The initial pass of this feature only envisioned BSS transition
management frames as the trigger to "roam blacklist" a BSS, hence
the original name. But some APs actually utilize status codes that
also indicate to the stations that they are busy, or not able to
handle more connections. This directly aligns with the original
motivation of the "roam blacklist" series and these events should
also trigger this type of blacklist.
First, since we will be applying this blacklist to cases other
than being told to roam, rename this reason code internally to
BLACKLIST_REASON_AP_BUSY. The config option is also being renamed
to [Blacklist].InitialAccessPointBusyTimeout while also supporting
the old config option, but warning that it is deprecated.
This adds a new (less severe) blacklist reason as well as an option
to configure the timeout. This blacklist reason will be used in cases
where a BSS has requested IWD roam elsewhere. At that time a new
blacklist entry will be added which will be used along with some
other criteria to determine if IWD should connect/roam to that BSS
again.
Now that we have multiple blacklist reasons there may be situations
where a blacklist entry already exists but with a different reason.
This is going to be handled by the reason severity. Since we have
just two reasons we will treat a connection failure as most severe
and a roam requested as less severe. This leaves us with two
possible situations:
1. BSS is roam blacklisted, then gets connection blacklisted:
The reason will be "promoted" to connection blacklisted.
2. BSS is connection blacklisted, then gets roam blacklisted:
The blacklist request will be ignored
When pruning the list check_if_expired was comparing to the maximum
amount of time a BSS can be blacklisted, not if the current time had
exceeded the expirationt time. This results in blacklist entries
hanging around longer than they should, which would result in them
poentially being blacklisted even longer if there was another reason
to blacklist in the future.
Instead on prune check the actual expiration and remove the entry if
its expired. Doing this removes the need to check any of the times
in blacklist_contains_bss since prune will remove any expired entries
correctly.
To both prepare for some new blacklisting behavior and allow for
easier consolidation of the network-specific blacklist include a
reason enum for each entry. This allows IWD to differentiate
between multiple blacklist types. For now only the existing
"permanent" type is being added which prevents connections to that
BSS via autoconnect until it expires.
Certain use cases may not need or want this feature so allowing it to
be disabled is a much cleaner way than doing something like setting
the timeouts very low.
Now [Blacklist].InitialTimeout can be set to zero which will prevent
any blacklisting.
In addition some other small changes were added:
- Warn if the multiplier is 0, and set to 1 if so.
- Warn if the initial timeout exceeds the maximum timeout.
- Log if the blacklist is disabled
- Use L_USEC_PER_SEC instead of magic numbers.
This will allow for blacklisting a BSS if the connection fails. The
actual blacklist module is simple and must be driven by station. All
it does is add BSS addresses, a timestamp, and a timeout to a queue.
Entries can also be removed, or checked if they exist. The blacklist
timeout is configuratble in main.conf, as well as the blacklist
timeout multiplier and maximum timeout. The multiplier is used after
a blacklisted BSS timeout expires but we still fail to connect on the
next connection attempt. We multiply the current timeout by the
multiplier so the BSS remains in the blacklist for a larger growing
amount of time until it reaches the maximum (24 hours by default).
