arc: bluetooth: Add gatt client functionality

components/arc/common/bluetooth.mojom

 // 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.
 
 module arc.mojom;
 
 [Extensible]
 enum BluetoothAdapterState {
   OFF = 0,
   ON
@@ skipping 110 matching lines @@
   BluetoothServiceRecord service_record;
   BluetoothScanMode adapter_scan_mode;
   array<BluetoothAddress> bonded_devices;
   uint32 discovery_timeout;
   string remote_friendly_name;
   int32 remote_rssi;
   BluetoothRemoteVersion remote_version;
   BluetoothLocalLEFeatures local_le_features;
 };
 
+// Bluetooth GATT types
+// Copy from Android API

[palmer, 2016/06/13 19:07:18]

So how do we ensure that we correctly track the changes to the Android API?

[puthik_chromium, 2016/06/13 20:50:27]

Android API will backward compatible.

+// https://developer.android.com/reference/android/bluetooth/BluetoothGatt.html
+[Extensible]
+enum BluetoothGattStatus {
+  GATT_SUCCESS = 0,
+  GATT_READ_NOT_PERMITTED = 0x2,
+  GATT_WRITE_NOT_PERMITTED = 0x3,
+  GATT_INSUFFICIENT_AUTHENTICATION = 0x5,
+  GATT_REQUEST_NOT_SUPPORTED = 0x6,
+  GATT_INVALID_OFFSET = 0x7,
+  GATT_INVALID_ATTRIBUTE_LENGTH = 0xd,
+  GATT_INSUFFICIENT_ENCRYPTION = 0xf,
+  GATT_CONNECTION_CONGESTED = 0x8f,
+  GATT_FAILURE = 0x101,
+};
+
+// Copy from Android API
+// https://source.android.com/devices/halref/structbtgatt__gatt__id__t.html
+struct BluetoothGattID {
+  BluetoothUUID uuid;
+  uint8 inst_id;
+};
+
+// Copy from Android API
+// is_primary is not a boolean because Android define it as uint8_t.

[palmer, 2016/06/13 19:07:18]

Typo: "defines"

[puthik_chromium, 2016/06/13 20:50:26]

Done.

+// https://source.android.com/devices/halref/structbtgatt__srvc__id__t.html
+struct BluetoothGattServiceID {
+  BluetoothGattID id;
+  uint8 is_primary;
+};
+
+struct BluetoothGattValue {
+  BluetoothGattStatus status;
+  uint32 len;

[palmer, 2016/06/13 19:07:18]

Use the full word here: |length|.

Is it really possible for the value to be 4 billion bytes long?

[puthik_chromium, 2016/06/13 20:50:27]

Removed. See below.

+  array<uint8> value;
+};
+
+// Copy from Bluetooth Assigned Numbers Document, Generic Access Profile
+// https://www.bluetooth.com/specifications/assigned-numbers/generic-access-profile
+[Extensible]
+enum BluetoothAdvertisingDataType {
+  DATA_TYPE_FLAGS = 0x01,
+  DATA_TYPE_SERVICE_UUIDS_128_BIT_COMPLETE = 0x07,
+  DATA_TYPE_LOCAL_NAME_COMPLETE = 0x09,
+  DATA_TYPE_TX_POWER_LEVEL = 0x0A,
+  DATA_TYPE_SERVICE_DATA = 0x16,
+  DATA_TYPE_MANUFACTURER_SPECIFIC_DATA = 0xff,
+};
+
+// Copy from Bluetooth Core v4.2 Volume 3 Part C Chapter 11
+// and Bluetooth Core Specification Supplement v6 Part A Chapter 1
+// https://www.bluetooth.com/specifications/adopted-specifications
+union BluetoothAdvertisingData {
+  uint8 flags;
+  array<BluetoothUUID> service_uuids;
+  string local_name;
+  uint8 tx_power_level;
+  BluetoothServiceData service_data;
+  array<uint8> manufacturer_data;

[palmer, 2016/06/13 19:07:18]

Why does |BluetoothGattValue| have a |length| field but these don't?

[puthik_chromium, 2016/06/13 20:50:26]

I don't actually need the |length| field in BluetoothGattValue.
Removed.

+  array<uint8> other_data;
+};
+
+struct BluetoothServiceData {
+  uint16 uuid_16bit;

[palmer, 2016/06/13 19:07:19]

16 bits doesn't really seem like a universally-unique ID.

[puthik_chromium, 2016/06/13 20:50:26]

The BT spec and Android side want 16 bits data for this. It's not universally
unique actually.

+  array<uint8> data;
+};
+
+[Extensible]
+enum BluetoothGattDBAttributeType {
+  BTGATT_DB_PRIMARY_SERVICE = 0,
+  BTGATT_DB_SECONDARY_SERVICE,
+  BTGATT_DB_INCLUDED_SERVICE,
+  BTGATT_DB_CHARACTERISTIC,
+  BTGATT_DB_DESCRIPTOR,
+};
+
+struct BluetoothGattDBElement {
+    uint8 id;

[palmer, 2016/06/13 19:07:18]

Nit: Indented too far.

[puthik_chromium, 2016/06/13 20:50:27]

Done.

+    BluetoothUUID uuid;
+    BluetoothGattDBAttributeType type;
+    uint16 attribute_handle;
+
+    /*
+     * If |type| is |BTGATT_DB_PRIMARY_SERVICE|, or
+     * |BTGATT_DB_SECONDARY_SERVICE|, this contains the start and end attribute
+     * handles.
+     */
+    uint16 start_handle;
+    uint16 end_handle;
+
+    /*
+     * If |type| is |BTGATT_DB_CHARACTERISTIC|, this contains the properties of
+     * the characteristic.
+     */
+    uint8 properties;
+};
+
 interface BluetoothHost {
   EnableAdapter() => (BluetoothAdapterState state);
   DisableAdapter() => (BluetoothAdapterState state);
   GetAdapterProperty(BluetoothPropertyType type);
   SetAdapterProperty(BluetoothProperty property);
   GetRemoteDeviceProperty(BluetoothAddress remote_addr,
                           BluetoothPropertyType type);
   SetRemoteDeviceProperty(BluetoothAddress remote_addr,
                           BluetoothProperty property);
   GetRemoteServiceRecord(BluetoothAddress remote_addr,
                          BluetoothUUID uuid);
   GetRemoteServices(BluetoothAddress remote_addr);
   StartDiscovery();
   CancelDiscovery();
   CreateBond(BluetoothAddress addr, int32 transport);
   RemoveBond(BluetoothAddress addr);
   CancelBond(BluetoothAddress addr);
 
   GetConnectionState(BluetoothAddress addr) => (bool connected);
+
+  // Bluetooth Gatt Client functions
+  [MinVersion=1] StartLEScan();
+  [MinVersion=1] StopLEScan();
+  [MinVersion=1] ConnectLEDevice(BluetoothAddress remote_addr);
+  [MinVersion=1] DisconnectLEDevice(BluetoothAddress remote_addr);
+  [MinVersion=1] SearchService(BluetoothAddress remote_addr);
+  [MinVersion=1] GetGattDB(BluetoothAddress remote_addr);
+  [MinVersion=1] StartLEListen() => (BluetoothGattStatus status);
+  [MinVersion=1] StopLEListen() => (BluetoothGattStatus status);
+  [MinVersion=1] ReadGattCharacteristic(BluetoothAddress remote_addr,
+                                        BluetoothGattServiceID service_id,
+                                        BluetoothGattID char_id)
+      => (BluetoothGattValue value);
+  [MinVersion=1] WriteGattCharacteristic(BluetoothAddress remote_addr,
+                                         BluetoothGattServiceID service_id,
+                                         BluetoothGattID char_id,
+                                         BluetoothGattValue value)
+      => (BluetoothGattStatus status);
+  [MinVersion=1] ReadGattDescriptor(BluetoothAddress remote_addr,
+                                    BluetoothGattServiceID service_id,
+                                    BluetoothGattID char_id,
+                                    BluetoothGattID desc_id)
+      => (BluetoothGattValue value);
+  [MinVersion=1] WriteGattDescriptor(BluetoothAddress remote_addr,
+                                     BluetoothGattServiceID service_id,
+                                     BluetoothGattID char_id,
+                                     BluetoothGattID desc_id,
+                                     BluetoothGattValue value)
+      => (BluetoothGattStatus status);
+  [MinVersion=1] RegisterForGattNotification(BluetoothAddress remote_addr,
+                                             BluetoothGattServiceID service_id,
+                                             BluetoothGattID char_id)
+      => (BluetoothGattStatus status);
+  [MinVersion=1] DeregisterForGattNotification(BluetoothAddress remote_addr,
+                                               BluetoothGattServiceID service_id,
+                                               BluetoothGattID char_id)
+      => (BluetoothGattStatus status);
+  [MinVersion=1] ReadRemoteRssi(BluetoothAddress remote_addr)
+      => (int32 rssi);
+
 };
 
 interface BluetoothInstance {
   Init(BluetoothHost host_ptr);
 
   OnAdapterProperties(BluetoothStatus status,
                       array<BluetoothProperty> properties);
   OnRemoteDeviceProperties(BluetoothStatus status,
                            BluetoothAddress address,
                            array<BluetoothProperty> properties);
   OnDeviceFound(array<BluetoothProperty> properties);
   OnDiscoveryStateChanged(BluetoothDiscoveryState state);
   OnBondStateChanged(BluetoothStatus status,
                      BluetoothAddress remote_addr,
                      BluetoothBondState state);
   OnAclStateChanged(BluetoothStatus status,
                     BluetoothAddress remote_addr,
                     BluetoothAclState state);
+
+  // Bluetooth Gatt Client callbacks
+  [MinVersion=1] OnLEDeviceFound(BluetoothAddress addr,
+                                 int32 rssi,
+                                 array<BluetoothAdvertisingData> adv_data);
+  [MinVersion=1] OnLEConnectionStateChange(BluetoothAddress remote_addr,
+                                           bool connected);
+  [MinVersion=1] OnSearchComplete(BluetoothAddress remote_addr,
+                                  BluetoothGattStatus status);
+  [MinVersion=1] OnGetGattDB(BluetoothAddress remote_addr,
+                             array<BluetoothGattDBElement> db);

[dcheng, 2016/06/13 20:19:27]

Out of curiosity, why aren't we taking advantage of Mojo to just asynchronously
return values in a callback? It's hard to see which methods are connected by
looking at the interface definitions.

[puthik_chromium, 2016/06/13 20:50:27]

On these functions, Chrome can call Android callback unprompted.

Example use case: User use ChromeOS side UI to scan for LE device.

+  [MinVersion=1] OnServicesRemoved(BluetoothAddress remote_addr,
+                                   uint16 start_handle,
+                                   uint16 end_handle);
+  [MinVersion=1] OnServicesAdded(BluetoothAddress remote_addr,
+                                 array<BluetoothGattDBElement> db);
 };