Add support for classless static routes (options 121 and 249) for DHCP ipam

[Domini]

At the moment DHCP ipam ignores classless static routes (option 121) and Microsoft classless static routes (option 249) options provided from DHCP server.

The workaround to hardcode the routes through podman network create --route does not work either.

The workaround to create the routes from within the container significantly increases complexity and also introduces security risks (CAP_NET_ADMIN required), and especially increases complexity if you are trying to run container PID 1 not from USER root.

As far as I can tell, netavark uses mozim for DHCP, and AFAICan tell mozim does not support classless static routes either.

[Luap99]

The workaround to hardcode the routes through podman network create --route does not work either.

That seems like a separate bug to me as this should certainly work I would say.

As far as I can tell, netavark uses mozim for DHCP, and AFAICan tell mozim does not support classless static routes either.

Yes these settings would need to first be exposed there and then we can use them. I have nothing against adding them but it is unlikely that we have the time to work on it. Contributions welcome.

[Domini]

The workaround to hardcode the routes through podman network create --route does not work either.

That seems like a separate bug to me as this should certainly work I would say.

Extracted to #1290.