A generic application might select netdev_default instead of
gnrc_netdev_default to pull in the default network interface.
So pull in gnrc_netif if netdev_default is selected with GNRC.
If we get a large (e.g. /62) prefix from e.g. DHCPv6, we can split it
into subnets automatically to configure downstream interfaces.
This allows for automatic configuration of daisy-chained nodes or
nodes connected in a tree topology.
To enable the feature, a new pseudo-module `gnrc_ipv6_auto_subnets` is
provided.
If the fib contains a route to a subnet via another host, it can not
be on-link.
Consider fib entries when deciding whether an address is on-link.
If a route via another host is a stronger match than an on-link
prefix, the address must be off-link.
Initialize addr with 0 first.
Otherwise if prefix is < 64 there will be random bits of stack memory
in the bits of the address that are neither touched by ipv6_addr_set_aiid()
nor ipv6_addr_init_prefix().
Sending a RA with ltime = 0 does not get us added to the default router
list, but the options (and therefore the RIO) are still parsed.
This even appears to work with Linux as a receiver.
When the default router was removed or could not be added, `dr` will
be NULL.
In this case, don't cease sending router solicitations - we still don't
have a default router.
dhcpv6_client_prefix_valid_until returned the valid timestamp
this fixes it according to the documentation given in
/sys/include/net/dhcpv6/client.h
to return seconds left
Consider the following: A node tries to forward a packet to another
host for which it does not know the route yet. It assumes it to be
on-link and starts a neighbor solicitation, putting the node address
in the destinatio cache.
Later the route is known (via a second hop) but the host is still in
the NIB.
The result is that gnrc_ipv6_nib_get_next_hop_l2addr() ends up in the
"nib: %s is in NC or on-link, start address resolution" case and does
not attempt to resolve the route.
This results in the host remaining unreachable even though now a route
is present.
Prefix delegation used to be the only supported feature of our DHCPv6
client, but by now it also supports MUD, DNS recursive name servers and
IA_NA is on the horizon. So it makes sense to make IA_PD an optional
module like all those other features are as well.