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1   /*
2    * Copyright 2012 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the 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.websocketx;
17  
18  import org.jboss.netty.buffer.ChannelBuffer;
19  import org.jboss.netty.channel.Channel;
20  import org.jboss.netty.channel.ChannelHandler.Sharable;
21  import org.jboss.netty.channel.ChannelHandlerContext;
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 server, take a look into the
28   * <tt>WebSocketServer</tt> example located in the {@code org.jboss.netty.example.http.websocket} package.
29   *
30   * @apiviz.landmark
31   * @apiviz.uses org.jboss.netty.handler.codec.http.websocket.WebSocketFrame
32   */
33  @Sharable
34  public class WebSocket00FrameEncoder extends OneToOneEncoder {
35  
36      @Override
37      protected Object encode(ChannelHandlerContext ctx, Channel channel, Object msg) throws Exception {
38          if (msg instanceof WebSocketFrame) {
39              WebSocketFrame frame = (WebSocketFrame) msg;
40              if (frame instanceof TextWebSocketFrame) {
41                  // Text frame
42                  ChannelBuffer data = frame.getBinaryData();
43                  ChannelBuffer encoded = channel.getConfig().getBufferFactory()
44                          .getBuffer(data.order(), data.readableBytes() + 2);
45                  encoded.writeByte((byte) 0x00);
46                  encoded.writeBytes(data, data.readerIndex(), data.readableBytes());
47                  encoded.writeByte((byte) 0xFF);
48                  return encoded;
49              } else if (frame instanceof CloseWebSocketFrame) {
50                  // Close frame
51                  ChannelBuffer data = frame.getBinaryData();
52                  ChannelBuffer encoded = channel.getConfig().getBufferFactory().getBuffer(data.order(), 2);
53                  encoded.writeByte((byte) 0xFF);
54                  encoded.writeByte((byte) 0x00);
55                  return encoded;
56              } else {
57                  // Binary frame
58                  ChannelBuffer data = frame.getBinaryData();
59                  int dataLen = data.readableBytes();
60                  ChannelBuffer encoded = channel.getConfig().getBufferFactory().getBuffer(data.order(), dataLen + 5);
61  
62                  // Encode type.
63                  encoded.writeByte((byte) 0x80);
64  
65                  // Encode length.
66                  int b1 = dataLen >>> 28 & 0x7F;
67                  int b2 = dataLen >>> 14 & 0x7F;
68                  int b3 = dataLen >>> 7 & 0x7F;
69                  int b4 = dataLen & 0x7F;
70                  if (b1 == 0) {
71                      if (b2 == 0) {
72                          if (b3 == 0) {
73                              encoded.writeByte(b4);
74                          } else {
75                              encoded.writeByte(b3 | 0x80);
76                              encoded.writeByte(b4);
77                          }
78                      } else {
79                          encoded.writeByte(b2 | 0x80);
80                          encoded.writeByte(b3 | 0x80);
81                          encoded.writeByte(b4);
82                      }
83                  } else {
84                      encoded.writeByte(b1 | 0x80);
85                      encoded.writeByte(b2 | 0x80);
86                      encoded.writeByte(b3 | 0x80);
87                      encoded.writeByte(b4);
88                  }
89  
90                  // Encode binary data.
91                  encoded.writeBytes(data, data.readerIndex(), dataLen);
92                  return encoded;
93              }
94          }
95          return msg;
96      }
97  }