/*
* Copyright 2014 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.extensions;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPromise;
import io.netty.handler.codec.CodecException;
import io.netty.handler.codec.http.HttpHeaders;
import io.netty.handler.codec.http.HttpRequest;
import io.netty.handler.codec.http.HttpResponse;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
/**
* This handler negotiates and initializes the WebSocket Extensions.
*
* This implementation negotiates the extension with the server in a defined order,
* ensures that the successfully negotiated extensions are consistent between them,
* and initializes the channel pipeline with the extension decoder and encoder.
*
* Find a basic implementation for compression extensions at
* <tt>io.netty.handler.codec.http.websocketx.extensions.compression.WebSocketClientCompressionHandler</tt>.
*/
public class WebSocketClientExtensionHandler extends ChannelHandlerAdapter {
private final List<WebSocketClientExtensionHandshaker> extensionHandshakers;
/**
* Constructor
*
* @param extensionHandshakers
* The extension handshaker in priority order. A handshaker could be repeated many times
* with fallback configuration.
*/
public WebSocketClientExtensionHandler(WebSocketClientExtensionHandshaker... extensionHandshakers) {
if (extensionHandshakers == null) {
throw new NullPointerException("extensionHandshakers");
}
if (extensionHandshakers.length == 0) {
throw new IllegalArgumentException("extensionHandshakers must contains at least one handshaker");
}
this.extensionHandshakers = Arrays.asList(extensionHandshakers);
}
@Override
public void write(final ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
if (msg instanceof HttpRequest && WebSocketExtensionUtil.isWebsocketUpgrade((HttpRequest) msg)) {
HttpRequest request = (HttpRequest) msg;
String headerValue = request.headers().get(HttpHeaders.Names.SEC_WEBSOCKET_EXTENSIONS);
for (WebSocketClientExtensionHandshaker extentionHandshaker : extensionHandshakers) {
WebSocketExtensionData extensionData = extentionHandshaker.newRequestData();
headerValue = WebSocketExtensionUtil.appendExtension(headerValue,
extensionData.name(), extensionData.parameters());
}
request.headers().set(HttpHeaders.Names.SEC_WEBSOCKET_EXTENSIONS, headerValue);
}
super.write(ctx, msg, promise);
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg)
throws Exception {
if (msg instanceof HttpResponse) {
HttpResponse response = (HttpResponse) msg;
if (WebSocketExtensionUtil.isWebsocketUpgrade(response)) {
String extensionsHeader = response.headers().get(HttpHeaders.Names.SEC_WEBSOCKET_EXTENSIONS);
if (extensionsHeader != null) {
List<WebSocketExtensionData> extensions =
WebSocketExtensionUtil.extractExtensions(extensionsHeader);
List<WebSocketClientExtension> validExtensions =
new ArrayList<WebSocketClientExtension>(extensions.size());
int rsv = 0;
for (WebSocketExtensionData extensionData : extensions) {
Iterator<WebSocketClientExtensionHandshaker> extensionHandshakersIterator =
extensionHandshakers.iterator();
WebSocketClientExtension validExtension = null;
while (validExtension == null && extensionHandshakersIterator.hasNext()) {
WebSocketClientExtensionHandshaker extensionHandshaker =
extensionHandshakersIterator.next();
validExtension = extensionHandshaker.handshakeExtension(extensionData);
}
if (validExtension != null && ((validExtension.rsv() & rsv) == 0)) {
rsv = rsv | validExtension.rsv();
validExtensions.add(validExtension);
} else {
throw new CodecException(
"invalid WebSocket Extension handhshake for \"" + extensionsHeader + "\"");
}
}
for (WebSocketClientExtension validExtension : validExtensions) {
WebSocketExtensionDecoder decoder = validExtension.newExtensionDecoder();
WebSocketExtensionEncoder encoder = validExtension.newExtensionEncoder();
ctx.pipeline().addAfter(ctx.name(), decoder.getClass().getName(), decoder);
ctx.pipeline().addAfter(ctx.name(), encoder.getClass().getName(), encoder);
}
}
ctx.pipeline().remove(ctx.name());
}
}
super.channelRead(ctx, msg);
}
}