Send call is successful but receives an empty response with nrf52840 dongle as bluetooth usb

[SachaPerson]

Hi,

I use this on Ubuntu 20.04 and Raspberry Pi OS 5.10 but this is not a Linux related issue.

I'm having an issue when I use ble.recon on with a different bluetooth dongle.

When I use it with a dongle using Realtek RTL8761b drivers ( MPOW MPBH456AB ) it works well, but when I use a NordicSemi nrf52840 dongle ( https://www.nordicsemi.com/Products/Development-hardware/nrf52840-dongle ) which is my goal, flashed with Zephyr RTOS' hci_usb sample ( https://github.com/zephyrproject-rtos/zephyr/tree/main/samples/bluetooth/hci_usb ) which is supposed to turn any micro controller using bluetooth into a regular bluetooth dongle that any computer is supposed to recognize as, it throws this error:

>> ble.recon on
   panic: runtime error: slice bounds out of range [:1] with capacity 0

   goroutine 1 [running]:
   github.com/bettercap/gatt/linux/cmd.(*Cmd).SendAndCheckResp(0x1c637c0, 0xa0c760, 0x1c64fe8, 0x1c6501c, 0x1, 0x1, 0x0, 0x0)
    /home/pi/go/pkg/mod/github.com/bettercap/gatt@v0.0.0-20210514133428-df6e615f2f67/linux/cmd/cmd.go:98 +0x1b4
   github.com/bettercap/gatt/linux.(*HCI).resetDevice(0x18ac0a0, 0x93dc10, 0x18ac0a0)
    /home/pi/go/pkg/mod/github.com/bettercap/gatt@v0.0.0-20210514133428-df6e615f2f67/linux/hci.go:273 +0x2f0
   github.com/bettercap/gatt/linux.NewHCI(0xffffffff, 0x184fd01, 0xff, 0x2, 0x0, 0x0)
    /home/pi/go/pkg/mod/github.com/bettercap/gatt@v0.0.0-20210514133428-df6e615f2f67/linux/hci.go:90 +0x4c0
   github.com/bettercap/gatt.NewDevice(0x184fd1c, 0x2, 0x2, 0x3c, 0x184fd24, 0x1, 0x1)
    /home/pi/go/pkg/mod/github.com/bettercap/gatt@v0.0.0-20210514133428-df6e615f2f67/device_linux.go:57 +0x114
   github.com/bettercap/bettercap/modules/ble.(*BLERecon).Configure(0x18a2780, 0x0, 0x4)
    /home/pi/go/pkg/mod/github.com/bettercap/bettercap@v2.24.1+incompatible/modules/ble/ble_recon.go:165 +0x1cc
   github.com/bettercap/bettercap/modules/ble.(*BLERecon).Start(0x18a2780, 0x1, 0x1b2c001)
    /home/pi/go/pkg/mod/github.com/bettercap/bettercap@v2.24.1+incompatible/modules/ble/ble_recon.go:183 +0x1c
   github.com/bettercap/bettercap/modules/ble.NewBLERecon.func1(0x0, 0x0, 0x0, 0x84f358, 0xc)
    /home/pi/go/pkg/mod/github.com/bettercap/bettercap@v2.24.1+incompatible/modules/ble/ble_recon.go:56 +0x1c
   github.com/bettercap/bettercap/session.(*ModuleHandler).Exec(0x1b2c0c0, 0x0, 0x0, 0x0, 0x0, 0x0)
    /home/pi/go/pkg/mod/github.com/bettercap/bettercap@v2.24.1+incompatible/session/module_handler.go:74 +0x80
   github.com/bettercap/bettercap/session.(*Session).Run(0x18fb2c0, 0x1c64e30, 0xc, 0x1, 0x1)
    /home/pi/go/pkg/mod/github.com/bettercap/bettercap@v2.24.1+incompatible/session/session.go:416 +0x284
   main.main()
    /home/pi/go/pkg/mod/github.com/bettercap/bettercap@v2.24.1+incompatible/main.go:94 +0x8c8

The problem is only when I'm using the nrf dongle, otherwise it works with the host's bluetooth and the other realtek dongle.

The nrf dongle works with the BlueZ stack, here are the results:

bluetoothctl ( has a BD address ) Scan does work

$ sudo bluetoothctl
  Agent registered
  [bluetooth]# list
  Controller EB:XX:XX:XX:XX:XX BlueZ 5.50 [default]

btmgmt ( finds the controller ) Scan does work

$ sudo btmgmt --index 0
   [hci0]# auto-power
   Found controller with index 0
   [hci0]# find -l

So, I assume the dongle works well with BlueZ, being the Linux official bluetooth stack it's a good sign, but I thought that Bettercap was also using BlueZ and in that sense the dongle should work.

The problem seems to come from https://github.com/bettercap/gatt/blob/master/linux/cmd/cmd.go#L98

Thank you so much for your help !