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.util.Collection;
  
  import io.netty.channel.ChannelPipeline;
  
  import static org.apache.cassandra.net.FrameDecoderCrc.HEADER_LENGTH;
  import static org.apache.cassandra.net.FrameDecoderCrc.isSelfContained;
  import static org.apache.cassandra.net.FrameDecoderCrc.payloadLength;
  import static org.apache.cassandra.net.FrameDecoderCrc.readHeader6b;
  import static org.apache.cassandra.net.FrameDecoderCrc.verifyHeader6b;
  
  /**
   * A frame decoder for unprotected frames, i.e. those without any modification or payload protection.
   * This is non-standard, and useful for systems that have a trusted transport layer that want
   * to avoid incurring the (very low) cost of computing a CRC.  All we do is accumulate the bytes
   * of the frame, verify the frame header, and pass through the bytes stripped of the header.
   *
   * 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)
   *
   *  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                            |
   * +                                                               +
   * |                                                               |
   * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   */
  final class FrameDecoderUnprotected extends FrameDecoderWith8bHeader
  {
      FrameDecoderUnprotected(BufferPoolAllocator allocator)
      {
          super(allocator);
      }
  
      public static FrameDecoderUnprotected create(BufferPoolAllocator allocator)
      {
          return new FrameDecoderUnprotected(allocator);
      }
  
      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_LENGTH;
      }
  
      final Frame unpackFrame(ShareableBytes bytes, int begin, int end, long header6b)
      {
          boolean isSelfContained = isSelfContained(header6b);
          return new IntactFrame(isSelfContained, bytes.slice(begin + HEADER_LENGTH, end));
      }
  
      void decode(Collection<Frame> into, ShareableBytes bytes)
      {
          decode(into, bytes, HEADER_LENGTH);
      }
  
      void addLastTo(ChannelPipeline pipeline)
      {
          pipeline.addLast("frameDecoderUnprotected", this);
      }
  }
  