[lwip-devel] [bug #45353] IPv6 router / neightbor relationship is not always consistent

[Stian Sebastian Skjelstad]

URL:
  <http://savannah.nongnu.org/bugs/?45353>

                 Summary: IPv6 router / neightbor relationship is not always
consistent
                 Project: lwIP - A Lightweight TCP/IP stack
            Submitted by: mywave
            Submitted on: Fri 19 Jun 2015 08:27:05 AM GMT
                Category: IPv6
                Severity: 3 - Normal
              Item Group: Faulty Behaviour
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: 
            lwIP version: CVS Head

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Details:

When creating a IPv6 router, it will first create a neightbor and reference
that with a pointer later:

inside nd6_new_router():
default_router_list[router_index].neighbor_entry =
&(neighbor_cache[neighbor_index])


However, if neighbor cache is exhausted or entry times out it will be removed,
but nd6_free_neighbor_cache_entry() has no knowledge of the
default_router_list[].


I suggest that neighbor_cache[] should also contain a link back to
default_router_list[], and invalid the neighbor_entry pointer if entry is
deleted (and hence kill the route entry), or the possibility to delete
neighbor_cache[] entries that are routers should be removed.

One thing to consider too in this situation is that a router (gw) might have
been added statically by the user. In that case, a FLAG should be set that
makes it impossible to recycle a neighboor_cache/router entry if created by
the user unless explicit deleted... or user needs to check every now and then
that his router/neigboor entry still exists...


I can create suggestion patches




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