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Java example source code file (WebSocketServerHandshaker00.java)

This example Java source code file (WebSocketServerHandshaker00.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

beginning_space, defaultfullhttpresponse, fullhttpresponse, handshake, httpheaders, override, pattern, protocol, regex, requested, string, websocket, websocket00framedecoder, websocketframeencoder, websocketserverhandshaker00

The WebSocketServerHandshaker00.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.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelPromise;
import io.netty.handler.codec.http.DefaultFullHttpResponse;
import io.netty.handler.codec.http.FullHttpRequest;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.HttpHeaderNames;
import io.netty.handler.codec.http.HttpHeaderValues;
import io.netty.handler.codec.http.HttpHeaders;
import io.netty.handler.codec.http.HttpResponseStatus;

import java.util.regex.Pattern;

import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1;

/**
 * <p>
 * Performs server side opening and closing handshakes for web socket specification version <a
 * href="http://tools.ietf.org/html/draft-ietf-hybi-thewebsocketprotocol-00" >draft-ietf-hybi-thewebsocketprotocol-
 * 00</a>
 * </p>
 * <p>
 * A very large portion of this code was taken from the Netty 3.2 HTTP example.
 * </p>
 */
public class WebSocketServerHandshaker00 extends WebSocketServerHandshaker {

    private static final Pattern BEGINNING_DIGIT = Pattern.compile("[^0-9]");
    private static final Pattern BEGINNING_SPACE = Pattern.compile("[^ ]");

    /**
     * Constructor specifying the destination web socket location
     *
     * @param webSocketURL
     *            URL for web socket communications. e.g "ws://myhost.com/mypath". Subsequent web socket frames will be
     *            sent to this URL.
     * @param subprotocols
     *            CSV of supported protocols
     * @param maxFramePayloadLength
     *            Maximum allowable frame payload length. Setting this value to your application's requirement may
     *            reduce denial of service attacks using long data frames.
     */
    public WebSocketServerHandshaker00(String webSocketURL, String subprotocols, int maxFramePayloadLength) {
        super(WebSocketVersion.V00, webSocketURL, subprotocols, maxFramePayloadLength);
    }

    /**
     * <p>
     * Handle the web socket handshake for the web socket specification <a href=
     * "http://tools.ietf.org/html/draft-ietf-hybi-thewebsocketprotocol-00">HyBi version 0</a> and lower. This standard
     * is really a rehash of <a href="http://tools.ietf.org/html/draft-hixie-thewebsocketprotocol-76" >hixie-76 and
     * <a href="http://tools.ietf.org/html/draft-hixie-thewebsocketprotocol-75" >hixie-75.
     * </p>
     *
     * <p>
     * Browser request to the server:
     * </p>
     *
     * <pre>
     * GET /demo HTTP/1.1
     * Upgrade: WebSocket
     * Connection: Upgrade
     * Host: example.com
     * Origin: http://example.com
     * Sec-WebSocket-Protocol: chat, sample
     * Sec-WebSocket-Key1: 4 @1  46546xW%0l 1 5
     * Sec-WebSocket-Key2: 12998 5 Y3 1  .P00
     *
     * ^n:ds[4U
     * </pre>
     *
     * <p>
     * Server response:
     * </p>
     *
     * <pre>
     * HTTP/1.1 101 WebSocket Protocol Handshake
     * Upgrade: WebSocket
     * Connection: Upgrade
     * Sec-WebSocket-Origin: http://example.com
     * Sec-WebSocket-Location: ws://example.com/demo
     * Sec-WebSocket-Protocol: sample
     *
     * 8jKS'y:G*Co,Wxa-
     * </pre>
     */
    @Override
    protected FullHttpResponse newHandshakeResponse(FullHttpRequest req, HttpHeaders headers) {

        // Serve the WebSocket handshake request.
        if (!req.headers().containsValue(HttpHeaderNames.CONNECTION, HttpHeaderValues.UPGRADE, true)
                || !HttpHeaderValues.WEBSOCKET.contentEqualsIgnoreCase(req.headers().get(HttpHeaderNames.UPGRADE))) {
            throw new WebSocketHandshakeException("not a WebSocket handshake request: missing upgrade");
        }

        // Hixie 75 does not contain these headers while Hixie 76 does
        boolean isHixie76 = req.headers().contains(HttpHeaderNames.SEC_WEBSOCKET_KEY1) &&
                            req.headers().contains(HttpHeaderNames.SEC_WEBSOCKET_KEY2);

        // Create the WebSocket handshake response.
        FullHttpResponse res = new DefaultFullHttpResponse(HTTP_1_1, new HttpResponseStatus(101,
                isHixie76 ? "WebSocket Protocol Handshake" : "Web Socket Protocol Handshake"));
        if (headers != null) {
            res.headers().add(headers);
        }

        res.headers().add(HttpHeaderNames.UPGRADE, HttpHeaderValues.WEBSOCKET);
        res.headers().add(HttpHeaderNames.CONNECTION, HttpHeaderValues.UPGRADE);

        // Fill in the headers and contents depending on handshake getMethod.
        if (isHixie76) {
            // New handshake getMethod with a challenge:
            res.headers().add(HttpHeaderNames.SEC_WEBSOCKET_ORIGIN, req.headers().get(HttpHeaderNames.ORIGIN));
            res.headers().add(HttpHeaderNames.SEC_WEBSOCKET_LOCATION, uri());

            String subprotocols = req.headers().get(HttpHeaderNames.SEC_WEBSOCKET_PROTOCOL);
            if (subprotocols != null) {
                String selectedSubprotocol = selectSubprotocol(subprotocols);
                if (selectedSubprotocol == null) {
                    if (logger.isDebugEnabled()) {
                        logger.debug("Requested subprotocol(s) not supported: {}", subprotocols);
                    }
                } else {
                    res.headers().add(HttpHeaderNames.SEC_WEBSOCKET_PROTOCOL, selectedSubprotocol);
                }
            }

            // Calculate the answer of the challenge.
            String key1 = req.headers().get(HttpHeaderNames.SEC_WEBSOCKET_KEY1);
            String key2 = req.headers().get(HttpHeaderNames.SEC_WEBSOCKET_KEY2);
            int a = (int) (Long.parseLong(BEGINNING_DIGIT.matcher(key1).replaceAll("")) /
                           BEGINNING_SPACE.matcher(key1).replaceAll("").length());
            int b = (int) (Long.parseLong(BEGINNING_DIGIT.matcher(key2).replaceAll("")) /
                           BEGINNING_SPACE.matcher(key2).replaceAll("").length());
            long c = req.content().readLong();
            ByteBuf input = Unpooled.buffer(16);
            input.writeInt(a);
            input.writeInt(b);
            input.writeLong(c);
            res.content().writeBytes(WebSocketUtil.md5(input.array()));
        } else {
            // Old Hixie 75 handshake getMethod with no challenge:
            res.headers().add(HttpHeaderNames.WEBSOCKET_ORIGIN, req.headers().get(HttpHeaderNames.ORIGIN));
            res.headers().add(HttpHeaderNames.WEBSOCKET_LOCATION, uri());

            String protocol = req.headers().get(HttpHeaderNames.WEBSOCKET_PROTOCOL);
            if (protocol != null) {
                res.headers().add(HttpHeaderNames.WEBSOCKET_PROTOCOL, selectSubprotocol(protocol));
            }
        }
        return res;
    }

    /**
     * Echo back the closing frame
     *
     * @param channel
     *            Channel
     * @param frame
     *            Web Socket frame that was received
     */
    @Override
    public ChannelFuture close(Channel channel, CloseWebSocketFrame frame, ChannelPromise promise) {
        return channel.writeAndFlush(frame, promise);
    }

    @Override
    protected WebSocketFrameDecoder newWebsocketDecoder() {
        return new WebSocket00FrameDecoder(maxFramePayloadLength());
    }

    @Override
    protected WebSocketFrameEncoder newWebSocketEncoder() {
        return new WebSocket00FrameEncoder();
    }
}

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