1178629 - Sometimes device name is empty when using LE Scan

Status: RESOLVED FIXED

(Firefox OS Graveyard :: Bluetooth, defect)

Description

[Jocelyn Liu [:jocelyn] [:joliu]]

When using bluetoothd as the backend, some devices' names are empty.
I suppose this is caused by
https://github.com/mozilla-b2g/platform_system_bluetoothd/blob/master/src/bt-gatt-io.c#L314.

adv_data might be truncated because of using strlen in this line.
We need to fix it in order to pass complete adv_data to gecko backend.

Comment 1

[Jocelyn Liu [:jocelyn] [:joliu]]

(In reply to Jocelyn Liu [:jocelyn] [:joliu] from comment #0)
> When using bluetoothd as the backend, some devices' names are empty.
some devices' names are empty when using LEScan.
> I suppose this is caused by
> https://github.com/mozilla-b2g/platform_system_bluetoothd/blob/master/src/bt-
> gatt-io.c#L314.
> 
> adv_data might be truncated because of using strlen in this line.
> We need to fix it in order to pass complete adv_data to gecko backend.

Comment 2

[Bruce Sun [:brsun]]

Attachment: https://github.com/mozilla-b2g/platform_system_bluetoothd/pull/35

Comment 3

[Bruce Sun [:brsun]]

Although the maximum length defined in spec (Vol. 3, Part C, Chapter 11) is 31 octets, bluedroid on AOSP uses 62 bytes to pass EIR data. So probably we need to calculate the total length by accumulating the length of each AD structure.

[1] http://androidxref.com/4.4.4_r1/xref/external/bluetooth/bluedroid/btif/src/btif_gatt_client.c#543

Comment 4

[Thomas Zimmermann [:tzimmermann] [:tdz]]

Comment on attachment 8627630 [details] [review]
https://github.com/mozilla-b2g/platform_system_bluetoothd/pull/35

Sorry for this review taking so long. I just returned from PTO.

Please see the Github repo for some nits. Does this require changes on the Gecko side when we're unpacking the notification?

Comment 5

[Bruce Sun [:brsun]]

(In reply to Thomas Zimmermann [:tzimmermann] [:tdz] from comment #4)
> Comment on attachment 8627630 [details] [review]
> https://github.com/mozilla-b2g/platform_system_bluetoothd/pull/35
> 
> Sorry for this review taking so long. I just returned from PTO.
> 

Not at all. Thanks for reviewing the patch. :)

> Please see the Github repo for some nits. Does this require changes on the
> Gecko side when we're unpacking the notification?

It seems Gecko side [1] is good already as long as the value of the length field is correct.

[1] https://dxr.mozilla.org/mozilla-central/source/dom/bluetooth/bluedroid/BluetoothDaemonGattInterface.cpp#1099

Comment 6

[Bruce Sun [:brsun]]

Hi Thomas,

Would you mind having a look on my comments in the patch before I request for checkin-needed? I am a little afraid that the comments are not short enough...

Comment 7

[Thomas Zimmermann [:tzimmermann] [:tdz]]

Done. Just a nit.

Comment 8

[Ryan VanderMeulen [:RyanVM]]

Master: https://github.com/mozilla-b2g/platform_system_bluetoothd/commit/3f6ccfc6bc73e28765d70bbe5c277a6276472b08