`_demux()` might change `pkt->data` in all kind of ways (moving it due
to `gnrc_pktbuf_mark()`, though unlikely; releasing it, because e.g. it
starts with a fragment header that marks a fragmented packet containing
only one fragment, etc.) so accessing the pointer *after* calling
`_demux()` is somewhat playing with fire. This change avoids this by
storing the value of `ext_hdr->nh` (all we are interested in here) in a
temporary variable that then is used to set the out-parameter `nh`.
`protnum` needs to be unchanged before the call to `_demux()` as it was
set by the previous iteration and determines what extension header
actually is handled.
If the interface's link-layer doesn't use link-layer addresses it
obviously doesn't make sense to auto-configure an IPv6 address from it.
Moreover, I think the address `fe80::` is actual illegal, but I
couldn't find any references for it.
According to the documentation of `gnrc_ipv6_nib_get_next_hop_l2addr()`
`pkt` may be `NULL`. However, whenever that function sends an error
message (the methods for that require `orig_pkt` not to be NULL) `pkt`
is not checked, which may lead to failed assertions.
Not only does this leave open a risk to crash the node for the check
in `_compressible()` but also is the `tmp` check below getting confused
when `ptr` is `NULL`, since `gnrc_pktbuf_start_write()` returns `NULL`
in that case.
With newlib nano-specs the debug output without this change will be
6lo: dispatch 0hx ... is not supported
With this PR this will provide a correct output, e.g.
6lo: dispatch 0x3f ... is not supported
Currently the constructed NA for a delayed NA case is neither used nor
released nor does it get an IPv6 header to be used properly. This fixes
that case.
When working on the previous commit I was unsure if a
garbage-collectible entry should remain in the list, so I added this
comment so I don't have to wonder about this in the future ;-).
Fragment size calculation previously failed for devices that are able to
transmit bigger layer 2 PDUs that 802.15.4 devices. This commit fixes the issue.
The `_next_removable` list manages the cache-out of the neighbor cache.
However, when a neighbor cache entry is removed, it is not removed
from that list, which may lead to a segmentation fault when that list is
accessed, since the whole entry (including its list pointer) is zeroed
after removal.
With this change the entry is removed from that list accordingly before
the zeroing happens.
When either `gnrc_sixlowpan_iphc_nhc` or `gnrc_udp` is not compiled
in `_compressible()` never returns `true`. This causes the
`dispatch` snip in `gnrc_sixlowpan_iphc_send()` to be of length 0,
meaning `dispatch->data` is `NULL`, causing possible crashes when
trying to send IPv6 packets over 6LoWPAN without NHC or UDP.
