Do I understand correctly, that dst contains an explicit bitmask, which is assumed to be continuous?

In D27416#612562, @lutz_donnerhacke.de wrote:

Do I understand correctly, that dst contains an explicit bitmask, which is assumed to be continuous?

Yes. Also, given we have proper multipath routing in tree, I'm going to forbid non-continuous netmasks, so we cleanup at least some parts of the legacy in 13.

Using the accessor functions and given the fact, that only continuous netmasks are allowed (not yet), the route-prefix could be shrinked by storing the prefix length instead of the mask.
The accessor function can then return the mask from a static netmask table.

In D27416#613471, @lutz_donnerhacke.de wrote:

Using the accessor functions and given the fact, that only continuous netmasks are allowed (not yet), the route-prefix could be shrinked by storing the prefix length instead of the mask.
The accessor function can then return the mask from a static netmask table.

Yes, sure. There are multiple ways of proceeding further. Prefix length can indeed be stored inside the radix mask as well, speeding up these calls. We need to be accurate with mask-only use case performance, as rtsock will use netmasks for quite a long time.
Anyway, the first step here is actually isolating access to the relevant rtentry fields.