WebSocket00FrameEncoder.java

/*
 * Copyright 2010 Red Hat, Inc.
 *
 * Red Hat 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 org.chililog.server.pubsub.websocket;

import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelHandler.Sharable;
import org.jboss.netty.handler.codec.oneone.OneToOneEncoder;

/**
 * Encodes a {@link WebSocketFrame} into a {@link ChannelBuffer}.
 * <p>
 * For the detailed instruction on adding add Web Socket support to your HTTP
 * server, take a look into the <tt>WebSocketServer</tt> example located in the
 * {@code org.jboss.netty.example.http.websocket} package.
 * 
 * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
 * @author Mike Heath (mheath@apache.org)
 * @author <a href="http://gleamynode.net/">Trustin Lee</a>
 * @version $Rev: 2362 $, $Date: 2010-09-09 19:59:22 +0900 (Thu, 09 Sep 2010) $
 * 
 * @apiviz.landmark
 * @apiviz.uses org.jboss.netty.handler.codec.http.websocket.WebSocketFrame
 */
@Sharable
public class WebSocket00FrameEncoder extends OneToOneEncoder {

	@Override
	protected Object encode(ChannelHandlerContext ctx, Channel channel, Object msg) throws Exception {
		if (msg instanceof WebSocketFrame) {
			WebSocketFrame frame = (WebSocketFrame) msg;
			if (frame instanceof TextWebSocketFrame) {
				// Text frame
				ChannelBuffer data = frame.getBinaryData();
				ChannelBuffer encoded = channel.getConfig().getBufferFactory()
						.getBuffer(data.order(), data.readableBytes() + 2);
				encoded.writeByte((byte) 0x00);
				encoded.writeBytes(data, data.readerIndex(), data.readableBytes());
				encoded.writeByte((byte) 0xFF);
				return encoded;
			} else if (frame instanceof CloseWebSocketFrame) {
				// Close frame
				ChannelBuffer data = frame.getBinaryData();
				ChannelBuffer encoded = channel.getConfig().getBufferFactory().getBuffer(data.order(), 2);
				encoded.writeByte((byte) 0xFF);
				encoded.writeByte((byte) 0x00);
				return encoded;
			} else {
				// Binary frame
				ChannelBuffer data = frame.getBinaryData();
				int dataLen = data.readableBytes();
				ChannelBuffer encoded = channel.getConfig().getBufferFactory().getBuffer(data.order(), dataLen + 5);

				// Encode type.
				encoded.writeByte((byte) 0x80);

				// Encode length.
				int b1 = dataLen >>> 28 & 0x7F;
				int b2 = dataLen >>> 14 & 0x7F;
				int b3 = dataLen >>> 7 & 0x7F;
				int b4 = dataLen & 0x7F;
				if (b1 == 0) {
					if (b2 == 0) {
						if (b3 == 0) {
							encoded.writeByte(b4);
						} else {
							encoded.writeByte(b3 | 0x80);
							encoded.writeByte(b4);
						}
					} else {
						encoded.writeByte(b2 | 0x80);
						encoded.writeByte(b3 | 0x80);
						encoded.writeByte(b4);
					}
				} else {
					encoded.writeByte(b1 | 0x80);
					encoded.writeByte(b2 | 0x80);
					encoded.writeByte(b3 | 0x80);
					encoded.writeByte(b4);
				}

				// Encode binary data.
				encoded.writeBytes(data, data.readerIndex(), dataLen);
				return encoded;
			}
		}
		return msg;
	}
}