If a beacon is received in RUN state, reset the management timer.

Some wifi drivers send a probe request if the hardware reports "missed beacon"
events. If the AP replies with a probe response it is still servicing us and
there is no need to search for a new AP. However, the management timer was not
reset if a beacon was received while in RUN state. So the interface watchdog
always ended up putting the driver into SCAN state after a missed beacon event,
even if the AP did respond to our probe request. Under some conditions this
bug would cause spurious disconnects.

Problem reported and fix tested by mlarkin@

(Using the management timer in RUN state is a new convention. Before support
for missed beacons was added, this timer was only used during the association
sequence to handle APs which don't respond to our assoc requests and such.)

1 files changed, 9 insertions, 1 deletions

diff --git a/sys/net80211/ieee80211_input.c b/sys/net80211/ieee80211_input.c
index 85a5e4aea0c..e7add1e4a75 100644
--- a/sys/net80211/ieee80211_input.c
+++ b/sys/net80211/ieee80211_input.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ieee80211_input.c,v 1.195 2017/08/04 17:31:05 stsp Exp $	*/
+/*	$OpenBSD: ieee80211_input.c,v 1.196 2017/09/04 09:11:46 stsp Exp $	*/
 
 /*-
  * Copyright (c) 2001 Atsushi Onoe
@@ -1582,6 +1582,14 @@ ieee80211_recv_probe_resp(struct ieee80211com *ic, struct mbuf *m,
 			    ic->ic_curmode == IEEE80211_MODE_11A ||
 			    (capinfo & IEEE80211_CAPINFO_SHORT_SLOTTIME));
 		}
+
+		/* 
+		 * Reset management timer. If it is non-zero in RUN state, the
+		 * driver sent a probe request after a missed beacon event.
+		 * This probe response indicates the AP is still serving us
+		 * so don't allow ieee80211_watchdog() to move us into SCAN.
+		 */
+		 ic->ic_mgt_timer = 0;
 	}
 	/*
 	 * We do not try to update EDCA parameters if QoS was not negotiated