net80211: document the crypto enmic/demic functions.

[adrian]

Summary

These functions implement what's needed for TKIP Michael MIC - which
is performed over the entire unencrypted MSDU. Each potential
fragmented MPDU is encrypted and has its own ICV/MIC.

CCMP/GCMP encrypts each MPDU separately (including the MPDUs that make
up an A-MPDU), so they'll implement null functions here and instead do
the MIC/ICV insertion inline in the crypto functions themselves.

Hopefully this makes it a bit clearer on how things should behave, and
will help figure out and clean up what further hardware offload
features we need.

[bz]

If both are TKIP-only I keep contemplating if they should be called mmic and we are done ;-)

[bz]

sys/net80211/ieee80211_crypto.h

219

Can we add a comment here above the two:

/* See ieee80211_crypto_enmic() / ieee80211_crypto_demic() for description. */

Just to make it clearer if we don't rename them to mmic. Or:

/*

• Currently only used by TKIP.
• See ieee80211_crypto_enmic() / ieee80211_crypto_demic() for description. */

[adrian]

feedback from bz

[adrian]

@bz would you mind reviewing this one in particular next? It's just a documentation commit and I'd like to get this landed :-)

Thanks!

[bz]

If you do the changes (if needed) just commit it.

sys/net80211/ieee80211_crypto.c

780

also here remove the // if you still have to change anything.

sys/net80211/ieee80211_crypto.h

251

is this before fragmentation? I'd not highlight the /before/ if you have to change it.

[adrian]

review from bz

[bz]

Thank you!