Multi-AP: Parse the Multi-AP element using a shared helper function

This makes it more convenient to handle extensions to the element and
allows code to be shared between hostapd and wpa_supplicant.

Signed-off-by: Manoj Sekar <quic_sekar@quicinc.com>

src/ap/ieee802_11.c

@@ -3416,37 +3416,26 @@ static u16 check_wmm(struct hostapd_data *hapd, struct sta_info *sta,
 static u16 check_multi_ap(struct hostapd_data *hapd, struct sta_info *sta,
 			  const u8 *multi_ap_ie, size_t multi_ap_len)
 {
-	u8 multi_ap_value = 0;
+	struct multi_ap_params multi_ap;
+	u16 status;
 
 	sta->flags &= ~WLAN_STA_MULTI_AP;
 
 	if (!hapd->conf->multi_ap)
 		return WLAN_STATUS_SUCCESS;
 
-	if (multi_ap_ie) {
+	status = check_multi_ap_ie(multi_ap_ie + 4, multi_ap_len - 4,
-		const u8 *multi_ap_subelem;
+				   &multi_ap);
+	if (status != WLAN_STATUS_SUCCESS)
+		return status;
 
-		multi_ap_subelem = get_ie(multi_ap_ie + 4,
+	if (multi_ap.capability && multi_ap.capability != MULTI_AP_BACKHAUL_STA)
-					  multi_ap_len - 4,
-					  MULTI_AP_SUB_ELEM_TYPE);
-		if (multi_ap_subelem && multi_ap_subelem[1] == 1) {
-			multi_ap_value = multi_ap_subelem[2];
-		} else {
-			hostapd_logger(hapd, sta->addr,
-				       HOSTAPD_MODULE_IEEE80211,
-				       HOSTAPD_LEVEL_INFO,
-				       "Multi-AP IE has missing or invalid Multi-AP subelement");
-			return WLAN_STATUS_INVALID_IE;
-		}
-	}
-
-	if (multi_ap_value && multi_ap_value != MULTI_AP_BACKHAUL_STA)
 		hostapd_logger(hapd, sta->addr, HOSTAPD_MODULE_IEEE80211,
 			       HOSTAPD_LEVEL_INFO,
 			       "Multi-AP IE with unexpected value 0x%02x",
-			       multi_ap_value);
+			       multi_ap.capability);
 
-	if (!(multi_ap_value & MULTI_AP_BACKHAUL_STA)) {
+	if (!(multi_ap.capability & MULTI_AP_BACKHAUL_STA)) {
 		if (hapd->conf->multi_ap & FRONTHAUL_BSS)
 			return WLAN_STATUS_SUCCESS;
 

src/common/ieee802_11_common.c

@@ -2571,6 +2571,54 @@ size_t mbo_add_ie(u8 *buf, size_t len, const u8 *attr, size_t attr_len)
 }
 
 
+u16 check_multi_ap_ie(const u8 *multi_ap_ie, size_t multi_ap_len,
+		      struct multi_ap_params *multi_ap)
+{
+	const struct element *elem;
+	bool ext_present = false;
+
+	os_memset(multi_ap, 0, sizeof(*multi_ap));
+
+	for_each_element(elem, multi_ap_ie, multi_ap_len) {
+		u8 id = elem->id, elen = elem->datalen;
+		const u8 *pos = elem->data;
+
+		switch (id) {
+		case MULTI_AP_SUB_ELEM_TYPE:
+			if (elen >= 1) {
+				multi_ap->capability = *pos;
+				ext_present = true;
+			} else {
+				wpa_printf(MSG_DEBUG,
+					   "Multi-AP invalid Multi-AP subelement");
+				return WLAN_STATUS_INVALID_IE;
+			}
+			break;
+		default:
+			wpa_printf(MSG_DEBUG,
+				   "Ignore unknown subelement %u in Multi-AP IE",
+				   id);
+			break;
+		}
+	}
+
+	if (!for_each_element_completed(elem, multi_ap_ie, multi_ap_len)) {
+		wpa_printf(MSG_DEBUG, "Multi AP IE parse failed @%d",
+			   (int) (multi_ap_ie + multi_ap_len -
+				  (const u8 *) elem));
+		wpa_hexdump(MSG_MSGDUMP, "IEs", multi_ap_ie, multi_ap_len);
+	}
+
+	if (!ext_present) {
+		wpa_printf(MSG_DEBUG,
+			   "Multi-AP element without Multi-AP Extension subelement");
+		return WLAN_STATUS_INVALID_IE;
+	}
+
+	return WLAN_STATUS_SUCCESS;
+}
+
+
 size_t add_multi_ap_ie(u8 *buf, size_t len,
 		       const struct multi_ap_params *multi_ap)
 {

src/common/ieee802_11_common.h

@@ -271,6 +271,8 @@ const u8 * get_vendor_ie(const u8 *ies, size_t len, u32 vendor_type);
 
 size_t mbo_add_ie(u8 *buf, size_t len, const u8 *attr, size_t attr_len);
 
+u16 check_multi_ap_ie(const u8 *multi_ap_ie, size_t multi_ap_len,
+		      struct multi_ap_params *multi_ap);
 size_t add_multi_ap_ie(u8 *buf, size_t len,
 		       const struct multi_ap_params *multi_ap);
 

wpa_supplicant/events.c

@@ -2996,25 +2996,24 @@ static void multi_ap_process_assoc_resp(struct wpa_supplicant *wpa_s,
 					const u8 *ies, size_t ies_len)
 {
 	struct ieee802_11_elems elems;
-	const u8 *map_sub_elem, *pos;
+	struct multi_ap_params multi_ap;
-	size_t len;
+	u16 status;
 
 	wpa_s->multi_ap_ie = 0;
 
 	if (!ies ||
 	    ieee802_11_parse_elems(ies, ies_len, &elems, 1) == ParseFailed ||
-	    !elems.multi_ap || elems.multi_ap_len < 7)
+	    !elems.multi_ap)
 		return;
 
-	pos = elems.multi_ap + 4;
+	status = check_multi_ap_ie(elems.multi_ap + 4, elems.multi_ap_len - 4,
-	len = elems.multi_ap_len - 4;
+				   &multi_ap);
-
+	if (status != WLAN_STATUS_SUCCESS)
-	map_sub_elem = get_ie(pos, len, MULTI_AP_SUB_ELEM_TYPE);
-	if (!map_sub_elem || map_sub_elem[1] < 1)
 		return;
 
-	wpa_s->multi_ap_backhaul = !!(map_sub_elem[2] & MULTI_AP_BACKHAUL_BSS);
+	wpa_s->multi_ap_backhaul = !!(multi_ap.capability &
-	wpa_s->multi_ap_fronthaul = !!(map_sub_elem[2] &
+				      MULTI_AP_BACKHAUL_BSS);
+	wpa_s->multi_ap_fronthaul = !!(multi_ap.capability &
 				       MULTI_AP_FRONTHAUL_BSS);
 	wpa_s->multi_ap_ie = 1;
 }