netty5/codec-http/src/main/java/io/netty/handler/codec/http/websocketx/WebSocketClientProtocolHandler.java

/*
 * Copyright 2013 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.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandler;
import io.netty.channel.ChannelPipeline;
import io.netty.handler.codec.http.HttpHeaders;

import java.net.URI;
import java.util.List;

/**
 * This handler does all the heavy lifting for you to run a websocket client.
 *
 * It takes care of websocket handshaking as well as processing of Ping, Pong frames. Text and Binary
 * data frames are passed to the next handler in the pipeline (implemented by you) for processing.
 * Also the close frame is passed to the next handler as you may want inspect it before close the connection if
 * the {@code handleCloseFrames} is {@code false}, default is {@code true}.
 *
 * This implementation will establish the websocket connection once the connection to the remote server was complete.
 *
 * To know once a handshake was done you can intercept the
 * {@link ChannelInboundHandler#userEventTriggered(ChannelHandlerContext, Object)} and check if the event was of type
 * {@link ClientHandshakeStateEvent#HANDSHAKE_ISSUED} or {@link ClientHandshakeStateEvent#HANDSHAKE_COMPLETE}.
 */
public class WebSocketClientProtocolHandler extends WebSocketProtocolHandler {

    private final WebSocketClientHandshaker handshaker;
    private final boolean handleCloseFrames;

    /**
     * Events that are fired to notify about handshake status
     */
    public enum ClientHandshakeStateEvent {
        /**
         * The Handshake was started but the server did not response yet to the request
         */
        HANDSHAKE_ISSUED,

        /**
         * The Handshake was complete succesful and so the channel was upgraded to websockets
         */
        HANDSHAKE_COMPLETE
    }

    /**
     * Base constructor
     *
     * @param webSocketURL
     *            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
     * @param handleCloseFrames
     *            {@code true} if close frames should not be forwarded and just close the channel
     */
    public WebSocketClientProtocolHandler(URI webSocketURL, WebSocketVersion version, String subprotocol,
                                                   boolean allowExtensions, HttpHeaders customHeaders,
                                                   int maxFramePayloadLength, boolean handleCloseFrames) {
        this(WebSocketClientHandshakerFactory.newHandshaker(webSocketURL, version, subprotocol,
                allowExtensions, customHeaders, maxFramePayloadLength), handleCloseFrames);
    }

    /**
     * Base constructor
     *
     * @param webSocketURL
     *            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
     */
    public WebSocketClientProtocolHandler(URI webSocketURL, WebSocketVersion version, String subprotocol,
                                          boolean allowExtensions, HttpHeaders customHeaders,
                                          int maxFramePayloadLength) {
        this(webSocketURL, version, subprotocol,
                allowExtensions, customHeaders, maxFramePayloadLength, true);
    }

    /**
     * Base constructor
     *
     * @param handshaker
     *            The {@link WebSocketClientHandshaker} which will be used to issue the handshake once the connection
     *            was established to the remote peer.
     * @param handleCloseFrames
     *            {@code true} if close frames should not be forwarded and just close the channel
     */
    public WebSocketClientProtocolHandler(WebSocketClientHandshaker handshaker, boolean handleCloseFrames) {
        this.handshaker = handshaker;
        this.handleCloseFrames = handleCloseFrames;
    }

    /**
     * Base constructor
     *
     * @param handshaker
     *            The {@link WebSocketClientHandshaker} which will be used to issue the handshake once the connection
     *            was established to the remote peer.
     */
    public WebSocketClientProtocolHandler(WebSocketClientHandshaker handshaker) {
        this(handshaker, true);
    }

    @Override
    protected void decode(ChannelHandlerContext ctx, WebSocketFrame frame, List<Object> out) throws Exception {
        if (handleCloseFrames && frame instanceof CloseWebSocketFrame) {
            ctx.close();
            return;
        }
        super.decode(ctx, frame, out);
    }

    @Override
    public void handlerAdded(ChannelHandlerContext ctx) {
        ChannelPipeline cp = ctx.pipeline();
        if (cp.get(WebSocketClientProtocolHandshakeHandler.class) == null) {
            // Add the WebSocketClientProtocolHandshakeHandler before this one.
            ctx.pipeline().addBefore(ctx.name(), WebSocketClientProtocolHandshakeHandler.class.getName(),
                    new WebSocketClientProtocolHandshakeHandler(handshaker));
        }
    }
}