Add mechanism for using GAS/ANQP to query Interworking related
information from APs. The received information is stored in the BSS
table and can be viewed with ctrl_iface BSS command.
New ctrl_iface command ANQP_GET can be used to fetch ANQP elements from
a specific AP. Additional commands FETCH_ANQP and STOP_FETCH_ANQP can be
used to initiate and stop an iteration through all APs in the BSS table
that indicate support Interworking to fetch ANQP elements from them.
Add an "Interface.FlushBSS" method to the new D-Bus API and a "flush"
method to the old API. Both take an age parameter that is a threshold
(in seconds) for selecting entries to evict. Setting this parameter
to zero flushes all entries from the cache.
This mechanism is useful for a connection manager to clear state at
startup and on resume (where the age parameter may be used to hold
onto recent/valid data).
This allows the driver wrappers to return two sets of IEs, so that
the BSS code can use information from both Beacon and Probe Response
frames if needed. For example, some Cisco APs seem to include more
information in Wireless Provisioning Services IE when it is in the
Beacon frame.
Get more information about scans when updating BSS table information.
This allows the missing-from-scans expiration rule to work properly
when only partial set of channels or SSIDs are being scanned.
This allows the BSS list to be iterated in order of increasing id
to avoid problems with new scans reordering entries. The order on the
wpa_s->bss list changes with most recently updated entries being moved
to the tail of the list while wpa_s->bss_id list maintains its order
with new entries being added to the tail and old entries being removed
when they expire.
Collect information from scan results into a BSS table that will not
expire information as quickly as scan results where every new scan,
no matter for how limited set of channels/SSIDs, clears all old
information.
For now, this is only used for D-Bus BSS added/removed notifications,
but this will likely be extended to be used internally instead of the
scan results to better support partial scans.
