HS 2.0R2: Add support for Policy/MaximumBSSLoadValue

The new credential parameter max_bss_load can be used to specify
restrictions on BSS Load in the home network.

Signed-hostap: Jouni Malinen <jouni@qca.qualcomm.com>

wpa_supplicant/README-HS20

@@ -237,6 +237,13 @@ Credentials can be pre-configured for automatic network selection:
 # min_dl_bandwidth_roaming
 # min_ul_bandwidth_roaming
 #
+# max_bss_load: Maximum BSS Load Channel Utilization (1..255)
+#	(PPS/<X+>/Policy/MaximumBSSLoadValue)
+#	This value is used as the maximum channel utilization for network
+#	selection purposes for home networks. If the AP does not advertise
+#	BSS Load or if the limit would prevent any connection, this constraint
+#	will be ignored.
+#
 # for example:
 #
 #cred={

wpa_supplicant/config.c

@@ -2473,6 +2473,11 @@ int wpa_config_set_cred(struct wpa_cred *cred, const char *var,
 		return 0;
 	}
 
+	if (os_strcmp(var, "max_bss_load") == 0) {
+		cred->max_bss_load = atoi(value);
+		return 0;
+	}
+
 	val = wpa_config_parse_string(value, &len);
 	if (val == NULL) {
 		wpa_printf(MSG_ERROR, "Line %d: invalid field '%s' string "

wpa_supplicant/config.h

@@ -256,6 +256,15 @@ struct wpa_cred {
 	unsigned int min_ul_bandwidth_home;
 	unsigned int min_dl_bandwidth_roaming;
 	unsigned int min_ul_bandwidth_roaming;
+
+	/**
+	 * max_bss_load - Maximum BSS Load Channel Utilization (1..255)
+	 * This value is used as the maximum channel utilization for network
+	 * selection purposes for home networks. If the AP does not advertise
+	 * BSS Load or if the limit would prevent any connection, this
+	 * constraint will be ignored.
+	 */
+	unsigned int max_bss_load;
 };
 
 

wpa_supplicant/config_file.c

@@ -822,6 +822,10 @@ static void wpa_config_write_cred(FILE *f, struct wpa_cred *cred)
 	if (cred->min_ul_bandwidth_roaming)
 		fprintf(f, "\tmin_ul_bandwidth_roaming=%u\n",
 			cred->min_ul_bandwidth_roaming);
+
+	if (cred->max_bss_load)
+		fprintf(f, "\tmax_bss_load=%u\n",
+			cred->max_bss_load);
 }
 
 

wpa_supplicant/interworking.c

@@ -1131,6 +1131,28 @@ static int cred_below_min_backhaul(struct wpa_supplicant *wpa_s,
 }
 
 
+static int cred_over_max_bss_load(struct wpa_supplicant *wpa_s,
+				  struct wpa_cred *cred, struct wpa_bss *bss)
+{
+	const u8 *ie;
+	int res;
+
+	if (!cred->max_bss_load)
+		return 0; /* No BSS Load constraint specified */
+
+	ie = wpa_bss_get_ie(bss, WLAN_EID_BSS_LOAD);
+	if (ie == NULL || ie[1] < 3)
+		return 0; /* No BSS Load advertised */
+
+	res = interworking_home_sp_cred(wpa_s, cred, bss->anqp ?
+					bss->anqp->domain_name : NULL);
+	if (res <= 0)
+		return 0; /* Not a home network */
+
+	return ie[4] > cred->max_bss_load;
+}
+
+
 static struct wpa_cred * interworking_credentials_available_roaming_consortium(
 	struct wpa_supplicant *wpa_s, struct wpa_bss *bss, int ignore_bw)
 {
@@ -1164,6 +1186,8 @@ static struct wpa_cred * interworking_credentials_available_roaming_consortium(
 			continue;
 		if (!ignore_bw && cred_below_min_backhaul(wpa_s, cred, bss))
 			continue;
+		if (!ignore_bw && cred_over_max_bss_load(wpa_s, cred, bss))
+			continue;
 
 		if (selected == NULL ||
 		    selected->priority < cred->priority)
@@ -1656,6 +1680,9 @@ static struct wpa_cred * interworking_credentials_available_3gpp(
 			if (!ignore_bw &&
 			    cred_below_min_backhaul(wpa_s, cred, bss))
 				continue;
+			if (!ignore_bw &&
+			    cred_over_max_bss_load(wpa_s, cred, bss))
+				continue;
 			if (selected == NULL ||
 			    selected->priority < cred->priority)
 				selected = cred;
@@ -1703,6 +1730,9 @@ static struct wpa_cred * interworking_credentials_available_realm(
 				if (!ignore_bw &&
 				    cred_below_min_backhaul(wpa_s, cred, bss))
 					continue;
+				if (!ignore_bw &&
+				    cred_over_max_bss_load(wpa_s, cred, bss))
+					continue;
 				if (selected == NULL ||
 				    selected->priority < cred->priority)
 					selected = cred;
@@ -1994,10 +2024,12 @@ static void interworking_select_network(struct wpa_supplicant *wpa_s)
 			type = "roaming";
 		else
 			type = "unknown";
-		wpa_msg(wpa_s, MSG_INFO, INTERWORKING_AP MACSTR " type=%s%s",
+		wpa_msg(wpa_s, MSG_INFO, INTERWORKING_AP MACSTR " type=%s%s%s",
 			MAC2STR(bss->bssid), type,
 			cred_below_min_backhaul(wpa_s, cred, bss) ?
-			" below_min_backhaul=1" : "");
+			" below_min_backhaul=1" : "",
+			cred_over_max_bss_load(wpa_s, cred, bss) ?
+			" over_max_bss_load=1" : "");
 		if (wpa_s->auto_select ||
 		    (wpa_s->conf->auto_interworking &&
 		     wpa_s->auto_network_select)) {

wpa_supplicant/wpa_supplicant.conf

@@ -456,6 +456,13 @@ fast_reauth=1
 # min_dl_bandwidth_roaming
 # min_ul_bandwidth_roaming
 #
+# max_bss_load: Maximum BSS Load Channel Utilization (1..255)
+#	(PPS/<X+>/Policy/MaximumBSSLoadValue)
+#	This value is used as the maximum channel utilization for network
+#	selection purposes for home networks. If the AP does not advertise
+#	BSS Load or if the limit would prevent any connection, this constraint
+#	will be ignored.
+#
 # for example:
 #
 #cred={