[dpdk-dev] Bug in IPv4 header checksum computation?

[N. Benes]

Hi,

I wrote to the users list a bit more a week ago concerning the IPv4
Header Checksum computation and received no comments on it yet:

https://mails.dpdk.org/archives/users/2019-March/004021.html
https://mails.dpdk.org/archives/users/2019-March/004022.html

I have the impression that the current implementation wrongly does a
conditional final inversion of the computed sum. This is correct for
e.g. UDP, but I think it is not for an IPv4 Header (header checksum is
not optional).

If it is a bug, this could result in a surprisingly high number of
invalid/dropped IPv4 packets, when the checksum is calculated manually
via the DPDK API (not NIC-offloaded) and the IPv4 header has an
appropriate combination of values e.g. the IP Identification field.

Cheers!