The function to infer the link-layer address length from the length of
a S/TLLAO is very dependent on the IPv6 over X specification and thus
should be grouped with the other IP over X functions.
While the recursion in `gnrc_sixlowpan_frag` shouldn't be infinite we
still should avoid using recursions in general (also to be able to
statically analyze stack usage). This unrolls the recursion.
When having a non-6LN interface and a 6LN interface (e.g. on a border
router) the assertion can hit when a Router Advertisement is received.
This makes the check an `if` statement rather than an assertion, to
account for that case.
Co-authored-by: Gunar Schorcht <gunar@schorcht.net>
When issueing the sending of the next fragment the current version of
`gnrc_sixlowpan_frag` doesn't check if the queue is full. This leads to
leakage of the packet buffer, since when it is full, the package never
gets released.
This change adds a checks and error exits in case the queue is full.
Since the recursion into `gnrc_ipv6_demux()` was removed in
`gnrc_ipv6_ext`, `gnrc_ipv6.c` is the only user of this function,
so it can be made private. It was only made public so it can be used
from `gnrc_ipv6_ext`.
As `pkt` isn't pre-parsed the write-protection of *the whole* packet
(except the netif-header) comes for free, when this was done in the
receive routine of IPv6.
Since with #10233 we now assume IPv6 packets always to not be
pre-parsed, we can iterate over the extension headers by gradually
"eating" them away. This allows us to move the iteration over them
out of `gnrc_ipv6_ext_demux()` and into `gnrc_ipv6_demux()`.
By moving the iteration over all extension headers out of
`gnrc_ipv6_ext_demux()` we also can
1. simplify the extension header handling a lot, as it now
just a loop inside `gnrc_ipv6_demux()`,
2. remove the recursion to `gnrc_ipv6_demux()` within
`gnrc_ipv6_ext_demux()`.
Since the packet is now guaranteed to be preparsed, the currently
handled IPv6 header will always be in the first snip. Because of this
the packet parser can't get confused anymore which IPv6 header is the
one to be handled so we don't need to remove the more outer ones.
Because of this we can just use the normal packet dispatching (which is
already used by other `GNRC_NETTYPE_*`-known protocol numbers such as
UDP).
This also reverts d54ac38f84.
Though this change might seem more complicated, it has the benefit, that
after #9484 we don't have to assume that a received packet within IPv6's
receive function can be handed to the function pre-parsed, making that
function far less complicated (will be provided in a future PR).
Also this might give the forwarding via routing header a little
performance boost, as we now don't *receive* the packet first only to
forward it later-on.
