AP MLD: Intersect per STA profile with the reporting BSS

If an element is present in the reporting BSS and it is also present in
the reported BSS and the contents are same, ideally, the reported BSS
need not carry such element in its per STA profile. Such elements are
assumed to be inherited from the reporting BSS.

Intersect the reported BSS profile with the reporting BSS and avoid such
element inclusion.

Signed-off-by: Sriram R <quic_srirrama@quicinc.com>
Signed-off-by: Aditya Kumar Singh <quic_adisi@quicinc.com>

src/ap/beacon.c

@@ -2870,21 +2870,32 @@ static bool is_restricted_ext_eid_in_sta_profile(u8 ext_id)
 }
 
 
-/* Create the link STA profiles.
+/* Create the link STA profiles based on inheritance from the reporting
+ * profile.
  *
  * NOTE: The same function is used for length calculation as well as filling
  * data in the given buffer. This avoids risk of not updating the length
  * function but filling function or vice versa.
  */
 static size_t hostapd_add_sta_profile(struct ieee80211_mgmt *link_fdata,
-				      size_t link_data_len, u8 *sta_profile,
+				      size_t link_data_len,
-				      bool tx_vap)
+				      struct ieee80211_mgmt *own_fdata,
+				      size_t own_data_len,
+				      u8 *sta_profile, bool tx_vap)
 {
 	const struct element *link_elem;
 	size_t sta_profile_len = 0;
 	const u8 *link_elem_data;
 	u8 link_ele_len;
 	u8 *link_data;
+	const struct element *own_elem;
+	u8 link_eid, own_eid, own_ele_len;
+	const u8 *own_elem_data;
+	u8 *own_data;
+	bool is_ext;
+	/* The bitmap of parsed EIDs. There are 256 EIDs and ext EIDs, so 32
+	 * bytes to store the bitmaps. */
+	u8 parsed_eid_bmap[32] = { 0 }, parsed_ext_eid_bmap[32] = { 0 };
 	/* extra len used in the logic includes the element id and len */
 	u8 extra_len = 2;
 
@@ -2896,19 +2907,102 @@ static size_t hostapd_add_sta_profile(struct ieee80211_mgmt *link_fdata,
 		sta_profile += sizeof(le16);
 	}
 
+	own_data = own_fdata->u.probe_resp.variable;
 	link_data = link_fdata->u.probe_resp.variable;
 
+	/* The below logic takes the reporting BSS data and reported BSS data
+	 * and performs intersection to build the STA profile of the reported
+	 * BSS. Certain elements are not added to the STA profile as
+	 * recommended in standard. Matching element information in the
+	 * reporting BSS profile are ignored in the STA profile. Remaining
+	 * elements pertaining to the STA profile are appended at the end. */
+	for_each_element(own_elem, own_data, own_data_len) {
+		is_ext = false;
+
+		/* Pick one of own elements and get its EID and length */
+		own_elem_data = own_elem->data;
+		own_ele_len = own_elem->datalen;
+
+		if (own_elem->id == WLAN_EID_EXTENSION) {
+			is_ext = true;
+			own_eid = *(own_elem_data);
+			if (is_restricted_ext_eid_in_sta_profile(own_eid))
+				continue;
+		} else {
+			own_eid = own_elem->id;
+			if (is_restricted_eid_in_sta_profile(own_eid, tx_vap))
+				continue;
+		}
+
+		for_each_element(link_elem, link_data, link_data_len) {
+			/* If the element type mismatches, do not consider
+			 * this link element for comparison. */
+			if ((link_elem->id == WLAN_EID_EXTENSION &&
+			     !is_ext) ||
+			    (is_ext && link_elem->id != WLAN_EID_EXTENSION))
+				continue;
+
+			/* Comparison can be done so get the link element and
+			 * its EID and length. */
+			link_elem_data = link_elem->data;
+			link_ele_len = link_elem->datalen;
+
+			if (link_elem->id == WLAN_EID_EXTENSION)
+				link_eid = *(link_elem_data);
+			else
+				link_eid = link_elem->id;
+
+			/* Ignore if EID does not match */
+			if (own_eid != link_eid)
+				continue;
+
+			/* Ignore if the contents is identical. */
+			if (own_ele_len == link_ele_len &&
+			    os_memcmp(own_elem->data, link_elem->data,
+				      own_ele_len) == 0)
+				continue;
+
+			/* This element is present in the reported profile
+			 * as well as present in the reporting profile.
+			 * However, there is a mismatch in the contents and
+			 * hence, include this in the per STA profile. */
+			sta_profile_len += link_ele_len + extra_len;
+			if (sta_profile) {
+				os_memcpy(sta_profile,
+					  link_elem->data - extra_len,
+					  link_ele_len + extra_len);
+				sta_profile += link_ele_len + extra_len;
+			}
+
+			/* Update the parsed EIDs bitmap */
+			if (is_ext)
+				parsed_ext_eid_bmap[own_eid / 8] |=
+					BIT(own_eid % 8);
+			else
+				parsed_eid_bmap[own_eid / 8] |=
+					BIT(own_eid % 8);
+			break;
+		}
+	}
+
+	/* Parse the remaining elements in the reported profile */
 	for_each_element(link_elem, link_data, link_data_len) {
 		link_elem_data = link_elem->data;
 		link_ele_len = link_elem->datalen;
 
 		if (link_elem->id == WLAN_EID_EXTENSION) {
-			if (is_restricted_ext_eid_in_sta_profile(
+			link_eid = *(link_elem_data);
-				    *link_elem_data))
+
+			if ((parsed_ext_eid_bmap[link_eid / 8] &
+			     BIT(link_eid % 8)) ||
+			    is_restricted_ext_eid_in_sta_profile(link_eid))
 				continue;
 		} else {
-			if (is_restricted_eid_in_sta_profile(link_elem->id,
+			link_eid = link_elem->id;
-							     tx_vap))
+
+			if ((parsed_eid_bmap[link_eid / 8] &
+			     BIT(link_eid % 8)) ||
+			    is_restricted_eid_in_sta_profile(link_eid, tx_vap))
 				continue;
 		}
 
@@ -2926,12 +3020,15 @@ static size_t hostapd_add_sta_profile(struct ieee80211_mgmt *link_fdata,
 
 static u8 * hostapd_gen_sta_profile(struct ieee80211_mgmt *link_data,
 				    size_t link_data_len,
+				    struct ieee80211_mgmt *own_data,
+				    size_t own_data_len,
 				    size_t *sta_profile_len, bool tx_vap)
 {
 	u8 *sta_profile;
 
 	/* Get the length first */
 	*sta_profile_len = hostapd_add_sta_profile(link_data, link_data_len,
+						   own_data, own_data_len,
 						   NULL, tx_vap);
 	if (!(*sta_profile_len) || *sta_profile_len > EHT_ML_MAX_STA_PROF_LEN)
 		return NULL;
@@ -2941,7 +3038,8 @@ static u8 * hostapd_gen_sta_profile(struct ieee80211_mgmt *link_data,
 		return NULL;
 
 	/* Now fill in the data */
-	hostapd_add_sta_profile(link_data, link_data_len, sta_profile, tx_vap);
+	hostapd_add_sta_profile(link_data, link_data_len, own_data,
+				own_data_len, sta_profile, tx_vap);
 
 	/* The caller takes care of freeing the returned sta_profile */
 	return sta_profile;
@@ -2952,8 +3050,11 @@ static void hostapd_gen_per_sta_profiles(struct hostapd_data *hapd)
 {
 	bool tx_vap = hapd == hostapd_mbssid_get_tx_bss(hapd);
 	size_t link_data_len, sta_profile_len;
+	size_t own_data_len;
 	struct probe_resp_params link_params;
+	struct probe_resp_params own_params;
 	struct ieee80211_mgmt *link_data;
+	struct ieee80211_mgmt *own_data;
 	struct mld_link_info *link_info;
 	struct hostapd_data *link_bss;
 	u8 link_id, *sta_profile;
@@ -2966,6 +3067,19 @@ static void hostapd_gen_per_sta_profiles(struct hostapd_data *hapd)
 
 	wpa_printf(MSG_DEBUG, "MLD: Reporting link %d", hapd->mld_link_id);
 
+	/* Generate a Probe Response template for self */
+	if (hostapd_get_probe_resp_tmpl(hapd, &own_params, false)) {
+		wpa_printf(MSG_ERROR,
+			   "MLD: Error in building per STA profiles");
+		return;
+	}
+
+	own_data = own_params.resp;
+	own_data_len = own_params.resp_len;
+
+	/* Consider the length of the variable fields */
+	own_data_len -= offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
+
 	for_each_mld_link(link_bss, hapd) {
 		if (link_bss == hapd || !link_bss->started)
 			continue;
@@ -2993,6 +3107,7 @@ static void hostapd_gen_per_sta_profiles(struct hostapd_data *hapd)
 					  u.probe_resp.variable);
 
 		sta_profile = hostapd_gen_sta_profile(link_data, link_data_len,
+						      own_data, own_data_len,
 						      &sta_profile_len, tx_vap);
 		if (!sta_profile) {
 			wpa_printf(MSG_ERROR,
@@ -3021,6 +3136,8 @@ static void hostapd_gen_per_sta_profiles(struct hostapd_data *hapd)
 		os_free(sta_profile);
 		os_free(link_params.resp);
 	}
+
+	os_free(own_params.resp);
 }
 
 #endif /* CONFIG_IEEE80211BE */