inet_ntoa() cannot be used safely in a multithreaded environment
because it uses a static local buffer. Instead, use inet_ntoa_r()
with a buffer on the caller's stack.
This code had an INET6 conditional before this commit, but opt_inet6.h
was not included, so INET6 was never defined. Apparently, pf's OS
fingerprinting hasn't worked with IPv6 for quite some time.
This commit might fix it, but I didn't test that.
Reviewed by: gnn, kp
MFC after: 2 weeks
Relnotes: yes (if I/someone can test pf OS fingerprinting with IPv6)
Sponsored by: Dell EMC
Differential Revision: https://reviews.freebsd.org/D9625
643faabe0d