Periodic scan requests are meant to be performed with a lower priority
than normal scan requests. They're thus given a different priority when
inserting them into the wiphy work queue. Unfortunately, the priority
is not taken into account when they are inserted into the
sr->requests queue. This can result in the scanning code being confused
since it assumes the top of the queue is always the next scheduled or
currently ongoing scan. As a result any further wiphy_work might never be
started properly.
Apr 27 16:34:40 iwd[5117]: ../iwd-1.26/src/wiphy.c:wiphy_radio_work_insert() Inserting work item 3
Apr 27 16:34:40 iwd[5117]: ../iwd-1.26/src/wiphy.c:wiphy_radio_work_next() Starting work item 3
Apr 27 16:34:40 iwd[5117]: ../iwd-1.26/src/scan.c:scan_periodic_timeout() 1
Apr 27 16:34:40 iwd[5117]: ../iwd-1.26/src/wiphy.c:wiphy_radio_work_insert() Inserting work item 4
Apr 27 16:34:43 iwd[5117]: ../iwd-1.26/src/wiphy.c:wiphy_radio_work_insert() Inserting work item 5
Apr 27 16:34:43 iwd[5117]: ../iwd-1.26/src/wiphy.c:wiphy_radio_work_done() Work item 3 done
Apr 27 16:34:43 iwd[5117]: ../iwd-1.26/src/wiphy.c:wiphy_radio_work_next() Starting work item 5
Apr 27 16:34:43 iwd[5117]: ../iwd-1.26/src/scan.c:scan_notify() Scan notification Trigger Scan(33)
Apr 27 16:34:43 iwd[5117]: ../iwd-1.26/src/scan.c:scan_request_triggered() Passive scan triggered for wdev 1
Apr 27 16:34:43 iwd[5117]: ../iwd-1.26/src/scan.c:scan_periodic_triggered() Periodic scan triggered for wdev 1
In the above log, scan request 5 (triggered by dbus) is started before
scan request 4 (periodic scan). Yet the scanning code thinks scan
request 4 was triggered.
Fix this by using the wiphy_work priority to sort the sr->requests queue
so that the scans are ordered in the same manner.
Reported-by: Alvin Šipraga <ALSI@bang-olufsen.dk>
This was already implemented in station but with no dependency on
that module at all. AP will need this for a scanning API so its
being moved into scan.c.
The periodic scan code was refactored to make normal scans and
periodic scans consistent by keeping both in the same queue. But
that change left out the abort path where periodic scans were not
actually removed from the queue.
This fixes a rare crash when a periodic scan has been triggered and
the device goes down. This path never removes the request from the
queue but still frees it. Then when the scan context is removed the
stale request is freed again.
0 0x4bb65b in scan_request_cancel src/scan.c:202
1 0x64313c in l_queue_clear ell/queue.c:107
2 0x643348 in l_queue_destroy ell/queue.c:82
3 0x4bbfb7 in scan_context_free src/scan.c:209
4 0x4c9a78 in scan_wdev_remove src/scan.c:2115
5 0x42fecd in netdev_free src/netdev.c:965
6 0x445827 in netdev_destroy src/netdev.c:6507
7 0x52beb9 in manager_config_notify src/manager.c:765
8 0x67084b in process_multicast ell/genl.c:1029
9 0x67084b in received_data ell/genl.c:1096
10 0x65e790 in io_callback ell/io.c:120
11 0x65aaae in l_main_iterate ell/main.c:478
12 0x65b213 in l_main_run ell/main.c:525
13 0x65b213 in l_main_run ell/main.c:507
14 0x65b72c in l_main_run_with_signal ell/main.c:647
15 0x4124e7 in main src/main.c:532
A select few drivers send this instead of SIGNAL_MBM. The docs say this
value is the signal 'in unspecified units, scaled to 0..100'. The range
for SIGNAL_MBM is -10000..0 so this can be scaled to the MBM range easy
enough...
Now, this isn't exactly correct because this value ultimately gets
returned from GetOrderedNetworks() and is documented as 100 * dBm where
in reality its just a unit-less signal strength value. Its not ideal, but
this patch at least will fix BSS ranking for these few drivers.
scan_request_failed and scan_finished remove the finished scan_request
from the request queue right away, before calling the callback. This
breaks those clients that rely on scan_cancel working on such requests
(i.e. to force the destroy callback to be invoked synchronously, see
a0911ca778 ("station: Make sure roam_scan_id is always canceled").
Fix this by removing the scan_request from the request queue after
invoking the callback. Also provide a re-entrancy guard that will make
sure that the scan_request isn't removed in scan_cancel itself.
There are similar operations being performed but with different
callbacks and userdata, depending on whether 'sr' is NULL or not.
Optimize the function flow slightly to make if-else unnecessary.
While here, update the comment. periodic scans are now scheduled only
based on the periodic timeout timer.
If periodic scan is active and we receive a SCAN_ABORTED event, we would
still invoke the periodic scan callback with an error. This is rather
pointless since the periodic scan callback cannot do anything useful
with this information. Fix that.
We should never reach a point where NEW_SCAN_RESULTS or SCAN_ABORTED are
received before a corresponding TRIGGER_SCAN is received. Even if this
does happen, there's no harm from processing the commands anyway.
This makes it a little easier to book-keep the started variable. Since
scan_request already has a 'passive' bit-field, there should be no
storage penalty.
If scan_cancel is called on a scan_request that is 'finished' but with
the GET_SCAN command still in flight, it will trigger a crash as
follows:
Received Deauthentication event, reason: 2, from_ap: true
src/station.c:station_disconnect_event() 11
src/station.c:station_disassociated() 11
src/station.c:station_reset_connection_state() 11
src/station.c:station_roam_state_clear() 11
src/scan.c:scan_cancel() Trying to cancel scan id 6 for wdev 200000002
src/scan.c:scan_cancel() Scan is at the top of the queue, but not triggered
src/scan.c:get_scan_done() get_scan_done
Aborting (signal 11) [/home/denkenz/iwd-master/src/iwd]
++++++++ backtrace ++++++++
#0 0x7f9871aef3f0 in /lib64/libc.so.6
#1 0x41f470 in station_roam_scan_notify() at /home/denkenz/iwd-master/src/station.c:2285
#2 0x43936a in scan_finished() at /home/denkenz/iwd-master/src/scan.c:1709
#3 0x439495 in get_scan_done() at /home/denkenz/iwd-master/src/scan.c:1739
#4 0x4bdef5 in destroy_request() at /home/denkenz/iwd-master/ell/genl.c:676
#5 0x4c070b in l_genl_family_cancel() at /home/denkenz/iwd-master/ell/genl.c:1960
#6 0x437069 in scan_cancel() at /home/denkenz/iwd-master/src/scan.c:842
#7 0x41dc2e in station_roam_state_clear() at /home/denkenz/iwd-master/src/station.c:1594
#8 0x41dd2b in station_reset_connection_state() at /home/denkenz/iwd-master/src/station.c:1619
#9 0x41dea4 in station_disassociated() at /home/denkenz/iwd-master/src/station.c:1644
The happens because get_scan_done callback is still called as a result of
l_genl_cancel. Add a re-entrancy guard in the form of 'canceled'
variable in struct scan_request. If set, get_scan_done will skip invoking
scan_finished.
It isn't clear what 'l_queue_peek_head() == results->sr' check was trying
to accomplish. If GET_SCAN dump was scheduled, then it should be
reported. Drop it.
results->sr is set to NULL for 'opportunistic' scans which were
triggered externally. See scan_notify() for details. However,
get_scan_done would only invoke scan_finished (and thus the periodic
scan callback sc->sp.callback) only if the scan queue was empty. It
should do so in all cases.
Periodic scans were handled specially where they were only
started if no other requests were pending in the scan queue.
This is fine, and what we want, but this can actually be
handled automatically by nature of the wiphy work queue rather
than needing to check the request queue explicitly.
Instead we can insert periodic scans at a lower priority than
other scans. This puts them at the end of the work queue, as
well as allows future requests to jump ahead if a periodic scan
has not yet started.
Eventually, once all pending scans are done, the peridoic scan
may begin. This is no different than the preivous behavior and
avoids the need for any special checks once scan requests
complete.
One check was added to address the problem of the periodic scan
timer firing before the scan could even start. Currently this
happened to be handled fine in scan_periodic_queue, as it checks
the queue length. Since this check was removed we must see check
for this condition inside scan_periodic_timeout.
This adds a priority argument to scan_common rather than hard
coding it when inserting the work item and uses the newly
defined wiphy priority for scanning.
- Mostly problems with whitespace:
- Use of spaces instead of tabs
- Stray spaces before closing ')
- Missing spaces
- Missing 'void' from function declarations & definitions that
take no arguments.
- Wrong indentation level
This changes scan_bss from using separate members for each
OWE transition element data type (ssid, ssid_len, and bssid)
to a structure that holds them all.
This is being done because OWE transition has option operating
class and channel bytes which will soon be parsed. This would
end up needing 5 separate members in scan_bss which is a bit
much for a single IE that needs to be parsed.
This makes checking the presense of the IE more convenient
as well since it can be done with a simple NULL pointer check
rather than having to l_memeqzero the BSSID.
Specifically OWE networks with multiple open/hidden BSS's are troublesome
to scan for with the current APIs. The scan parameters are limited to a
single SSID and even if that was changed we have the potential of hitting
the max SSID's per scan limit. In all, it puts the burden onto the caller
to sort out the SSIDs/frequencies to scan for.
Rather than requiring station to handle this a new scan API was added,
scan_owe_hidden() which takes a list of open BSS's and will automatically
scan for the SSIDs in the OWE transition IE for each.
It is slightly optimized to first check if all the hidden SSID's are the
same. This is the most likely case (e.g. single pair or single network)
and a single scan command can be used. Otherwise individual scan commands
are queued for each SSID/frequency combo.
IWD has restricted SSIDs to only utf8 so they can be displayed but
with the addition of OWE transition networks this is an unneeded
restriction (for these networks). The SSID of an OWE transition
network is never displayed to the user so limiting to utf8 isn't
required.
Allow non-utf8 SSIDs to be scanned for by including the length in
the scan parameters and not relying on strlen().
Under certain conditions, access points with very low signal could be
detected. This signal is too low to estimate a data rate and causes
this L_WARN to fire. Fix this by returning a -ENETUNREACH error code in
case the signal is too low for any of the supported rates.
Some network settings keys are set / parsed in multiple files. Add a
utility to parse all common network configuration settings in one place.
Also add some defines to make sure settings are always saved in the
expected group/key.
scan_parse_result used to parse the wdev and return this to the caller
where it was compared against the expected wdev. Simplify this by
extract the wdev first, and proceeding with the bss parsing afterwards.
NL80211_BSS_LAST_SEEN_BOOTTIME is expressed in nanoseconds, while BSS
timestamps are expressed in microseconds internally. Convert the
attribute to microseconds when using it to timestamp a BSS. This makes
iwd expire absent BSSes within 30 seconds as intended.
Fixes: 454cee12d4 ("scan: Use kernel-reported time-stamp if provided")
It was observed that IWD's ranking for BSS's did not always
end up with the fastest being chosen. This was due to IWD's
heavy weight on signal strength. This is a decent way of ranking
but even better is calculating a theoretical data rate which
was also done and factored in. The problem is the data rate
factor was always outdone by the signal strength.
Intead remove signal strength entirely as this is already taken
into account with the data rate calculation. This also removes
the check for rate IEs. If no IEs are found the parser will
base the data rate soley on RSSI.
There were a few other factors removed which will be added back
when ranking *networks* rather than BSS's. WPA version (or open)
was removed as well as the privacy capability. These values really
should not differ between BSS's in the same SSID and as such
should be used for network ranking instead.
Adds support for getting firmware scan results from the kernel.
This is intended to be used after the firmware roamed automatically
and the scan result is require for handshake initialization.
The scan 'request' is competely separate from the normal scan
queue, though scan_results, scan_request, and the scan_context
are all used for consistency and code reuse.
