At the top of the file:
extern crate mac_utun;
use mac_utun::get_utun;
Just need to call this function. It will search for the first available utun-device starting from 0. As you may know, root permission is necessary to create a utun-device.
pub fn get_utun() -> Result<(UdpSocket,String)>
In case of error, the last OS-Error will be returned. In case of success, an UDP-socket and the interface name (e.g. "utun0") will be returned.
UDP-socket is a nice choice, because rust will perform the necessary clean up itself.
There is only one test case defined:
It checks the list of network interfaces before, during and after utun is opened. Expected behaviour: The returned utun is only in the list during utun is opened.