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1   /*
2    * Copyright 2010 Red Hat, Inc.
3    *
4    * Red Hat licenses this file to you under the Apache License, version 2.0
5    * (the "License"); you may not use this file except in compliance with the
6    * License.  You may obtain a copy of the License at:
7    *
8    *    http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package org.jboss.netty.handler.codec.http.websocket;
17  
18  import org.jboss.netty.buffer.ChannelBuffer;
19  import org.jboss.netty.channel.Channel;
20  import org.jboss.netty.channel.ChannelHandlerContext;
21  import org.jboss.netty.channel.ChannelHandler.Sharable;
22  import org.jboss.netty.handler.codec.oneone.OneToOneEncoder;
23  
24  /**
25   * Encodes a {@link WebSocketFrame} into a {@link ChannelBuffer}.
26   * <p>
27   * For the detailed instruction on adding add Web Socket support to your HTTP
28   * server, take a look into the <tt>WebSocketServer</tt> example located in the
29   * {@code org.jboss.netty.example.http.websocket} package.
30   *
31   * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
32   * @author Mike Heath (mheath@apache.org)
33   * @author <a href="http://gleamynode.net/">Trustin Lee</a>
34   * @version $Rev: 2362 $, $Date: 2010-09-09 19:59:22 +0900 (Thu, 09 Sep 2010) $
35   *
36   * @apiviz.landmark
37   * @apiviz.uses org.jboss.netty.handler.codec.http.websocket.WebSocketFrame
38   */
39  @Sharable
40  public class WebSocketFrameEncoder extends OneToOneEncoder {
41  
42      @Override
43      protected Object encode(ChannelHandlerContext ctx, Channel channel, Object msg) throws Exception {
44          if (msg instanceof WebSocketFrame) {
45              WebSocketFrame frame = (WebSocketFrame) msg;
46              int type = frame.getType();
47              if (frame.isText()) {
48                  // Text frame
49                  ChannelBuffer data = frame.getBinaryData();
50                  ChannelBuffer encoded =
51                      channel.getConfig().getBufferFactory().getBuffer(
52                              data.order(), data.readableBytes() + 2);
53                  encoded.writeByte((byte) type);
54                  encoded.writeBytes(data, data.readerIndex(), data.readableBytes());
55                  encoded.writeByte((byte) 0xFF);
56                  return encoded;
57              } else {
58                  // Binary frame
59                  ChannelBuffer data = frame.getBinaryData();
60                  int dataLen = data.readableBytes();
61                  ChannelBuffer encoded =
62                      channel.getConfig().getBufferFactory().getBuffer(
63                              data.order(), dataLen + 5);
64  
65                  // Encode type.
66                  encoded.writeByte((byte) type);
67  
68                  // Encode length.
69                  int b1 = dataLen >>> 28 & 0x7F;
70                  int b2 = dataLen >>> 14 & 0x7F;
71                  int b3 = dataLen >>> 7 & 0x7F;
72                  int b4 = dataLen & 0x7F;
73                  if (b1 == 0) {
74                      if (b2 == 0) {
75                          if (b3 == 0) {
76                              encoded.writeByte(b4);
77                          } else {
78                              encoded.writeByte(b3 | 0x80);
79                              encoded.writeByte(b4);
80                          }
81                      } else {
82                          encoded.writeByte(b2 | 0x80);
83                          encoded.writeByte(b3 | 0x80);
84                          encoded.writeByte(b4);
85                      }
86                  } else {
87                      encoded.writeByte(b1 | 0x80);
88                      encoded.writeByte(b2 | 0x80);
89                      encoded.writeByte(b3 | 0x80);
90                      encoded.writeByte(b4);
91                  }
92  
93                  // Encode binary data.
94                  encoded.writeBytes(data, data.readerIndex(), dataLen);
95                  return encoded;
96              }
97          }
98          return msg;
99      }
100 }