nearby/connections/implementation/mediums/ble/ble_packet.h

// Copyright 2020 Google LLC
//
// 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
//
//     https://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.

#ifndef CORE_INTERNAL_MEDIUMS_BLE_BLE_PACKET_H_
#define CORE_INTERNAL_MEDIUMS_BLE_BLE_PACKET_H_

#include <string>

#include "absl/status/status.h"
#include "absl/status/statusor.h"
#include "absl/strings/string_view.h"
#include "internal/platform/byte_array.h"
#include "proto/mediums/ble_frames.pb.h"

namespace nearby {
namespace connections {
namespace mediums {

// Represents the format of data sent over Ble sockets.
//
// [SERVICE_ID_HASH][DATA]
//
// See go/nearby-ble-design for more information.
class BlePacket {
 public:
  static constexpr int kServiceIdHashLength = 3;

  // Creates an Introduction frame for Control packet with the given
  // 'service_id_hash'. The size of 'service_id_hash' must equal to
  // 'kServiceIdHashLength', otherwise returns an error.
  //
  // service_id_hash - hash of client service id.
  static absl::StatusOr<BlePacket> CreateControlIntroductionPacket(
      const ByteArray& service_id_hash);

  // Creates an Disconnection frame for Control packet with the given
  // 'service_id_hash'. The size of 'service_id_hash' must equal to
  // 'kServiceIdHashLength', otherwise returns an error.
  //
  // service_id_hash - hash of client service id.
  static absl::StatusOr<BlePacket> CreateControlDisconnectionPacket(
      const ByteArray& service_id_hash);

  // Creates an Packet Acknowledgement frame for Control packet with the given
  // 'service_id_hash'. The size of 'service_id_hash' must equal to
  // 'kServiceIdHashLength', otherwise returns an error.
  //
  // service_id_hash - hash of client service id.
  // received_size - payload size received sucessfully.
  static absl::StatusOr<BlePacket> CreateControlPacketAcknowledgementPacket(
      const ByteArray& service_id_hash, int received_size);

  // Creates a Control packet. Returns error when data size has exceeded maximum
  // size.
  //
  // data - the raw bytes exported by |SocketControlFrame| that supports all the
  // |ControlFrameType|.
  static absl::StatusOr<BlePacket> CreateControlPacket(const ByteArray& data);

  // Creates a Data packet. Returns error when the size of 'service_id_hash' is
  // not equal to 'kServiceIdHashLength', or data size has exceeded maximum
  // size.
  //
  // service_id_hash : hash of client service id. It should be other than
  // 0x000000 that is reserved for Control packet.
  static absl::StatusOr<BlePacket> CreateDataPacket(
      const ByteArray& service_id_hash, const ByteArray& data);

  static bool IsControlPacketBytes(const ByteArray& packet_bytes);

  static std::string SocketControlFrameTypeToString(
      ::location::nearby::mediums::SocketControlFrame::ControlFrameType
          control_frame_type) {
    switch (control_frame_type) {
      case ::location::nearby::mediums::SocketControlFrame::INTRODUCTION:
        return "INTRODUCTION";
      case ::location::nearby::mediums::SocketControlFrame::DISCONNECTION:
        return "DISCONNECTION";
      case ::location::nearby::mediums::SocketControlFrame::
          PACKET_ACKNOWLEDGEMENT:
        return "PACKET_ACKNOWLEDGEMENT";
      case ::location::nearby::mediums::SocketControlFrame::
          UNKNOWN_CONTROL_FRAME_TYPE:
        return "UNKNOWN_FRAME_TYPE";
    }
  }

  explicit BlePacket(const ByteArray& ble_packet_byte);
  BlePacket(const BlePacket&) = default;
  BlePacket& operator=(const BlePacket&) = default;
  BlePacket(BlePacket&&) = default;
  BlePacket& operator=(BlePacket&&) = default;
  ~BlePacket() = default;

  explicit operator ByteArray() const;

  bool IsValid() const;
  ByteArray GetServiceIdHash() const { return service_id_hash_; }
  ByteArray GetData() const { return data_; }
  int GetPacketSize() const { return data_.size() + kServiceIdHashLength; }
  bool IsControlPacket() const;
  void ParseControlPacketData(absl::string_view data);
  ::location::nearby::mediums::SocketControlFrame::ControlFrameType
  GetControlFrameType() const {
    return control_frame_type_;
  }
  absl::StatusOr<::location::nearby::mediums::SocketVersion>
  GetIntroductonSocketVersion() const {
    if (control_frame_type_ !=
        ::location::nearby::mediums::SocketControlFrame::INTRODUCTION) {
      return absl::NotFoundError("Introduction socket version is not set.");
    }
    return introducton_socket_version_;
  }
  absl::StatusOr<int> GetPacketAcknowledgementReceivedSize() const {
    if (control_frame_type_ != ::location::nearby::mediums::SocketControlFrame::
                                   PACKET_ACKNOWLEDGEMENT) {
      return absl::NotFoundError(
          "Packet acknowledgement received size is not set.");
    }
    return packet_acknowledgement_received_size_;
  }

 private:
  enum class BlePacketType {
    kInvalid = 0,
    kData,
    kControl,
  };

  BlePacket() = default;

  BlePacketType packet_type_ = BlePacketType::kInvalid;
  ByteArray service_id_hash_;
  ByteArray data_;
  ::location::nearby::mediums::SocketControlFrame::ControlFrameType
      control_frame_type_ = ::location::nearby::mediums::SocketControlFrame::
          UNKNOWN_CONTROL_FRAME_TYPE;
  ::location::nearby::mediums::SocketVersion introducton_socket_version_ =
      ::location::nearby::mediums::SocketVersion::UNKNOWN_SOCKET_VERSION;
  int packet_acknowledgement_received_size_ = 0;
};

}  // namespace mediums
}  // namespace connections
}  // namespace nearby

#endif  // CORE_INTERNAL_MEDIUMS_BLE_BLE_PACKET_H_