Handle Castor USB VID/PID

[mchack-work]

Bellatrix has USB VID/PID 0x1207, 0x8887.

Castor has VID/PID 0x1209, 0x8885.

tkeyclient-py needs to be able detect both Bellatrix and Castors as valid TKeys. It looks like this is done in filter_device() in hw.py.

Since Castor needs special treatment from the client it would also be necessary to somehow tell the client app about what kind of model has been detected.

Relates to tillitis/tkeyclient#19

[kchr]

@mchack-work I could see a scenario where we use feature flags that are enabled/disabled depending on the USB_PID detected; for example disabling device app loading for Castor. Is this something along the lines of what you were thinking?

[mchack-work]

Castor will still support device app loading. It's just a little bit more complicated: The client app needs to send a reset request (not defined yet) to the FIDO2 app first.

For this particular issue I was thinking that, at first, we
first make filter_device handle both older and new USB VID/PIDs.

Then we want the caller to know what we found. So, perhaps, something like:

import tkeyclient.tkey as TKey

tkey = TKey('/dev/ttyACM0')
if tkey.model == castor:
  ...
else:
  ...

Then the caller might be able to decide what to do next. If it detects Castor it will hopefully know what to do, even if it's not precisely defined yet.

[mchack-work]

Rewrote orginal issue text to be more clear.

[kchr]

@mchack-work Thanks for the clarification, and the suggested use case.

I'll look into exposing the current model as a type that can be compared with different models, which in turn can be added as you release new ones.