arc: bluetooth: Implement Gatt server request to read/write

components/arc/bluetooth/arc_bluetooth_bridge.cc

Index: components/arc/bluetooth/arc_bluetooth_bridge.cc
diff --git a/components/arc/bluetooth/arc_bluetooth_bridge.cc b/components/arc/bluetooth/arc_bluetooth_bridge.cc
index 17ddb50b4d881a08d5691f3bcc6f2cbdec0405be..7c9e7a8d7afccd0c6e645ea81e3bd5d3b3346bc1 100644
--- a/components/arc/bluetooth/arc_bluetooth_bridge.cc
+++ b/components/arc/bluetooth/arc_bluetooth_bridge.cc
@@ -50,6 +50,7 @@ using device::BluetoothUUID;
 namespace {
 constexpr int32_t kMinBtleVersion = 1;
 constexpr int32_t kMinBtleNotifyVersion = 2;
+constexpr int32_t kMinGattServerVersion = 3;
 constexpr uint32_t kGattReadPermission =
     BluetoothGattCharacteristic::Permission::PERMISSION_READ |
     BluetoothGattCharacteristic::Permission::PERMISSION_READ_ENCRYPTED |
@@ -137,6 +138,29 @@ void OnGattReadError(const GattReadCallback& callback,
   callback.Run(std::move(gattValue));
 }
 
+// Callback function for mojom::BluetoothInstance::RequestGattRead
+void OnGattServerRead(
+    const BluetoothLocalGattService::Delegate::ValueCallback& success_callback,
+    const BluetoothLocalGattService::Delegate::ErrorCallback& error_callback,
+    arc::mojom::BluetoothGattStatus status,
+    mojo::Array<uint8_t> value) {
+  if (status == arc::mojom::BluetoothGattStatus::GATT_SUCCESS)
+    success_callback.Run(value.To<std::vector<uint8_t>>());
+  else
+    error_callback.Run();
+}
+
+// Callback function for mojom::BluetoothInstance::RequestGattWrite
+void OnGattServerWrite(
+    const base::Closure& success_callback,
+    const BluetoothLocalGattService::Delegate::ErrorCallback& error_callback,
+    arc::mojom::BluetoothGattStatus status) {
+  if (status == arc::mojom::BluetoothGattStatus::GATT_SUCCESS)
+    success_callback.Run();
+  else
+    error_callback.Run();
+}
+
 }  // namespace
 
 namespace arc {
@@ -374,12 +398,61 @@ void ArcBluetoothBridge::GattDescriptorValueChanged(
   // Placeholder for GATT client functionality
 }
 
+template <class LocalGattAttribute>
+void ArcBluetoothBridge::OnGattAttributeReadRequest(
+    const BluetoothDevice* device,
+    const LocalGattAttribute* gatt_obj,
+    int offset,
+    const ValueCallback& success_callback,
+    const ErrorCallback& error_callback) {
+  DCHECK(CalledOnValidThread());
+  if (!HasBluetoothInstance() ||
+      !CheckBluetoothInstanceVersion(kMinGattServerVersion) || offset < 0) {

[palmer, 2016/07/22 01:46:10]

Is there an upper bound for offset? Or, if sanity is checked inside
|arc_bridge_service()->bluetooth()->instance()->RequestGattRead|, is it
redundant to also check here?

[puthik_chromium, 2016/07/22 02:12:33]

The upper bound is the size of the Gatt Attribute which we don't know at this
time.

|arc_bridge_service()->bluetooth()->instance()->RequestGattRead| will propagate
to Android app that request GattServer. And it's up to app developer to do the
boundary check there. Thay why I think it is better to also do the sanity check
here.

[palmer, 2016/07/22 21:49:11]

I'm not sure I'm looking at the right thing, but this:

https://community.nxp.com/thread/332030

seems to say that the maximum size for a GATT attribute is 512 bytes.

[puthik_chromium, 2016/07/22 22:41:05]

Done. Found it in the spec.

+    error_callback.Run();
+    return;
+  }
+
+  DCHECK(gatt_handle_.find(gatt_obj->GetIdentifier()) != gatt_handle_.end());

[palmer, 2016/07/22 01:46:10]

This could only happen by programmer error? I ask because I'm not sure what all
callers this function has.

[puthik_chromium, 2016/07/22 02:12:33]

The caller of these function is On{Characteristic,Descriptor}ReadRequest
which is override from device::BluetoothLocalGattService::Delegate.
We are delegate to only GattAtrribute that we create. So this DCHECK will fail
only by programmer error.

[palmer, 2016/07/22 21:49:11]

Great, thanks.

+
+  arc_bridge_service()->bluetooth()->instance()->RequestGattRead(
+      mojom::BluetoothAddress::From(device->GetAddress()),
+      gatt_handle_[gatt_obj->GetIdentifier()], offset, false /* is_long */,
+      base::Bind(&OnGattServerRead, success_callback, error_callback));
+}
+
+template <class LocalGattAttribute>
+void ArcBluetoothBridge::OnGattAttributeWriteRequest(

[palmer, 2016/07/22 01:46:10]

Same questions as above for this function.

[puthik_chromium, 2016/07/22 02:12:33]

Same answer as above

+    const BluetoothDevice* device,
+    const LocalGattAttribute* gatt_obj,
+    const std::vector<uint8_t>& value,
+    int offset,
+    const base::Closure& success_callback,
+    const ErrorCallback& error_callback) {
+  DCHECK(CalledOnValidThread());
+  if (!HasBluetoothInstance() ||
+      !CheckBluetoothInstanceVersion(kMinGattServerVersion) || offset < 0) {
+    error_callback.Run();
+    return;
+  }
+
+  DCHECK(gatt_handle_.find(gatt_obj->GetIdentifier()) != gatt_handle_.end());
+
+  arc_bridge_service()->bluetooth()->instance()->RequestGattWrite(
+      mojom::BluetoothAddress::From(device->GetAddress()),
+      gatt_handle_[gatt_obj->GetIdentifier()], offset,
+      mojo::Array<uint8_t>::From(value),
+      base::Bind(&OnGattServerWrite, success_callback, error_callback));
+}
+
 void ArcBluetoothBridge::OnCharacteristicReadRequest(
     const BluetoothDevice* device,
     const BluetoothLocalGattCharacteristic* characteristic,
     int offset,
     const ValueCallback& callback,
-    const ErrorCallback& error_callback) {}
+    const ErrorCallback& error_callback) {
+  OnGattAttributeReadRequest(device, characteristic, offset, callback,
+                             error_callback);
+}
 
 void ArcBluetoothBridge::OnCharacteristicWriteRequest(
     const BluetoothDevice* device,
@@ -387,14 +460,20 @@ void ArcBluetoothBridge::OnCharacteristicWriteRequest(
     const std::vector<uint8_t>& value,
     int offset,
     const base::Closure& callback,
-    const ErrorCallback& error_callback) {}
+    const ErrorCallback& error_callback) {
+  OnGattAttributeWriteRequest(device, characteristic, value, offset, callback,
+                              error_callback);
+}
 
 void ArcBluetoothBridge::OnDescriptorReadRequest(
     const BluetoothDevice* device,
     const BluetoothLocalGattDescriptor* descriptor,
     int offset,
     const ValueCallback& callback,
-    const ErrorCallback& error_callback) {}
+    const ErrorCallback& error_callback) {
+  OnGattAttributeReadRequest(device, descriptor, offset, callback,
+                             error_callback);
+}
 
 void ArcBluetoothBridge::OnDescriptorWriteRequest(
     const BluetoothDevice* device,
@@ -402,7 +481,10 @@ void ArcBluetoothBridge::OnDescriptorWriteRequest(
     const std::vector<uint8_t>& value,
     int offset,
     const base::Closure& callback,
-    const ErrorCallback& error_callback) {}
+    const ErrorCallback& error_callback) {
+  OnGattAttributeWriteRequest(device, descriptor, value, offset, callback,
+                              error_callback);
+}
 
 void ArcBluetoothBridge::OnNotificationsStart(
     const BluetoothDevice* device,
@@ -1071,6 +1153,7 @@ int32_t ArcBluetoothBridge::CreateGattAttributeHandle(
   int32_t handle = next_gatt_server_attribute_handle();
   const std::string& identifier = gatt_attr->GetIdentifier();
   gatt_identifier_[handle] = identifier;
+  gatt_handle_[identifier] = handle;
   return handle;
 }
 
@@ -1171,9 +1254,9 @@ void ArcBluetoothBridge::DeleteService(int32_t service_handle,
   BluetoothLocalGattService* service =
       bluetooth_adapter_->GetGattService(gatt_identifier_[service_handle]);
   DCHECK(service);
-
-  service->Delete();
   gatt_identifier_.erase(service_handle);
+  gatt_handle_.erase(service->GetIdentifier());
+  service->Delete();
   OnGattOperationDone(callback);
 }