LengthFieldBasedFrameDecoder.h

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/*
 * Copyright 2017-present Facebook, Inc.
 *
 * Licensed 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.
 */

#pragma once

#include <folly/io/Cursor.h>
#include <wangle/codec/ByteToMessageDecoder.h>

namespace wangle {

class LengthFieldBasedFrameDecoder : public ByteToByteDecoder {
 public:
  explicit LengthFieldBasedFrameDecoder(uint32_t lengthFieldLength = 4,
                                        uint32_t maxFrameLength = UINT_MAX,
                                        uint32_t lengthFieldOffset = 0,
                                        int32_t lengthAdjustment = 0,
                                        uint32_t initialBytesToStrip = 4,
                                        bool networkByteOrder = true);

  bool decode(Context* ctx,
              folly::IOBufQueue& buf,
              std::unique_ptr<folly::IOBuf>& result,
              size_t&) override;

 private:

  uint64_t getUnadjustedFrameLength(
    folly::IOBufQueue& buf, int offset, int length, bool networkByteOrder);

  uint32_t lengthFieldLength_;
  uint32_t maxFrameLength_;
  uint32_t lengthFieldOffset_;
  int32_t lengthAdjustment_;
  uint32_t initialBytesToStrip_;
  bool networkByteOrder_;

  uint32_t lengthFieldEndOffset_;
};

} // namespace wangle