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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.cassandra.net;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.Collection;
import java.util.zip.CRC32;
import io.netty.channel.ChannelPipeline;
import static org.apache.cassandra.net.Crc.*;
/**
* Framing format that protects integrity of data in movement with CRCs (of both header and payload).
*
* Every on-wire frame contains:
* 1. Payload length (17 bits)
* 2. {@code isSelfContained} flag (1 bit)
* 3. Header padding (6 bits)
* 4. CRC24 of the header (24 bits)
* 5. Payload (up to 2 ^ 17 - 1 bits)
* 6. Payload CRC32 (32 bits)
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Payload Length |C| |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* CRC24 of Header | |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
* | |
* + +
* | Payload |
* + +
* | |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | CRC32 of Payload |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
public final class FrameDecoderCrc extends FrameDecoderWith8bHeader
{
public FrameDecoderCrc(BufferPoolAllocator allocator)
{
super(allocator);
}
public static FrameDecoderCrc create(BufferPoolAllocator allocator)
{
return new FrameDecoderCrc(allocator);
}
static final int HEADER_LENGTH = 6;
private static final int TRAILER_LENGTH = 4;
private static final int HEADER_AND_TRAILER_LENGTH = 10;
static boolean isSelfContained(long header6b)
{
return 0 != (header6b & (1L << 17));
}
static int payloadLength(long header6b)
{
return ((int) header6b) & 0x1FFFF;
}
private static int headerCrc(long header6b)
{
return ((int) (header6b >>> 24)) & 0xFFFFFF;
}
static long readHeader6b(ByteBuffer frame, int begin)
{
long header6b;
if (frame.limit() - begin >= 8)
{
header6b = frame.getLong(begin);
if (frame.order() == ByteOrder.BIG_ENDIAN)
header6b = Long.reverseBytes(header6b);
header6b &= 0xffffffffffffL;
}
else
{
header6b = 0;
for (int i = 0 ; i < HEADER_LENGTH ; ++i)
header6b |= (0xffL & frame.get(begin + i)) << (8 * i);
}
return header6b;
}
static CorruptFrame verifyHeader6b(long header6b)
{
int computeLengthCrc = crc24(header6b, 3);
int readLengthCrc = headerCrc(header6b);
return readLengthCrc == computeLengthCrc ? null : CorruptFrame.unrecoverable(readLengthCrc, computeLengthCrc);
}
final long readHeader(ByteBuffer frame, int begin)
{
return readHeader6b(frame, begin);
}
final CorruptFrame verifyHeader(long header6b)
{
return verifyHeader6b(header6b);
}
final int frameLength(long header6b)
{
return payloadLength(header6b) + HEADER_AND_TRAILER_LENGTH;
}
final Frame unpackFrame(ShareableBytes bytes, int begin, int end, long header6b)
{
ByteBuffer in = bytes.get();
boolean isSelfContained = isSelfContained(header6b);
CRC32 crc = crc32();
int readFullCrc = in.getInt(end - TRAILER_LENGTH);
if (in.order() == ByteOrder.BIG_ENDIAN)
readFullCrc = Integer.reverseBytes(readFullCrc);
updateCrc32(crc, in, begin + HEADER_LENGTH, end - TRAILER_LENGTH);
int computeFullCrc = (int) crc.getValue();
if (readFullCrc != computeFullCrc)
return CorruptFrame.recoverable(isSelfContained, (end - begin) - HEADER_AND_TRAILER_LENGTH, readFullCrc, computeFullCrc);
return new IntactFrame(isSelfContained, bytes.slice(begin + HEADER_LENGTH, end - TRAILER_LENGTH));
}
void decode(Collection into, ShareableBytes bytes)
{
decode(into, bytes, HEADER_LENGTH);
}
void addLastTo(ChannelPipeline pipeline)
{
pipeline.addLast("frameDecoderCrc", this);
}
}