src/connectivity/bluetooth/core/bt-host/common/supplement_data.h

// Copyright 2020 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef SRC_CONNECTIVITY_BLUETOOTH_CORE_BT_HOST_COMMON_SUPPLEMENT_DATA_H_
#define SRC_CONNECTIVITY_BLUETOOTH_CORE_BT_HOST_COMMON_SUPPLEMENT_DATA_H_

#include <cstddef>
#include <cstdint>

#include "src/connectivity/bluetooth/core/bt-host/common/byte_buffer.h"

namespace bt {

// EIR Data Type, Advertising Data Type (AD Type), OOB Data Type definitions.
// clang-format off
enum class DataType : uint8_t {
  kFlags                        = 0x01,
  kIncomplete16BitServiceUuids  = 0x02,
  kComplete16BitServiceUuids    = 0x03,
  kIncomplete32BitServiceUuids  = 0x04,
  kComplete32BitServiceUuids    = 0x05,
  kIncomplete128BitServiceUuids = 0x06,
  kComplete128BitServiceUuids   = 0x07,
  kShortenedLocalName           = 0x08,
  kCompleteLocalName            = 0x09,
  kTxPowerLevel                 = 0x0A,
  kClassOfDevice                = 0x0D,
  kSSPOOBHash                   = 0x0E,
  kSSPOOBRandomizer             = 0x0F,
  kServiceData16Bit             = 0x16,
  kAppearance                   = 0x19,
  kServiceData32Bit             = 0x20,
  kServiceData128Bit            = 0x21,
  kURI                          = 0x24,
  kManufacturerSpecificData     = 0xFF,
  // TODO(armansito): Complete this list.
};
// clang-format on

// Convenience classes for reading and writing the contents
// of Advertising Data, Scan Response Data, or Extended Inquiry Response Data
// payloads. The format in which data is stored looks like the following:
//
//    [1-octet LENGTH][1-octet TYPE][LENGTH-1 octets DATA]
//
// Used for parsing data in TLV-format as described at the beginning of the file
// above.
class SupplementDataReader {
 public:
  // |data| must point to a valid piece of memory for the duration in which this
  // object is to remain alive.
  explicit SupplementDataReader(const ByteBuffer& data);

  // Returns false if the fields of |data| have been formatted incorrectly. For
  // example, this could happen if the length of an advertising data structure
  // would exceed the bounds of the buffer.
  inline bool is_valid() const { return is_valid_; }

  // Returns the data and type fields of the next advertising data structure in
  // |out_data| and |out_type|. Returns false if there is no more data to read
  // or if the data is formatted incorrectly.
  bool GetNextField(DataType* out_type, BufferView* out_data);

  // Returns true if there is more data to read. Returns false if the end of
  // data has been reached or if the current segment is malformed in a way that
  // would exceed the bounds of the data this reader was initialized with.
  bool HasMoreData() const;

 private:
  bool is_valid_;
  BufferView remaining_;
};

// Used for writing data in TLV-format as described at the beginning of the file
// above.
class SupplementDataWriter {
 public:
  // |buffer| is the piece of memory on which this SupplementDataWriter should
  // operate. The buffer must out-live this instance and must point to a valid
  // piece of memory.
  explicit SupplementDataWriter(MutableByteBuffer* buffer);

  // Writes the given piece of type/tag and data into the next available segment
  // in the underlying buffer. Returns false if there isn't enough space left in
  // the buffer for writing. Returns true on success.
  bool WriteField(DataType type, const ByteBuffer& data);

  // The total number of bytes that have been written into the buffer.
  size_t bytes_written() const { return bytes_written_; }

 private:
  MutableByteBuffer* buffer_;
  size_t bytes_written_;
};

}  // namespace bt

#endif  // SRC_CONNECTIVITY_BLUETOOTH_CORE_BT_HOST_COMMON_SUPPLEMENT_DATA_H_