Simpler to use for loops instead of handling next pointer selection
in all places. In addition, couple of functions could have ended up
in an infinite loop on error path since the pointer update was missed.
In addition, remove Quality and Noise properties since the BSS table
is not the correct place for fetching per-channel information (Noise)
and Quality is not well-defined (nor available from many drivers).
We don't actually need to define separate user_data argument for
each method handler and property getter/setter. Instead, we can define
one argument for the whole object. That will make it easier to register
objects like BSS or Networks which require allocating and freeing
memory for their arguments.
This was mostly identical code that had been copied for the new D-Bus
API implementation and as such, should really have been shared from
the beginning. In addition, the copied code ended up generating
interesting stack traces since the actual D-Bus connection was being
shared even though the pointer to it was stored in two distinct
data structures. The old D-Bus code ended up dispatching some
D-Bus callbacks which ended up running the new D-Bus code.
Since the private context pointers were mostly identical, everything
seemed to more or less work, but this design was just making things
more complex and potentially very easy to break.
Do not try to unregister BSS objects twice (the latter one with invalid
path) and make sure all network objects get added and removed properly
(the ones read from configuration file were not being registered, but
were tried to be unregistered).
This will allow more cleanup to be done for scan results processing
since all code can now be made to depend on the BSS table instead of
the temporary scan results.
Once remaining code has been converted to use the BSS table, the new
scan results can be freed immediately after the BSS table has been
updated. In addition, filtering of BSS information should be added
to better support systems with limited resources. For now, memory
use can be limited by defining WPA_BSS_MAX_COUNT to be smaller.
Anyway, better filtering of results to only the configured networks
should be added to improve this.
Replace the scan results -based implementation with the use of information
from the new BSS table maintained by wpa_supplicant to get a more stable
source of BSS data. Change the use of BSSID as the key for the BSS object
to use the BSS table unique identifier so that multi-SSID APs can be
handled properly.
In addition, provide another option for iterating through the BSS
entries. The old iteration: "BSS 0", "BSS 1", .. with index number.
The new iteration: "BSS FIRST", "BSS NEXT-<prev id>", .. with id
fetched from the previous output (id=<id> line).
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.
This allows the driver interface to be deinitialized before
struct hostapd_data instance gets freed. This needs to be done so
that the driver wrapper does not maintain a context pointer to
freed memory.
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.
