netstats: add stats to more modules

[OlegHahm]

Currently only L2 netstats are available and only for some drivers.
The following modules should provide netstats, too:

• GNRC IPv6 (see net: introduce IPv6 netstats #5178)
• GNRC UDP
• ethos
• xbee
• GNRC SLIP

Optionally also:

• lwip
• emb6

[kaspar030]

[] GNRC IPv6

[] GNRC UDP

Nice, soon we'll surpass Linux in what we know about what's going on in
the network stack!

[OlegHahm]

Sounds like a reasonable goal for an OS that is developed by a lot of people with a background in research on computer networks, doesn't it? ;-)

[kYc0o]

Updated and moved for the next release.

[bergzand]

I was looking at a way to implement the GNRC UDP stats since it doesn't seem te be a lot of work and it looks like an easy way to learn something about the network stack.

First, there doesn't seem to be some kind of struct in the UDP handler to store the stats in. Am I right in this or have I just missed it?

Second: the IPv6 stats does not seem to care about errors in the lower layers, such that for example, if a ping reply is assumed lost according to the transceiver, the L2 stats can count an error in the TX stats, but the IPv6 stats don't show a TX error.
Is this by design and wanted? Or is an implementation where the upper layer also counts an error wanted?

[OlegHahm]

First, there doesn't seem to be some kind of struct in the UDP handler to store the stats in. Am I right in this or have I just missed it?

In principle sock could hold this information, I guess.

Second: the IPv6 stats does not seem to care about errors in the lower layers, such that for example, if a ping reply is assumed lost according to the transceiver, the L2 stats can count an error in the TX stats, but the IPv6 stats don't show a TX error.
Is this by design and wanted? Or is an implementation where the upper layer also counts an error wanted?

My design idea was that the layer statistics count only what is under their control. I.e. if IPv6 passes a datagram to the link layer, it assumes the packet to be sent -> TX success. If it cannot pass the datagram to the lower layer, because, for instance, no proper interface could be determined, it would count it as a TX error.

[miri64]

First, there doesn't seem to be some kind of struct in the UDP handler to store the stats in. Am I right in this or have I just missed it?

In principle sock could hold this information, I guess.

Please don't mix-in sock into gnrc_udp. The latter should be able to be used without sock_udp. All things considered the gnrc_udp can be considered as singleton (having multiple gnrc_udp instances doesn't make much sense), so you could just store this kind of data statically in the module I would propose.