security v3: valid_at_location

[khevessy]

I am not completely sure if we did not already discuss this, but some of the location checks for V3 certificate are not implemented:

https://github.com/riebl/vanetza/blame/40776241ecc758100b0b3b17caac7dcdfcacb0ec/vanetza/security/v3/certificate.cpp#L107

https://github.com/riebl/vanetza/blame/40776241ecc758100b0b3b17caac7dcdfcacb0ec/vanetza/security/v3/certificate.cpp#L110

We encountered the Region one in real life. Our fix was to just put return true; in the appropriate case. To be honest this approach does not seem right, but basically silently failing took a little time to debug. Maybe there could be some option for toggling this check on/off?

Btw the region restriction seems like a nightmare to check based on location.

[riebl]

Yes, the nightmare is the exact reason why it has not been implemented so far.
Should we create an interface class, such as LocationChecker, so one can easily switch policies? A more elaborate checker may then come with a database of regions and their identifiers.

[khevessy]

Great idea! Can you have a look at my location-checker branch to see if we imagine the architecture the same way?

[riebl]

Looks good! Meanwhile, I have some code ready for PolygonalRegion checks.

[riebl]

Update: LocationChecker by @khevessy (Thanks!) is merged. is_inside checks are added for asn1::PolygonalRegion.

For checking IdentifiedRegion, it might be necessary to load data from the filesystem at runtime. I have found an open data set containing the boundaries of countries. Thanks to Boost.Geometry, we could load these shapes into an R-tree and test relevant polygons for a given location.