Re: btvirt with two virtual controllers: Cannot connect to GATT server

Hi Olivier,

On 2020-04-08 21:40:03, Olivier MARTIN wrote:

Hi Luiz,

On 07.04.20 08:30, Olivier MARTIN wrote:

quoted

Hi Luiz,

On 07.04.20 02:26, Luiz Augusto von Dentz wrote:

quoted

Hi Olivier,

On Mon, Apr 6, 2020 at 4:06 PM Olivier MARTIN [off-list ref]
wrote:

quoted

Hi all,

I am trying to test BLE connection between two virtual controllers
(created with 'btvirt'). But when trying to connect to the GATT server
running on the first virtual controller, I have the error
"src/device.c:att_connect_cb() connect error: Transport endpoint is not
connected (107)"


To test my test case, I am using the head of Bluez (2a7df9323e, Sunday
5th April).

Here is the test case:

1. Start btvirt for BLE: sudo ./emulator/btvirt -L -U2 (you will
need my
patch to fix command line parsing I sent a couple of minutes ago)

2. Start bluetoothctl to initialize the Virtual Controller that would
play the role of GATT Server:

     $ bluetoothctl
     [NEW] Controller DB:E3:2A:E8:90:C4 olivier-ThinkPad-T480 #2
[default]
     [NEW] Device E3:01:36:88:4C:DE TestAdvertisement
     [NEW] Controller E3:01:36:88:4C:DE olivier-ThinkPad-T480
     [NEW] Device DB:E3:2A:E8:90:C4 TestAdvertisement

     [bluetooth]# list
     Controller DB:E3:2A:E8:90:C4 olivier-ThinkPad-T480 #2 [default]
     Controller E3:01:36:88:4C:DE olivier-ThinkPad-T480

     [bluetooth]# power on
     Changing power on succeeded
     [CHG] Controller DB:E3:2A:E8:90:C4 Powered: yes

     [bluetooth]# discoverable on
     Changing discoverable on succeeded
     [CHG] Controller DB:E3:2A:E8:90:C4 Discoverable: yes

Try with advertise.discoverable on, advertise instances actually have
their discoverable flag.

I am not sure to understand how "advertise.discoverable on" will fix
my issue.

I do not have any issue to discover the GATT server running on the
first instance of the virtual controller from the second one (see log
below).

The only issue is when I try connecting to the GATT server with
'connect DB:E3:2A:E8:90:C4', I have the error "Failed to connect:
org.bluez.Error.Failed" with the error in bluetoothd
"src/device.c:att_connect_cb() connect error: Transport endpoint is
not connected (107)".

I still wanted to make sure "advertise.discoverable on" would not solve
my issue. I have just tested with the latest bluez (commit 60423fed392a)
by adding "menu advertise" + "discoverable on" to the steps to duplicate
the issue. And I still see the error:

bluetoothd[14755]: src/device.c:btd_device_set_temporary() temporary 0
bluetoothd[14755]: src/device.c:device_connect_le() Connection attempt
to: DB:E3:2A:E8:90:C4
bluetoothd[14755]: src/device.c:att_connect_cb() connect error:
Transport endpoint is not connected (107)

I was having similar issues with getting btvirt working. I resolved my
issue by using btmgmt to set the virtual adapter I was trying to
connect to have "connectable on".

As you can see below, the two virtual adapters are created without
being connectable:

pi@raspberrypi:~ $ btmgmt info | grep -P "hci|current settings"
hci2:   Primary controller
        current settings: powered bondable ssp br/edr le secure-conn
hci1:   Primary controller
        current settings: powered bondable ssp br/edr le secure-conn
hci0:   Primary controller
        current settings: powered connectable bondable ssp br/edr le secure-conn
pi@raspberrypi:~ $ sudo btmgmt --index 1 connectable on
hci1 Set Connectable complete, settings: powered connectable bondable
ssp br/edr le secure-conn
pi@raspberrypi:~ $ btmgmt info | grep -P "hci|current settings"
hci2:   Primary controller
        current settings: powered bondable ssp br/edr le secure-conn
hci1:   Primary controller
        current settings: powered connectable bondable ssp br/edr le secure-conn
hci0:   Primary controller
        current settings: powered connectable bondable ssp br/edr le secure-conn

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     [bluetooth]# advertise on
     [CHG] Controller DB:E3:2A:E8:90:C4 SupportedInstances: 0x04
     [CHG] Controller DB:E3:2A:E8:90:C4 ActiveInstances: 0x01
     Advertising object registered


3. Use './test/example-gatt-server' to simulate GATT server. I confirm
the server is started on DB:E3:2A:E8:90:C4 (first virtual controller)

4. Return to bluetoothctl to switch to second virtual controller and
connect to the first one

     [bluetooth]# select E3:01:36:88:4C:DE
     Controller E3:01:36:88:4C:DE olivier-ThinkPad-T480 [default]

     [bluetooth]# power on
     Changing power on succeeded
     [CHG] Controller E3:01:36:88:4C:DE Powered: yes

     [bluetooth]# scan on
     Discovery started
     [CHG] Controller E3:01:36:88:4C:DE Discovering: yes
     [NEW] Device DB:E3:2A:E8:90:C4
     [bluetooth]# scan off
     Discovery stopped
     [CHG] Controller E3:01:36:88:4C:DE Discovering: no

     [bluetooth]# connect DB:E3:2A:E8:90:C4
     Attempting to connect to DB:E3:2A:E8:90:C4
     Failed to connect: org.bluez.Error.Failed
     [CHG] Controller DB:E3:2A:E8:90:C4 Discoverable: no


And in the bluetoothd log:

     bluetoothd[15175]: src/adapter.c:start_discovery() sender :1.6483
     bluetoothd[15175]: src/adapter.c:update_discovery_filter()
     bluetoothd[15175]: src/adapter.c:discovery_filter_to_mgmt_cp()
     bluetoothd[15175]: src/adapter.c:trigger_start_discovery()
     bluetoothd[15175]: src/adapter.c:cancel_passive_scanning()
     bluetoothd[15175]: src/adapter.c:start_discovery_timeout()
     bluetoothd[15175]: src/adapter.c:start_discovery_timeout()
adapter->current_discovery_filter == 0
     bluetoothd[15175]: src/adapter.c:start_discovery_complete()
status 0x00
     bluetoothd[15175]: src/adapter.c:discovering_callback() hci0
type 6 discovering 1 method 0
     bluetoothd[15175]: src/adapter.c:device_found_callback() hci0
addr DB:E3:2A:E8:90:C4, rssi 0 flags 0x0000 eir_len 3
     bluetoothd[15175]: src/device.c:device_set_legacy() legacy 0
     bluetoothd[15175]: src/device.c:device_set_flags() flags 6
     bluetoothd[15175]: src/adapter.c:stop_discovery() sender :1.6483
     bluetoothd[15175]: src/adapter.c:stop_discovery_complete()
status 0x00
     bluetoothd[15175]: src/adapter.c:trigger_passive_scanning()
     bluetoothd[15175]: src/adapter.c:discovery_remove() owner :1.6483
     bluetoothd[15175]: src/adapter.c:discovering_callback() hci0
type 6 discovering 0 method 0
     bluetoothd[15175]: src/device.c:device_connect_le() Connection
attempt to: DB:E3:2A:E8:90:C4
     bluetoothd[15175]: src/device.c:att_connect_cb() connect error:
Transport endpoint is not connected (107)