components/proximity_auth/ble/bluetooth_low_energy_characteristics_finder.h

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef COMPONENTS_PROXIMITY_AUTH_BLE_BLUETOOTH_LOW_ENERGY_CHARACTERISTICS_FINDER_H
   6 #define COMPONENTS_PROXIMITY_AUTH_BLE_BLUETOOTH_LOW_ENERGY_CHARACTERISTICS_FINDER_H
   7
   8 #include "base/callback.h"
   9 #include "base/macros.h"
  10 #include "base/memory/ref_counted.h"
  11 #include "components/proximity_auth/ble/remote_attribute.h"
  12 #include "device/bluetooth/bluetooth_adapter.h"
  13 #include "device/bluetooth/bluetooth_device.h"
  14 #include "device/bluetooth/bluetooth_gatt_characteristic.h"
  15 #include "device/bluetooth/bluetooth_uuid.h"
  16
  17 namespace proximity_auth {
  18
  19 // Looks for given characteristics in a remote device, for which a GATT
  20 // connection was already established. In the current BLE connection protocol
  21 // (device::BluetoothDevice::CreateGattConnection), remote characteristic
  22 // discovery starts immediatelly after a GATT connection was established. So,
  23 // this class simply adds an observer for a characteristic discovery event and
  24 // call |success_callback_| once all necessary characteristics were discovered.
  25 class BluetoothLowEnergyCharacteristicsFinder
  26     : public device::BluetoothAdapter::Observer {
  27  public:
  28   // This callbacks takes as arguments (in this order): |remote_service_|,
  29   // |to_peripheral_char_| and |from_peripheral_char_|. Note that, since this is
  30   // called after the characteristics were discovered, their id field (e.g.
  31   // to_peripheral_char_.id) will be non-blank.
  32   typedef base::Callback<void(const RemoteAttribute&,
  33                               const RemoteAttribute&,
  34                               const RemoteAttribute&)> SuccessCallback;
  35
  36   // This callback takes as arguments (in this order): |to_peripheral_char_| and
  37   // |from_peripheral_char_|. A blank id field in the characteristics indicate
  38   // that the characteristics was not found in the remote service.
  39   // TODO(sacomoto): Remove RemoteAttributes and add an error message instead.
  40   // The caller of this object should not care if only a subset of the
  41   // characteristics was found. See crbug.com/495511.
  42   typedef base::Callback<void(const RemoteAttribute&, const RemoteAttribute&)>
  43       ErrorCallback;
  44
  45   // Constructs the object and registers itself as an observer for |adapter|,
  46   // waiting for |to_peripheral_char| and |from_peripheral_char| to be found.
  47   // When both characteristics were found |success_callback| is called. After
  48   // all characteristics of |service| were discovered, if |from_periphral_char|
  49   // or |to_peripheral| was not found, it calls |error_callback|. The object
  50   // will perform at most one call of the callbacks.
  51   BluetoothLowEnergyCharacteristicsFinder(
  52       scoped_refptr<device::BluetoothAdapter> adapter,
  53       device::BluetoothDevice* device,
  54       const RemoteAttribute& remote_service,
  55       const RemoteAttribute& to_peripheral_char,
  56       const RemoteAttribute& from_peripheral_char,
  57       const SuccessCallback& success_callback,
  58       const ErrorCallback& error_callback);
  59
  60   ~BluetoothLowEnergyCharacteristicsFinder() override;
  61
  62  protected:
  63   // device::BluetoothAdapter::Observer:
  64   void GattDiscoveryCompleteForService(
  65       device::BluetoothAdapter* adapter,
  66       device::BluetoothGattService* service) override;
  67   void GattCharacteristicAdded(
  68       device::BluetoothAdapter* adapter,
  69       device::BluetoothGattCharacteristic* characteristic) override;
  70
  71   // For testing. Used to mock this class.
  72   BluetoothLowEnergyCharacteristicsFinder();
  73
  74  private:
  75   // Handles the discovery of a new characteristic.
  76   void HandleCharacteristicUpdate(
  77       device::BluetoothGattCharacteristic* characteristic);
  78
  79   // Scans the remote chracteristics of the service with |uuid| in |device|
  80   // calling HandleCharacteristicUpdate() for each of them.
  81   void ScanRemoteCharacteristics(device::BluetoothDevice* device,
  82                                  const device::BluetoothUUID& uuid);
  83
  84   // Updates the value of |to_peripheral_char_| and
  85   // |from_peripheral_char_|
  86   // when |characteristic| was found.
  87   void UpdateCharacteristicsStatus(
  88       device::BluetoothGattCharacteristic* characteristic);
  89
  90   // Resets |success_callback_| and |success_callback_|. This should be called
  91   // whenever a callback is called to avoid multiple callbacks calls.
  92   void ResetCallbacks();
  93
  94   // The Bluetooth adapter where the connection was established.
  95   scoped_refptr<device::BluetoothAdapter> adapter_;
  96
  97   // Remote service the |connection_| was established with.
  98   RemoteAttribute remote_service_;
  99
 100   // Characteristic used to receive data from the remote device.
 101   RemoteAttribute to_peripheral_char_;
 102
 103   // Characteristic used to receive data from the remote device.
 104   RemoteAttribute from_peripheral_char_;
 105
 106   // Called when all characteristics were found.
 107   SuccessCallback success_callback_;
 108
 109   // Called when there is an error.
 110   ErrorCallback error_callback_;
 111
 112   DISALLOW_COPY_AND_ASSIGN(BluetoothLowEnergyCharacteristicsFinder);
 113 };
 114
 115 }  // namespace proximity_auth
 116
 117 #endif  // COMPONENTS_PROXIMITY_AUTH_BLE_BLUETOOTH_CHARACTERISTICS_FINDER_H