The NULL case can not regularly be reached (because regularly
gcoap_register_listener sets thel link_encoder to a default one), but if
it is (eg. because an application unsets its link_encoder to hide a
resource set at runtime), the existing `continue` is a good idea (skip
over this entry) but erroneously created an endless loop by skipping the
advancement step.
Change 'CONFIG_LORA_SF_DEFAULT' to 'SF7' and
'CONFIG_LORA_CR_DEFAULT' to 'LORA_CR_4_5' to
allow shorter air times and make it easier to meet country
specific regulations.
Non-routing 6LNs do not have to join the solicited nodes address, so
probing for a neighbor using that address may be in vain and only
spamming the LLN with unnecessary messages. RFC 6775 basically assumes
this in section 5.2:
> There is no need to join the solicited-node multicast address, since
> nobody multicasts NSs in this type of network.
Using `gnrc_border_router` with `uhcp` is quite noisy.
uhcpc will regularly refresh the prefix and print a bunch of status messages.
Allow the user to tone it down by setting a higher `LOG_LEVEL`.
For this, convert calls to `printf()` and `puts()` to `LOG_xxx()`.
This requires a dummy header for `uhcpd`.
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.
xtimer.h must not be included, when the xtimer module is not use. Otherwise
compilation on the waspmote-pro with https://github.com/RIOT-OS/RIOT/pull/14799
will not longer work. gnrc_netif_pktq includes xtimer.h and uses xtimer, but
gnrc_netif includes gnrc_netif_pktq.h regardless of whether gnrc_netif_pktq
is used. This makes sure that gnrc_netif_pktq.h is only included when actually
used.
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.
