[PATCH] Send CTRL-EVENT-NETWORK-NOT-FOUND if no suitable network was found

[Jouni Malinen]

On Fri, Jun 26, 2015 at 02:31:17PM -0700, Dmitry Shmidt wrote:
> The issue our wifi manager developers are trying to resolve is next:
> We select network to connect but let's say it is not in real scan results.
> wpa_supplicant will "do nothing". It will print debug log, but wifi manager
> will not know that it is not planning to do anything else.

The place here in wpas_select_network_from_last_scan() is far from an
indication of not planning on doing anything else.. Once asked to
connect, wpa_supplicant will continue trying to do so until told
otherwise.

> If there is other way to catch this situation, rather then explicitly
> send the event above, it will be great.

Assuming the goal is to know that the first scan results (or any
scan trying to connect after this) did not result in an action other
than rescheduling the connection scan, a small change to the patch can
be used to cover this. The wpa_msg_ctrl() call just needs to be moved
down a bit in the function to avoid the cases where there are other
actions taken. The patch below shows this and I think I'll apply this.

That said, even the existing control interface events would allow most
of this to be figured out:

SELECT_NETWORK 0
--->
<3>CTRL-EVENT-SCAN-STARTED 
<3>CTRL-EVENT-BSS-ADDED 0 02:00:00:00:03:00
<3>CTRL-EVENT-SCAN-RESULTS 
<3>CTRL-EVENT-NETWORK-NOT-FOUND 
(5 seconds)
<3>CTRL-EVENT-SCAN-STARTED 
<3>CTRL-EVENT-SCAN-RESULTS 
<3>CTRL-EVENT-NETWORK-NOT-FOUND 

In this case, the matching network was not there and there was no
connection attempt after the scan results event. A bit more complex to
notice this case since this would depend on waiting a bit to see if
anything follows CTRL-EVENT-SCAN-RESULTS, so adding the new event here
is justifiable.

SELECT_NETWORK any
<3>CTRL-EVENT-SCAN-STARTED 
<3>CTRL-EVENT-SCAN-RESULTS 
<3>SME: Trying to authenticate with 02:00:00:00:03:00 (SSID='open' freq=2412 MHz)
<3>Trying to associate with 02:00:00:00:03:00 (SSID='open' freq=2412 MHz)
<3>Associated with 02:00:00:00:03:00
<3>CTRL-EVENT-CONNECTED - Connection to 02:00:00:00:03:00 completed [id=1 id_str=]

Here the "Trying to associate" event message would show up more or less
immediately after CTRL-EVENT-SCAN-RESULTS.


The updated patch:

This provides more information to upper layer programs on what happens
with connection attempts in cases where the enabled networks are not
found in scan results.

Signed-off-by: Dmitry Shmidt <dimitrysh at google.com>
---
 src/common/wpa_ctrl.h   | 2 ++
 wpa_supplicant/events.c | 3 +++
 2 files changed, 5 insertions(+)

diff --git a/src/common/wpa_ctrl.h b/src/common/wpa_ctrl.h
index e3a816f..e700523 100644
--- a/src/common/wpa_ctrl.h
+++ b/src/common/wpa_ctrl.h
@@ -68,6 +68,8 @@ extern "C" {
 #define WPA_EVENT_BSS_ADDED "CTRL-EVENT-BSS-ADDED "
 /** A BSS entry was removed (followed by BSS entry id and BSSID) */
 #define WPA_EVENT_BSS_REMOVED "CTRL-EVENT-BSS-REMOVED "
+/** No suitable network was found */
+#define WPA_EVENT_NETWORK_NOT_FOUND "CTRL-EVENT-NETWORK-NOT-FOUND "
 /** Change in the signal level was reported by the driver */
 #define WPA_EVENT_SIGNAL_CHANGE "CTRL-EVENT-SIGNAL-CHANGE "
 /** Regulatory domain channel */
diff --git a/wpa_supplicant/events.c b/wpa_supplicant/events.c
index 601ddb3..aa171ef 100644
--- a/wpa_supplicant/events.c
+++ b/wpa_supplicant/events.c
@@ -1628,6 +1628,9 @@ static int wpas_select_network_from_last_scan(struct wpa_supplicant *wpa_s,
 			if (wpa_supplicant_req_sched_scan(wpa_s))
 				wpa_supplicant_req_new_scan(wpa_s, timeout_sec,
 							    timeout_usec);
+
+			wpa_msg_ctrl(wpa_s, MSG_INFO,
+				     WPA_EVENT_NETWORK_NOT_FOUND);
 		}
 	}
 	return 0;
-- 
1.9.1



-- 
Jouni Malinen                                            PGP id EFC895FA