scan: Include AP MLD ID in ML probe request if needed

According to IEEE P802.11be/D4.0, 35.3.4.2, the AP MLD ID must be
included in the Probe Request ML element in case it is sent to a
transmitted BSS in which case it should be set to 0. If it is sent to an
non-transmitted BSSID, the AP MLD ID should not be included.

Signed-off-by: Ilan Peer <ilan.peer@intel.com>
Signed-off-by: Andrei Otcheretianski <andrei.otcheretianski@intel.com>

wpa_supplicant/bss.c

@@ -1571,6 +1571,7 @@ wpa_bss_parse_ml_rnr_ap_info(struct wpa_supplicant *wpa_s,
  *   should be initialized and #MAX_NUM_MLD_LINKS elements long
  * @missing_links: Result bitmask of links that were not discovered (or %NULL)
  * @ssid: Target SSID (or %NULL)
+ * @ap_mld_id: On return would hold the corresponding AP MLD ID (or %NULL)
  * Returns: 0 on success or -1 for non-MLD or parsing failures
  *
  * Parses the Basic Multi-Link element of the BSS into @link_info using the scan
@@ -1582,7 +1583,8 @@ int wpa_bss_parse_basic_ml_element(struct wpa_supplicant *wpa_s,
 				   struct wpa_bss *bss,
 				   u8 *ap_mld_addr,
 				   u16 *missing_links,
-				   struct wpa_ssid *ssid)
+				   struct wpa_ssid *ssid,
+				   u8 *ap_mld_id)
 {
 	struct ieee802_11_elems elems;
 	struct wpabuf *mlbuf;
@@ -1747,6 +1749,9 @@ int wpa_bss_parse_basic_ml_element(struct wpa_supplicant *wpa_s,
 	if (missing_links)
 		*missing_links = missing;
 
+	if (ap_mld_id)
+		*ap_mld_id = mbssid_idx;
+
 	ret = 0;
 out:
 	wpabuf_free(mlbuf);

wpa_supplicant/bss.h

@@ -216,7 +216,8 @@ int wpa_bss_parse_basic_ml_element(struct wpa_supplicant *wpa_s,
 				   struct wpa_bss *bss,
 				   u8 *ap_mld_addr,
 				   u16 *missing_links,
-				   struct wpa_ssid *ssid);
+				   struct wpa_ssid *ssid,
+				   u8 *ap_mld_id);
 u16 wpa_bss_parse_reconf_ml_element(struct wpa_supplicant *wpa_s,
 				    struct wpa_bss *bss);
 

wpa_supplicant/events.c

@@ -1153,7 +1153,7 @@ static bool wpas_valid_ml_bss(struct wpa_supplicant *wpa_s, struct wpa_bss *bss)
 {
 	u16 removed_links;
 
-	if (wpa_bss_parse_basic_ml_element(wpa_s, bss, NULL, NULL, NULL))
+	if (wpa_bss_parse_basic_ml_element(wpa_s, bss, NULL, NULL, NULL, NULL))
 		return true;
 
 	if (bss->n_mld_links == 0)
@@ -1871,6 +1871,7 @@ static int wpa_supplicant_connect_ml_missing(struct wpa_supplicant *wpa_s,
 {
 	int *freqs;
 	u16 missing_links = 0, removed_links;
+	u8 ap_mld_id;
 
 	if (!((wpa_s->drv_flags2 & WPA_DRIVER_FLAGS2_MLO) &&
 	      (wpa_s->drv_flags & WPA_DRIVER_FLAGS_SME)))
@@ -1878,7 +1879,8 @@ static int wpa_supplicant_connect_ml_missing(struct wpa_supplicant *wpa_s,
 
 	/* Try to resolve any missing link information */
 	if (wpa_bss_parse_basic_ml_element(wpa_s, selected, NULL,
-					   &missing_links, ssid) ||
+					   &missing_links, ssid,
+					   &ap_mld_id) ||
 	    !missing_links)
 		return 0;
 
@@ -1910,7 +1912,19 @@ static int wpa_supplicant_connect_ml_missing(struct wpa_supplicant *wpa_s,
 	wpa_s->manual_scan_freqs = freqs;
 
 	os_memcpy(wpa_s->ml_probe_bssid, selected->bssid, ETH_ALEN);
+
+	/*
+	 * In case the ML probe request is intended to retrieve information from
+	 * the transmitted BSS, the AP MLD ID should be included and should be
+	 * set to zero.
+	 * In case the ML probe requested is intended to retrieve information
+	 * from a non-transmitted BSS, the AP MLD ID should not be included.
+	 */
+	if (ap_mld_id)
 		wpa_s->ml_probe_mld_id = -1;
+	else
+		wpa_s->ml_probe_mld_id = 0;
+
 	wpa_s->ml_probe_links = missing_links;
 
 	wpa_s->normal_scans = 0;

wpa_supplicant/sme.c

@@ -575,7 +575,7 @@ static void sme_send_authentication(struct wpa_supplicant *wpa_s,
 
 	if ((wpa_s->drv_flags2 & WPA_DRIVER_FLAGS2_MLO) &&
 	    !wpa_bss_parse_basic_ml_element(wpa_s, bss, wpa_s->ap_mld_addr,
-					    NULL, ssid) &&
+					    NULL, ssid, NULL) &&
 	    bss->n_mld_links) {
 		wpa_printf(MSG_DEBUG, "MLD: In authentication");
 		wpas_sme_set_mlo_links(wpa_s, bss);