If a node has two interfaces A with 2001:16b8:45b5:9af8:5884:3bff:fe4f:a903
and B with 2001:16b8:45b5:9afa:5884:3bff:fe4f:a902 and receives a neighbor
solicitation on A for an address configured on interface B, answer the neighbor
solicitation instead of bailing out with
> Target address 2001:16b8:45b5:9afa:5884:3bff:fe4f:a902 is not assigned
> to the local interface
If we switch the interface in gnrc_ipv6_nib_get_next_hop_l2addr()
we must also re-get the nib entry from the 'proper' interface.
Otherwise we will always find the host unreachable on the 'wrong'
interface.
Consider the following configuration:
nib prefix
2001:16b8:4569:88fc::/62 dev #7 expires 7081 sec deprecates 3481 sec
2001:16b8:4569:88fe::/63 dev #6
If `_on_link()` stops at the first match, a packet received from #7 with a
destination in the downstream subnet in #6 would always be sent back via #7
if this happens to be the first entry in the list.
Instead, consider all prefixes and return the one that is the closest match.
When two threads use `gnrc_ipv6_nib_get_next_hop_l2addr()` to determine
a next hop (e.g. when there is both an IPv6 sender and a 6LoWPAN
fragment forwarder), a race condition may happen, where one thread
acquires the NIB and the other acquires the network interface resulting
in a deadlock. By releasing the NIB (if acquired) before trying to
acquire the network interface and re-acquiring the NIB after the network
interface is acquired, this is fixed.
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.
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 a new queue entry is tried to be allocated for a neighbor who's
address is currently tried to be resolved there was no error case
before. The packet that was tried to be put in the queue was thus not
released and stayed in the packet buffer for ever.
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>
