Hi François, On Wed, Jun 29, 2016 at 10:24 AM, François Beaufort <beaufort.francois@xxxxxxxxx> wrote: > I have a bogus BLE device which exposes "badly" a characteristic > notification. Even though it doesn't find a characteristic descriptor, > I'm still able to start notifications and even receive value changed > events. > > For info, Android and macOS raise an exception when trying to start > notifications. See > https://github.com/WebBluetoothCG/ble-test-peripheral-android/issues/63 > > See logs: > > < ACL Data TX: Handle 32 flags 0x00 dlen 9 > [hci0] 403.621325 > ATT: Find Information Request (0x04) len 4 > Handle range: 0x002b-0xffff >> HCI Event: Number of Completed Packets (0x13) plen 5 [hci0] 403.689256 > Num handles: 1 > Handle: 32 > Count: 1 >> ACL Data RX: Handle 32 flags 0x02 dlen 9 [hci0] 403.755926 > ATT: Error Response (0x01) len 4 > Find Information Request (0x04) > Handle: 0x002b > Error: Attribute Not Found (0x0a) > > --- > > [Nexus 5X]# list-attributes > Primary Service > /org/bluez/hci0/dev_46_EE_57_93_31_08/service0001 > Generic Attribute Profile > Characteristic > /org/bluez/hci0/dev_46_EE_57_93_31_08/service0001/char0002 > Service Changed > Primary Service > /org/bluez/hci0/dev_46_EE_57_93_31_08/service0028 > Battery Service > Characteristic > /org/bluez/hci0/dev_46_EE_57_93_31_08/service0028/char0029 > Battery Level > [Nexus 5X]# select-attribute > /org/bluez/hci0/dev_46_EE_57_93_31_08/service0028/char0029 > [Nexus 5X:/service0028/char0029]# notify on > [CHG] Attribute > /org/bluez/hci0/dev_46_EE_57_93_31_08/service0028/char0029 Notifying: > yes > Notify started > [CHG] Attribute > /org/bluez/hci0/dev_46_EE_57_93_31_08/service0028/char0029 Value: 0x32 > [Nexus 5X:/service0028/char0029]# notify off > [CHG] Attribute > /org/bluez/hci0/dev_46_EE_57_93_31_08/service0028/char0029 Notifying: > no > Notify stopped > -- Just to make it public what I have stated in the irc, currently we allow enabling notification even without CCC (out of the spect unsolicited notification): commit 46aad83687251bef0fa0ac60583e5898170b0f10 Author: Arman Uguray <armansito@xxxxxxxxxxxx> Date: Tue Feb 3 19:58:22 2015 -0800 shared/gatt: Allow register_notify without CCC Most OSes allow to register characteristics without a CCC even if they do support notification/indication, this is not according to the specification and may not even work in practice since there is no way to enable notifications/indications without a CCC to write to but there has been some applications that do that anyway. Perhaps Arman had it exactly for these broken application that don't register a CCC which Im guessing is because the GATT API don't do it by default (Android?) leaving it up to the app which can screw up we can observe here. -- Luiz Augusto von Dentz -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
