Add scheduled scan driver operations

In new Linux kernel versions (>=3.0), nl80211 adds scheduled scan
capability. In order to use this feature to its full extent, we need
to support it in the wpa_supplicant core, so that it can also be used
by other drivers.

This commit adds initial scheduled scan support operations and events.

Signed-off-by: Luciano Coelho <coelho@ti.com>

src/drivers/driver.h

@@ -694,6 +694,8 @@ struct wpa_driver_capa {
 	unsigned int flags;
 
 	int max_scan_ssids;
+	int max_sched_scan_ssids;
+	int sched_scan_supported;
 
 	/**
 	 * max_remain_on_chan - Maximum remain-on-channel duration in msec
@@ -2455,6 +2457,35 @@ struct wpa_driver_ops {
 	 * the station gets added by FT-over-DS.
 	 */
 	int (*add_sta_node)(void *priv, const u8 *addr, u16 auth_alg);
+
+	/**
+	 * sched_scan - Request the driver to initiate scheduled scan
+	 * @priv: Private driver interface data
+	 * @params: Scan parameters
+	 * @interval: Interval between scan cycles in milliseconds
+	 * Returns: 0 on success, -1 on failure
+	 *
+	 * This operation should be used for scheduled scan offload to
+	 * the hardware. Every time scan results are available, the
+	 * driver should report scan results event for wpa_supplicant
+	 * which will eventually request the results with
+	 * wpa_driver_get_scan_results2(). This operation is optional
+	 * and if not provided or if it returns -1, we fall back to
+	 * normal host-scheduled scans.
+	 */
+	int (*sched_scan)(void *priv, struct wpa_driver_scan_params *params,
+			  u32 interval);
+
+	/**
+	 * stop_sched_scan - Request the driver to stop a scheduled scan
+	 * @priv: Private driver interface data
+	 * Returns: 0 on success, -1 on failure
+	 *
+	 * This should cause the scheduled scan to be stopped and
+	 * results should stop being sent. Must be supported if
+	 * sched_scan is supported.
+	 */
+	int (*stop_sched_scan)(void *priv);
 };
 
 
@@ -2867,7 +2898,12 @@ enum wpa_event_type {
 	 * completed Group Key Handshake while the host (including
 	 * wpa_supplicant was sleeping).
 	 */
-	EVENT_DRIVER_GTK_REKEY
+	EVENT_DRIVER_GTK_REKEY,
+
+	/**
+	 * EVENT_SCHED_SCAN_STOPPED - Scheduled scan was stopped
+	 */
+	EVENT_SCHED_SCAN_STOPPED
 };
 
 

src/drivers/driver_ndis.c

@@ -3331,5 +3331,7 @@ const struct wpa_driver_ops wpa_driver_ndis_ops = {
 	NULL /* sta_assoc */,
 	NULL /* sta_auth */,
 	NULL /* add_tspec */,
-	NULL /* add_sta_node */
+	NULL /* add_sta_node */,
+	NULL /* sched_scan */,
+	NULL /* stop_sched_scan */
 };

wpa_supplicant/driver_i.h

@@ -79,6 +79,23 @@ static inline int wpa_drv_scan(struct wpa_supplicant *wpa_s,
 	return -1;
 }
 
+static inline int wpa_drv_sched_scan(struct wpa_supplicant *wpa_s,
+				     struct wpa_driver_scan_params *params,
+				     u32 interval)
+{
+	if (wpa_s->driver->sched_scan)
+		return wpa_s->driver->sched_scan(wpa_s->drv_priv,
+						 params, interval);
+	return -1;
+}
+
+static inline int wpa_drv_stop_sched_scan(struct wpa_supplicant *wpa_s)
+{
+	if (wpa_s->driver->stop_sched_scan)
+		return wpa_s->driver->stop_sched_scan(wpa_s->drv_priv);
+	return -1;
+}
+
 static inline struct wpa_scan_results * wpa_drv_get_scan_results2(
 	struct wpa_supplicant *wpa_s)
 {

wpa_supplicant/events.c

@@ -2263,6 +2263,17 @@ void wpa_supplicant_event(void *ctx, enum wpa_event_type event,
 		wpa_sm_update_replay_ctr(wpa_s->wpa,
 					 data->driver_gtk_rekey.replay_ctr);
 		break;
+	case EVENT_SCHED_SCAN_STOPPED:
+		wpa_s->sched_scanning = 0;
+		wpa_supplicant_notify_scanning(wpa_s, 0);
+
+		/*
+		 * If we timed out, start a new sched scan to continue
+		 * searching for more SSIDs.
+		 */
+		if (wpa_s->sched_scan_timed_out)
+			wpa_supplicant_req_sched_scan(wpa_s);
+		break;
 	default:
 		wpa_msg(wpa_s, MSG_INFO, "Unknown event %d", event);
 		break;

wpa_supplicant/scan.c

@@ -215,6 +215,54 @@ int wpa_supplicant_trigger_scan(struct wpa_supplicant *wpa_s,
 }
 
 
+static void
+wpa_supplicant_sched_scan_timeout(void *eloop_ctx, void *timeout_ctx)
+{
+	struct wpa_supplicant *wpa_s = eloop_ctx;
+
+	wpa_dbg(wpa_s, MSG_DEBUG, "Sched scan timeout - stopping it");
+
+	wpa_s->sched_scan_timed_out = 1;
+	wpa_supplicant_cancel_sched_scan(wpa_s);
+}
+
+
+static int
+wpa_supplicant_start_sched_scan(struct wpa_supplicant *wpa_s,
+				struct wpa_driver_scan_params *params,
+				int interval)
+{
+	int ret;
+
+	if (wpa_s->drv_flags & WPA_DRIVER_FLAGS_USER_SPACE_MLME)
+		return -1;
+
+	wpa_supplicant_notify_scanning(wpa_s, 1);
+	ret = wpa_drv_sched_scan(wpa_s, params, interval * 1000);
+	if (ret)
+		wpa_supplicant_notify_scanning(wpa_s, 0);
+	else
+		wpa_s->sched_scanning = 1;
+
+	return ret;
+}
+
+
+static int wpa_supplicant_stop_sched_scan(struct wpa_supplicant *wpa_s)
+{
+	int ret;
+
+	ret = wpa_drv_stop_sched_scan(wpa_s);
+	if (ret) {
+		wpa_dbg(wpa_s, MSG_DEBUG, "stopping sched_scan failed!");
+		/* TODO: what to do if stopping fails? */
+		return -1;
+	}
+
+	return ret;
+}
+
+
 static struct wpa_driver_scan_filter *
 wpa_supplicant_build_filter_ssids(struct wpa_config *conf, size_t *num_ssids)
 {
@@ -566,6 +614,130 @@ void wpa_supplicant_req_scan(struct wpa_supplicant *wpa_s, int sec, int usec)
 }
 
 
+/**
+ * wpa_supplicant_req_sched_scan - Start a periodic scheduled scan
+ * @wpa_s: Pointer to wpa_supplicant data
+ *
+ * This function is used to schedule periodic scans for neighboring
+ * access points repeating the scan continuously.
+ */
+int wpa_supplicant_req_sched_scan(struct wpa_supplicant *wpa_s)
+{
+	struct wpa_driver_scan_params params;
+	enum wpa_states prev_state;
+	struct wpa_ssid *ssid;
+	struct wpabuf *wps_ie = NULL;
+	int ret;
+	int use_wildcard = 0;
+	unsigned int max_sched_scan_ssids;
+
+	if (!wpa_s->sched_scan_supported)
+		return -1;
+
+	if (wpa_s->max_sched_scan_ssids > WPAS_MAX_SCAN_SSIDS)
+		max_sched_scan_ssids = WPAS_MAX_SCAN_SSIDS;
+	else
+		max_sched_scan_ssids = wpa_s->max_sched_scan_ssids;
+
+	if (wpa_s->sched_scanning)
+		return 0;
+
+	os_memset(&params, 0, sizeof(params));
+
+	prev_state = wpa_s->wpa_state;
+	if (wpa_s->wpa_state == WPA_DISCONNECTED ||
+	    wpa_s->wpa_state == WPA_INACTIVE)
+		wpa_supplicant_set_state(wpa_s, WPA_SCANNING);
+
+	/* Find the starting point from which to continue scanning */
+	ssid = wpa_s->conf->ssid;
+	if (wpa_s->prev_sched_ssid) {
+		while (ssid) {
+			if (ssid == wpa_s->prev_sched_ssid) {
+				ssid = ssid->next;
+				break;
+			}
+			ssid = ssid->next;
+		}
+	}
+
+	if (!ssid || !wpa_s->prev_sched_ssid) {
+		wpa_dbg(wpa_s, MSG_DEBUG, "Beginning of SSID list");
+
+		wpa_s->sched_scan_interval = 2;
+		wpa_s->sched_scan_timeout = max_sched_scan_ssids * 2;
+		wpa_s->first_sched_scan = 1;
+		ssid = wpa_s->conf->ssid;
+		wpa_s->prev_sched_ssid = ssid;
+	}
+
+	while (ssid) {
+		if (ssid->disabled) {
+			wpa_s->prev_sched_ssid = ssid;
+			ssid = ssid->next;
+			continue;
+		}
+
+		if (!ssid->scan_ssid)
+			use_wildcard = 1;
+		else {
+			params.ssids[params.num_ssids].ssid =
+				ssid->ssid;
+			params.ssids[params.num_ssids].ssid_len =
+				ssid->ssid_len;
+			params.num_ssids++;
+			if (params.num_ssids + 1 >= max_sched_scan_ssids) {
+				wpa_s->prev_sched_ssid = ssid;
+				break;
+			}
+		}
+		wpa_s->prev_sched_ssid = ssid;
+		ssid = ssid->next;
+	}
+
+	if (ssid || use_wildcard) {
+		wpa_dbg(wpa_s, MSG_DEBUG, "Include wildcard SSID in "
+			"the sched scan request");
+		params.num_ssids++;
+	} else {
+		wpa_dbg(wpa_s, MSG_DEBUG, "ssid %p - list ended", ssid);
+	}
+
+	if (!params.num_ssids)
+		return 0;
+
+	if (wpa_s->wps)
+		wps_ie = wpa_supplicant_extra_ies(wpa_s, &params);
+
+	wpa_dbg(wpa_s, MSG_DEBUG,
+		"Starting sched scan: interval %d timeout %d",
+		wpa_s->sched_scan_interval, wpa_s->sched_scan_timeout);
+
+	ret = wpa_supplicant_start_sched_scan(wpa_s, &params,
+					      wpa_s->sched_scan_interval);
+	wpabuf_free(wps_ie);
+	if (ret) {
+		wpa_msg(wpa_s, MSG_WARNING, "Failed to initiate sched scan");
+		if (prev_state != wpa_s->wpa_state)
+			wpa_supplicant_set_state(wpa_s, prev_state);
+		return ret;
+	}
+
+	/* If we have more SSIDs to scan, add a timeout so we scan them too */
+	if (ssid || !wpa_s->first_sched_scan) {
+		wpa_s->sched_scan_timed_out = 0;
+		eloop_register_timeout(wpa_s->sched_scan_timeout, 0,
+				       wpa_supplicant_sched_scan_timeout,
+				       wpa_s, NULL);
+		wpa_s->first_sched_scan = 0;
+		wpa_s->sched_scan_timeout /= 2;
+		wpa_s->sched_scan_interval *= 2;
+	}
+
+	return 0;
+}
+
+
 /**
  * wpa_supplicant_cancel_scan - Cancel a scheduled scan request
  * @wpa_s: Pointer to wpa_supplicant data
@@ -580,6 +752,23 @@ void wpa_supplicant_cancel_scan(struct wpa_supplicant *wpa_s)
 }
 
 
+/**
+ * wpa_supplicant_cancel_sched_scan - Stop running scheduled scans
+ * @wpa_s: Pointer to wpa_supplicant data
+ *
+ * This function is used to stop a periodic scheduled scan.
+ */
+void wpa_supplicant_cancel_sched_scan(struct wpa_supplicant *wpa_s)
+{
+	if (!wpa_s->sched_scanning)
+		return;
+
+	wpa_dbg(wpa_s, MSG_DEBUG, "Cancelling sched scan");
+	eloop_cancel_timeout(wpa_supplicant_sched_scan_timeout, wpa_s, NULL);
+	wpa_supplicant_stop_sched_scan(wpa_s);
+}
+
+
 void wpa_supplicant_notify_scanning(struct wpa_supplicant *wpa_s,
 				    int scanning)
 {

wpa_supplicant/scan.h

@@ -17,7 +17,9 @@
 
 int wpa_supplicant_enabled_networks(struct wpa_config *conf);
 void wpa_supplicant_req_scan(struct wpa_supplicant *wpa_s, int sec, int usec);
+int wpa_supplicant_req_sched_scan(struct wpa_supplicant *wpa_s);
 void wpa_supplicant_cancel_scan(struct wpa_supplicant *wpa_s);
+void wpa_supplicant_cancel_sched_scan(struct wpa_supplicant *wpa_s);
 void wpa_supplicant_notify_scanning(struct wpa_supplicant *wpa_s,
 				    int scanning);
 struct wpa_driver_scan_params;

wpa_supplicant/wpa_supplicant.c

@@ -2114,6 +2114,7 @@ static struct wpa_supplicant * wpa_supplicant_alloc(void)
 	wpa_s->scan_interval = 5;
 	wpa_s->new_connection = 1;
 	wpa_s->parent = wpa_s;
+	wpa_s->sched_scanning = 0;
 
 	return wpa_s;
 }
@@ -2278,6 +2279,8 @@ next_driver:
 				return -1;
 		}
 		wpa_s->max_scan_ssids = capa.max_scan_ssids;
+		wpa_s->max_sched_scan_ssids = capa.max_sched_scan_ssids;
+		wpa_s->sched_scan_supported = capa.sched_scan_supported;
 		wpa_s->max_remain_on_chan = capa.max_remain_on_chan;
 		wpa_s->max_stations = capa.max_stations;
 	}

wpa_supplicant/wpa_supplicant_i.h

@@ -387,6 +387,12 @@ struct wpa_supplicant {
 					  */
 #define WILDCARD_SSID_SCAN ((struct wpa_ssid *) 1)
 
+	struct wpa_ssid *prev_sched_ssid; /* last SSID used in sched scan */
+	int sched_scan_timeout;
+	int sched_scan_interval;
+	int first_sched_scan;
+	int sched_scan_timed_out;
+
 	void (*scan_res_handler)(struct wpa_supplicant *wpa_s,
 				 struct wpa_scan_results *scan_res);
 	struct dl_list bss; /* struct wpa_bss::list */
@@ -405,6 +411,7 @@ struct wpa_supplicant {
 
 	enum wpa_states wpa_state;
 	int scanning;
+	int sched_scanning;
 	int new_connection;
 	int reassociated_connection;
 
@@ -428,6 +435,8 @@ struct wpa_supplicant {
 	struct wpa_client_mlme mlme;
 	unsigned int drv_flags;
 	int max_scan_ssids;
+	int max_sched_scan_ssids;
+	int sched_scan_supported;
 	unsigned int max_remain_on_chan;
 	unsigned int max_stations;