https://tomcat.apache.org/: Tomcat Connectors and HTTP parser 
/*
 * 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.net.SocketTimeoutException;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.util.Collections;
import java.util.List;

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 org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;
import org.apache.tomcat.util.buf.ByteBufferUtils;
import org.apache.tomcat.util.compat.JreCompat;
import org.apache.tomcat.util.net.NioEndpoint.NioSocketWrapper;
import org.apache.tomcat.util.net.TLSClientHelloExtractor.ExtractorResult;
import org.apache.tomcat.util.net.openssl.ciphers.Cipher;
import org.apache.tomcat.util.res.StringManager;


Implementation of a secure socket channel

/**
 * Implementation of a secure socket channel
 */
public class SecureNioChannel extends NioChannel {

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

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

    private final NioEndpoint endpoint;

    protected ByteBuffer netInBuffer;
    protected ByteBuffer netOutBuffer;

    protected SSLEngine sslEngine;

    protected boolean sniComplete = false;

    protected boolean handshakeComplete = false;
    protected HandshakeStatus handshakeStatus; //gets set by handshake

    protected boolean closed = false;
    protected boolean closing = false;

    public SecureNioChannel(SocketBufferHandler bufHandler, NioEndpoint endpoint) {
        super(bufHandler);

        // Create the network buffers (these hold the encrypted data).
        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);
        }

        this.endpoint = endpoint;
    }

    @Override
    public void reset(SocketChannel channel, NioSocketWrapper socketWrapper) throws IOException {
        super.reset(channel, socketWrapper);
        sslEngine = null;
        sniComplete = false;
        handshakeComplete = false;
        closed = false;
        closing = false;
        netInBuffer.clear();
    }

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

//===========================================================================================
//                  NIO SSL METHODS
//===========================================================================================

    
Flushes the buffer to the network, non blocking

Params:
  • buf – ByteBuffer
Throws:
Returns:boolean true if the buffer has been emptied out, false otherwise
/**
     * Flushes the buffer to the network, non blocking
     * @param buf ByteBuffer
     * @return boolean true if the buffer has been emptied out, false otherwise
     * @throws IOException An IO error occurred writing data
     */
    protected boolean flush(ByteBuffer buf) throws IOException {
        int remaining = buf.remaining();
        if (remaining > 0) {
            return (sc.write(buf) >= remaining);
        } else {
            return true;
        }
    }

    
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. If the return
value from this method is positive, the selection key should be
registered interestOps given by the return value.

Params:
  • read – boolean - true if the underlying channel is readable
  • write – boolean - true if the underlying channel is writable
Throws:
  • IOException – If an I/O error occurs during the handshake or if the
                    handshake fails during wrapping or unwrapping
Returns:0 if hand shake is complete, -1 if an error (other than an
        IOException) occurred, otherwise it returns a SelectionKey
        interestOps value
/**
     * 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. If the return
     * value from this method is positive, the selection key should be
     * registered interestOps given by the return value.
     *
     * @param read boolean - true if the underlying channel is readable
     * @param write boolean - true if the underlying channel is writable
     *
     * @return 0 if hand shake is complete, -1 if an error (other than an
     *         IOException) occurred, otherwise it returns a SelectionKey
     *         interestOps value
     *
     * @throws IOException If an I/O error occurs during the handshake or if the
     *                     handshake fails during wrapping or unwrapping
     */
    @Override
    public int handshake(boolean read, boolean write) 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;
            }
        }

        if (!flush(netOutBuffer)) {
            return SelectionKey.OP_WRITE; //we still have data to write
        }

        SSLEngineResult handshake = null;

        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 if (JreCompat.isAlpnSupported()) {
                            socketWrapper.setNegotiatedProtocol(
                                    JreCompat.getInstance().getApplicationProtocol(sslEngine));
                        }
                    }
                    //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
                    return handshakeComplete ? 0 : SelectionKey.OP_WRITE;
                case NEED_WRAP:
                    //perform the wrap function
                    try {
                        handshake = handshakeWrap(write);
                    } catch (SSLException e) {
                        if (log.isDebugEnabled()) {
                            log.debug(sm.getString("channel.nio.ssl.wrapException"), e);
                        }
                        handshake = handshakeWrap(write);
                    }
                    if (handshake.getStatus() == Status.OK) {
                        if (handshakeStatus == HandshakeStatus.NEED_TASK) {
                            handshakeStatus = tasks();
                        }
                    } else if (handshake.getStatus() == Status.CLOSED) {
                        flush(netOutBuffer);
                        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 || (!flush(netOutBuffer))) {
                        //should actually return OP_READ if we have NEED_UNWRAP
                        return SelectionKey.OP_WRITE;
                    }
                    //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(read);
                    if (handshake.getStatus() == Status.OK) {
                        if (handshakeStatus == HandshakeStatus.NEED_TASK) {
                            handshakeStatus = tasks();
                        }
                    } else if ( handshake.getStatus() == Status.BUFFER_UNDERFLOW ){
                        //read more data, reregister for OP_READ
                        return SelectionKey.OP_READ;
                    } else {
                        throw new IOException(sm.getString("channel.nio.ssl.unexpectedStatusDuringWrap", handshake.getStatus()));
                    }
                    break;
                case NEED_TASK:
                    handshakeStatus = tasks();
                    break;
                default:
                    throw new IllegalStateException(sm.getString("channel.nio.ssl.invalidStatus", handshakeStatus));
            }
        }
        // Handshake is complete if this point is reached
        return 0;
    }


    /*
     * 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.
     *
     * @return 0 if SNI processing is complete, -1 if an error (other than an
     *         IOException) occurred, otherwise it returns a SelectionKey
     *         interestOps value
     *
     * @throws IOException If an I/O error occurs during the SNI processing
     */
    private int processSNI() throws IOException {
        // Read some data into the network input buffer so we can peek at it.
        int bytesRead = sc.read(netInBuffer);
        if (bytesRead == -1) {
            // Reached end of stream before SNI could be processed.
            return -1;
        }
        TLSClientHelloExtractor extractor = new TLSClientHelloExtractor(netInBuffer);

        while (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);
            extractor = new TLSClientHelloExtractor(netInBuffer);
        }

        String hostName = null;
        List<Cipher> clientRequestedCiphers = null;
        List<String> clientRequestedApplicationProtocols = 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();
            break;
        case NEED_READ:
            return SelectionKey.OP_READ;
        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();
            flushOutbound();
            throw new IOException(sm.getString("channel.nio.ssl.foundHttp"));
        }

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

        sslEngine = endpoint.createSSLEngine(hostName, clientRequestedCiphers,
                clientRequestedApplicationProtocols);

        // 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.

Params:
  • timeout – - timeout in milliseconds for each socket operation
Throws:
/**
     * 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.
     * @param timeout - timeout in milliseconds for each socket operation
     * @throws IOException - if an IO exception occurs or if application or network buffers contain data
     * @throws SocketTimeoutException - if a socket operation timed out
     */
    @SuppressWarnings("null") // key cannot be null
    public void rehandshake(long timeout) 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"));
        }
        handshakeComplete = false;
        boolean isReadable = false;
        boolean isWriteable = false;
        boolean handshaking = true;
        Selector selector = null;
        SelectionKey key = null;
        try {
            sslEngine.beginHandshake();
            handshakeStatus = sslEngine.getHandshakeStatus();
            while (handshaking) {
                int hsStatus = this.handshake(isReadable, isWriteable);
                switch (hsStatus) {
                    case -1 :
                        throw new EOFException(sm.getString("channel.nio.ssl.eofDuringHandshake"));
                    case  0 :
                        handshaking = false;
                        break;
                    default :
                        long now = System.currentTimeMillis();
                        if (selector == null) {
                            selector = Selector.open();
                            key = getIOChannel().register(selector, hsStatus);
                        } else {
                            key.interestOps(hsStatus); // null warning suppressed
                        }
                        int keyCount = selector.select(timeout);
                        if (keyCount == 0 && ((System.currentTimeMillis()-now) >= timeout)) {
                            throw new SocketTimeoutException(sm.getString("channel.nio.ssl.timeoutDuringHandshake"));
                        }
                        isReadable = key.isReadable();
                        isWriteable = key.isWritable();
                }
            }
        } catch (IOException x) {
            closeSilently();
            throw x;
        } catch (Exception cx) {
            closeSilently();
            IOException x = new IOException(cx);
            throw x;
        } finally {
            if (key != null) {
                try {
                    key.cancel();
                } catch (Exception ignore) {
                }
            }
            if (selector != null) {
                try {
                    selector.close();
                } catch (Exception ignore) {
                }
            }
        }
    }



    
Executes all the tasks needed on the same thread.

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

    
Performs the WRAP function

Params:
  • doWrite – boolean
Throws:
Returns:the result
/**
     * Performs the WRAP function
     * @param doWrite boolean
     * @return the result
     * @throws IOException An IO error occurred
     */
    protected SSLEngineResult handshakeWrap(boolean doWrite) 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();
        //optimization, if we do have a writable channel, write it now
        if (doWrite) {
            flush(netOutBuffer);
        }
        return result;
    }

    
Perform handshake unwrap

Params:
  • doread – boolean
Throws:
Returns:the result
/**
     * Perform handshake unwrap
     * @param doread boolean
     * @return the result
     * @throws IOException An IO error occurred
     */
    protected SSLEngineResult handshakeUnwrap(boolean doread) throws IOException {

        if (netInBuffer.position() == netInBuffer.limit()) {
            //clear the buffer if we have emptied it out on data
            netInBuffer.clear();
        }
        if (doread)  {
            //if we have data to read, read it
            int read = sc.read(netInBuffer);
            if (read == -1) {
                throw new IOException(sm.getString("channel.nio.ssl.eofDuringHandshake"));
            }
        }
        SSLEngineResult result;
        boolean cont = false;
        //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());
            //compact the buffer, this is an optional method, wonder what would happen if we didn't
            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;
    }

    
Sends an SSL close message, will not physically close the connection here.

To close the connection, you could do something like


  close();
  while (isOpen() && !myTimeoutFunction()) Thread.sleep(25);
  if ( isOpen() ) close(true); //forces a close if you timed out



Throws:
  • IOException – if an I/O error occurs
  • IOException – if there is data on the outgoing network buffer and
                    we are unable to flush it
/**
     * 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;
        sslEngine.closeOutbound();

        if (!flush(netOutBuffer)) {
            throw new IOException(sm.getString("channel.nio.ssl.remainingDataDuringClose"));
        }
        //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
        flush(netOutBuffer);

        //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);
        }
    }


    
Reads a sequence of bytes from this channel into the given buffer.

Params:
  • dst – The buffer into which bytes are to be transferred
Throws:
Returns:The number of bytes read, possibly zero, or -1 if
        the channel has reached end-of-stream
/**
     * 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 IOException If some other I/O error occurs
     * @throws IllegalArgumentException if the destination buffer is different
     *                                  than getBufHandler().getReadBuffer()
     */
    @Override
    public int read(ByteBuffer dst) throws IOException {
        //are we in the middle of closing or closed?
        if (closing || closed) {
            return -1;
        }
        //did we finish our handshake?
        if (!handshakeComplete) {
            throw new IllegalStateException(sm.getString("channel.nio.ssl.incompleteHandshake"));
        }

        //read from the network
        int netread = sc.read(netInBuffer);
        //did we reach EOF? if so send EOF up one layer.
        if (netread == -1) {
            return -1;
        }

        //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, dst);
            //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();
                }
                //if we need more network data, then bail out for now.
                if (unwrap.getStatus() == Status.BUFFER_UNDERFLOW) {
                    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 (getAppReadBufHandler() != null && 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 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()));
            }
        } while (netInBuffer.position() != 0); //continue to unwrapping as long as the input buffer has stuff
        return read;
    }

    @Override
    public long read(ByteBuffer[] dsts, int offset, int length)
            throws IOException {
        //are we in the middle of closing or closed?
        if (closing || closed) {
            return -1;
        }
        //did we finish our handshake?
        if (!handshakeComplete) {
            throw new IllegalStateException(sm.getString("channel.nio.ssl.incompleteHandshake"));
        }

        //read from the network
        int netread = sc.read(netInBuffer);
        //did we reach EOF? if so send EOF up one layer.
        if (netread == -1) {
            return -1;
        }

        //the data read
        int read = 0;
        //the SSL engine result
        SSLEngineResult unwrap;
        OverflowState overflowState = OverflowState.NONE;
        do {
            if (overflowState == OverflowState.PROCESSING) {
                overflowState = OverflowState.DONE;
            }
            //prepare the buffer
            netInBuffer.flip();
            //unwrap the data
            unwrap = sslEngine.unwrap(netInBuffer, dsts, offset, length);
            //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();
                }
                //if we need more network data, then bail out for now.
                if (unwrap.getStatus() == Status.BUFFER_UNDERFLOW) {
                    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 {
                    ByteBuffer readBuffer = getBufHandler().getReadBuffer();
                    boolean found = false;
                    boolean resized = true;
                    for (int i = 0; i < length; 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
                        ByteBuffer[] 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];
                            }
                        }
                        dsts = dsts2;
                        length++;
                        getBufHandler().configureReadBufferForWrite();
                        overflowState = OverflowState.PROCESSING;
                    }
                }
            } else {
                // Something else went wrong
                throw new IOException(sm.getString("channel.nio.ssl.unwrapFail", unwrap.getStatus()));
            }
        } while ((netInBuffer.position() != 0 || overflowState == OverflowState.PROCESSING) &&
                overflowState != OverflowState.DONE);
        return read;
    }

    
Writes a sequence of bytes to this channel from the given buffer.

Params:
  • src – The buffer from which bytes are to be retrieved
Throws:
Returns:The number of bytes written, possibly zero
/**
     * 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
     * @throws IOException If some other I/O error occurs
     */
    @Override
    public int write(ByteBuffer src) throws IOException {
        checkInterruptStatus();
        if (src == this.netOutBuffer) {
            //we can get here through a recursive call
            //by using the NioBlockingSelector
            int written = sc.write(src);
            return written;
        } else {
            // Are we closing or closed?
            if (closing || closed) {
                throw new IOException(sm.getString("channel.nio.ssl.closing"));
            }

            if (!flush(netOutBuffer)) {
                // We haven't emptied out the buffer yet
                return 0;
            }

            // The data buffer is empty, we can reuse the entire buffer.
            netOutBuffer.clear();

            SSLEngineResult result = sslEngine.wrap(src, netOutBuffer);
            // The number of bytes written
            int written = result.bytesConsumed();
            netOutBuffer.flip();

            if (result.getStatus() == Status.OK) {
                if (result.getHandshakeStatus() == HandshakeStatus.NEED_TASK) {
                    tasks();
                }
            } else {
                throw new IOException(sm.getString("channel.nio.ssl.wrapFail", result.getStatus()));
            }

            // Force a flush
            flush(netOutBuffer);

            return written;
        }
    }

    @Override
    public long write(ByteBuffer[] srcs, int offset, int length)
            throws IOException {
        checkInterruptStatus();
        // Are we closing or closed?
        if (closing || closed) {
            throw new IOException(sm.getString("channel.nio.ssl.closing"));
        }

        if (!flush(netOutBuffer)) {
            // We haven't emptied out the buffer yet
            return 0;
        }

        // The data buffer is empty, we can reuse the entire buffer.
        netOutBuffer.clear();

        SSLEngineResult result = sslEngine.wrap(srcs, offset, length, netOutBuffer);
        // The number of bytes written
        int written = result.bytesConsumed();
        netOutBuffer.flip();

        if (result.getStatus() == Status.OK) {
            if (result.getHandshakeStatus() == HandshakeStatus.NEED_TASK) tasks();
        } else {
            throw new IOException(sm.getString("channel.nio.ssl.wrapFail", result.getStatus()));
        }

        // Force a flush
        flush(netOutBuffer);

        return written;
    }

    @Override
    public int getOutboundRemaining() {
        return netOutBuffer.remaining();
    }

    @Override
    public boolean flushOutbound() throws IOException {
        int remaining = netOutBuffer.remaining();
        flush(netOutBuffer);
        int remaining2 = netOutBuffer.remaining();
        return remaining2 < remaining;
    }

    @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;
    }
}