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Subject: btvirt with two virtual controllers: Cannot connect to GATT server
References: <6cf0d3da-a7d0-c820-3343-3f3722bae9a4@labapart.com>
To:     linux-bluetooth@vger.kernel.org
From:   Olivier MARTIN <olivier@labapart.com>
Message-ID: <638ce0f7-3075-c7d2-57c4-55392f8f5e0a@labapart.com>
Date:   Tue, 7 Apr 2020 00:45:03 +0200
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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

    [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)