Use generic checksum calculation for TCP SYN+ACK packets.
Our syn cache did checksum calculation by hand, instead of the
established mechanism in ip output. The software-checksummed counter
increased once per incoming TCP connection.
Just set the flag M_TCP_CSUM_OUT in syn_cache_respond() and let
in_proto_cksum_out() do the work later. Then hardware checksumming
is used where available. Also remove redundant code. The unhandled
af case is handled in the first switch statement of the function.
tested by Hrvoje Popovski; OK mvs@
projects / openbsd / commit