While it is an edge case in our configuration it is technically
possible for a (6Lo) router not to maintain an address resolution state
machine. This fix allows for that with the `gnrc_ndp` module.
Check for:
- if it exists (critical error condition -- non-IPv6 headers should
not trigger these functions) => assert
- if it has a multicast source (that shouldn't really happen but
people might try weird stuff ;-)
- if it has an unspecified source (can't determine receiver of error
message => don't send it, don't build it)
Without this the first packet to a new link-local address will not be
delivered in non-6Lo environments, since the interface is not provided.
With this change, if an internet was provided to the address resolver it
will be stored within an allocated `gnrc_netif_hdr_t`.
At this point [IPv6 already striped](netif strip) the packet of its
netif header, so there is no risk that there will be to, in case it was
provided and the `netif` came from its existence.
`_decapsulate()` is called by callees of `_receive()` so the call to
the latter function within the first creates a recursion we don't want.
Using `gnrc_netapi` instead removes that and provides the added benefit
that other subscribers to IPv6 are also informed.
gnrc_sock_recv used to duplicate functionality of gnrc_ipv6_get_header,
but additionally checked whether the IPv6 snip is large enough.
All checks are now included in gnrc_ipv6_get_header, but as most of them
stem from programming / user errors, they were moved into asserts; this
constitutes an API change.
Our `gnrc_minimal` example configures the link-local address from the
IEEE 802.15.4 short address since it does not include 6Lo-ND.
This causes the application to be incompatible with our other GNRC
application that do include 6Lo-ND, since it [assumes][1] the link-local
address to be based on the EUI-64 for address resolution.
This enforces long addresses (aka EUI-64) for all IEEE 802.15.4 devices
when IPv6 is compiled in so `gnrc_minimal` is compatible again to the
rest.
Fixes#9910
[1]: https://tools.ietf.org/html/rfc6775#section-5.2
Linux doesn't have ARO support at the moment so this is a workaround to
try to speak 6Lo-ND while still being able to do DAD with a border
router that doesn't.
