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_WRITE_RE > Q, > server->att, > prep_write_complete_cb, > pwcd); > > > Best regards > Konstantin > -- Luiz Augusto von Dentz
