120 lines
4.2 KiB
Java
120 lines
4.2 KiB
Java
/*
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* Copyright 2015 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.handler.codec.protobuf;
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import com.google.protobuf.CodedInputStream;
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import com.google.protobuf.nano.CodedInputByteBufferNano;
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import io.netty.buffer.ByteBuf;
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import io.netty.channel.ChannelHandlerContext;
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import io.netty.handler.codec.ByteToMessageDecoder;
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import io.netty.handler.codec.CorruptedFrameException;
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/**
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* A decoder that splits the received {@link ByteBuf}s dynamically by the
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* value of the Google Protocol Buffers
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* <a href="https://developers.google.com/protocol-buffers/docs/encoding#varints">Base
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* 128 Varints</a> integer length field in the message. For example:
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* <pre>
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* BEFORE DECODE (302 bytes) AFTER DECODE (300 bytes)
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* +--------+---------------+ +---------------+
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* | Length | Protobuf Data |----->| Protobuf Data |
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* | 0xAC02 | (300 bytes) | | (300 bytes) |
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* +--------+---------------+ +---------------+
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* </pre>
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*
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* @see CodedInputStream
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* @see CodedInputByteBufferNano
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*/
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public class ProtobufVarint32FrameDecoder extends ByteToMessageDecoder {
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// TODO maxFrameLength + safe skip + fail-fast option
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// (just like LengthFieldBasedFrameDecoder)
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@Override
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protected void decode(ChannelHandlerContext ctx, ByteBuf in)
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throws Exception {
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int readerIndex = in.readerIndex();
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int preIndex = in.readerIndex();
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int length = readRawVarint32(in);
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if (preIndex == in.readerIndex()) {
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return;
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}
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if (length < 0) {
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throw new CorruptedFrameException("negative length: " + length);
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}
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if (in.readableBytes() < length) {
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in.readerIndex(readerIndex);
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} else {
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ctx.fireChannelRead(in.readRetainedSlice(length));
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}
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}
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/**
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* Reads variable length 32bit int from buffer
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*
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* @return decoded int if buffers readerIndex has been forwarded else nonsense value
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*/
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private static int readRawVarint32(ByteBuf buffer) {
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if (!buffer.isReadable()) {
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return 0;
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}
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int readerIndex = buffer.readerIndex();
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byte tmp = buffer.readByte();
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if (tmp >= 0) {
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return tmp;
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} else {
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int result = tmp & 127;
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if (!buffer.isReadable()) {
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buffer.readerIndex(readerIndex);
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return 0;
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}
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if ((tmp = buffer.readByte()) >= 0) {
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result |= tmp << 7;
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} else {
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result |= (tmp & 127) << 7;
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if (!buffer.isReadable()) {
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buffer.readerIndex(readerIndex);
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return 0;
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}
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if ((tmp = buffer.readByte()) >= 0) {
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result |= tmp << 14;
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} else {
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result |= (tmp & 127) << 14;
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if (!buffer.isReadable()) {
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buffer.readerIndex(readerIndex);
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return 0;
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}
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if ((tmp = buffer.readByte()) >= 0) {
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result |= tmp << 21;
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} else {
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result |= (tmp & 127) << 21;
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if (!buffer.isReadable()) {
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buffer.readerIndex(readerIndex);
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return 0;
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}
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result |= (tmp = buffer.readByte()) << 28;
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if (tmp < 0) {
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throw new CorruptedFrameException("malformed varint.");
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}
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}
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}
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}
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return result;
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}
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}
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}
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