For info, we'll track check for CCC descriptors at https://bugs.chromium.org/p/chromium/issues/detail?id=624763 On Thu, Jun 30, 2016 at 1:41 PM, François Beaufort <beaufort.francois@xxxxxxxxx> wrote: > Thank you Luiz, I'm not sure what are most OSes there because macOS > and Android don't allow register characteristics without a CCC. > > I'll ping armansito@ and let you know ;) > > On Thu, Jun 30, 2016 at 1:36 PM, Luiz Augusto von Dentz > <luiz.dentz@xxxxxxxxx> wrote: >> 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
