In accordance with RFC 6775, section 5.2 an NCE should be set STALE
when an ARO renews the address registration for the address:
> The routers SHOULD NOT garbage-collect Registered NCEs (see
> Section 3.4), since they need to retain them until the Registration
> Lifetime expires. Similarly, if NUD on the router determines that
> the host is UNREACHABLE (based on the logic in [RFC4861]), the NCE
> SHOULD NOT be deleted but rather retained until the Registration
> Lifetime expires. A renewed ARO should mark the cache entry as
> STALE. Thus, for 6LoWPAN routers, the Neighbor Cache doesn't behave
> like a cache. Instead, it behaves as a registry of all the host
> addresses that are attached to the router.
When `nce` is NULL on the duplicate check, the later re-fetching of the
`nce` might result in an actual NCE entry that then contains a
duplicate, so we need to re-check the EUI-64 again as well.
This changes the prefixes of the symbols generated from USEMODULE and
USEPKG variables. The changes are as follow:
KCONFIG_MODULE_ => KCONFIG_USEMODULE_
KCONFIG_PKG_ => KCONFIG_USEPKG_
MODULE_ => USEMODULE_
PKG_ => USEPKG_
Replace direct accesses to sched_active_thread and sched_active_pid with
the helper functions thread_getpid() and thread_get_active(). This serves
two purposes:
1. It makes accidental writes to those variable from outside core less likely.
2. Casting off the volatile qualifier is now well contained to those two
functions
Coverty scan found this:
> CID 298295 (#1 of 1): Operands don't affect result (CONSTANT_EXPRESSION_RESULT) result_independent_of_operands:
> (ipv6_hdr_get_fl(ipv6_hdr) & 255) >> 8 is 0 regardless of the values of its operands.
Looking at the code, this appears to be a copy & paste error from the previous line.
Coverty scan found this:
> CID 298279 (#1 of 1): Out-of-bounds read (OVERRUN)
> 21. overrun-local: Overrunning array of 16 bytes at byte offset 64 by dereferencing pointer
The original intention was probably to advance the destination pointer by 4 bytes, not
4 * the destination type size.
Using pointer difference already gives us the number of elements of
size of what the pointer is pointing to.
Dividing by size will lead to the wrong (always 0) result.
Since `min(a,b)` is a very frequently used function, several libraries such as ESP8266 SDK define a `MIN` macro in their header files. Therefore the `MIN` macro should be undefined before its definition to avoid compilation errors if it is defined anywhere else before.
Add a message bus where threads can listen for nib events.
Currently only the GNRC_IPV6_NIB_EVENT_ADDR_VALID event is
implemented which informs subscribers that an address got
valid.
With multiple 6LoWPAN interfaces the router for the given interface
—the one the triggering RA came over—should be used to register the
address with.
Co-Authored-By: Benjamin Valentin <benpicco@googlemail.com>
