NLnetLabs
feat(xdp): add checksum verification on rx path
This PR introduces checksum verification for IPv4 and UDP in the XDP rx path. It fixes #465
For UDP I utilized the available functions in xdp-util.h. As for IP, I followed the example from xdp-project, and I "borrowed" the functions from the Kernel (I don't think this causes any issues in terms of Licensing).
Furthermore, since this implies some extra computing per each packet/request, I wanted to measure the performance implications. With a server running on a machine with an Intel i5-9500 and an Intel 10G X550T NIC, at a rate of 1M packets/requests per second, the average CPU usage across all CPU cores went from 11.18% to 11.57%.
For a single client sending synchronous requests, its rate drops from an average of 12360 req/s to 12315 req/s.
If this minor performance hit is an issue, we could perhaps add a compile flag so checksum verification would become optional.
