Is scanning mandatory when doing a SelectNetwork?

[Adrien Bustany]

Hi,

while analyzing why associating to a wifi network (in open mode, no
encryption) would take around 2 seconds on my device, I saw that
(apparently) wpa_supplicant will run a scan (scanning for the specific
SSID of the network) before initiating the actual association. I was
wondering if wpa_supplicant could somehow cache the previous scan
results to avoid this scan operation when associating. Reading the code
I stumbled on the wpa_bss_add function in bss.c, which looks like it
could maintain a cache of scan results, however this function does not
seem to be used anywhere in the code.
Do you know if such a caching would be "legal"? wlancond, the daemon
used on Nokia devices, seems to maintain such a cache, and association 
+
DHCP then takes around 400ms on the same network.

Cheers

Adrien