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Today's Topics:

   1. When BackgroundScanning = false, connman's Scan() dbus method
      is broken (Jonah Petri)
   2. Re: When BackgroundScanning = false, connman's Scan() dbus
      method is broken (Sam Nazarko)


----------------------------------------------------------------------

Message: 1
Date: Tue, 8 Aug 2017 11:10:07 -0400
From: Jonah Petri <jo...@sense.com>
To: connman@lists.01.org
Subject: When BackgroundScanning = false, connman's Scan() dbus method
        is broken
Message-ID: <e8173777-fec3-4130-9ac1-84b3dddb9...@sense.com>
Content-Type: text/plain; charset=us-ascii

Hello,

I want to report an issue with connman.  We set BackgroundScanning = false in 
main.conf.  However, I have found that this also causes connman to give an 
erroneous empty response to the Scan() dbus call, potentially permanently 
disabling the device.

The key preconditions seem to be:
1) wpa_supplicant reports a max_ssids > 1
2) the computer must have been previously associated to a SSID which is no 
longer visible
3) as above, BackgroundScanning must be set to false

This causes the logic of wifi.c:wifi_scan() to fail.  In particular:
1) wifi_scan_simple is not used, due to the above preconditions.
2) connman requests an active scan via wpa_supplicant for the ssids returned by 
get_latest_connections.
3) connman does not request a followup passive scan, as BackgroundScanning is 
turned off, which causes start_autoscan() to exit early.

This means that in the scenario above, connman will never see any wifi 
networks.  Scan() will always return an empty list, even if other SSIDs are 
available.  This is potentially fatal for embedded systems, so in my view this 
is a very serious issue.

This issue affects at least connman 1.33 and 1.34.  I cannot test older 
versions due to other dependencies.

One workaround is to enable BackgroundScanning.

Best,
Jonah

------------------------------

Message: 2
Date: Tue, 8 Aug 2017 15:22:05 +0000
From: Sam Nazarko <em...@samnazarko.co.uk>
To: Jonah Petri <jo...@sense.com>, "connman@lists.01.org"
        <connman@lists.01.org>
Subject: Re: When BackgroundScanning = false, connman's Scan() dbus
        method is broken
Message-ID: <1502205725348.85...@samnazarko.co.uk>
Content-Type: text/plain; charset="iso-8859-1"

________________________________________
From: connman <connman-boun...@lists.01.org> on behalf of Jonah Petri 
<jo...@sense.com>
Sent: 08 August 2017 16:10
To: connman@lists.01.org
Subject: When BackgroundScanning = false, connman's Scan() dbus method is broken

I want to report an issue with connman.  We set BackgroundScanning = false in 
main.conf.  However, I have found that this also causes connman to give an 
erroneous empty response to the Scan() dbus call, potentially permanently 
disabling the device.
_______________________________________________
connman mailing list
connman@lists.01.org
https://lists.01.org/mailman/listinfo/connman

Hello,

I can reproduce this issue. We wanted to disable BackgroundScanning as we 
support
a few wireless drivers that experience disruption to the connection when 
scanning
occurs. After disabling BackgroundScanning in ConnMan 1.34, we had numerous
reports of users unable to find any WiFi networks.

Sam

------------------------------

Subject: Digest Footer

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------------------------------

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