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 io.netty.handler.codec.protobuf;
17
18 import io.netty.buffer.ByteBuf;
19 import io.netty.channel.ChannelHandlerContext;
20 import io.netty.handler.codec.ByteToMessageDecoder;
21 import io.netty.handler.codec.CorruptedFrameException;
22
23 import java.util.List;
24
25 import com.google.protobuf.CodedInputStream;
26
27 /**
28 * A decoder that splits the received {@link ByteBuf}s dynamically by the
29 * value of the Google Protocol Buffers
30 * <a href="https://developers.google.com/protocol-buffers/docs/encoding#varints">Base
31 * 128 Varints</a> integer length field in the message. For example:
32 * <pre>
33 * BEFORE DECODE (302 bytes) AFTER DECODE (300 bytes)
34 * +--------+---------------+ +---------------+
35 * | Length | Protobuf Data |----->| Protobuf Data |
36 * | 0xAC02 | (300 bytes) | | (300 bytes) |
37 * +--------+---------------+ +---------------+
38 * </pre>
39 *
40 * @see CodedInputStream
41 */
42 public class ProtobufVarint32FrameDecoder extends ByteToMessageDecoder {
43
44 // TODO maxFrameLength + safe skip + fail-fast option
45 // (just like LengthFieldBasedFrameDecoder)
46
47 @Override
48 protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
49 in.markReaderIndex();
50 final byte[] buf = new byte[5];
51 for (int i = 0; i < buf.length; i ++) {
52 if (!in.isReadable()) {
53 in.resetReaderIndex();
54 return;
55 }
56
57 buf[i] = in.readByte();
58 if (buf[i] >= 0) {
59 int length = CodedInputStream.newInstance(buf, 0, i + 1).readRawVarint32();
60 if (length < 0) {
61 throw new CorruptedFrameException("negative length: " + length);
62 }
63
64 if (in.readableBytes() < length) {
65 in.resetReaderIndex();
66 return;
67 } else {
68 out.add(in.readSlice(length).retain());
69 return;
70 }
71 }
72 }
73
74 // Couldn't find the byte whose MSB is off.
75 throw new CorruptedFrameException("length wider than 32-bit");
76 }
77 }