Pass an additional parameter to the scan results notify functions to
tell them whether the scan was successful. If it wasn't don't bother
passing an empty bss_list queue, pass NULL as bss_list. This way the
callbacks can tell whether the scan indicates there are no BSSes in
range or simply was aborted and the old scan results should be kept.
Also handle the case of a periodic scan when handling a
NL80211_CMD_SCAN_ABORTED. The goal is to make sure the supplied callback
is always called if .trigger was called before, but this should also fix
some other corner cases.
* I add a sp.triggered field for periodic scans since sc->state doesn't
tell us whether the scan in progress was triggered by ourselved o
someone else (in that case .trigger has not been called)
* Since the NL80211_CMD_SCAN_ABORTED becomes similar to get_scan_done I
move the common code to scan_finished
* I believe this fixes a situation where we weren't updating sc->state
if we'd not triggered the scan, because both get_scan_done and the
NL80211_CMD_SCAN_ABORTED would return directly.
If the current request is not freed when we receive the
NL80211_CMD_SCAN_ABORTED event, device.c will keep thinking that
we're still scanning and the scan.c logic also gets confused and may
resend the current request at some point and call sr->trigger again
causing a segfault in device.c.
I pass an empty bss_list to the callback, another possibility would be
to pass NULL to let the callback know not to replace old results yet.
The callbacks would need to handle a NULL first.
Add sr NULL check before accessing sr->id. Call scan_request_free on
request structure and call the destroy callback. Cancel the netlink
TRIGGER_SCAN command if still running and try starting the next scan
in the queue. It'll probably still fail with EBUSY but it'll be
reattempted later.
Always call start_next_scan_request when a scan request has finished,
with a success or a failure, including a periodic scan attempt. Inside
that function check if there's any work to be done, either for one-off
scan requests or periodic scan, instead of having this check only inside
get_scan_done. Call start_next_scan_request in scan_periodic_start and
scan_periodic_timeout.
Also call the trigger callback with an error code when sending the
netlink command fails after the scan request has been queued because
another scan was in progress when the scan was requested.
Program received signal SIGSEGV, Segmentation fault.
0x0000000000419d38 in scan_done (msg=0x692580, userdata=0x688250)
at src/scan.c:250
250 sc->state = sr->passive ? SCAN_STATE_PASSIVE : SCAN_STATE_ACTIVE;
(gdb) bt
0 0x0000000000419d38 in scan_done (msg=0x692580, userdata=0x688250)
at src/scan.c:250
1 0x000000000043cac0 in process_unicast (genl=0x686d60, nlmsg=0x7fffffffc3b0)
at ell/genl.c:390
2 0x000000000043ceb0 in received_data (io=0x686e60, user_data=0x686d60)
at ell/genl.c:506
3 0x000000000043967d in io_callback (fd=6, events=1, user_data=0x686e60)
at ell/io.c:120
4 0x000000000043824d in l_main_run () at ell/main.c:381
5 0x000000000040303c in main (argc=1, argv=0x7fffffffe668) at src/main.c:259
The reasoning is that the logic inside scan_common is reversed. Instead
of freeing the scan request on error, we always do it. This causes the
trigger_scan callback to receive invalid userdata.
Save the ids of the netlink trigger scan commands that we send and
cancel them in scan_ifindex_remove to fix a race leading to a
segfault. The segfault would happen every time if scan_ifindex_remove
was called in the same main loop iteration in which we sent the
command, on shutdown:
^CTerminate
src/netdev.c:netdev_free() Freeing netdev wlan3[6]
src/device.c:device_disassociated() 6
src/device.c:device_enter_state() Old State: connected, new state:
disconnected
src/device.c:device_enter_state() Old State: disconnected, new state:
autoconnect
src/scan.c:scan_periodic_start() Starting periodic scan for ifindex: 6
src/device.c:device_free()
src/device.c:bss_free() Freeing BSS 02:00:00:00:00:00
src/device.c:bss_free() Freeing BSS 02:00:00:00:01:00
Removing scan context for ifindex: 6
src/scan.c:scan_context_free() sc: 0x5555557ca290
src/scan.c:scan_notify() Scan notification 33
src/netdev.c:netdev_operstate_down_cb() netdev: 6, success: 1
src/scan.c:scan_periodic_done()
src/scan.c:scan_periodic_done() Periodic scan triggered for ifindex:
1434209520
Program received signal SIGSEGV, Segmentation fault.
0x0000000000000064 in ?? ()
(gdb) bt
#0 0x0000000000000064 in ?? ()
#1 0x0000555555583560 in process_unicast (nlmsg=0x7fffffffc1a0,
genl=0x5555557c1d60) at ell/genl.c:390
#2 received_data (io=<optimized out>, user_data=0x5555557c1d60)
at ell/genl.c:506
#3 0x0000555555580d45 in io_callback (fd=<optimized out>,
events=1, user_data=0x5555557c1e60) at ell/io.c:120
#4 0x000055555558005f in l_main_run () at ell/main.c:381
#5 0x00005555555599c1 in main (argc=<optimized out>, argv=<optimized out>)
at src/main.c:259
Add a flush flag to scan_parameters to tell the kernel to flush the
cache of scan results before the new scan. Use this flag in the
active scan during roaming.
Add a version of scan_active that accepts a struct with the scan
parameters so we can more easily add new parameters. Since the genl
message is now built within scan_active_start the extra_ie memory
can be freed by the caller at any time.
In many cases the pairwise and group cipher information is not the only
information needed from the BSS RSN/WPA elements in order to make a
decision. For example, th MFPC/MFPR bits might be needed, or
pre-authentication capability bits, group management ciphers, etc.
This patch refactors bss_get_supported_ciphers into the more general
scan_bss_get_rsn_info function
This function takes an Operating Channel and a Country String to convert
it into a band. Using scan_oper_class_to_band and scan_channel_to_freq,
an Operating Channel, a Country String and a Channel Number together can
be converted into an actual frequency. EU and US country codes based on
wpa_supplicant's tables.
Sometimes the periodic scan is started and stopped before the timeout
was created. If periodic_scan_stop was called before, the timeout
object was not reset to NULL, which can lead to a crash.
Denis Kenzior