Add ieee80211_beacon_miss for processing sta mode beacon miss events

in the 802.11 layer: we send a directed probe request frame to the
current ap bmiss_max times (w/o answer) before scanning for a new ap.

MFC after:	2 weeks

5 files changed, 47 insertions, 0 deletions

diff --git a/sys/net80211/ieee80211_freebsd.c b/sys/net80211/ieee80211_freebsd.c
index e05744a..4fa0207 100644
--- a/sys/net80211/ieee80211_freebsd.c
+++ b/sys/net80211/ieee80211_freebsd.c
@@ -126,6 +126,9 @@ ieee80211_sysctl_attach(struct ieee80211com *ic)
 	SYSCTL_ADD_INT(ctx, SYSCTL_CHILDREN(oid), OID_AUTO,
 		"driver_caps", CTLFLAG_RW, &ic->ic_caps, 0,
 		"driver capabilities");
+	SYSCTL_ADD_INT(ctx, SYSCTL_CHILDREN(oid), OID_AUTO,
+		"bmiss_max", CTLFLAG_RW, &ic->ic_bmiss_max, 0,
+		"consecutive beacon misses before scanning");
 	ic->ic_sysctl = ctx;
 }
 
diff --git a/sys/net80211/ieee80211_input.c b/sys/net80211/ieee80211_input.c
index 1b3c3fb..80a64d7 100644
--- a/sys/net80211/ieee80211_input.c
+++ b/sys/net80211/ieee80211_input.c
@@ -1942,6 +1942,7 @@ ieee80211_recv_mgmt(struct ieee80211com *ic, struct mbuf *m0,
 			if (ic->ic_flags & IEEE80211_F_SCAN)
 				ieee80211_add_scan(ic, &scan, wh,
 					subtype, rssi, rstamp);
+			ic->ic_bmiss_count = 0;
 			return;
 		}
 		/*
diff --git a/sys/net80211/ieee80211_proto.c b/sys/net80211/ieee80211_proto.c
index 8f3abd8..f7834f9 100644
--- a/sys/net80211/ieee80211_proto.c
+++ b/sys/net80211/ieee80211_proto.c
@@ -97,6 +97,7 @@ ieee80211_proto_attach(struct ieee80211com *ic)
 	ic->ic_rtsthreshold = IEEE80211_RTS_DEFAULT;
 	ic->ic_fragthreshold = IEEE80211_FRAG_DEFAULT;
 	ic->ic_fixed_rate = IEEE80211_FIXED_RATE_NONE;
+	ic->ic_bmiss_max = IEEE80211_BMISS_MAX;
 	ic->ic_mcast_rate = IEEE80211_MCAST_RATE_DEFAULT;
 	ic->ic_protmode = IEEE80211_PROT_CTSONLY;
 	ic->ic_roaming = IEEE80211_ROAMING_AUTO;
@@ -817,6 +818,43 @@ ieee80211_wme_updateparams(struct ieee80211com *ic)
 	}
 }
 
+void
+ieee80211_beacon_miss(struct ieee80211com *ic)
+{
+
+	if (ic->ic_flags & IEEE80211_F_SCAN) {
+		/* XXX check ic_curchan != ic_bsschan? */
+		return;
+	}
+	IEEE80211_DPRINTF(ic,
+		IEEE80211_MSG_STATE | IEEE80211_MSG_DEBUG,
+		"%s\n", "beacon miss");
+
+	/*
+	 * Our handling is only meaningful for stations that are
+	 * associated; any other conditions else will be handled
+	 * through different means (e.g. the tx timeout on mgt frames).
+	 */
+	if (ic->ic_opmode != IEEE80211_M_STA || ic->ic_state != IEEE80211_S_RUN)
+		return;
+
+	if (++ic->ic_bmiss_count < ic->ic_bmiss_max) {
+		/*
+		 * Send a directed probe req before falling back to a scan;
+		 * if we receive a response ic_bmiss_count will be reset.
+		 * Some cards mistakenly report beacon miss so this avoids
+		 * the expensive scan if the ap is still there.
+		 */
+		ieee80211_send_probereq(ic->ic_bss, ic->ic_myaddr,
+			ic->ic_bss->ni_bssid, ic->ic_bss->ni_bssid,
+			ic->ic_bss->ni_essid, ic->ic_bss->ni_esslen,
+			ic->ic_opt_ie, ic->ic_opt_ie_len);
+		return;
+	}
+	ic->ic_bmiss_count = 0;
+	ieee80211_new_state(ic, IEEE80211_S_SCAN, 0);
+}
+
 static void
 sta_disassoc(void *arg, struct ieee80211_node *ni)
 {
diff --git a/sys/net80211/ieee80211_proto.h b/sys/net80211/ieee80211_proto.h
index 694eff5b..ea05da8 100644
--- a/sys/net80211/ieee80211_proto.h
+++ b/sys/net80211/ieee80211_proto.h
@@ -218,6 +218,7 @@ void	ieee80211_wme_updateparams_locked(struct ieee80211com *);
 
 #define	ieee80211_new_state(_ic, _nstate, _arg) \
 	(((_ic)->ic_newstate)((_ic), (_nstate), (_arg)))
+void	ieee80211_beacon_miss(struct ieee80211com *);
 void	ieee80211_print_essid(const u_int8_t *, int);
 void	ieee80211_dump_pkt(const u_int8_t *, int, int, int);
 
diff --git a/sys/net80211/ieee80211_var.h b/sys/net80211/ieee80211_var.h
index b4be276..3c918f5 100644
--- a/sys/net80211/ieee80211_var.h
+++ b/sys/net80211/ieee80211_var.h
@@ -70,6 +70,8 @@
 #define	IEEE80211_BINTVAL_MIN	25	/* min beacon interval (TU's) */
 #define	IEEE80211_BINTVAL_DEFAULT 100	/* default beacon interval (TU's) */
 
+#define	IEEE80211_BMISS_MAX	2	/* maximum consecutive bmiss allowed */
+
 #define	IEEE80211_PS_SLEEP	0x1	/* STA is in power saving mode */
 #define	IEEE80211_PS_MAX_QUEUE	50	/* maximum saved packets */
 
@@ -142,6 +144,8 @@ struct ieee80211com {
 	int			ic_mcast_rate;	/* rate for mcast frames */
 	u_int16_t		ic_rtsthreshold;
 	u_int16_t		ic_fragthreshold;
+	u_int8_t		ic_bmiss_count;	/* current beacon miss count */
+	int			ic_bmiss_max;	/* max bmiss before scan */
 	struct ieee80211_node	*(*ic_node_alloc)(struct ieee80211_node_table*);
 	void			(*ic_node_free)(struct ieee80211_node *);
 	void			(*ic_node_cleanup)(struct ieee80211_node *);