hostapd: Process management frames only once per BSS

At least in nl80211, broadcast management frames like Probe Request
frames, may be processed multiple times per BSS if multi-BSS is active
and NL80211_CMD_FRAME event is used to deliver them. In the case of
Probe Request frames, hostapd will create multiple redundant Probe
Response frames which are problematic when many BSS are on one channel.

This problem is caused by driver_nl80211 generating an event for
wpa_supplicant_event() for each BSS, and hostapd_mgmt_rx() calls
ieee802_11_mgmt() for each BSS, too.

Fix this by processing broadcast events only for the BSS the driver
intended to. The behavior is not changed for drivers not setting a BSS.

Signed-hostap: Simon Wunderlich <simon@open-mesh.com>

src/ap/drv_callbacks.c

@@ -721,6 +721,12 @@ static int hostapd_mgmt_rx(struct hostapd_data *hapd, struct rx_mgmt *rx_mgmt)
 		size_t i;
 		ret = 0;
 		for (i = 0; i < iface->num_bss; i++) {
+			/* if bss is set, driver will call this function for
+			 * each bss individually. */
+			if (rx_mgmt->drv_priv &&
+			    (iface->bss[i]->drv_priv != rx_mgmt->drv_priv))
+				continue;
+
 			if (ieee802_11_mgmt(iface->bss[i], rx_mgmt->frame,
 					    rx_mgmt->frame_len, &fi) > 0)
 				ret = 1;

src/drivers/driver.h

@@ -3584,6 +3584,15 @@ union wpa_event_data {
 		size_t frame_len;
 		u32 datarate;
 
+		/**
+		 * drv_priv - Pointer to store driver private BSS information
+		 *
+		 * If not set to NULL, this is used for comparison with
+		 * hostapd_data->drv_priv to determine which BSS should process
+		 * the frame.
+		 */
+		void *drv_priv;
+
 		/**
 		 * freq - Frequency (in MHz) on which the frame was received
 		 */

src/drivers/driver_nl80211.c

@@ -1681,10 +1681,11 @@ static void mlme_timeout_event(struct wpa_driver_nl80211_data *drv,
 }
 
 
-static void mlme_event_mgmt(struct wpa_driver_nl80211_data *drv,
+static void mlme_event_mgmt(struct i802_bss *bss,
 			    struct nlattr *freq, struct nlattr *sig,
 			    const u8 *frame, size_t len)
 {
+	struct wpa_driver_nl80211_data *drv = bss->drv;
 	const struct ieee80211_mgmt *mgmt;
 	union wpa_event_data event;
 	u16 fc, stype;
@@ -1715,6 +1716,7 @@ static void mlme_event_mgmt(struct wpa_driver_nl80211_data *drv,
 	event.rx_mgmt.frame = frame;
 	event.rx_mgmt.frame_len = len;
 	event.rx_mgmt.ssi_signal = ssi_signal;
+	event.rx_mgmt.drv_priv = bss;
 	wpa_supplicant_event(drv->ctx, EVENT_RX_MGMT, &event);
 }
 
@@ -1939,7 +1941,7 @@ static void mlme_event(struct i802_bss *bss,
 					   nla_data(frame), nla_len(frame));
 		break;
 	case NL80211_CMD_FRAME:
-		mlme_event_mgmt(drv, freq, sig, nla_data(frame),
+		mlme_event_mgmt(bss, freq, sig, nla_data(frame),
 				nla_len(frame));
 		break;
 	case NL80211_CMD_FRAME_TX_STATUS: