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

components/arc/bluetooth/arc_bluetooth_bridge.cc

 // 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.
 
 #include "components/arc/bluetooth/arc_bluetooth_bridge.h"
 
 #include <fcntl.h>
 #include <stddef.h>
 
 #include <iomanip>
@@ skipping 280 matching lines @@
       true /* is_notify */, mojo::Array<uint8_t>::From(value));
 }
 
 void ArcBluetoothBridge::GattDescriptorValueChanged(
     BluetoothAdapter* adapter,
     BluetoothRemoteGattDescriptor* descriptor,
     const std::vector<uint8_t>& value) {
   // Placeholder for GATT client functionality
 }
 
+// We will use odd transaction_id for read and even id for write.

[rkc, 2016/07/01 22:51:32]

Why?

[puthik_chromium, 2016/07/01 22:56:09]

1. To make sure that it does not repeat same number.
2. To make it easy to check that the transaction is read or write

Feel free to suggest the alternative.

[rkc, 2016/07/01 23:04:02]

You got me wrong :) I was saying that the comment says what we're doing, but not
why. i.e., just add a line also explaining why we're doing it.

[puthik_chromium, 2016/07/14 22:45:11]

Done.

+int32_t ArcBluetoothBridge::CreateGattReadTransaction(
+    const ValueCallback& successCallback,
+    const ErrorCallback& errorCallback) {
+  static int32_t transaction_id = 1;
+  transaction_id += 2;
+  gatt_read_callbacks_.emplace(

[rkc, 2016/07/01 22:51:32]

Can't use map::emplace.
https://chromium-cpp.appspot.com - notes section for emplace.

[puthik_chromium, 2016/07/14 22:45:12]

Done.

+      transaction_id,
+      std::pair<ValueCallback, ErrorCallback>(successCallback, errorCallback));

[Eric Caruso, 2016/06/30 23:46:20]

Instead of using std::pair here and pair::first and pair::second below, would it
be easier to read if we made a struct for this and called the members ::success
and ::error? I was pretty confused by SendResponse for a bit.

[puthik_chromium, 2016/07/14 22:45:12]

Done.

+  return transaction_id;
+}
+
+int32_t ArcBluetoothBridge::CreateGattWriteTransaction(
+    const base::Closure& successCallback,
+    const ErrorCallback& errorCallback) {
+  static int32_t transaction_id = 2;
+  transaction_id += 2;
+  gatt_write_callbacks_.emplace(
+      transaction_id,
+      std::pair<base::Closure, ErrorCallback>(successCallback, errorCallback));
+  return transaction_id;
+}
+
+template <class T>
+void ArcBluetoothBridge::OnGattAttributeReadRequest(
+    const BluetoothDevice* device,
+    const T* gatt_obj,
+    int offset,
+    const ValueCallback& callback,
+    const ErrorCallback& error_callback) {
+  if (!HasBluetoothInstance())
+    return;
+
+  if (!CheckBluetoothInstanceVersion(kMinBtleNotifyVersion))
+    return;
+
+  int32_t transaction_id = CreateGattReadTransaction(callback, error_callback);
+
+  arc_bridge_service()->bluetooth_instance()->RequestGattRead(
+      mojom::BluetoothAddress::From(device->GetAddress()), transaction_id,
+      ConvertGattIdentifierToId(gatt_obj->GetIdentifier()), offset,
+      false /*is_long */);
+}
+
+template <class T>
+void ArcBluetoothBridge::OnGattAttributeWriteRequest(
+    const BluetoothDevice* device,
+    const T* gatt_obj,
+    const std::vector<uint8_t>& value,
+    int offset,
+    const base::Closure& callback,
+    const ErrorCallback& error_callback) {
+  if (!HasBluetoothInstance())
+    return;
+
+  if (!CheckBluetoothInstanceVersion(kMinBtleNotifyVersion))
+    return;
+
+  int32_t transaction_id = CreateGattWriteTransaction(callback, error_callback);
+
+  arc_bridge_service()->bluetooth_instance()->RequestGattWrite(
+      mojom::BluetoothAddress::From(device->GetAddress()), transaction_id,
+      ConvertGattIdentifierToId(gatt_obj->GetIdentifier()), offset,
+      mojo::Array<uint8_t>::From(value));
+}
+
 void ArcBluetoothBridge::OnCharacteristicReadRequest(
     const BluetoothDevice* device,
     const BluetoothLocalGattCharacteristic* characteristic,
     int offset,
     const ValueCallback& callback,
-    const ErrorCallback& error_callback) {}
+    const ErrorCallback& error_callback) {
+  OnGattAttributeReadRequest<BluetoothLocalGattCharacteristic>(
+      device, characteristic, offset, callback, error_callback);
+}
 
 void ArcBluetoothBridge::OnCharacteristicWriteRequest(
     const BluetoothDevice* device,
     const BluetoothLocalGattCharacteristic* characteristic,
     const std::vector<uint8_t>& value,
     int offset,
     const base::Closure& callback,
-    const ErrorCallback& error_callback) {}
+    const ErrorCallback& error_callback) {
+  OnGattAttributeWriteRequest<BluetoothLocalGattCharacteristic>(
+      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<BluetoothLocalGattDescriptor>(
+      device, descriptor, offset, callback, error_callback);
+}
 
 void ArcBluetoothBridge::OnDescriptorWriteRequest(
     const BluetoothDevice* device,
     const BluetoothLocalGattDescriptor* descriptor,
     const std::vector<uint8_t>& value,
     int offset,
     const base::Closure& callback,
-    const ErrorCallback& error_callback) {}
+    const ErrorCallback& error_callback) {
+  OnGattAttributeWriteRequest<BluetoothLocalGattDescriptor>(
+      device, descriptor, value, offset, callback, error_callback);
+}
 
 void ArcBluetoothBridge::OnNotificationsStart(
     const BluetoothDevice* device,
     const BluetoothLocalGattCharacteristic* characteristic) {}
 
 void ArcBluetoothBridge::OnNotificationsStop(
     const BluetoothDevice* device,
     const BluetoothLocalGattCharacteristic* characteristic) {}
 
 void ArcBluetoothBridge::EnableAdapter(const EnableAdapterCallback& callback) {
@@ skipping 798 matching lines @@
 void ArcBluetoothBridge::SendIndication(
     int32_t attribute_handle,
     mojom::BluetoothAddressPtr address,
     int32_t confirm,
     mojo::Array<uint8_t> value,
     const SendIndicationCallback& callback) {}
 
 void ArcBluetoothBridge::SendResponse(int32_t trans_id,
                                       int32_t status,
                                       mojo::Array<uint8_t> value,
-                                      const SendResponseCallback& callback) {}
+                                      const SendResponseCallback& callback) {
+  // We will use odd transaction_id for read and even id for write.
+  if (trans_id & 1) {  // read
+    DCHECK(gatt_read_callbacks_.find(trans_id) != gatt_read_callbacks_.end());
+    if (status)
+      gatt_read_callbacks_[trans_id].second.Run();
+    else
+      gatt_read_callbacks_[trans_id].first.Run(
+          value.To<std::vector<uint8_t>>());
+  } else {  // write
+    DCHECK(gatt_write_callbacks_.find(trans_id) != gatt_write_callbacks_.end());
+    if (status)
+      gatt_write_callbacks_[trans_id].second.Run();
+    else
+      gatt_write_callbacks_[trans_id].first.Run();
+  }
+  OnGattOperationDone(callback);
+}
 
 void ArcBluetoothBridge::OnDiscoveryError() {
   LOG(WARNING) << "failed to change discovery state";
 }
 
 void ArcBluetoothBridge::OnPairing(mojom::BluetoothAddressPtr addr) const {
   if (!HasBluetoothInstance())
     return;
 
   arc_bridge_service()->bluetooth_instance()->OnBondStateChanged(
@@ skipping 319 matching lines @@
     int32_t version_need) const {
   int32_t version = arc_bridge_service()->bluetooth_version();
   if (version >= version_need)
     return true;
   LOG(WARNING) << "Bluetooth instance is too old (version " << version
                << ") need version " << version_need;
   return false;
 }
 
 }  // namespace arc