Hi Luiz, Thank you for the answer and sorry for using wrong term, yes, it's about prepare write. > is the correct behaviour, if you need that for authorizing the > prepare Do you mean, I have to add "authorize" flag to the characteristic's properties in order to enable writing, even if I'm not using any security mechanisms? Please note that 'btgatt-server' application does not use D-Bus API. I'm sorry for my comments that may sound stupid, I'm quite new to Bluetooth LE. Best regards, Konstantin On Wed, 2019-12-18 at 11:02 -0800, Luiz Augusto von Dentz wrote: > Hi Konstantin, > > On Wed, Dec 18, 2019 at 2:36 AM Konstantin Forostyan > < > konstantin.forostyan@xxxxxxxxxxxxx > > wrote: > > Hi, > > > > During Bluetooth Qualification tests with PTS I found out that if > > an > > attribute provided by a GATT server created by BlueZ 5.50 running > > on my > > IUT is written by remote, the value of this attribute is not > > provided > > by 'bluetoothd' to the upper layer. With a minor modification of > > 'bluetoothd' I managed to get the tests through, so I'd like to get > > feedback from the community, whether this modification was > > necessary or > > may be there's another way of getting attribute write working. > > > > For GATT tests I used 'btgatt-server' application provided by > > BlueZ. In > > order to test writing characteristic value I made "Device Name" > > provided by the application writable. It turned out, that the > > 'gap_device_name_write_cb' function that is called by the daemon > > upon > > writing "Device Name" always receives 'value=NULL' and 'len=0'. The > > reason for this is that in the 'gatt_db_attribute_write' call in > > 'prep_write_cb' in 'gatt-server.c' file in 'bluetoothd' both > > 'value' > > and 'len' are hard-coded to NULL and 0 respectively. > > Well not actually a write but a prepare write, so until execute is > called nothing shall be written, so except if I missing something > this > is the correct behaviour, if you need that for authorizing the > prepare > the you should look into: > > https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/doc/gatt-api.txt#n104 > > https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/doc/gatt-api.txt#n273 > > > > With the following modification in 'gatt-server.c' the callback in > > 'btgatt-server' application receives the arguments it expects and > > the > > GATT tests can be passed: > > > > --- a/src/shared/gatt-server.c 2018-06-01 10:37:36.000000000 +0200 > > +++ b/src/shared/gatt-server.c 2019-12-13 12:16:58.000000000 +0100 > > @@ -1291,7 +1291,7 @@ > > pwcd->length = length; > > pwcd->server = server; > > > > - status = gatt_db_attribute_write(attr, offset, NULL, 0, > > + status = gatt_db_attribute_write(attr, offset, pwcd->pdu + > > 4, > > pwcd->length - 4, > > BT_ATT_OP_PREP_WRIT > > E_RE > > Q, > > server->att, > > prep_write_complete > > _cb, > > pwcd); > > > > > > Best regards > > Konstantin > > > > >
