Weave Packet Receiver

components/proximity_auth/ble/bluetooth_low_energy_weave_packet_receiver.h

+// Copyright 2015 The Chromium Authors. All rights reserved.

[Tim Song, 2016/06/09 22:08:35]

nit:2016

[jingxuy, 2016/06/09 23:29:04]

Done.

+// 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
+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 {
+    EXCHANGING_CONTROLS = 0x00,

[Tim Song, 2016/06/09 22:08:35]

A better name for this state might be CONNECTING. I would also add a CONNECTED
state to distinguish from the DATA_READY state.

[jingxuy, 2016/06/09 23:29:04]

Currently connecting and connected are the same state. I can change the name
though.

[Kyle Horimoto, 2016/06/09 23:59:45]

Shouldn't the "connected" state equivalent to receiving data?

[jingxuy, 2016/06/11 00:10:46]

I think what Tim has as connected is the equivalent of receiving data

+    RECEIVING_DATA = 0x01,
+    DATA_READY = 0x02,
+    CONNECTION_CLOSED = 0x03,
+    ERROR = 0x04
+  };
+
+  ~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();
+
+  // Return something valid only when receiver in CONNECTION_CLOSED
+  BluetoothLowEnergyWeavePacketGenerator::ReasonForClose GetReasonForClose();
+
+  // Returns non empty string only when the receiver is in DATA_READY
+  std::string GetDataMessage();
+
+  // Add a packet that's just been received over Connection to the receiver
+  void ReceivePacket(const Packet& packet);

[Tim Song, 2016/06/09 22:08:35]

Perhaps you should return the current state as well, so the caller can do
something like:

if (receiver_->ReceivePacket(packet) == State::DATA_READY) {
  ProcessMessage(receiver_->GetDataMessage());
}

[jingxuy, 2016/06/09 23:29:04]

Done.

+
+ protected:
+  BluetoothLowEnergyWeavePacketReceiver();
+
+ private:
+  uint16_t GetShortField(const Packet& packet, uint32_t index);
+  BluetoothLowEnergyWeavePacketGenerator::PacketType GetPacketType(
+      const Packet& packet);
+  BluetoothLowEnergyWeavePacketGenerator::ControlPacketCommand
+  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
+  std::vector<uint8_t> data_message_;
+};
+
+}  // namespace proximity_auth
+
+#endif  // COMPONENTS_PROXIMITY_AUTH_BLE_BLUETOOTH_LOW_ENERGY_WEAVE_PACKET_RECEIVER_H_