Java example source code file (WebSocketClientHandshaker.java)

This example Java source code file (WebSocketClientHandshaker.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

channelfuture, channelhandlercontext, channelpipeline, channelpromise, closedchannelexception, fullhttpresponse, httpclientcodec, httpresponsedecoder, illegalstateexception, net, network, nullpointerexception, override, string, throwable, websocketversion

The WebSocketClientHandshaker.java Java example source code

/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project 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 io.netty.handler.codec.http.websocketx;

import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.ChannelPromise;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.FullHttpRequest;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.HttpClientCodec;
import io.netty.handler.codec.http.HttpContentDecompressor;
import io.netty.handler.codec.http.HttpHeaderNames;
import io.netty.handler.codec.http.HttpHeaders;
import io.netty.handler.codec.http.HttpObjectAggregator;
import io.netty.handler.codec.http.HttpRequestEncoder;
import io.netty.handler.codec.http.HttpResponse;
import io.netty.handler.codec.http.HttpResponseDecoder;
import io.netty.handler.codec.http.HttpScheme;
import io.netty.util.ReferenceCountUtil;
import io.netty.util.internal.StringUtil;
import io.netty.util.internal.ThrowableUtil;

import java.net.URI;
import java.nio.channels.ClosedChannelException;

/**
 * Base class for web socket client handshake implementations
 */
public abstract class WebSocketClientHandshaker {
    private static final ClosedChannelException CLOSED_CHANNEL_EXCEPTION = ThrowableUtil.unknownStackTrace(
            new ClosedChannelException(), WebSocketClientHandshaker.class, "processHandshake(...)");

    private final URI uri;

    private final WebSocketVersion version;

    private volatile boolean handshakeComplete;

    private final String expectedSubprotocol;

    private volatile String actualSubprotocol;

    protected final HttpHeaders customHeaders;

    private final int maxFramePayloadLength;

    /**
     * Base constructor
     *
     * @param uri
     *            URL for web socket communications. e.g "ws://myhost.com/mypath". Subsequent web socket frames will be
     *            sent to this URL.
     * @param version
     *            Version of web socket specification to use to connect to the server
     * @param subprotocol
     *            Sub protocol request sent to the server.
     * @param customHeaders
     *            Map of custom headers to add to the client request
     * @param maxFramePayloadLength
     *            Maximum length of a frame's payload
     */
    protected WebSocketClientHandshaker(URI uri, WebSocketVersion version, String subprotocol,
                                        HttpHeaders customHeaders, int maxFramePayloadLength) {
        this.uri = uri;
        this.version = version;
        expectedSubprotocol = subprotocol;
        this.customHeaders = customHeaders;
        this.maxFramePayloadLength = maxFramePayloadLength;
    }

    /**
     * Returns the URI to the web socket. e.g. "ws://myhost.com/path"
     */
    public URI uri() {
        return uri;
    }

    /**
     * Version of the web socket specification that is being used
     */
    public WebSocketVersion version() {
        return version;
    }

    /**
     * Returns the max length for any frame's payload
     */
    public int maxFramePayloadLength() {
        return maxFramePayloadLength;
    }

    /**
     * Flag to indicate if the opening handshake is complete
     */
    public boolean isHandshakeComplete() {
        return handshakeComplete;
    }

    private void setHandshakeComplete() {
        handshakeComplete = true;
    }

    /**
     * Returns the CSV of requested subprotocol(s) sent to the server as specified in the constructor
     */
    public String expectedSubprotocol() {
        return expectedSubprotocol;
    }

    /**
     * Returns the subprotocol response sent by the server. Only available after end of handshake.
     * Null if no subprotocol was requested or confirmed by the server.
     */
    public String actualSubprotocol() {
        return actualSubprotocol;
    }

    private void setActualSubprotocol(String actualSubprotocol) {
        this.actualSubprotocol = actualSubprotocol;
    }

    /**
     * Begins the opening handshake
     *
     * @param channel
     *            Channel
     */
    public ChannelFuture handshake(Channel channel) {
        if (channel == null) {
            throw new NullPointerException("channel");
        }
        return handshake(channel, channel.newPromise());
    }

    /**
     * Begins the opening handshake
     *
     * @param channel
     *            Channel
     * @param promise
     *            the {@link ChannelPromise} to be notified when the opening handshake is sent
     */
    public final ChannelFuture handshake(Channel channel, final ChannelPromise promise) {
        FullHttpRequest request =  newHandshakeRequest();

        HttpResponseDecoder decoder = channel.pipeline().get(HttpResponseDecoder.class);
        if (decoder == null) {
            HttpClientCodec codec = channel.pipeline().get(HttpClientCodec.class);
            if (codec == null) {
               promise.setFailure(new IllegalStateException("ChannelPipeline does not contain " +
                       "a HttpResponseDecoder or HttpClientCodec"));
               return promise;
            }
        }

        channel.writeAndFlush(request).addListener(new ChannelFutureListener() {
            @Override
            public void operationComplete(ChannelFuture future) {
                if (future.isSuccess()) {
                    ChannelPipeline p = future.channel().pipeline();
                    ChannelHandlerContext ctx = p.context(HttpRequestEncoder.class);
                    if (ctx == null) {
                        ctx = p.context(HttpClientCodec.class);
                    }
                    if (ctx == null) {
                        promise.setFailure(new IllegalStateException("ChannelPipeline does not contain " +
                                "a HttpRequestEncoder or HttpClientCodec"));
                        return;
                    }
                    p.addAfter(ctx.name(), "ws-encoder", newWebSocketEncoder());

                    promise.setSuccess();
                } else {
                    promise.setFailure(future.cause());
                }
            }
        });
        return promise;
    }

    /**
     * Returns a new {@link FullHttpRequest) which will be used for the handshake.
     */
    protected abstract FullHttpRequest newHandshakeRequest();

    /**
     * Validates and finishes the opening handshake initiated by {@link #handshake}}.
     *
     * @param channel
     *            Channel
     * @param response
     *            HTTP response containing the closing handshake details
     */
    public final void finishHandshake(Channel channel, FullHttpResponse response) {
        verify(response);

        // Verify the subprotocol that we received from the server.
        // This must be one of our expected subprotocols - or null/empty if we didn't want to speak a subprotocol
        String receivedProtocol = response.headers().get(HttpHeaderNames.SEC_WEBSOCKET_PROTOCOL);
        receivedProtocol = receivedProtocol != null ? receivedProtocol.trim() : null;
        String expectedProtocol = expectedSubprotocol != null ? expectedSubprotocol : "";
        boolean protocolValid = false;

        if (expectedProtocol.isEmpty() && receivedProtocol == null) {
            // No subprotocol required and none received
            protocolValid = true;
            setActualSubprotocol(expectedSubprotocol); // null or "" - we echo what the user requested
        } else if (!expectedProtocol.isEmpty() && receivedProtocol != null && !receivedProtocol.isEmpty()) {
            // We require a subprotocol and received one -> verify it
            for (String protocol : StringUtil.split(expectedSubprotocol, ',')) {
                if (protocol.trim().equals(receivedProtocol)) {
                    protocolValid = true;
                    setActualSubprotocol(receivedProtocol);
                    break;
                }
            }
        } // else mixed cases - which are all errors

        if (!protocolValid) {
            throw new WebSocketHandshakeException(String.format(
                    "Invalid subprotocol. Actual: %s. Expected one of: %s",
                    receivedProtocol, expectedSubprotocol));
        }

        setHandshakeComplete();

        final ChannelPipeline p = channel.pipeline();
        // Remove decompressor from pipeline if its in use
        HttpContentDecompressor decompressor = p.get(HttpContentDecompressor.class);
        if (decompressor != null) {
            p.remove(decompressor);
        }

        // Remove aggregator if present before
        HttpObjectAggregator aggregator = p.get(HttpObjectAggregator.class);
        if (aggregator != null) {
            p.remove(aggregator);
        }

        ChannelHandlerContext ctx = p.context(HttpResponseDecoder.class);
        if (ctx == null) {
            ctx = p.context(HttpClientCodec.class);
            if (ctx == null) {
                throw new IllegalStateException("ChannelPipeline does not contain " +
                        "a HttpRequestEncoder or HttpClientCodec");
            }
            final HttpClientCodec codec =  (HttpClientCodec) ctx.handler();
            // Remove the encoder part of the codec as the user may start writing frames after this method returns.
            codec.removeOutboundHandler();

            p.addAfter(ctx.name(), "ws-decoder", newWebsocketDecoder());

            // Delay the removal of the decoder so the user can setup the pipeline if needed to handle
            // WebSocketFrame messages.
            // See https://github.com/netty/netty/issues/4533
            channel.eventLoop().execute(new Runnable() {
                @Override
                public void run() {
                    p.remove(codec);
                }
            });
        } else {
            if (p.get(HttpRequestEncoder.class) != null) {
                // Remove the encoder part of the codec as the user may start writing frames after this method returns.
                p.remove(HttpRequestEncoder.class);
            }
            final ChannelHandlerContext context = ctx;
            p.addAfter(context.name(), "ws-decoder", newWebsocketDecoder());

            // Delay the removal of the decoder so the user can setup the pipeline if needed to handle
            // WebSocketFrame messages.
            // See https://github.com/netty/netty/issues/4533
            channel.eventLoop().execute(new Runnable() {
                @Override
                public void run() {
                    p.remove(context.handler());
                }
            });
        }
    }

    /**
     * Process the opening handshake initiated by {@link #handshake}}.
     *
     * @param channel
     *            Channel
     * @param response
     *            HTTP response containing the closing handshake details
     * @return future
     *            the {@link ChannelFuture} which is notified once the handshake completes.
     */
    public final ChannelFuture processHandshake(final Channel channel, HttpResponse response) {
        return processHandshake(channel, response, channel.newPromise());
    }

    /**
     * Process the opening handshake initiated by {@link #handshake}}.
     *
     * @param channel
     *            Channel
     * @param response
     *            HTTP response containing the closing handshake details
     * @param promise
     *            the {@link ChannelPromise} to notify once the handshake completes.
     * @return future
     *            the {@link ChannelFuture} which is notified once the handshake completes.
     */
    public final ChannelFuture processHandshake(final Channel channel, HttpResponse response,
                                                final ChannelPromise promise) {
        if (response instanceof FullHttpResponse) {
            try {
                finishHandshake(channel, (FullHttpResponse) response);
                promise.setSuccess();
            } catch (Throwable cause) {
                promise.setFailure(cause);
            }
        } else {
            ChannelPipeline p = channel.pipeline();
            ChannelHandlerContext ctx = p.context(HttpResponseDecoder.class);
            if (ctx == null) {
                ctx = p.context(HttpClientCodec.class);
                if (ctx == null) {
                    return promise.setFailure(new IllegalStateException("ChannelPipeline does not contain " +
                            "a HttpResponseDecoder or HttpClientCodec"));
                }
            }
            // Add aggregator and ensure we feed the HttpResponse so it is aggregated. A limit of 8192 should be more
            // then enough for the websockets handshake payload.
            //
            // TODO: Make handshake work without HttpObjectAggregator at all.
            String aggregatorName = "httpAggregator";
            p.addAfter(ctx.name(), aggregatorName, new HttpObjectAggregator(8192));
            p.addAfter(aggregatorName, "handshaker", new SimpleChannelInboundHandler<FullHttpResponse>() {
                @Override
                protected void channelRead0(ChannelHandlerContext ctx, FullHttpResponse msg) throws Exception {
                    // Remove ourself and do the actual handshake
                    ctx.pipeline().remove(this);
                    try {
                        finishHandshake(channel, msg);
                        promise.setSuccess();
                    } catch (Throwable cause) {
                        promise.setFailure(cause);
                    }
                }

                @Override
                public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
                    // Remove ourself and fail the handshake promise.
                    ctx.pipeline().remove(this);
                    promise.setFailure(cause);
                }

                @Override
                public void channelInactive(ChannelHandlerContext ctx) throws Exception {
                    // Fail promise if Channel was closed
                    promise.tryFailure(CLOSED_CHANNEL_EXCEPTION);
                    ctx.fireChannelInactive();
                }
            });
            try {
                ctx.fireChannelRead(ReferenceCountUtil.retain(response));
            } catch (Throwable cause) {
                promise.setFailure(cause);
            }
        }
        return promise;
    }

    /**
     * Verfiy the {@link FullHttpResponse} and throws a {@link WebSocketHandshakeException} if something is wrong.
     */
    protected abstract void verify(FullHttpResponse response);

    /**
     * Returns the decoder to use after handshake is complete.
     */
    protected abstract WebSocketFrameDecoder newWebsocketDecoder();

    /**
     * Returns the encoder to use after the handshake is complete.
     */
    protected abstract WebSocketFrameEncoder newWebSocketEncoder();

    /**
     * Performs the closing handshake
     *
     * @param channel
     *            Channel
     * @param frame
     *            Closing Frame that was received
     */
    public ChannelFuture close(Channel channel, CloseWebSocketFrame frame) {
        if (channel == null) {
            throw new NullPointerException("channel");
        }
        return close(channel, frame, channel.newPromise());
    }

    /**
     * Performs the closing handshake
     *
     * @param channel
     *            Channel
     * @param frame
     *            Closing Frame that was received
     * @param promise
     *            the {@link ChannelPromise} to be notified when the closing handshake is done
     */
    public ChannelFuture close(Channel channel, CloseWebSocketFrame frame, ChannelPromise promise) {
        if (channel == null) {
            throw new NullPointerException("channel");
        }
        return channel.writeAndFlush(frame, promise);
    }

    /**
     * Return the constructed raw path for the give {@link URI}.
     */
    static String rawPath(URI wsURL) {
        String path = wsURL.getRawPath();
        String query = wsURL.getQuery();
        if (query != null && !query.isEmpty()) {
            path = path + '?' + query;
        }

        return path == null || path.isEmpty() ? "/" : path;
    }

    static int websocketPort(URI wsURL) {
        // Format request
        int wsPort = wsURL.getPort();
        // check if the URI contained a port if not set the correct one depending on the schema.
        // See https://github.com/netty/netty/pull/1558
        if (wsPort == -1) {
            return "wss".equals(wsURL.getScheme()) ? HttpScheme.HTTPS.port() : HttpScheme.HTTP.port();
        }
        return wsPort;
    }

    static CharSequence websocketOriginValue(String host, int wsPort) {
        String originValue = (wsPort == HttpScheme.HTTPS.port() ?
                HttpScheme.HTTPS.name() : HttpScheme.HTTP.name()) + "://" + host;
        if (wsPort != HttpScheme.HTTP.port() && wsPort != HttpScheme.HTTPS.port()) {
            // if the port is not standard (80/443) its needed to add the port to the header.
            // See http://tools.ietf.org/html/rfc6454#section-6.2
            return originValue + ':' + wsPort;
        }
        return originValue;
    }
}