Weave Packet Generator

components/proximity_auth/ble/bluetooth_low_energy_weave_packet_generator.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_GENERATOR_H_
+#define COMPONENTS_PROXIMITY_AUTH_BLE_BLUETOOTH_LOW_ENERGY_WEAVE_PACKET_GENERATOR_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "build/build_config.h"
+
+namespace proximity_auth {
+// Generates the messages sent using the uWeave protocol.
+class BluetoothLowEnergyWeavePacketGenerator {
+ public:
+  class Factory {
+   public:
+    static std::unique_ptr<BluetoothLowEnergyWeavePacketGenerator>
+    NewInstance();
+
+    // Exposed for testing.
+    static void SetInstanceForTesting(Factory* factory);
+
+   protected:
+    // Exposed for testing.
+    virtual std::unique_ptr<BluetoothLowEnergyWeavePacketGenerator>
+    BuildInstance();
+
+   private:
+    static Factory* factory_instance_;
+  };
+
+  // Determine whether a packet is a control packet or a data packet.
+  enum PacketType { DATA = 0x00, CONTROL = 0x01 };
+
+  // Identify the action intended by the control packet.
+  enum ControlCommand {
+    CONNECTION_REQUEST = 0x00,
+    CONNECTION_RESPONSE = 0x01,
+    CONNECTION_CLOSE = 0x02
+  };
+
+  // Sent with the ConnectionClose control packet.
+  // Identify why the client/server wished to close the connection.
+  enum ReasonForClose {
+    CLOSE_WITHOUT_ERROR = 0x00,
+    UNKNOWN_ERROR = 0x01,
+    NO_COMMON_VERSION_SUPPORTED = 0x02,
+    RECEIVED_PACKET_OUT_OF_SEQUENCE = 0x03,
+    APPLICATION_ERROR = 0x80
+  };
+
+  typedef std::vector<uint8_t> Packet;
+
+  Packet CreateConnectionRequest();
+  Packet CreateConnectionResponse();
+  Packet CreateConnectionClose(ReasonForClose reason_for_close);
+
+  // Packet size must be greater than or equal to 20.
+  void SetMaxPacketSize(uint32_t size);
+
+  // Will crash if message is empty.
+  std::vector<Packet> EncodeDataMessage(std::string message);
+
+ protected:
+  BluetoothLowEnergyWeavePacketGenerator();
+
+ private:
+  void SetShortField(uint32_t byte_offset, uint16_t val, Packet* packet);
+  void SetPacketTypeBit(PacketType val, Packet* packet);
+  void SetControlCommand(ControlCommand val, Packet* packet);
+  void SetPacketCounter(Packet* packet);
+  void SetDataFirstBit(Packet* packet);
+  void SetDataLastBit(Packet* packet);
+
+  // The default max packet length is 20 unless SetDataPacketLength() is called
+  // and specified otherwise.
+  uint32_t max_packet_size_;
+
+  // Counter for the number of packets sent, starting at 0.
+  uint32_t next_packet_counter_;
+};
+
+}  // namespace proximity_auth
+
+#endif  // COMPONENTS_PROXIMITY_AUTH_BLE_BLUETOOTH_LOW_ENERGY_WEAVE_PACKET_GENERATOR_H_