http://www.jboss.org/undertow-parent/undertow-core: Undertow (JBoss by Red Hat) 
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 * Copyright 2014 Red Hat, Inc., and individual contributors
 * as indicated by the @author tags.
 *
 * Licensed 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 io.undertow.websockets.core;

import io.undertow.conduits.IdleTimeoutConduit;
import io.undertow.server.protocol.framed.AbstractFramedChannel;
import io.undertow.server.protocol.framed.AbstractFramedStreamSourceChannel;
import io.undertow.server.protocol.framed.FrameHeaderData;
import io.undertow.websockets.extensions.ExtensionFunction;
import org.xnio.ChannelExceptionHandler;
import org.xnio.ChannelListener;
import org.xnio.ChannelListeners;
import org.xnio.IoUtils;
import org.xnio.OptionMap;
import io.undertow.connector.ByteBufferPool;
import io.undertow.connector.PooledByteBuffer;
import org.xnio.StreamConnection;
import org.xnio.channels.StreamSinkChannel;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;


A ConnectedChannel which can be used to send and receive WebSocket Frames. 
Author:Norman Maurer, Stuart Douglas
/**
 * A {@link org.xnio.channels.ConnectedChannel} which can be used to send and receive WebSocket Frames.
 *
 * @author <a href="mailto:nmaurer@redhat.com">Norman Maurer</a>
 * @author Stuart Douglas
 */
public abstract class WebSocketChannel extends AbstractFramedChannel<WebSocketChannel, StreamSourceFrameChannel, StreamSinkFrameChannel> {

    private final boolean client;

    private final WebSocketVersion version;
    private final String wsUrl;

    private volatile boolean closeFrameReceived;
    private volatile boolean closeFrameSent;
    
If this is true then the web socket close was initiated by the remote peer

/**
     * If this is true then the web socket close was initiated by the remote peer
     */
    private volatile boolean closeInitiatedByRemotePeer;
    private volatile int closeCode = -1;
    private volatile String closeReason;
    private final String subProtocol;
    protected final boolean extensionsSupported;
    protected final ExtensionFunction extensionFunction;
    protected final boolean hasReservedOpCode;

    
an incoming frame that has not been created yet

/**
     * an incoming frame that has not been created yet
     */
    private volatile PartialFrame partialFrame;

    private final Map<String, Object> attributes = Collections.synchronizedMap(new HashMap<String, Object>());

    protected StreamSourceFrameChannel fragmentedChannel;

    
Represents all web socket channels that are attached to the same endpoint.

/**
     * Represents all web socket channels that are attached to the same endpoint.
     */
    private final Set<WebSocketChannel> peerConnections;

    
Create a new WebSocketChannel 8 
Params:
  • connectedStreamChannel – The ConnectedStreamChannel over which the WebSocket Frames should get send and received. Be aware that it already must be "upgraded".
  • bufferPool –  The Pool which will be used to acquire ByteBuffer's from.
  • version –  The WebSocketVersion of the WebSocketChannel
  • wsUrl –                  The url for which the channel was created.
  • client – 
  • peerConnections –        The concurrent set that is used to track open connections associtated with an endpoint
/**
     * Create a new {@link WebSocketChannel}
     * 8
     *
     * @param connectedStreamChannel The {@link org.xnio.channels.ConnectedStreamChannel} over which the WebSocket Frames should get send and received.
     *                               Be aware that it already must be "upgraded".
     * @param bufferPool             The {@link org.xnio.Pool} which will be used to acquire {@link java.nio.ByteBuffer}'s from.
     * @param version                The {@link WebSocketVersion} of the {@link WebSocketChannel}
     * @param wsUrl                  The url for which the channel was created.
     * @param client
     * @param peerConnections        The concurrent set that is used to track open connections associtated with an endpoint
     */
    protected WebSocketChannel(final StreamConnection connectedStreamChannel, ByteBufferPool bufferPool, WebSocketVersion version, String wsUrl, String subProtocol, final boolean client, boolean extensionsSupported, final ExtensionFunction extensionFunction, Set<WebSocketChannel> peerConnections, OptionMap options) {
        super(connectedStreamChannel, bufferPool, new WebSocketFramePriority(), null, options);
        this.client = client;
        this.version = version;
        this.wsUrl = wsUrl;
        this.extensionsSupported = extensionsSupported;
        this.extensionFunction = extensionFunction;
        this.hasReservedOpCode = extensionFunction.hasExtensionOpCode();
        this.subProtocol = subProtocol;
        this.peerConnections = peerConnections;
        addCloseTask(new ChannelListener<WebSocketChannel>() {
            @Override
            public void handleEvent(WebSocketChannel channel) {
                extensionFunction.dispose();
                WebSocketChannel.this.peerConnections.remove(WebSocketChannel.this);
            }
        });
    }

    @Override
    protected Collection<AbstractFramedStreamSourceChannel<WebSocketChannel, StreamSourceFrameChannel, StreamSinkFrameChannel>> getReceivers() {
        if(fragmentedChannel == null) {
            return Collections.emptyList();
        }
        return Collections.<AbstractFramedStreamSourceChannel<WebSocketChannel, StreamSourceFrameChannel, StreamSinkFrameChannel>>singleton(fragmentedChannel);
    }

    @Override
    protected IdleTimeoutConduit createIdleTimeoutChannel(final StreamConnection connectedStreamChannel) {
        return new IdleTimeoutConduit(connectedStreamChannel) {
            @Override
            protected void doClose() {
                WebSockets.sendClose(CloseMessage.GOING_AWAY, null, WebSocketChannel.this, null);
            }
        };
    }

    @Override
    protected boolean isLastFrameSent() {
        return closeFrameSent;
    }

    @Override
    protected boolean isLastFrameReceived() {
        return closeFrameReceived;
    }

    @Override
    protected void markReadsBroken(Throwable cause) {
        super.markReadsBroken(cause);
    }

    @Override
    protected void lastDataRead() {
        if(!closeFrameReceived && !closeFrameSent) {
            //the peer has likely already gone away, but try and send a close frame anyway
            //this will likely just result in the write() failing an immediate connection termination
            //which is what we want
            closeFrameReceived = true; //not strictly true, but the read side is gone
            try {
                sendClose();
            } catch (IOException e) {
                IoUtils.safeClose(this);
            }
        }
    }

    protected boolean isReadsBroken() {
        return super.isReadsBroken();
    }

    @Override
    protected FrameHeaderData parseFrame(ByteBuffer data) throws IOException {
        if (partialFrame == null) {
            partialFrame = receiveFrame();
        }
        try {
            partialFrame.handle(data);
        } catch (WebSocketException e) {
            //the data was corrupt
            //send a close message
            WebSockets.sendClose(new CloseMessage(CloseMessage.WRONG_CODE, e.getMessage()).toByteBuffer(), this, null);
            markReadsBroken(e);
            if (WebSocketLogger.REQUEST_LOGGER.isDebugEnabled()) {
                WebSocketLogger.REQUEST_LOGGER.debugf(e, "receive failed due to Exception");
            }

            throw new IOException(e);
        }
        if (partialFrame.isDone()) {
            PartialFrame p = this.partialFrame;
            this.partialFrame = null;
            return p;
        }
        return null;
    }


    
Create a new StreamSourceFrameChannel which can be used to read the data of the received Frame 
Returns:channel A StreamSourceFrameChannel will be used to read a Frame from. This will return null if the right StreamSourceFrameChannel could not be detected with the given buffer and so more data is needed.
/**
     * Create a new {@link io.undertow.websockets.core.StreamSourceFrameChannel}  which can be used to read the data of the received Frame
     *
     * @return channel                  A {@link io.undertow.websockets.core.StreamSourceFrameChannel} will be used to read a Frame from.
     *         This will return {@code null} if the right {@link io.undertow.websockets.core.StreamSourceFrameChannel} could not be detected with the given
     *         buffer and so more data is needed.
     */
    protected abstract PartialFrame receiveFrame();

    @Override
    protected StreamSourceFrameChannel createChannel(FrameHeaderData frameHeaderData, PooledByteBuffer frameData) {
        PartialFrame partialFrame = (PartialFrame) frameHeaderData;
        StreamSourceFrameChannel channel = partialFrame.getChannel(frameData);
        if (channel.getType() == WebSocketFrameType.CLOSE) {
            if(!closeFrameSent) {
                closeInitiatedByRemotePeer = true;
            }
            closeFrameReceived = true;
        }
        return channel;
    }

    public final boolean setAttribute(String key, Object value) {
        if (value == null) {
            return attributes.remove(key) != null;
        } else {
            return attributes.put(key, value) == null;
        }
    }

    public final Object getAttribute(String key) {
        return attributes.get(key);
    }

    
Returns true if extensions are supported by this WebSocket Channel. 
/**
     * Returns {@code true} if extensions are supported by this WebSocket Channel.
     */
    public boolean areExtensionsSupported() {
        return extensionsSupported;
    }

    @Override
    protected void handleBrokenSourceChannel(Throwable e) {
        if (e instanceof UnsupportedEncodingException) {
            getFramePriority().immediateCloseFrame();
            WebSockets.sendClose(new CloseMessage(CloseMessage.MSG_CONTAINS_INVALID_DATA, e.getMessage()).toByteBuffer(), this, null);
        } else if (e instanceof WebSocketInvalidCloseCodeException) {
            WebSockets.sendClose(new CloseMessage(CloseMessage.WRONG_CODE, e.getMessage()).toByteBuffer(), this, null);
        } else if (e instanceof WebSocketFrameCorruptedException) {
            getFramePriority().immediateCloseFrame();
            WebSockets.sendClose(new CloseMessage(CloseMessage.WRONG_CODE, e.getMessage()).toByteBuffer(), this, null);
        }
    }

    @Override
    protected void handleBrokenSinkChannel(Throwable e) {

    }

    
Returns an unmodifiable Set of the selected subprotocols if any. 
/**
     * Returns an unmodifiable {@link Set} of the selected subprotocols if any.
     */
    @Deprecated
    public Set<String> getSubProtocols() {
        return Collections.singleton(subProtocol);
    }

    public String getSubProtocol() {
        return subProtocol;
    }

    public boolean isCloseFrameReceived() {
        return closeFrameReceived;
    }

    public boolean isCloseFrameSent() {
        return closeFrameSent;
    }

    
Get the request URI scheme. Normally this is one of ws or wss. 
Returns:the request URI scheme
/**
     * Get the request URI scheme. Normally this is one of {@code ws} or {@code wss}.
     *
     * @return the request URI scheme
     */
    public String getRequestScheme() {
        if (getUrl().startsWith("wss:")) {
            return "wss";
        } else {
            return "ws";
        }
    }

    
Return true if this is handled via WebSocket Secure. 
/**
     * Return {@code true} if this is handled via WebSocket Secure.
     */
    public boolean isSecure() {
        return "wss".equals(getRequestScheme());
    }

    
Return the URL of the WebSocket endpoint.

Returns:url The URL of the endpoint
/**
     * Return the URL of the WebSocket endpoint.
     *
     * @return url The URL of the endpoint
     */
    public String getUrl() {
        return wsUrl;
    }

    
Return the WebSocketVersion which is used 
Returns:version The WebSocketVersion which is in use
/**
     * Return the {@link WebSocketVersion} which is used
     *
     * @return version The {@link WebSocketVersion} which is in use
     */
    public WebSocketVersion getVersion() {
        return version;
    }

    
Get the source address of the WebSocket Channel.

Returns:the source address of the WebSocket Channel
/**
     * Get the source address of the WebSocket Channel.
     *
     * @return the source address of the WebSocket Channel
     */
    public InetSocketAddress getSourceAddress() {
        return getPeerAddress(InetSocketAddress.class);
    }

    
Get the destination address of the WebSocket Channel.

Returns:the destination address of the WebSocket Channel
/**
     * Get the destination address of the WebSocket Channel.
     *
     * @return the destination address of the WebSocket Channel
     */
    public InetSocketAddress getDestinationAddress() {
        return getLocalAddress(InetSocketAddress.class);
    }

    public boolean isClient() {
        return client;
    }

    
Returns a new StreamSinkFrameChannel for sending the given WebSocketFrameType with the given payload. If this method is called multiple times, subsequent StreamSinkFrameChannel's will not be writable until all previous frames were completely written. 
Params:
/**
     * Returns a new {@link StreamSinkFrameChannel} for sending the given {@link WebSocketFrameType} with the given payload.
     * If this method is called multiple times, subsequent {@link StreamSinkFrameChannel}'s will not be writable until all previous frames
     * were completely written.
     *
     * @param type        The {@link WebSocketFrameType} for which a {@link StreamSinkChannel} should be created
     */
    public final StreamSinkFrameChannel send(WebSocketFrameType type) throws IOException {
        if(closeFrameSent || (closeFrameReceived && type != WebSocketFrameType.CLOSE)) {
            throw WebSocketMessages.MESSAGES.channelClosed();
        }
        if (isWritesBroken()) {
            throw WebSocketMessages.MESSAGES.streamIsBroken();
        }


        StreamSinkFrameChannel ch = createStreamSinkChannel(type);
        getFramePriority().addToOrderQueue(ch);
        if (type == WebSocketFrameType.CLOSE) {
            closeFrameSent = true;
        }
        return ch;
    }

    
Send a Close frame without a payload

/**
     * Send a Close frame without a payload
     */
    public void sendClose() throws IOException {
        closeReason = "";
        closeCode = CloseMessage.NORMAL_CLOSURE;
        StreamSinkFrameChannel closeChannel = send(WebSocketFrameType.CLOSE);
        closeChannel.shutdownWrites();
        if (!closeChannel.flush()) {
            closeChannel.getWriteSetter().set(ChannelListeners.flushingChannelListener(
                    null, new ChannelExceptionHandler<StreamSinkChannel>() {
                @Override
                public void handleException(final StreamSinkChannel channel, final IOException exception) {
                    IoUtils.safeClose(WebSocketChannel.this);
                }
            }
            ));
            closeChannel.resumeWrites();
        }
    }


    
Create a new StreamSinkFrameChannel which can be used to send a WebSocket Frame of the type WebSocketFrameType. 
Params:
/**
     * Create a new StreamSinkFrameChannel which can be used to send a WebSocket Frame of the type {@link WebSocketFrameType}.
     *
     * @param type        The {@link WebSocketFrameType} of the WebSocketFrame which will be send over this {@link StreamSinkFrameChannel}
     */
    protected abstract StreamSinkFrameChannel createStreamSinkChannel(WebSocketFrameType type);


    protected WebSocketFramePriority getFramePriority() {
        return (WebSocketFramePriority) super.getFramePriority();
    }

    
Returns all 'peer' web socket connections that were created from the same endpoint.

Returns:all 'peer' web socket connections
/**
     * Returns all 'peer' web socket connections that were created from the same endpoint.
     *
     *
     * @return all 'peer' web socket connections
     */
    public Set<WebSocketChannel> getPeerConnections() {
        return Collections.unmodifiableSet(peerConnections);
    }

    
If this is true the session is being closed because the remote peer sent a close frame

Returns:true if the remote peer closed the connection
/**
     * If this is true the session is being closed because the remote peer sent a close frame
     * @return <code>true</code> if the remote peer closed the connection
     */
    public boolean isCloseInitiatedByRemotePeer() {
        return closeInitiatedByRemotePeer;
    }

    
Interface that represents a frame channel that is in the process of being created

/**
     * Interface that represents a frame channel that is in the process of being created
     */
    public interface PartialFrame extends FrameHeaderData {

        
Returns:The channel, or null if the channel is not available yet
/**
         * @return The channel, or null if the channel is not available yet
         */
        StreamSourceFrameChannel getChannel(final PooledByteBuffer data);

        
Handles the data, any remaining data will be pushed back

/**
         * Handles the data, any remaining data will be pushed back
         */
        void handle(ByteBuffer data) throws WebSocketException;

        
Returns:true if the channel is available
/**
         * @return true if the channel is available
         */
        boolean isDone();
    }

    
Returns:The close reason
/**
     *
     * @return The close reason
     */
    public String getCloseReason() {
        return closeReason;
    }

    public void setCloseReason(String closeReason) {
        this.closeReason = closeReason;
    }

    
Returns:The close code
/**
     *
     * @return The close code
     */
    public int getCloseCode() {
        return closeCode;
    }

    public void setCloseCode(int closeCode) {
        this.closeCode = closeCode;
    }

    public ExtensionFunction getExtensionFunction() {
        return extensionFunction;
    }
}