Weave Packet Receiver

components/proximity_auth/ble/bluetooth_low_energy_weave_packet_receiver.h

+// Copyright 2016 The Chromium 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 COMPONENTS_PROXIMITY_AUTH_BLE_BLUETOOTH_LOW_ENERGY_WEAVE_PACKET_RECEIVER_H_
+#define COMPONENTS_PROXIMITY_AUTH_BLE_BLUETOOTH_LOW_ENERGY_WEAVE_PACKET_RECEIVER_H_
+
+#include <stdint.h>
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "components/proximity_auth/ble/bluetooth_low_energy_weave_packet_generator.h"
+
+namespace proximity_auth {
+// Receive the messages sent with uWeave protocol.
+// TODO(jingxuy): move the enums from BluetoothLowEnergyWeavePacketGenerator to
+// a shared location
+// TODO(jingxuy): a complete state transition comment
+class BluetoothLowEnergyWeavePacketReceiver {
+ public:
+  class Factory {
+   public:
+    static std::unique_ptr<BluetoothLowEnergyWeavePacketReceiver> NewInstance();
+
+    // Exposed for testing.
+    static void SetInstanceForTesting(Factory* factory);
+
+   protected:
+    // Exposed for testing.
+    BluetoothLowEnergyWeavePacketReceiver* BuildInstance();
+
+   private:
+    static Factory* factory_instance_;
+  };
+
+  enum State {
+    CONNECTING = 0x00,
+    RECEIVING_DATA = 0x01,
+    DATA_READY = 0x02,
+    CONNECTION_CLOSED = 0x03,
+    ERROR = 0x04
+  };

[sacomoto, 2016/06/13 17:16:40]

When this class detect an error, e.g. wrong packet counter or version not
supported, you'll have to send a connection close packet to the other peer
containing the reason for close. 

So, when you are in the Error state, you will need an appropriated reason for
close. 

You should probably add a new |GetReasonForClose()| method, and change the name
of method below to |GetReceivedReasonForClose()|. Also, add the corresponding
|reason_for_close_| and |received_reason_for_close_|.

[jingxuy, 2016/06/16 08:42:28]

Done.

+
+  ~BluetoothLowEnergyWeavePacketReceiver();
+
+  typedef std::vector<uint8_t> Packet;
+
+  // Get the receiver’s state.
+  State GetState();
+
+  // Return the packet size that the receiver parsed out of request/response.
+  uint32_t GetPacketSize();
+
+  // Will crash unless receiver is in State::CONNECTION_CLOSED.
+  BluetoothLowEnergyWeavePacketGenerator::ReasonForClose GetReasonForClose();
+
+  // Will crash unless receiver is in State::DATA_READY.
+  // NOTE: if this function is not called in DATA_READY state and the receiver
+  // transitions out of that state, the data will be gone!
+  std::string GetDataMessage();
+
+  // Add a packet that's just been received over Connection to the receiver.
+  State ReceivePacket(const Packet& packet);
+
+ protected:
+  BluetoothLowEnergyWeavePacketReceiver();
+
+ private:
+  void ReceiveControlPacket(const Packet& packet);
+  void ReceiveDataPacket(const Packet& packet);
+
+  void ReceiveConnectionRequest(const Packet& packet);
+  void ReceiveConnectionResponse(const Packet& packet);
+  void ReceiveConnectionClose(const Packet& packet);
+  void AppendData(const Packet& packet);
+
+  uint16_t GetShortField(const Packet& packet, uint32_t index);
+  uint8_t GetPacketType(const Packet& packet);
+  uint8_t GetControlCommand(const Packet& packet);
+  void VerifyPacketCounter(const Packet& packet);
+  bool IsFirstDataPacket(const Packet& packet);
+  bool IsLastDataPacket(const Packet& packet);
+
+  // Max packet size of the connection.
+  // Default is 0 which means the server will determine the size by observing
+  // ATT_MTU of the client.
+  uint32_t packet_size_;
+
+  // Counter for the number of packets sent, starting at 0.
+  uint32_t packet_number_;
+
+  // Current state of the receiver.
+  // Certain functions will only return valid value if the receiver is in the
+  // appropriate state.
+  State state_;
+
+  // The reason why the connection was closed if any.
+  BluetoothLowEnergyWeavePacketGenerator::ReasonForClose reason_for_close_;
+
+  // The data message if there is one.
+  Packet data_message_;
+};
+
+}  // namespace proximity_auth
+
+#endif  // COMPONENTS_PROXIMITY_AUTH_BLE_BLUETOOTH_LOW_ENERGY_WEAVE_PACKET_RECEIVER_H_