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Subject: Re: btvirt with two virtual controllers: Cannot connect to GATT
 server
To:     Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Cc:     "linux-bluetooth@vger.kernel.org" <linux-bluetooth@vger.kernel.org>
References: <6cf0d3da-a7d0-c820-3343-3f3722bae9a4@labapart.com>
 <638ce0f7-3075-c7d2-57c4-55392f8f5e0a@labapart.com>
 <CABBYNZKpLr6Bj4U7ryJe7512uuGPW7v84xb+8Z-BKAd_rHNURQ@mail.gmail.com>
From:   Olivier MARTIN <olivier@labapart.com>
Message-ID: <f0a196cc-cf28-cd8b-d4a7-3d646e128db8@labapart.com>
Date:   Tue, 7 Apr 2020 08:30:50 +0200
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Hi Luiz,

On 07.04.20 02:26, Luiz Augusto von Dentz wrote:
> Hi Olivier,
>
> On Mon, Apr 6, 2020 at 4:06 PM Olivier MARTIN <olivier@labapart.com> wrote:
>> 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)".

>>      [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)
>>
>