Take a first cut at cleaning up ifnet removal and multicast socket
panics, which occur when stale ifnet pointers are left in struct
moptions hung off of inpcbs:
- Add in_ifdetach(), which matches in6_ifdetach(), and allows the
protocol to perform early tear-down on the interface early in
if_detach().
- Annotate that if_detach() needs careful consideration.
- Remove calls to in_pcbpurgeif0() in the handling of SIOCDIFADDR --
this is not the place to detect interface removal! This also
removes what is basically a nasty (and now unnecessary) hack.
- Invoke in_pcbpurgeif0() from in_ifdetach(), in both raw and UDP
IPv4 sockets.
It is now possible to run the msocket_ifnet_remove regression test
using HEAD without panicking.
Reported by: Gavin Atkinson <gavin dot atkinson at ury dot york dot ac dot uk>
Approved by: re (scottl)