When the destination address is the loopback address (`::1`) in GNRC
the selected network interface typically is `NULL`, as with GNRC no
loopback interface de facto exists. So the assertion when checking if
the source address is valid if `netif != NULL` fails on that check.
This change fixes that issue by checking if the destination address is
the loopback address, before checking the validity of the source
address.
The RTT callback for a super-frame cycle uses the `arg` pointer to set
the message value that then is handed to the GoMacH thread. However,
in both instances the timer is scheduled the constant
`GNRC_GOMACH_EVENT_RTT_NEW_CYCLE` is provided. This means the argument
is not really necessary.
This fits with the semantics of this function which doesn't provide or
uses any state of the reassembly buffer provided by the user, but finds
the entry itself and then removes it. This gives the user no chance to
remove the packet in the reassembly buffer entry, so
`gnrc_sixlowpan_frag_rb_rm_by_datagram()` has to release the packet
(other than `gnrc_sixlowpan_frag_rb_remove()` where not releasing the
packet is desired as it might be handed up to an upper layer).
This allows to set a timer between the completion of a datagram in the
reassembly buffer and the deletion of the corresponding reassembly
buffer entry. This allows to ignore potentially late incoming link-layer
duplicates of fragments of the datagram that then will have the
reassembly buffer entry be blocked.
This was noted in this [discussion] for classic 6LoWPAN reassembly (and
minimal fragment forwarding) and is recommended in the current
[selective fragment recovery draft][SFR draft].
[discussion]: https://mailarchive.ietf.org/arch/msg/6lo/Ez0tzZDqawVn6AFhYzAFWUOtJns
[SFR draft]: https://tools.ietf.org/html/draft-ietf-6lo-fragment-recovery-07#section-6
As analyzed in #12678 there are cases where different reports can be
generated for the different snips of the packet send via the `sock`.
To catch all errors generated by the stack, the sock has to subscribe
for all snips of the packet sent. If any of the snips reports an error
distinct from `GNRC_NETERR_SUCCESS` or the previous one, we report that
status instead of just the first we receive. This way we are ensured to
have the first error reported by the stack for the given packet.
The name `fragment_msg` or `frag_msg`/`msg_frag` always to me was a bit
misplaced, as it basically implements an asynchronous fragmentation
buffer and doesn't necessarily have anything to do with messages.
This change
1. changes the name to `fb` (for fragmentation buffer)
2. factors its code out to its own sub-module so it can be re-used by
other 6LoWPAN fragmentation schemes like [Selective Fragment
Recovery]
[Selective Fragment Recovery]: https://tools.ietf.org/html/draft-ietf-6lo-fragment-recovery-05
The interface is already fetched in the beginning of the function and
doesn't change during its run, so getting the interface again at this
point is just redundant.
When decoding IPHC in a fragmented datagram, relying on the size of the
allocated space for the decoded packet is wrong when fragments are
forwarded and decoded on an intermediate node (for which the reassembly
buffer's space is used): Using the full datagram size for allocation in
this case would be wasteful, so the allocated space is only marginally
larger than the fragment's compressed form.
This in turn results in the wrong UDP payload size being chosen and
even worse being forwarded to the subsequent nodes.
This change uses the (virtual) reassembly buffer's `datagram_size`
instead of relying on the allocated space for the encoded
datagram/fragment.
`_match_to_idx()` was removed from source address selection (which was
the only one setting the filter parameter to a non-NULL value), so it
is the parameter is not needed anymore.
When source address selection is done, both RFC and comments in the code
state, that a longest prefix match should *only* be used as a
tie-breaker between more than one viable candidate. If there is only one
address, there is
a) no need for a tie-breaker
b) in the case of either the destination address or the single remaining
address being ULAs ([which are considered to be of global scope]
[RFC4193]) possibly not matching, as `fd00::/7` and e.g. `2001::/8`
do not have a common prefix.
(b) in fact causes the match function to return -1, causing the source
address selection to return -1, causing the outer function to return the
first address it found (which most often is the link-local address),
causing e.g. a ping to an ULA to fail, even is there is a global
address.
[RFC4193]: https://tools.ietf.org/html/rfc4193
Different platforms evaluate `printf()` for NULL pointers differently,
resulting tests checking for a certain output to fail. This unifies that
(debug) output for the static packet buffer statistics.
Similar as with #12513, when the NIB is compiled in 6LN mode (but not
6LR mode), the address-resolution state-machine (ARSM) functionality is
disabled in favor of the more simpler address resolution proposed in RFC
6775.
However, if a non-6LN interface is also compiled in (without making it
a router or border router) it will never join the solicited-nodes
multicast address of addresses added to it, resulting in address
resolution to that interface to fail.
If the interface is not a 6LN (which in case 6LN mode is disabled is
always false), a warning is now printed, encouraging the user to
activate the ARSM functionality if needed.
