Add support for multi-SSID scan requests

If the driver reports support for more than one SSID per scan request,
optimize scan_ssid=1 operations in ap_scan=1 mode. This speeds up
scanning whenever scan_ssid=1 is used since the broadcast SSID can be
included in every scan request and if driver supports more than two
SSIDs in the scan request, the benefits are even larger when multiple
networks have been configured with ap_scan=1.

This is also cleaning up wpa_supplicant_scan() function by moving code
around so that the SSID list is not processed unnecessarily if the
operation mode does not need this.

wpa_supplicant/scan.c

@@ -65,38 +65,69 @@ static int wpas_wps_in_use(struct wpa_config *conf,
 }
 #endif /* CONFIG_WPS */
 
+
+static int wpa_supplicant_enabled_networks(struct wpa_config *conf)
+{
+	struct wpa_ssid *ssid = conf->ssid;
+	while (ssid) {
+		if (!ssid->disabled)
+			return 1;
+		ssid = ssid->next;
+	}
+	return 0;
+}
+
+
+static void wpa_supplicant_assoc_try(struct wpa_supplicant *wpa_s,
+				     struct wpa_ssid *ssid)
+{
+	while (ssid) {
+		if (!ssid->disabled)
+			break;
+		ssid = ssid->next;
+	}
+
+	/* ap_scan=2 mode - try to associate with each SSID. */
+	if (ssid == NULL) {
+		wpa_printf(MSG_DEBUG, "wpa_supplicant_scan: Reached "
+			   "end of scan list - go back to beginning");
+		wpa_s->prev_scan_ssid = BROADCAST_SSID_SCAN;
+		wpa_supplicant_req_scan(wpa_s, 0, 0);
+		return;
+	}
+	if (ssid->next) {
+		/* Continue from the next SSID on the next attempt. */
+		wpa_s->prev_scan_ssid = ssid;
+	} else {
+		/* Start from the beginning of the SSID list. */
+		wpa_s->prev_scan_ssid = BROADCAST_SSID_SCAN;
+	}
+	wpa_supplicant_associate(wpa_s, NULL, ssid);
+}
+
+
 static void wpa_supplicant_scan(void *eloop_ctx, void *timeout_ctx)
 {
 	struct wpa_supplicant *wpa_s = eloop_ctx;
 	struct wpa_ssid *ssid;
-	int enabled, scan_req = 0, ret;
+	int scan_req = 0, ret;
 	struct wpabuf *wps_ie = NULL;
-	const u8 *extra_ie = NULL;
-	size_t extra_ie_len = 0;
 	int wps = 0;
 #ifdef CONFIG_WPS
 	enum wps_request_type req_type = WPS_REQ_ENROLLEE_INFO;
 #endif /* CONFIG_WPS */
+	struct wpa_driver_scan_params params;
+	size_t max_ssids;
 
 	if (wpa_s->disconnected && !wpa_s->scan_req)
 		return;
 
-	enabled = 0;
-	ssid = wpa_s->conf->ssid;
-	while (ssid) {
-		if (!ssid->disabled) {
-			enabled++;
-			break;
-		}
-		ssid = ssid->next;
-	}
-	if (!enabled && !wpa_s->scan_req) {
+	if (!wpa_supplicant_enabled_networks(wpa_s->conf) &&
+	    !wpa_s->scan_req) {
 		wpa_printf(MSG_DEBUG, "No enabled networks - do not scan");
 		wpa_supplicant_set_state(wpa_s, WPA_INACTIVE);
 		return;
 	}
-	scan_req = wpa_s->scan_req;
-	wpa_s->scan_req = 0;
 
 	if (wpa_s->conf->ap_scan != 0 &&
 	    wpa_s->driver && IS_WIRED(wpa_s->driver)) {
@@ -110,10 +141,38 @@ static void wpa_supplicant_scan(void *eloop_ctx, void *timeout_ctx)
 		return;
 	}
 
+	if (wpa_s->use_client_mlme || wpa_s->conf->ap_scan == 2)
+		max_ssids = 1;
+	else {
+		max_ssids = wpa_s->max_scan_ssids;
+		if (max_ssids > WPAS_MAX_SCAN_SSIDS)
+			max_ssids = WPAS_MAX_SCAN_SSIDS;
+	}
+
+#ifdef CONFIG_WPS
+	wps = wpas_wps_in_use(wpa_s->conf, &req_type);
+#endif /* CONFIG_WPS */
+
+	if (wpa_s->scan_res_tried == 0 && wpa_s->conf->ap_scan == 1 &&
+	    !wpa_s->use_client_mlme && wps != 2) {
+		wpa_s->scan_res_tried++;
+		wpa_printf(MSG_DEBUG, "Trying to get current scan results "
+			   "first without requesting a new scan to speed up "
+			   "initial association");
+		wpa_supplicant_event(wpa_s, EVENT_SCAN_RESULTS, NULL);
+		return;
+	}
+
+	scan_req = wpa_s->scan_req;
+	wpa_s->scan_req = 0;
+
+	os_memset(&params, 0, sizeof(params));
+
 	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_scan_ssid != BROADCAST_SSID_SCAN) {
 		while (ssid) {
@@ -124,58 +183,53 @@ static void wpa_supplicant_scan(void *eloop_ctx, void *timeout_ctx)
 			ssid = ssid->next;
 		}
 	}
-	while (ssid) {
-		if (!ssid->disabled &&
-		    (ssid->scan_ssid || wpa_s->conf->ap_scan == 2))
-			break;
-		ssid = ssid->next;
-	}
 
 	if (scan_req != 2 && wpa_s->conf->ap_scan == 2) {
+		wpa_supplicant_assoc_try(wpa_s, ssid);
+		return;
+	} else if (wpa_s->conf->ap_scan == 2) {
 		/*
-		 * ap_scan=2 mode - try to associate with each SSID instead of
-		 * scanning for each scan_ssid=1 network.
+		 * User-initiated scan request in ap_scan == 2; use broadcast
+		 * scan.
 		 */
-		if (ssid == NULL) {
-			wpa_printf(MSG_DEBUG, "wpa_supplicant_scan: Reached "
-				   "end of scan list - go back to beginning");
-			wpa_s->prev_scan_ssid = BROADCAST_SSID_SCAN;
-			wpa_supplicant_req_scan(wpa_s, 0, 0);
-			return;
-		}
-		if (ssid->next) {
-			/* Continue from the next SSID on the next attempt. */
-			wpa_s->prev_scan_ssid = ssid;
-		} else {
-			/* Start from the beginning of the SSID list. */
-			wpa_s->prev_scan_ssid = BROADCAST_SSID_SCAN;
+		ssid = NULL;
+	} else {
+		struct wpa_ssid *start = ssid;
+		if (ssid == NULL && max_ssids > 1)
+			ssid = wpa_s->conf->ssid;
+		while (ssid) {
+			if (!ssid->disabled && ssid->scan_ssid) {
+				wpa_hexdump_ascii(MSG_DEBUG, "Scan SSID",
+						  ssid->ssid, ssid->ssid_len);
+				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_ssids)
+					break;
+			}
+			ssid = ssid->next;
+			if (ssid == start)
+				break;
+			if (ssid == NULL && max_ssids > 1 &&
+			    start != wpa_s->conf->ssid)
+				ssid = wpa_s->conf->ssid;
 		}
-		wpa_supplicant_associate(wpa_s, NULL, ssid);
-		return;
 	}
 
-	wpa_printf(MSG_DEBUG, "Starting AP scan (%s SSID)",
-		   ssid ? "specific": "broadcast");
 	if (ssid) {
-		wpa_hexdump_ascii(MSG_DEBUG, "Scan SSID",
-				  ssid->ssid, ssid->ssid_len);
 		wpa_s->prev_scan_ssid = ssid;
-	} else
+		if (max_ssids > 1) {
+			wpa_printf(MSG_DEBUG, "Include broadcast SSID in the "
+				   "scan request");
+			params.num_ssids++; /* Broadcast scan */
+		}
+		wpa_printf(MSG_DEBUG, "Starting AP scan for specific SSID(s)");
+	} else {
 		wpa_s->prev_scan_ssid = BROADCAST_SSID_SCAN;
-
-#ifdef CONFIG_WPS
-	wps = wpas_wps_in_use(wpa_s->conf, &req_type);
-#endif /* CONFIG_WPS */
-
-	if (wpa_s->scan_res_tried == 0 && wpa_s->conf->ap_scan == 1 &&
-	    !wpa_s->use_client_mlme && wps != 2) {
-		wpa_s->scan_res_tried++;
-		wpa_s->scan_req = scan_req;
-		wpa_printf(MSG_DEBUG, "Trying to get current scan results "
-			   "first without requesting a new scan to speed up "
-			   "initial association");
-		wpa_supplicant_event(wpa_s, EVENT_SCAN_RESULTS, NULL);
-		return;
+		params.num_ssids++;
+		wpa_printf(MSG_DEBUG, "Starting AP scan for broadcast SSID");
 	}
 
 #ifdef CONFIG_WPS
@@ -183,27 +237,20 @@ static void wpa_supplicant_scan(void *eloop_ctx, void *timeout_ctx)
 		wps_ie = wps_build_probe_req_ie(wps == 2, &wpa_s->wps->dev,
 						wpa_s->wps->uuid, req_type);
 		if (wps_ie) {
-			extra_ie = wpabuf_head(wps_ie);
-			extra_ie_len = wpabuf_len(wps_ie);
+			params.extra_ies = wpabuf_head(wps_ie);
+			params.extra_ies_len = wpabuf_len(wps_ie);
 		}
 	}
 #endif /* CONFIG_WPS */
 
 	if (wpa_s->use_client_mlme) {
-		ieee80211_sta_set_probe_req_ie(wpa_s, extra_ie, extra_ie_len);
-		ret = ieee80211_sta_req_scan(wpa_s, ssid ? ssid->ssid : NULL,
-					     ssid ? ssid->ssid_len : 0);
+		ieee80211_sta_set_probe_req_ie(wpa_s, params.extra_ies,
+					       params.extra_ies_len);
+		ret = ieee80211_sta_req_scan(wpa_s, params.ssids[0].ssid,
+					     params.ssids[0].ssid_len);
 	} else {
-		struct wpa_driver_scan_params params;
-		os_memset(&params, 0, sizeof(params));
-		wpa_drv_set_probe_req_ie(wpa_s, extra_ie, extra_ie_len);
-		if (ssid) {
-			params.ssids[0].ssid = ssid->ssid;
-			params.ssids[0].ssid_len = ssid->ssid_len;
-		}
-		params.num_ssids = 1;
-		params.extra_ies = extra_ie;
-		params.extra_ies_len = extra_ie_len;
+		wpa_drv_set_probe_req_ie(wpa_s, params.extra_ies,
+					 params.extra_ies_len);
 		ret = wpa_drv_scan(wpa_s, &params);
 	}