pf: distinguish forwarding and output cases for pf_refragment6()

[kp]

Summary

Re-introduce PFIL_FWD, because pf's pf_refragment6() needs to know if
we're ip6_forward()-ing or ip6_output()-ing.

ip6_forward() relies on m->m_pkthdr.rcvif, at least for link-local
traffic (for in6_get_unicast_scopeid()). rcvif is not set for locally
generated traffic (e.g. from icmp6_reflect()), so we need to call the
correct output function.

Sponsored by: Rubicon Communications, LLC ("Netgate")

[glebius]

sys/net/pfil.c

204–205

This somewhat relaxes the old assertion. I think it is still important to protect against dumb case of two directions. Maybe add two assertions?

sys/netpfil/pf/pf.c

7956

		action = pf_refragment6(ifp, m0, mtag, pflags & PFIL_FWD);

sys/netpfil/pf/pf_norm.c

47

This won't be needed if using bool argument.

945–946

I'd suggest to use bool forward here instead of int pflags, but it is up to you.

1016–1017

Style: should be one line

[kp]

Review remarks