BLE GATT Server ask for pairing

[GurgenHOVH]

When trying to connect to the server hosted on an Android device, it opens a pairing request on both server and client.

The service and advertising looks like this:

 await BlePeripheral.addService(
        BleService(
          uuid: serviceTicketing,
          primary: true,
          characteristics: [
            BleCharacteristic(
              uuid: characteristicTicketing,
              properties: [
                CharacteristicProperties.write.index,
              ],
              value: null,
              permissions: [AttributePermissions.writeable.index],
            ),
          ],
        ),
      );

      /// set callback for advertising state
      BlePeripheral.setAdvertisingStatusUpdateCallback(
          (bool advertising, String? error) {
        print("AdvertisingStatus: $advertising Error $error");
      });

      BlePeripheral.setWriteRequestCallback(
          (deviceId, characteristicId, offset, value) {
        print(
            "WriteRequest: $deviceId ${String.fromCharCodes(value?.toList() ?? [])} : $offset : $value ");

        final userId = String.fromCharCodes(value?.toList() ?? []);

        if (userId.isNotEmpty) {
          addUserId(userId);
        }

        return null;
      });

      // Start advertising
      await BlePeripheral.startAdvertising(
        services: [serviceTicketing],
        localName: "ticketing",
      );

[rohitsangwan01]

@GurgenHOVH yes android will try to pair if any device will try to connect,
if you think your use case does not requires pairing on android, you can try to replace this code, and check if it still works for you without bonding

BluetoothProfile.STATE_CONNECTED -> {
                            handler?.post {
                                gattServer?.connect(device, true)
                            }
                            synchronized(bluetoothDevicesMap) {
                                bluetoothDevicesMap.put(
                                    device.address,
                                    device
                                )
                            }
                        onConnectionUpdate(device, status, newState)
                    }

[GurgenHOVH]

Thanks @rohitsangwan01 for the quick reply. Will try and update here tomorrow.

[GurgenHOVH]

Hi @rohitsangwan01 . The code you have provided works. Would be great to turn this into a setting and update the package. Thanks!

[rohitsangwan01]

@gurgenAya not sure if you are using any encrypted Char which causes Pairing request, or maybe thats the default android behaviour, but now that you have removed the pairing code from the native part, that program should not be responsible for making pair requests, you can cross check with Nrf Connect app maybe, in NrfConnect you can create a GattServer, and then try to see if that also makes any pairing request

[rohitsangwan01]

Hi @rohitsangwan01 . The code you have provided works. Would be great to turn this into a setting and update the package. Thanks!

Sure, maybe will add this as an optional setting to StartScan in next update

[SimonSchnitker]

@rohitsangwan01 Hey, thanks for your work! It would be nice if you could add a parameter like autoPairing = false or something similar in the BlePeripheral.startAdvertising() method.

[clragon]

Pairing impedes with our usecase of background data exchange, so we will have to fork this plugin until we get this as an official option.

Here is what we changed, for anyone requiring this:

ble_peripheral/android/src/main/kotlin/com/rohit/ble_peripheral/BlePeripheralPlugin.kt

Lines 292 to 309 in 52b1458

	BluetoothProfile.STATE_CONNECTED -> {
	if (device.bondState == BluetoothDevice.BOND_NONE) {
	// Wait for bonding
	listOfDevicesWaitingForBond.add(device.address)
	device.createBond()
	} else if (device.bondState == BluetoothDevice.BOND_BONDED) {
	handler?.post {
	gattServer?.connect(device, true)
	}
	synchronized(bluetoothDevicesMap) {
	bluetoothDevicesMap.put(
	device.address,
	device
	)
	}
	}
	onConnectionUpdate(device, status, newState)
	}

replaced with:

BluetoothProfile.STATE_CONNECTED -> {
    val requiresBonding = gattServer?.services?.any { service ->
        service.characteristics.any { characteristic ->
            characteristic.permissions and (
                BluetoothGattCharacteristic.PERMISSION_READ_ENCRYPTED or
                BluetoothGattCharacteristic.PERMISSION_WRITE_ENCRYPTED or
                BluetoothGattCharacteristic.PERMISSION_READ_ENCRYPTED_MITM or
                BluetoothGattCharacteristic.PERMISSION_WRITE_ENCRYPTED_MITM
            ) != 0
        }
    } ?: false

    if (requiresBonding && device.bondState == BluetoothDevice.BOND_NONE) {
        listOfDevicesWaitingForBond.add(device.address)
        device.createBond()
    } else {
        handler?.post {
            gattServer?.connect(device, true)
        }
        synchronized(bluetoothDevicesMap) {
            bluetoothDevicesMap[device.address] = device
        }
    }

    onConnectionUpdate(device, status, newState)
}