From: Abishek Ganapathy <abishekg@qti.qualcomm.com>
Date: Thu, 30 Oct 2025 19:14:06 +0000 (+0530)
Subject: Add helper functions for parsing Basic MLE to fetch EML capa and Link ID
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b6ffe31493215dd47f8142ff4d5ed1ce80f11dc9;p=thirdparty%2Fhostap.git

Add helper functions for parsing Basic MLE to fetch EML capa and Link ID

Add helper functions to fetch the EML Capabilities field and the Link ID
Info field from a Basic Multi-Link element.

Co-developed-by: Rohan Dutta <drohan@qti.qualcomm.com>
Signed-off-by: Rohan Dutta <drohan@qti.qualcomm.com>
Signed-off-by: Abishek Ganapathy <abishekg@qti.qualcomm.com>
---

diff --git a/src/common/ieee802_11_common.c b/src/common/ieee802_11_common.c
index 82a4c1f73..a0b51c014 100644
--- a/src/common/ieee802_11_common.c
+++ b/src/common/ieee802_11_common.c
@@ -3562,3 +3562,83 @@ const u8 * get_basic_mle_mld_addr(const u8 *buf, size_t len)
 
 	return &buf[mld_addr_pos];
 }
+
+
+const u8 * get_basic_mle_eml_capa(const u8 *buf, size_t len)
+{
+	const struct ieee80211_eht_ml *ml =
+		(const struct ieee80211_eht_ml *) buf;
+	u16 ctrl;
+	size_t eml_capa_pos =
+		MULTI_LINK_CONTROL_LEN + /* Multi-Link Control field */
+		1 + /* Common Info Length field (Basic) */
+		ETH_ALEN; /* MLD MAC Address field (Basic) */
+	size_t common_info_limit;
+	u8 common_info_len;
+
+	if (len < MULTI_LINK_CONTROL_LEN)
+		return NULL;
+
+	ctrl = le_to_host16(ml->ml_control);
+	if ((ctrl & MULTI_LINK_CONTROL_TYPE_MASK) !=
+	    MULTI_LINK_CONTROL_TYPE_BASIC)
+		return NULL;
+	if (!(ctrl & BASIC_MULTI_LINK_CTRL_PRES_EML_CAPA))
+		return NULL;
+
+	/* Validate Common Info Length against available data */
+	common_info_len = buf[MULTI_LINK_CONTROL_LEN];
+	if (len < (size_t) MULTI_LINK_CONTROL_LEN + common_info_len)
+		return NULL;
+	common_info_limit = MULTI_LINK_CONTROL_LEN + common_info_len;
+
+	if (ctrl & BASIC_MULTI_LINK_CTRL_PRES_LINK_ID)
+		eml_capa_pos += EHT_ML_LINK_ID_LEN;
+
+	if (ctrl & BASIC_MULTI_LINK_CTRL_PRES_BSS_PARAM_CH_COUNT)
+		eml_capa_pos++;
+
+	if (ctrl & BASIC_MULTI_LINK_CTRL_PRES_MSD_INFO)
+		eml_capa_pos += 2;
+
+	/* Ensure EML Capabilities field fits within the declared Common Info */
+	if (eml_capa_pos + EHT_ML_EML_CAPA_LEN > common_info_limit)
+		return NULL;
+
+	return &buf[eml_capa_pos];
+}
+
+
+int get_basic_mle_link_id(const u8 *buf, size_t len)
+{
+	struct ieee80211_eht_ml *ml = (struct ieee80211_eht_ml *) buf;
+	u16 ctrl;
+	size_t link_id_pos =
+		MULTI_LINK_CONTROL_LEN + /* Multi-Link Control field */
+		1 + /* Common Info Length field (Basic) */
+		ETH_ALEN; /* MLD MAC Address field (Basic) */
+	size_t common_info_limit;
+	u8 common_info_len;
+
+	if (len < MULTI_LINK_CONTROL_LEN)
+		return -1;
+
+	ctrl = le_to_host16(ml->ml_control);
+	if ((ctrl & MULTI_LINK_CONTROL_TYPE_MASK) !=
+	    MULTI_LINK_CONTROL_TYPE_BASIC)
+		return -1;
+
+	/* Validate Common Info Length against available data */
+	common_info_len = buf[MULTI_LINK_CONTROL_LEN];
+	if (len < (size_t) MULTI_LINK_CONTROL_LEN + common_info_len)
+		return -1;
+	common_info_limit = MULTI_LINK_CONTROL_LEN + common_info_len;
+
+	if (!(ctrl & BASIC_MULTI_LINK_CTRL_PRES_LINK_ID))
+		return -1;
+
+	if (link_id_pos + EHT_ML_LINK_ID_LEN > common_info_limit)
+		return -1;
+
+	return buf[link_id_pos] & BASIC_MLE_STA_CTRL_LINK_ID_MASK;
+}
diff --git a/src/common/ieee802_11_common.h b/src/common/ieee802_11_common.h
index 906c13854..af011a357 100644
--- a/src/common/ieee802_11_common.h
+++ b/src/common/ieee802_11_common.h
@@ -387,5 +387,7 @@ size_t ieee802_11_defrag_mle_subelem(struct wpabuf *mlbuf,
 				     size_t *defrag_len);
 const u8 * get_ml_ie(const u8 *ies, size_t len, u8 type);
 const u8 * get_basic_mle_mld_addr(const u8 *buf, size_t len);
+const u8 * get_basic_mle_eml_capa(const u8 *buf, size_t len);
+int get_basic_mle_link_id(const u8 *buf, size_t len);
 
 #endif /* IEEE802_11_COMMON_H */
diff --git a/src/common/ieee802_11_defs.h b/src/common/ieee802_11_defs.h
index 1d803660c..d969f0503 100644
--- a/src/common/ieee802_11_defs.h
+++ b/src/common/ieee802_11_defs.h
@@ -2859,6 +2859,12 @@ struct eht_ml_basic_common_info {
 	u8 variable[];
 } STRUCT_PACKED;
 
+/* Length of the EML Capabilities field in the Common Info field (in octets) */
+#define EHT_ML_EML_CAPA_LEN  2
+
+/* Length of the Link ID Info field in the Common Info field (in octets) */
+#define EHT_ML_LINK_ID_LEN  1
+
 #define EHT_ML_LINK_ID_MSK   0x0f
 
 #define EHT_ML_MEDIUM_SYNC_DELAY_DURATION   0x00ff