content: /*
   * 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.utils.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<Frame> into, ShareableBytes bytes)
      {
          decode(into, bytes, HEADER_LENGTH);
      }
  
      void addLastTo(ChannelPipeline pipeline)
      {
          pipeline.addLast("frameDecoderCrc", this);
      }
  }
  