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
