This adds a counter and adds sequence numbering to FT RRB packets. The
sequence number is checked against r0kh/r1kh sequence number cache.
Special attention is needed in case the remote AP reboots and thus loses
its state. I prefer it to recover automatically even without synchronized
clocks. Therefore an identifier called dom is generated randomly along the
initial sequence number. If the dom transmitted does not match or the
sequence number is not in the range currently expected, the sender is asked
for a fresh confirmation of its currently used sequence numbers. The packet
that triggered this is cached and processed again later.
Additionally, in order to ensure freshness, the remote AP includes an
timestamp with its messages. It is then verified that the received
messages are indeed fresh by comparing it to the older timestamps
received and the time elapsed since then. Therefore FT_RRB_TIMESTAMP is
no longer needed.
This assigns new OUI 00:13:74 vendor-specific subtype 0x0001 subtypes:
4 (SEQ_REQ) and 5 (SEQ_RESP).
This breaks backward compatibility, i.e., hostapd needs to be updated
on all APs at the same time to allow FT to remain functional.
Signed-off-by: Michael Braun <michael-dev@fami-braun.de>
eefe863015