Add multiple command line arguments for UDC, Interface, BT alias

[KreAch3R]

The below patches are complimentary to the awesome work you have done with this repo.

They install:

--btalias          Specify the name of the BLE host device
--interface      Specify the interface of the Wi-Fi hotspot
--udc              Specify the UDC controller to use

It is an attempt to stop aa-proxy-rs and aawg from hardcoding a lot of stuff, which should be tunable. Network information is being actively parsed from system.

Choosing udc controller may be a minor detail, but it's needed if one needs to use dummy_hcd as the controller, and it's better to specify than the default "choose the first one" option.

Bear in mind that this is my first time writing anything in Rust/C++, so comments / fixes are welcome.

[manio]

Thank you for the PR!

I added some cleanup commits but at the final test on the Pi it ended up with panic because wrong hostapd.conf location. Let's just stick with the location which is on the WirelessAndroidAutoDongle project - if you need other for your application please provide additional PR for setting this as a parameter.

[KreAch3R]

Thank you for the cleanup commits, I learned some things! And thank you for merging.

I was stumped at the hostapd.conf location. It didn't even cross my mind that it isn't the default location, I didn't notice the path on the WirelessAndroidAutoDongle project.

I found the reason, it's because on Raspbian (buster, at least), hostapd starts from a systemd service that sets the DAEMON_CONF to /etc/hostapd/hostapd.conf :

pi@raspberrypi:/etc/init.d $ cat /lib/systemd/system/hostapd.service
...
[Service]
Type=forking
PIDFile=/run/hostapd.pid
Restart=on-failure
RestartSec=2
Environment=DAEMON_CONF=/etc/hostapd/hostapd.conf
EnvironmentFile=-/etc/default/hostapd
ExecStart=/usr/sbin/hostapd -B -P /run/hostapd.pid -B $DAEMON_OPTS ${DAEMON_CONF}
...

While on buildroot created systems, it's getting installed on /etc/hostapd.conf for no reason, as far as I can tell: buildroot/buildroot@13f364d and then it gets used here.

That's a bummer, I wish the Buildroot developers kept the path same like on other distros. I'm not sure I like adding another argument for that, seems too specific, I can certainly keep the change local. If I come up with something elegant, I'll submit another PR.

[manio]

If I come up with something elegant, I'll submit another PR.

done in: b2bbf1a

[KreAch3R]

If I come up with something elegant, I'll submit another PR.

done in: b2bbf1a

Oh nice, it was indeed like 4 lines of code, nice usage of default value again. Great, thanks!