.ProtocolInfo) sslEngine).getNegotiatedProtocol());
                        } else {
                            socketWrapper.setNegotiatedProtocol(sslEngine.getApplicationProtocol());
                        }
                    }
                    // we are complete if we have delivered the last package
                    handshakeComplete = !netOutBuffer.hasRemaining();
                    // return 0 if we are complete, otherwise we still have data to write
                    if (handshakeComplete) {
                        return 0;
                    } else {
                        if (async) {
                            sc.write(netOutBuffer, AbstractEndpoint.toTimeout(timeout), TimeUnit.MILLISECONDS,
                                    socketWrapper, handshakeWriteCompletionHandler);
                        } else {
                            try {
                                if (timeout > 0) {
                                    sc.write(netOutBuffer).get(timeout, TimeUnit.MILLISECONDS);
                                } else {
                                    sc.write(netOutBuffer).get();
                                }
                            } catch (InterruptedException | ExecutionException | TimeoutException e) {
                                throw new IOException(sm.getString("channel.nio.ssl.handshakeError"));
                            }
                        }
                        return 1;
                    }
                }
                case NEED_WRAP: {
                    // perform the wrap function
                    try {
                        handshake = handshakeWrap();
                    } catch (SSLException e) {
                        handshake = handshakeWrap();
                        throw e;
                    }
                    if (handshake.getStatus() == Status.OK) {
                        if (handshakeStatus == HandshakeStatus.NEED_TASK) {
                            handshakeStatus = tasks();
                        }
                    } else if (handshake.getStatus() == Status.CLOSED) {
                        return -1;
                    } else {
                        // wrap should always work with our buffers
                        throw new IOException(
                                sm.getString("channel.nio.ssl.unexpectedStatusDuringWrap", handshake.getStatus()));
                    }
                    if (handshakeStatus != HandshakeStatus.NEED_UNWRAP || netOutBuffer.remaining() > 0) {
                        // should actually return OP_READ if we have NEED_UNWRAP
                        if (async) {
                            sc.write(netOutBuffer, AbstractEndpoint.toTimeout(timeout), TimeUnit.MILLISECONDS,
                                    socketWrapper, handshakeWriteCompletionHandler);
                        } else {
                            try {
                                if (timeout > 0) {
                                    sc.write(netOutBuffer).get(timeout, TimeUnit.MILLISECONDS);
                                } else {
                                    sc.write(netOutBuffer).get();
                                }
                            } catch (InterruptedException | ExecutionException | TimeoutException e) {
                                throw new IOException(sm.getString("channel.nio.ssl.handshakeError"));
                            }
                        }
                        return 1;
                    }
                    // fall down to NEED_UNWRAP on the same call, will result in a
                    // BUFFER_UNDERFLOW if it needs data
                }
                //$FALL-THROUGH$
                case NEED_UNWRAP: {
                    // perform the unwrap function
                    handshake = handshakeUnwrap();
                    if (handshake.getStatus() == Status.OK) {
                        if (handshakeStatus == HandshakeStatus.NEED_TASK) {
                            handshakeStatus = tasks();
                        }
                    } else if (handshake.getStatus() == Status.BUFFER_UNDERFLOW) {
                        // read more data
                        if (async) {
                            sc.read(netInBuffer, AbstractEndpoint.toTimeout(timeout), TimeUnit.MILLISECONDS,
                                    socketWrapper, handshakeReadCompletionHandler);
                        } else {
                            try {
                                int read;
                                if (timeout > 0) {
                                    read = sc.read(netInBuffer).get(timeout, TimeUnit.MILLISECONDS).intValue();
                                } else {
                                    read = sc.read(netInBuffer).get().intValue();
                                }
                                if (read == -1) {
                                    throw new EOFException();
                                }
                            } catch (InterruptedException | ExecutionException | TimeoutException e) {
                                throw new IOException(sm.getString("channel.nio.ssl.handshakeError"));
                            }
                        }
                        return 1;
                    } else {
                        throw new IOException(
                                sm.getString("channel.nio.ssl.unexpectedStatusDuringUnwrap", handshake.getStatus()));
                    }
                    break;
                }
                case NEED_TASK: {
                    handshakeStatus = tasks();
                    break;
                }
                default:
                    throw new IllegalStateException(sm.getString("channel.nio.ssl.invalidStatus", handshakeStatus));
            }
        }
        // return 0 if we are complete, otherwise recurse to process the task
        return handshakeComplete ? 0 : handshakeInternal(async);
    }


    /*
     * Peeks at the initial network bytes to determine if the SNI extension is present and, if it is, what host name has
     * been requested. Based on the provided host name, configure the SSLEngine for this connection.
     */
    protected int processSNI() throws IOException {
        // If there is no data to process, trigger a read immediately. This is
        // an optimisation for the typical case so we don't create an
        // SNIExtractor only to discover there is no data to process
        if (netInBuffer.position() == 0) {
            sc.read(netInBuffer, AbstractEndpoint.toTimeout(endpoint.getConnectionTimeout()), TimeUnit.MILLISECONDS,
                    socketWrapper, handshakeReadCompletionHandler);
            return 1;
        }

        TLSClientHelloExtractor extractor = new TLSClientHelloExtractor(netInBuffer);

        if (extractor.getResult() == ExtractorResult.UNDERFLOW &&
                netInBuffer.capacity() < endpoint.getSniParseLimit()) {
            // extractor needed more data to process but netInBuffer was full so
            // expand the buffer and read some more data.
            int newLimit = Math.min(netInBuffer.capacity() * 2, endpoint.getSniParseLimit());
            log.info(sm.getString("channel.nio.ssl.expandNetInBuffer", Integer.toString(newLimit)));

            netInBuffer = ByteBufferUtils.expand(netInBuffer, newLimit);
            sc.read(netInBuffer, AbstractEndpoint.toTimeout(endpoint.getConnectionTimeout()), TimeUnit.MILLISECONDS,
                    socketWrapper, handshakeReadCompletionHandler);
            return 1;
        }

        String hostName = null;
        List<Cipher> clientRequestedCiphers = null;
        List<String> clientRequestedApplicationProtocols = null;
        List<Group> clientSupportedGroups = null;
        List<SignatureScheme> clientSignatureSchemes = null;
        switch (extractor.getResult()) {
            case COMPLETE:
                hostName = extractor.getSNIValue();
                clientRequestedApplicationProtocols = extractor.getClientRequestedApplicationProtocols();
                //$FALL-THROUGH$ to set the client requested ciphers
            case NOT_PRESENT:
                clientRequestedCiphers = extractor.getClientRequestedCiphers();
                clientSupportedGroups = extractor.getClientSupportedGroups();
                clientSignatureSchemes = extractor.getClientSignatureSchemes();
                break;
            case NEED_READ:
                sc.read(netInBuffer, AbstractEndpoint.toTimeout(endpoint.getConnectionTimeout()), TimeUnit.MILLISECONDS,
                        socketWrapper, handshakeReadCompletionHandler);
                return 1;
            case UNDERFLOW:
                // Unable to buffer enough data to read SNI extension data
                if (log.isDebugEnabled()) {
                    log.debug(sm.getString("channel.nio.ssl.sniDefault"));
                }
                hostName = endpoint.getDefaultSSLHostConfigName();
                clientRequestedCiphers = Collections.emptyList();
                break;
            case NON_SECURE:
                netOutBuffer.clear();
                netOutBuffer.put(TLSClientHelloExtractor.USE_TLS_RESPONSE);
                netOutBuffer.flip();
                flush();
                throw new IOException(sm.getString("channel.nio.ssl.foundHttp"));
        }

        if (log.isTraceEnabled()) {
            log.trace(sm.getString("channel.nio.ssl.sniHostName", sc, hostName));
        }

        createSSLEngine(hostName, clientRequestedCiphers, clientRequestedApplicationProtocols,
                extractor.getClientRequestedProtocols(), clientSupportedGroups, clientSignatureSchemes);

        // Populate additional TLS attributes obtained from the handshake that
        // aren't available from the session
        additionalTlsAttributes.put(SSLSupport.REQUESTED_PROTOCOL_VERSIONS_KEY,
                extractor.getClientRequestedProtocols());
        additionalTlsAttributes.put(SSLSupport.REQUESTED_CIPHERS_KEY, extractor.getClientRequestedCipherNames());

        // Ensure the application buffers (which have to be created earlier) are
        // big enough.
        getBufHandler().expand(sslEngine.getSession().getApplicationBufferSize());
        if (netOutBuffer.capacity() < sslEngine.getSession().getApplicationBufferSize()) {
            // Info for now as we may need to increase DEFAULT_NET_BUFFER_SIZE
            log.info(sm.getString("channel.nio.ssl.expandNetOutBuffer",
                    Integer.toString(sslEngine.getSession().getApplicationBufferSize())));
        }
        netInBuffer = ByteBufferUtils.expand(netInBuffer, sslEngine.getSession().getPacketBufferSize());
        netOutBuffer = ByteBufferUtils.expand(netOutBuffer, sslEngine.getSession().getPacketBufferSize());

        // Set limit and position to expected values
        netOutBuffer.position(0);
        netOutBuffer.limit(0);

        // Initiate handshake
        sslEngine.beginHandshake();
        handshakeStatus = sslEngine.getHandshakeStatus();

        return 0;
    }


    /**
     * Force a blocking handshake to take place for this key. This requires that both network and application buffers
     * have been emptied out prior to this call taking place, or a IOException will be thrown.
     *
     * @throws IOException                     - if an IO exception occurs or if application or network buffers contain
     *                                             data
     * @throws java.net.SocketTimeoutException - if a socket operation timed out
     */
    public void rehandshake() throws IOException {
        // validate the network buffers are empty
        if (netInBuffer.position() > 0 && netInBuffer.position() < netInBuffer.limit()) {
            throw new IOException(sm.getString("channel.nio.ssl.netInputNotEmpty"));
        }
        if (netOutBuffer.position() > 0 && netOutBuffer.position() < netOutBuffer.limit()) {
            throw new IOException(sm.getString("channel.nio.ssl.netOutputNotEmpty"));
        }
        if (!getBufHandler().isReadBufferEmpty()) {
            throw new IOException(sm.getString("channel.nio.ssl.appInputNotEmpty"));
        }
        if (!getBufHandler().isWriteBufferEmpty()) {
            throw new IOException(sm.getString("channel.nio.ssl.appOutputNotEmpty"));
        }

        netOutBuffer.position(0);
        netOutBuffer.limit(0);
        netInBuffer.position(0);
        netInBuffer.limit(0);
        getBufHandler().reset();

        handshakeComplete = false;
        // initiate handshake
        sslEngine.beginHandshake();
        handshakeStatus = sslEngine.getHandshakeStatus();

        boolean handshaking = true;
        try {
            while (handshaking) {
                int hsStatus = handshakeInternal(false);
                switch (hsStatus) {
                    case -1:
                        throw new EOFException(sm.getString("channel.nio.ssl.eofDuringHandshake"));
                    case 0:
                        handshaking = false;
                        break;
                    default: // Some blocking IO occurred, so iterate
                }
            }
        } catch (IOException x) {
            closeSilently();
            throw x;
        } catch (Exception cx) {
            closeSilently();
            throw new IOException(cx);
        }
    }


    /**
     * Executes all the tasks needed on the same thread.
     *
     * @return the status
     */
    protected SSLEngineResult.HandshakeStatus tasks() {
        Runnable r;
        while ((r = sslEngine.getDelegatedTask()) != null) {
            r.run();
        }
        return sslEngine.getHandshakeStatus();
    }

    /**
     * Performs the WRAP function
     *
     * @return the result
     *
     * @throws IOException An IO error occurred
     */
    protected SSLEngineResult handshakeWrap() throws IOException {
        // this should never be called with a network buffer that contains data
        // so we can clear it here.
        netOutBuffer.clear();
        // perform the wrap
        getBufHandler().configureWriteBufferForRead();
        SSLEngineResult result = sslEngine.wrap(getBufHandler().getWriteBuffer(), netOutBuffer);
        // prepare the results to be written
        netOutBuffer.flip();
        // set the status
        handshakeStatus = result.getHandshakeStatus();
        return result;
    }

    /**
     * Perform handshake unwrap
     *
     * @return the result
     *
     * @throws IOException An IO error occurred
     */
    protected SSLEngineResult handshakeUnwrap() throws IOException {
        SSLEngineResult result;
        boolean cont;
        // loop while we can perform pure SSLEngine data
        do {
            // prepare the buffer with the incoming data
            netInBuffer.flip();
            // call unwrap
            getBufHandler().configureReadBufferForWrite();
            result = sslEngine.unwrap(netInBuffer, getBufHandler().getReadBuffer());
            /*
             * ByteBuffer.compact() is an optional method but netInBuffer is created from either ByteBuffer.allocate()
             * or ByteBuffer.allocateDirect() and the ByteBuffers returned by those methods do implement compact(). The
             * ByteBuffer must be in 'read from' mode when compact() is called and will be in 'write to' mode
             * afterwards.
             */
            netInBuffer.compact();
            // read in the status
            handshakeStatus = result.getHandshakeStatus();
            if (result.getStatus() == SSLEngineResult.Status.OK &&
                    result.getHandshakeStatus() == HandshakeStatus.NEED_TASK) {
                // execute tasks if we need to
                handshakeStatus = tasks();
            }
            // perform another unwrap?
            cont = result.getStatus() == SSLEngineResult.Status.OK && handshakeStatus == HandshakeStatus.NEED_UNWRAP;
        } while (cont);
        return result;
    }

    public SSLSupport getSSLSupport() {
        if (sslEngine != null) {
            SSLSession session = sslEngine.getSession();
            return endpoint.getSslImplementation().getSSLSupport(session, additionalTlsAttributes);
        }
        return null;
    }

    /**
     * Sends an SSL close message, will not physically close the connection here.<br>
     * To close the connection, you could do something like
     *
     * <pre>
     * <code>
     *   close();
     *   while (isOpen() &amp;&amp; !myTimeoutFunction()) Thread.sleep(25);
     *   if ( isOpen() ) close(true); //forces a close if you timed out
     * </code>
     * </pre>
     *
     * @throws IOException if an I/O error occurs
     * @throws IOException if there is data on the outgoing network buffer, and we are unable to flush it
     */
    @Override
    public void close() throws IOException {
        if (closing) {
            return;
        }
        closing = true;
        if (sslEngine == null) {
            netOutBuffer.clear();
            closed = true;
            return;
        }
        sslEngine.closeOutbound();
        long timeout = endpoint.getConnectionTimeout();

        try {
            if (timeout > 0) {
                if (!flush().get(timeout, TimeUnit.MILLISECONDS).booleanValue()) {
                    closeSilently();
                    throw new IOException(sm.getString("channel.nio.ssl.remainingDataDuringClose"));
                }
            } else {
                if (!flush().get().booleanValue()) {
                    closeSilently();
                    throw new IOException(sm.getString("channel.nio.ssl.remainingDataDuringClose"));
                }
            }
        } catch (InterruptedException | ExecutionException | TimeoutException e) {
            closeSilently();
            throw new IOException(sm.getString("channel.nio.ssl.remainingDataDuringClose"), e);
        } catch (WritePendingException e) {
            closeSilently();
            throw new IOException(sm.getString("channel.nio.ssl.pendingWriteDuringClose"), e);
        }
        // prep the buffer for the close message
        netOutBuffer.clear();
        // perform the close, since we called sslEngine.closeOutbound
        SSLEngineResult handshake = sslEngine.wrap(getEmptyBuf(), netOutBuffer);
        // we should be in a close state
        if (handshake.getStatus() != SSLEngineResult.Status.CLOSED) {
            throw new IOException(sm.getString("channel.nio.ssl.invalidCloseState"));
        }
        // prepare the buffer for writing
        netOutBuffer.flip();
        // if there is data to be written
        try {
            if (timeout > 0) {
                if (!flush().get(timeout, TimeUnit.MILLISECONDS).booleanValue()) {
                    closeSilently();
                    throw new IOException(sm.getString("channel.nio.ssl.remainingDataDuringClose"));
                }
            } else {
                if (!flush().get().booleanValue()) {
                    closeSilently();
                    throw new IOException(sm.getString("channel.nio.ssl.remainingDataDuringClose"));
                }
            }
        } catch (InterruptedException | ExecutionException | TimeoutException e) {
            closeSilently();
            throw new IOException(sm.getString("channel.nio.ssl.remainingDataDuringClose"), e);
        } catch (WritePendingException e) {
            closeSilently();
            throw new IOException(sm.getString("channel.nio.ssl.pendingWriteDuringClose"), e);
        }

        // is the channel closed?
        closed = (!netOutBuffer.hasRemaining() && (handshake.getHandshakeStatus() != HandshakeStatus.NEED_WRAP));
    }


    @Override
    public void close(boolean force) throws IOException {
        try {
            close();
        } finally {
            if (force || closed) {
                closed = true;
                sc.close();
            }
        }
    }


    private void closeSilently() {
        try {
            close(true);
        } catch (IOException ioe) {
            // This is expected - swallowing the exception is the reason this
            // method exists. Log at debug in case someone is interested.
            log.debug(sm.getString("channel.nio.ssl.closeSilentError"), ioe);
        }
    }


    private class FutureRead implements Future<Integer> {
        private ByteBuffer dst;
        private Future<Integer> integer;

        private FutureRead(ByteBuffer dst) {
            this.dst = dst;
            if (unwrapBeforeRead || netInBuffer.position() > 0) {
                this.integer = null;
            } else {
                this.integer = sc.read(netInBuffer);
            }
        }

        @Override
        public boolean cancel(boolean mayInterruptIfRunning) {
            return integer != null && integer.cancel(mayInterruptIfRunning);
        }

        @Override
        public boolean isCancelled() {
            return integer != null && integer.isCancelled();
        }

        @Override
        public boolean isDone() {
            return integer == null || integer.isDone();
        }

        @Override
        public Integer get() throws InterruptedException, ExecutionException {
            try {
                return (integer == null) ? unwrap(netInBuffer.position(), -1, TimeUnit.MILLISECONDS) :
                        unwrap(integer.get().intValue(), -1, TimeUnit.MILLISECONDS);
            } catch (TimeoutException e) {
                // Cannot happen: no timeout
                throw new ExecutionException(e);
            }
        }

        @Override
        public Integer get(long timeout, TimeUnit unit)
                throws InterruptedException, ExecutionException, TimeoutException {
            return (integer == null) ? unwrap(netInBuffer.position(), timeout, unit) :
                    unwrap(integer.get(timeout, unit).intValue(), timeout, unit);
        }

        private Integer unwrap(int nRead, long timeout, TimeUnit unit)
                throws ExecutionException, TimeoutException, InterruptedException {
            // are we in the middle of closing or closed?
            if (closing || closed) {
                return Integer.valueOf(-1);
            }
            // did we reach EOF? if so send EOF up one layer.
            if (nRead < 0) {
                return Integer.valueOf(-1);
            }
            // the data read
            int read = 0;
            // the SSL engine result
            SSLEngineResult unwrap;
            do {
                // prepare the buffer
                netInBuffer.flip();
                // unwrap the data
                try {
                    unwrap = sslEngine.unwrap(netInBuffer, dst);
                } catch (SSLException e) {
                    throw new ExecutionException(e);
                }
                // compact the buffer
                netInBuffer.compact();
                if (unwrap.getStatus() == Status.OK || unwrap.getStatus() == Status.BUFFER_UNDERFLOW) {
                    // we did receive some data, add it to our total
                    read += unwrap.bytesProduced();
                    // perform any tasks if needed
                    if (unwrap.getHandshakeStatus() == HandshakeStatus.NEED_TASK) {
                        tasks();
                    } else if (unwrap.getHandshakeStatus() == HandshakeStatus.NEED_WRAP) {
                        if (handshakeWrapQueueLength.incrementAndGet() > HANDSHAKE_WRAP_QUEUE_LENGTH_LIMIT) {
                            throw new ExecutionException(
                                    new IOException(sm.getString("channel.nio.ssl.handshakeWrapQueueTooLong")));
                        }
                    }
                    // if we need more network data, then bail out for now.
                    if (unwrap.getStatus() == Status.BUFFER_UNDERFLOW) {
                        if (read == 0) {
                            integer = sc.read(netInBuffer);
                            if (timeout > 0) {
                                return unwrap(integer.get(timeout, unit).intValue(), timeout, unit);
                            } else {
                                return unwrap(integer.get().intValue(), -1, TimeUnit.MILLISECONDS);
                            }
                        } else {
                            break;
                        }
                    }
                } else if (unwrap.getStatus() == Status.BUFFER_OVERFLOW) {
                    if (read > 0) {
                        // Buffer overflow can happen if we have read data. Return
                        // so the destination buffer can be emptied before another
                        // read is attempted
                        break;
                    } else {
                        // The SSL session has increased the required buffer size
                        // since the buffer was created.
                        if (dst == getBufHandler().getReadBuffer()) {
                            // This is the normal case for this code
                            getBufHandler().expand(sslEngine.getSession().getApplicationBufferSize());
                            dst = getBufHandler().getReadBuffer();
                        } else if (dst == getAppReadBufHandler().getByteBuffer()) {
                            getAppReadBufHandler().expand(sslEngine.getSession().getApplicationBufferSize());
                            dst = getAppReadBufHandler().getByteBuffer();
                        } else {
                            // Can't expand the buffer as there is no way to signal
                            // to the caller that the buffer has been replaced.
                            throw new ExecutionException(new IOException(
                                    sm.getString("channel.nio.ssl.unwrapFailResize", unwrap.getStatus())));
                        }
                    }
                } else {
                    // Something else went wrong
                    throw new ExecutionException(
                            new IOException(sm.getString("channel.nio.ssl.unwrapFail", unwrap.getStatus())));
                }
            } while (netInBuffer.position() != 0); // continue to unwrapping as long as the input buffer has stuff
            unwrapBeforeRead = !dst.hasRemaining();
            return Integer.valueOf(read);
        }
    }

    /**
     * Reads a sequence of bytes from this channel into the given buffer.
     *
     * @param dst The buffer into which bytes are to be transferred
     *
     * @return The number of bytes read, possibly zero, or <code>-1</code> if the channel has reached end-of-stream
     *
     * @throws IllegalStateException if the handshake was not completed
     */
    @Override
    public Future<Integer> read(ByteBuffer dst) {
        if (!handshakeComplete) {
            throw new IllegalStateException(sm.getString("channel.nio.ssl.incompleteHandshake"));
        }
        return new FutureRead(dst);
    }

    private class FutureWrite implements Future<Integer> {
        private final ByteBuffer src;
        private Future<Integer> integer = null;
        private int written = 0;
        private Throwable t = null;

        private FutureWrite(ByteBuffer src) {
            this.src = src;
            // are we closing or closed?
            if (closing || closed) {
                t = new IOException(sm.getString("channel.nio.ssl.closing"));
            } else {
                wrap();
            }
        }

        @Override
        public boolean cancel(boolean mayInterruptIfRunning) {
            return integer.cancel(mayInterruptIfRunning);
        }

        @Override
        public boolean isCancelled() {
            return integer.isCancelled();
        }

        @Override
        public boolean isDone() {
            return integer.isDone();
        }

        @Override
        public Integer get() throws InterruptedException, ExecutionException {
            if (t != null) {
                throw new ExecutionException(t);
            }
            if (integer.get().intValue() > 0 && written == 0) {
                wrap();
                return get();
            } else if (netOutBuffer.hasRemaining()) {
                integer = sc.write(netOutBuffer);
                return get();
            } else {
                return Integer.valueOf(written);
            }
        }

        @Override
        public Integer get(long timeout, TimeUnit unit)
                throws InterruptedException, ExecutionException, TimeoutException {
            if (t != null) {
                throw new ExecutionException(t);
            }
            if (integer.get(timeout, unit).intValue() > 0 && written == 0) {
                wrap();
                return get(timeout, unit);
            } else if (netOutBuffer.hasRemaining()) {
                integer = sc.write(netOutBuffer);
                return get(timeout, unit);
            } else {
                return Integer.valueOf(written);
            }
        }

        protected void wrap() {
            try {
                if (!netOutBuffer.hasRemaining()) {
                    netOutBuffer.clear();
                    SSLEngineResult result = sslEngine.wrap(src, netOutBuffer);
                    // Call to wrap() will have included any required handshake data
                    handshakeWrapQueueLength.set(0);
                    written = result.bytesConsumed();
                    netOutBuffer.flip();
                    if (result.getStatus() == Status.OK) {
                        if (result.getHandshakeStatus() == HandshakeStatus.NEED_TASK) {
                            tasks();
                        }
                    } else {
                        t = new IOException(sm.getString("channel.nio.ssl.wrapFail", result.getStatus()));
                    }
                }
                integer = sc.write(netOutBuffer);
            } catch (SSLException e) {
                t = e;
            }
        }
    }

    /**
     * Writes a sequence of bytes to this channel from the given buffer.
     *
     * @param src The buffer from which bytes are to be retrieved
     *
     * @return The number of bytes written, possibly zero
     */
    @Override
    public Future<Integer> write(ByteBuffer src) {
        return new FutureWrite(src);
    }

    @Override
    public <A> void read(final ByteBuffer dst, final long timeout, final TimeUnit unit, final A attachment,
            final CompletionHandler<Integer,? super A> handler) {
        // Check state
        if (closing || closed) {
            handler.completed(Integer.valueOf(-1), attachment);
            return;
        }
        if (!handshakeComplete) {
            throw new IllegalStateException(sm.getString("channel.nio.ssl.incompleteHandshake"));
        }
        CompletionHandler<Integer,A> readCompletionHandler = new CompletionHandler<>() {
            @Override
            public void completed(Integer nBytes, A attach) {
                if (nBytes.intValue() < 0) {
                    failed(new EOFException(), attach);
                } else {
                    try {
                        ByteBuffer dst2 = dst;
                        // the data read
                        int read = 0;
                        // the SSL engine result
                        SSLEngineResult unwrap;
                        do {
                            // prepare the buffer
                            netInBuffer.flip();
                            // unwrap the data
                            unwrap = sslEngine.unwrap(netInBuffer, dst2);
                            // compact the buffer
                            netInBuffer.compact();
                            if (unwrap.getStatus() == Status.OK || unwrap.getStatus() == Status.BUFFER_UNDERFLOW) {
                                // we did receive some data, add it to our total
                                read += unwrap.bytesProduced();
                                // perform any tasks if needed
                                if (unwrap.getHandshakeStatus() == HandshakeStatus.NEED_TASK) {
                                    tasks();
                                } else if (unwrap.getHandshakeStatus() == HandshakeStatus.NEED_WRAP) {
                                    if (handshakeWrapQueueLength
                                            .incrementAndGet() > HANDSHAKE_WRAP_QUEUE_LENGTH_LIMIT) {
                                        throw new ExecutionException(new IOException(
                                                sm.getString("channel.nio.ssl.handshakeWrapQueueTooLong")));
                                    }
                                }
                                // if we need more network data, then bail out for now.
                                if (unwrap.getStatus() == Status.BUFFER_UNDERFLOW) {
                                    if (read == 0) {
                                        sc.read(netInBuffer, timeout, unit, attachment, this);
                                        return;
                                    } else {
                                        break;
                                    }
                                }
                            } else if (unwrap.getStatus() == Status.BUFFER_OVERFLOW) {
                                if (read > 0) {
                                    // Buffer overflow can happen if we have read data. Return
                                    // so the destination buffer can be emptied before another
                                    // read is attempted
                                    break;
                                } else {
                                    // The SSL session has increased the required buffer size
                                    // since the buffer was created.
                                    if (dst2 == getBufHandler().getReadBuffer()) {
                                        // This is the normal case for this code
                                        getBufHandler().expand(sslEngine.getSession().getApplicationBufferSize());
                                        dst2 = getBufHandler().getReadBuffer();
                                    } else if (getAppReadBufHandler() != null &&
                                            dst2 == getAppReadBufHandler().getByteBuffer()) {
                                        getAppReadBufHandler()
                                                .expand(sslEngine.getSession().getApplicationBufferSize());
                                        dst2 = getAppReadBufHandler().getByteBuffer();
                                    } else {
                                        // Can't expand the buffer as there is no way to signal
                                        // to the caller that the buffer has been replaced.
                                        throw new IOException(
                                                sm.getString("channel.nio.ssl.unwrapFailResize", unwrap.getStatus()));
                                    }
                                }
                            } else {
                                // Something else went wrong
                                throw new IOException(sm.getString("channel.nio.ssl.unwrapFail", unwrap.getStatus()));
                            }
                            // continue to unwrap as long as the input buffer has stuff
                        } while (netInBuffer.position() != 0);
                        unwrapBeforeRead = !dst2.hasRemaining();
                        // If everything is OK, so complete
                        handler.completed(Integer.valueOf(read), attach);
                    } catch (Exception e) {
                        failed(e, attach);
                    }
                }
            }

            @Override
            public void failed(Throwable exc, A attach) {
                handler.failed(exc, attach);
            }
        };
        if (unwrapBeforeRead || netInBuffer.position() > 0) {
            readCompletionHandler.completed(Integer.valueOf(netInBuffer.position()), attachment);
        } else {
            sc.read(netInBuffer, timeout, unit, attachment, readCompletionHandler);
        }
    }

    @Override
    public <A> void read(final ByteBuffer[] dsts, final int offset, final int length, final long timeout,
            final TimeUnit unit, final A attachment, final CompletionHandler<Long,? super A> handler) {
        if (offset < 0 || dsts == null || (offset + length) > dsts.length) {
            throw new IllegalArgumentException();
        }
        if (closing || closed) {
            handler.completed(Long.valueOf(-1), attachment);
            return;
        }
        if (!handshakeComplete) {
            throw new IllegalStateException(sm.getString("channel.nio.ssl.incompleteHandshake"));
        }
        CompletionHandler<Integer,A> readCompletionHandler = new CompletionHandler<>() {
            @Override
            public void completed(Integer nBytes, A attach) {
                if (nBytes.intValue() < 0) {
                    failed(new EOFException(), attach);
                } else {
                    try {
                        // the data read
                        long read = 0;
                        // the SSL engine result
                        SSLEngineResult unwrap;
                        ByteBuffer[] dsts2 = dsts;
                        int length2 = length;
                        OverflowState overflowState = OverflowState.NONE;
                        do {
                            if (overflowState == OverflowState.PROCESSING) {
                                overflowState = OverflowState.DONE;
                            }
                            // prepare the buffer
                            netInBuffer.flip();
                            // unwrap the data
                            unwrap = sslEngine.unwrap(netInBuffer, dsts2, offset, length2);
                            // compact the buffer
                            netInBuffer.compact();
                            if (unwrap.getStatus() == Status.OK || unwrap.getStatus() == Status.BUFFER_UNDERFLOW) {
                                // we did receive some data, add it to our total
                                read += unwrap.bytesProduced();
                                if (overflowState == OverflowState.DONE) {
                                    // Remove the data read into the overflow buffer
                                    read -= getBufHandler().getReadBuffer().position();
                                }
                                // perform any tasks if needed
                                if (unwrap.getHandshakeStatus() == HandshakeStatus.NEED_TASK) {
                                    tasks();
                                } else if (unwrap.getHandshakeStatus() == HandshakeStatus.NEED_WRAP) {
                                    if (handshakeWrapQueueLength
                                            .incrementAndGet() > HANDSHAKE_WRAP_QUEUE_LENGTH_LIMIT) {
                                        throw new ExecutionException(new IOException(
                                                sm.getString("channel.nio.ssl.handshakeWrapQueueTooLong")));
                                    }
                                }
                                // if we need more network data, then bail out for now.
                                if (unwrap.getStatus() == Status.BUFFER_UNDERFLOW) {
                                    if (read == 0) {
                                        sc.read(netInBuffer, timeout, unit, attachment, this);
                                        return;
                                    } else {
                                        break;
                                    }
                                }
                            } else if (unwrap.getStatus() == Status.BUFFER_OVERFLOW && read > 0) {
                                // buffer overflow can happen, if we have read data, then
                                // empty out the dst buffer before we do another read
                                break;
                            } else if (unwrap.getStatus() == Status.BUFFER_OVERFLOW) {
                                // here we should trap BUFFER_OVERFLOW and call expand on the buffer
                                // for now, throw an exception, as we initialized the buffers
                                // in the constructor
                                ByteBuffer readBuffer = getBufHandler().getReadBuffer();
                                boolean found = false;
                                boolean resized = true;
                                for (int i = 0; i < length2; i++) {
                                    // The SSL session has increased the required buffer size
                                    // since the buffer was created.
                                    if (dsts[offset + i] == getBufHandler().getReadBuffer()) {
                                        getBufHandler().expand(sslEngine.getSession().getApplicationBufferSize());
                                        if (dsts[offset + i] == getBufHandler().getReadBuffer()) {
                                            resized = false;
                                        }
                                        dsts[offset + i] = getBufHandler().getReadBuffer();
                                        found = true;
                                    } else if (getAppReadBufHandler() != null &&
                                            dsts[offset + i] == getAppReadBufHandler().getByteBuffer()) {
                                        getAppReadBufHandler()
                                                .expand(sslEngine.getSession().getApplicationBufferSize());
                                        if (dsts[offset + i] == getAppReadBufHandler().getByteBuffer()) {
                                            resized = false;
                                        }
                                        dsts[offset + i] = getAppReadBufHandler().getByteBuffer();
                                        found = true;
                                    }
                                }
                                if (found) {
                                    if (!resized) {
                                        throw new IOException(
                                                sm.getString("channel.nio.ssl.unwrapFail", unwrap.getStatus()));
                                    }
                                } else {
                                    // Add the main read buffer in the destinations and try again
                                    dsts2 = new ByteBuffer[dsts.length + 1];
                                    int dstOffset = 0;
                                    for (int i = 0; i < dsts.length + 1; i++) {
                                        if (i == offset + length) {
                                            dsts2[i] = readBuffer;
                                            dstOffset = -1;
                                        } else {
                                            dsts2[i] = dsts[i + dstOffset];
                                        }
                                    }
                                    length2 = length + 1;
                                    getBufHandler().configureReadBufferForWrite();
                                    overflowState = OverflowState.PROCESSING;
                                }
                            } else if (unwrap.getStatus() == Status.CLOSED) {
                                break;
                            } else {
                                throw new IOException(sm.getString("channel.nio.ssl.unwrapFail", unwrap.getStatus()));
                            }
                        } while ((netInBuffer.position() != 0 || overflowState == OverflowState.PROCESSING) &&
                                overflowState != OverflowState.DONE);
                        int capacity = 0;
                        final int endOffset = offset + length;
                        for (int i = offset; i < endOffset; i++) {
                            capacity += dsts[i].remaining();
                        }
                        unwrapBeforeRead = capacity == 0;
                        // If everything is OK, so complete
                        handler.completed(Long.valueOf(read), attach);
                    } catch (Exception e) {
                        failed(e, attach);
                    }
                }
            }

            @Override
            public void failed(Throwable exc, A attach) {
                handler.failed(exc, attach);
            }
        };
        if (unwrapBeforeRead || netInBuffer.position() > 0) {
            readCompletionHandler.completed(Integer.valueOf(netInBuffer.position()), attachment);
        } else {
            sc.read(netInBuffer, timeout, unit, attachment, readCompletionHandler);
        }
    }

    @Override
    public <A> void write(final ByteBuffer src, final long timeout, final TimeUnit unit, final A attachment,
            final CompletionHandler<Integer,? super A> handler) {
        // Check state
        if (closing || closed) {
            handler.failed(new IOException(sm.getString("channel.nio.ssl.closing")), attachment);
            return;
        }
        try {
            // Prepare the output buffer
            netOutBuffer.clear();
            // Wrap the source data into the internal buffer
            SSLEngineResult result = sslEngine.wrap(src, netOutBuffer);
            // Call to wrap() will have included any required handshake data
            handshakeWrapQueueLength.set(0);
            final int written = result.bytesConsumed();
            netOutBuffer.flip();
            if (result.getStatus() == Status.OK) {
                if (result.getHandshakeStatus() == HandshakeStatus.NEED_TASK) {
                    tasks();
                }
                // Write data to the channel
                sc.write(netOutBuffer, timeout, unit, attachment, new CompletionHandler<>() {
                    @Override
                    public void completed(Integer nBytes, A attach) {
                        if (nBytes.intValue() < 0) {
                            failed(new EOFException(), attach);
                        } else if (netOutBuffer.hasRemaining()) {
                            sc.write(netOutBuffer, timeout, unit, attachment, this);
                        } else if (written == 0) {
                            // Special case, start over to avoid code duplication
                            write(src, timeout, unit, attachment, handler);
                        } else {
                            // Call the handler completed method with the
                            // consumed bytes number
                            handler.completed(Integer.valueOf(written), attach);
                        }
                    }

                    @Override
                    public void failed(Throwable exc, A attach) {
                        handler.failed(exc, attach);
                    }
                });
            } else {
                throw new IOException(sm.getString("channel.nio.ssl.wrapFail", result.getStatus()));
            }
        } catch (Exception e) {
            handler.failed(e, attachment);
        }
    }

    @Override
    public <A> void write(final ByteBuffer[] srcs, final int offset, final int length, final long timeout,
            final TimeUnit unit, final A attachment, final CompletionHandler<Long,? super A> handler) {
        if ((offset < 0) || (length < 0) || (offset > srcs.length - length)) {
            throw new IndexOutOfBoundsException();
        }
        // Check state
        if (closing || closed) {
            handler.failed(new IOException(sm.getString("channel.nio.ssl.closing")), attachment);
            return;
        }
        try {
            // Prepare the output buffer
            netOutBuffer.clear();
            // Wrap the source data into the internal buffer
            SSLEngineResult result = sslEngine.wrap(srcs, offset, length, netOutBuffer);
            final int written = result.bytesConsumed();
            netOutBuffer.flip();
            if (result.getStatus() == Status.OK) {
                if (result.getHandshakeStatus() == HandshakeStatus.NEED_TASK) {
                    tasks();
                }
                // Write data to the channel
                sc.write(netOutBuffer, timeout, unit, attachment, new CompletionHandler<>() {
                    @Override
                    public void completed(Integer nBytes, A attach) {
                        if (nBytes.intValue() < 0) {
                            failed(new EOFException(), attach);
                        } else if (netOutBuffer.hasRemaining()) {
                            sc.write(netOutBuffer, timeout, unit, attachment, this);
                        } else if (written == 0) {
                            // Special case, start over to avoid code duplication
                            write(srcs, offset, length, timeout, unit, attachment, handler);
                        } else {
                            // Call the handler completed method with the
                            // consumed bytes number
                            handler.completed(Long.valueOf(written), attach);
                        }
                    }

                    @Override
                    public void failed(Throwable exc, A attach) {
                        handler.failed(exc, attach);
                    }
                });
            } else {
                throw new IOException(sm.getString("channel.nio.ssl.wrapFail", result.getStatus()));
            }
        } catch (Exception e) {
            handler.failed(e, attachment);
        }
    }

    @Override
    public boolean isHandshakeComplete() {
        return handshakeComplete;
    }

    @Override
    public boolean isClosing() {
        return closing;
    }

    public SSLEngine getSslEngine() {
        return sslEngine;
    }

    public ByteBuffer getEmptyBuf() {
        return emptyBuf;
    }


    private enum OverflowState {
        NONE,
        PROCESSING,
        DONE
    }
}