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.handler.codec.frame.TooLongFrameException;
22 import org.jboss.netty.handler.codec.replay.ReplayingDecoder;
23 import org.jboss.netty.handler.codec.replay.VoidEnum;
24
25 /**
26 * Decodes {@link ChannelBuffer}s into {@link WebSocketFrame}s.
27 * <p>
28 * For the detailed instruction on adding add Web Socket support to your HTTP
29 * server, take a look into the <tt>WebSocketServer</tt> example located in the
30 * {@code org.jboss.netty.example.http.websocket} package.
31 *
32 * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
33 * @author Mike Heath (mheath@apache.org)
34 * @author <a href="http://gleamynode.net/">Trustin Lee</a>
35 * @version $Rev: 2342 $, $Date: 2010-07-07 14:07:39 +0900 (Wed, 07 Jul 2010) $
36 *
37 * @apiviz.landmark
38 * @apiviz.uses org.jboss.netty.handler.codec.http.websocket.WebSocketFrame
39 */
40 public class WebSocketFrameDecoder extends ReplayingDecoder<VoidEnum> {
41
42 public static final int DEFAULT_MAX_FRAME_SIZE = 16384;
43
44 private final int maxFrameSize;
45 private boolean receivedClosingHandshake;
46
47 public WebSocketFrameDecoder() {
48 this(DEFAULT_MAX_FRAME_SIZE);
49 }
50
51 /**
52 * Creates a new instance of {@code WebSocketFrameDecoder} with the specified {@code maxFrameSize}. If the client
53 * sends a frame size larger than {@code maxFrameSize}, the channel will be closed.
54 *
55 * @param maxFrameSize the maximum frame size to decode
56 */
57 public WebSocketFrameDecoder(int maxFrameSize) {
58 this.maxFrameSize = maxFrameSize;
59 }
60
61 @Override
62 protected Object decode(ChannelHandlerContext ctx, Channel channel,
63 ChannelBuffer buffer, VoidEnum state) throws Exception {
64
65 // Discard all data received if closing handshake was received before.
66 if (receivedClosingHandshake) {
67 buffer.skipBytes(actualReadableBytes());
68 return null;
69 }
70
71 // Decode a frame otherwise.
72 byte type = buffer.readByte();
73 if ((type & 0x80) == 0x80) {
74 // If the MSB on type is set, decode the frame length
75 return decodeBinaryFrame(type, buffer);
76 } else {
77 // Decode a 0xff terminated UTF-8 string
78 return decodeTextFrame(type, buffer);
79 }
80 }
81
82 private WebSocketFrame decodeBinaryFrame(int type, ChannelBuffer buffer) throws TooLongFrameException {
83 long frameSize = 0;
84 int lengthFieldSize = 0;
85 byte b;
86 do {
87 b = buffer.readByte();
88 frameSize <<= 7;
89 frameSize |= b & 0x7f;
90 if (frameSize > maxFrameSize) {
91 throw new TooLongFrameException();
92 }
93 lengthFieldSize ++;
94 if (lengthFieldSize > 8) {
95 // Perhaps a malicious peer?
96 throw new TooLongFrameException();
97 }
98 } while ((b & 0x80) == 0x80);
99
100 if (type == 0xFF && frameSize == 0) {
101 receivedClosingHandshake = true;
102 }
103
104 return new DefaultWebSocketFrame(
105 type, buffer.readBytes((int) frameSize));
106 }
107
108 private WebSocketFrame decodeTextFrame(int type, ChannelBuffer buffer) throws TooLongFrameException {
109 int ridx = buffer.readerIndex();
110 int rbytes = actualReadableBytes();
111 int delimPos = buffer.indexOf(ridx, ridx + rbytes, (byte) 0xFF);
112 if (delimPos == -1) {
113 // Frame delimiter (0xFF) not found
114 if (rbytes > maxFrameSize) {
115 // Frame length exceeded the maximum
116 throw new TooLongFrameException();
117 } else {
118 // Wait until more data is received
119 return null;
120 }
121 }
122
123 int frameSize = delimPos - ridx;
124 if (frameSize > maxFrameSize) {
125 throw new TooLongFrameException();
126 }
127
128 ChannelBuffer binaryData = buffer.readBytes(frameSize);
129 buffer.skipBytes(1);
130 return new DefaultWebSocketFrame(type, binaryData);
131 }
132 }