AP: Support building Basic Multi-Link element

Define a struct to hold MLD station info and implement publishing of the
Basic Multi-Link element. Add it into Beacon and Probe Response frames.

Signed-off-by: Andrei Otcheretianski <andrei.otcheretianski@intel.com>

src/ap/beacon.c

@@ -605,6 +605,14 @@ static u8 * hostapd_gen_probe_resp(struct hostapd_data *hapd,
 		buflen += 3 + sizeof(struct ieee80211_eht_operation);
 		if (hapd->iconf->punct_bitmap)
 			buflen += EHT_OPER_DISABLED_SUBCHAN_BITMAP_SIZE;
+
+		/*
+		 * TODO: Multi-Link element has variable length and can be
+		 * long based on the common info and number of per
+		 * station profiles. For now use 256.
+		 */
+		if (hapd->conf->mld_ap)
+			buflen += 256;
 	}
 #endif /* CONFIG_IEEE80211BE */
 
@@ -755,6 +763,8 @@ static u8 * hostapd_gen_probe_resp(struct hostapd_data *hapd,
 
 #ifdef CONFIG_IEEE80211BE
 	if (hapd->iconf->ieee80211be && !hapd->conf->disable_11be) {
+		if (hapd->conf->mld_ap)
+			pos = hostapd_eid_eht_basic_ml(hapd, pos, NULL, true);
 		pos = hostapd_eid_eht_capab(hapd, pos, IEEE80211_MODE_AP);
 		pos = hostapd_eid_eht_operation(hapd, pos);
 	}
@@ -1711,6 +1721,14 @@ int ieee802_11_build_ap_params(struct hostapd_data *hapd,
 		tail_len += 3 + sizeof(struct ieee80211_eht_operation);
 		if (hapd->iconf->punct_bitmap)
 			tail_len += EHT_OPER_DISABLED_SUBCHAN_BITMAP_SIZE;
+
+		/*
+		 * TODO: Multi-Link element has variable length and can be
+		 * long based on the common info and number of per
+		 * station profiles. For now use 256.
+		 */
+		if (hapd->conf->mld_ap)
+			tail_len += 256;
 	}
 #endif /* CONFIG_IEEE80211BE */
 
@@ -1881,6 +1899,9 @@ int ieee802_11_build_ap_params(struct hostapd_data *hapd,
 
 #ifdef CONFIG_IEEE80211BE
 	if (hapd->iconf->ieee80211be && !hapd->conf->disable_11be) {
+		if (hapd->conf->mld_ap)
+			tailpos = hostapd_eid_eht_basic_ml(hapd, tailpos, NULL,
+							   true);
 		tailpos = hostapd_eid_eht_capab(hapd, tailpos,
 						IEEE80211_MODE_AP);
 		tailpos = hostapd_eid_eht_operation(hapd, tailpos);

src/ap/hostapd.c

@@ -4260,3 +4260,26 @@ void hostapd_ocv_check_csa_sa_query(void *eloop_ctx, void *timeout_ctx)
 	}
 }
 #endif /* CONFIG_OCV */
+
+
+#ifdef CONFIG_IEEE80211BE
+struct hostapd_data * hostapd_mld_get_link_bss(struct hostapd_data *hapd,
+					       u8 link_id)
+{
+	unsigned int i;
+
+	for (i = 0; i < hapd->iface->interfaces->count; i++) {
+		struct hostapd_iface *h = hapd->iface->interfaces->iface[i];
+		struct hostapd_data *h_hapd = h->bss[0];
+		struct hostapd_bss_config *hconf = h_hapd->conf;
+
+		if (!hconf->mld_ap || hconf->mld_id != hapd->conf->mld_id)
+			continue;
+
+		if (h_hapd->mld_link_id == link_id)
+			return h_hapd;
+	}
+
+	return NULL;
+}
+#endif /* CONFIG_IEEE80211BE */

src/ap/hostapd.h

@@ -764,5 +764,7 @@ void fst_hostapd_fill_iface_obj(struct hostapd_data *hapd,
 int hostapd_set_acl(struct hostapd_data *hapd);
 struct hostapd_data * hostapd_mbssid_get_tx_bss(struct hostapd_data *hapd);
 int hostapd_mbssid_get_bss_index(struct hostapd_data *hapd);
+struct hostapd_data * hostapd_mld_get_link_bss(struct hostapd_data *hapd,
+					       u8 link_id);
 
 #endif /* HOSTAPD_H */

src/ap/ieee802_11.h

@@ -84,6 +84,8 @@ void hostapd_get_eht_capab(struct hostapd_data *hapd,
 			   const struct ieee80211_eht_capabilities *src,
 			   struct ieee80211_eht_capabilities *dest,
 			   size_t len);
+u8 * hostapd_eid_eht_basic_ml(struct hostapd_data *hapd, u8 *eid,
+			      struct sta_info *info, bool include_mld_id);
 int hostapd_get_aid(struct hostapd_data *hapd, struct sta_info *sta);
 u16 copy_sta_ht_capab(struct hostapd_data *hapd, struct sta_info *sta,
 		      const u8 *ht_capab);

src/ap/ieee802_11_eht.c

@@ -417,3 +417,207 @@ void hostapd_get_eht_capab(struct hostapd_data *hapd,
 	os_memset(dest, 0, sizeof(*dest));
 	os_memcpy(dest, src, len);
 }
+
+
+u8 * hostapd_eid_eht_basic_ml(struct hostapd_data *hapd, u8 *eid,
+			      struct sta_info *info, bool include_mld_id)
+{
+	struct wpabuf *buf;
+	u16 control;
+	u8 *pos = eid;
+	const u8 *ptr;
+	size_t len, slice_len;
+	u8 link_id;
+	u8 common_info_len;
+
+	/*
+	 * As the Multi-Link element can exceed the size of 255 bytes need to
+	 * first build it and then handle fragmentation.
+	 */
+	buf = wpabuf_alloc(1024);
+	if (!buf)
+		return pos;
+
+	/* Multi-Link Control field */
+	control = MULTI_LINK_CONTROL_TYPE_BASIC |
+		BASIC_MULTI_LINK_CTRL_PRES_LINK_ID |
+		BASIC_MULTI_LINK_CTRL_PRES_BSS_PARAM_CH_COUNT |
+		BASIC_MULTI_LINK_CTRL_PRES_EML_CAPA |
+		BASIC_MULTI_LINK_CTRL_PRES_MLD_CAPA;
+
+	/*
+	 * Set the basic Multi-Link common information. Hard code the common
+	 * info length to 13 based on the length of the present fields:
+	 * Length (1) + MLD address (6) + Link ID (1) +
+	 * BSS Parameters Change Count (1) + EML Capabilities (2) +
+	 * MLD Capabilities and Operations (2)
+	 */
+	common_info_len = 13;
+
+	if (include_mld_id) {
+		/* AP MLD ID */
+		control |= BASIC_MULTI_LINK_CTRL_PRES_AP_MLD_ID;
+		common_info_len++;
+	}
+
+	wpabuf_put_le16(buf, control);
+
+	wpabuf_put_u8(buf, common_info_len);
+
+	/* Own MLD MAC Address */
+	wpabuf_put_data(buf, hapd->mld_addr, ETH_ALEN);
+
+	/* Own Link ID */
+	wpabuf_put_u8(buf, hapd->mld_link_id);
+
+	/* Currently hard code the BSS Parameters Change Count to 0x1 */
+	wpabuf_put_u8(buf, 0x1);
+
+	wpa_printf(MSG_DEBUG, "MLD: EML Capabilities=0x%x",
+		   hapd->iface->mld_eml_capa);
+	wpabuf_put_le16(buf, hapd->iface->mld_eml_capa);
+
+	wpa_printf(MSG_DEBUG, "MLD: MLD Capabilities and Operations=0x%x",
+		   hapd->iface->mld_mld_capa);
+	wpabuf_put_le16(buf, hapd->iface->mld_mld_capa);
+
+	if (include_mld_id) {
+		wpa_printf(MSG_DEBUG, "MLD: AP MLD ID=0x%x",
+			   hapd->conf->mld_id);
+		wpabuf_put_u8(buf, hapd->conf->mld_id);
+	}
+
+	if (!info)
+		goto out;
+
+	/* Add link info for the other links */
+	for (link_id = 0; link_id < MAX_NUM_MLD_LINKS; link_id++) {
+		struct mld_link_info *link = &info->mld_info.links[link_id];
+		struct hostapd_data *link_bss;
+
+		/*
+		 * control (2) + station info length (1) + MAC address (6) +
+		 * beacon interval (2) + TSF offset (8) + DTIM info (2) + BSS
+		 * parameters change counter (1) + station profile length.
+		 */
+		const size_t fixed_len = 22;
+		size_t total_len = fixed_len + link->resp_sta_profile_len;
+
+		/* Skip the local one */
+		if (link_id == hapd->mld_link_id || !link->valid)
+			continue;
+
+		link_bss = hostapd_mld_get_link_bss(hapd, link_id);
+		if (!link_bss) {
+			wpa_printf(MSG_ERROR,
+				   "MLD: Couldn't find link BSS - skip it");
+			continue;
+		}
+
+		/* Per-STA Profile subelement */
+		wpabuf_put_u8(buf, EHT_ML_SUB_ELEM_PER_STA_PROFILE);
+
+		if (total_len <= 255)
+			wpabuf_put_u8(buf, total_len);
+		else
+			wpabuf_put_u8(buf, 255);
+
+		/* STA Control */
+		control = (link_id & 0xf) |
+			EHT_PER_STA_CTRL_MAC_ADDR_PRESENT_MSK |
+			EHT_PER_STA_CTRL_COMPLETE_PROFILE_MSK |
+			EHT_PER_STA_CTRL_TSF_OFFSET_PRESENT_MSK |
+			EHT_PER_STA_CTRL_BEACON_INTERVAL_PRESENT_MSK |
+			EHT_PER_STA_CTRL_DTIM_INFO_PRESENT_MSK |
+			EHT_PER_STA_CTRL_BSS_PARAM_CNT_PRESENT_MSK;
+		wpabuf_put_le16(buf, control);
+
+		/* STA Info */
+
+		/* STA Info Length */
+		wpabuf_put_u8(buf, fixed_len - 2);
+		wpabuf_put_data(buf, link->local_addr, ETH_ALEN);
+		wpabuf_put_le16(buf, link_bss->iconf->beacon_int);
+
+		/* TSF Offset */
+		/*
+		 * TODO: Currently setting TSF offset to zero. However, this
+		 * information needs to come from the driver.
+		 */
+		wpabuf_put_le64(buf, 0);
+
+		/* DTIM Info */
+		wpabuf_put_le16(buf, link_bss->conf->dtim_period);
+
+		/* BSS Parameters Change Count */
+		/* TODO: Currently hard code the BSS Parameters Change Count to
+		 * 0x1 */
+		wpabuf_put_u8(buf, 0x1);
+
+		/* Fragment the sub element if needed */
+		if (total_len <= 255) {
+			wpabuf_put_data(buf, link->resp_sta_profile,
+					link->resp_sta_profile_len);
+		} else {
+			ptr = link->resp_sta_profile;
+			len = link->resp_sta_profile_len;
+
+			slice_len = 255 - fixed_len;
+
+			wpabuf_put_data(buf, ptr, slice_len);
+			len -= slice_len;
+			ptr += slice_len;
+
+			while (len) {
+				if (len <= 255)
+					slice_len = len;
+				else
+					slice_len = 255;
+
+				wpabuf_put_u8(buf, EHT_ML_SUB_ELEM_FRAGMENT);
+				wpabuf_put_u8(buf, slice_len);
+				wpabuf_put_data(buf, ptr, slice_len);
+
+				len -= slice_len;
+				ptr += slice_len;
+			}
+		}
+	}
+
+out:
+	/* Fragment the Multi-Link element, if needed */
+	len = wpabuf_len(buf);
+	ptr = wpabuf_head(buf);
+
+	if (len <= 254)
+		slice_len = len;
+	else
+		slice_len = 254;
+
+	*pos++ = WLAN_EID_EXTENSION;
+	*pos++ = slice_len + 1;
+	*pos++ = WLAN_EID_EXT_MULTI_LINK;
+	os_memcpy(pos, ptr, slice_len);
+
+	ptr += slice_len;
+	pos += slice_len;
+	len -= slice_len;
+
+	while (len) {
+		if (len <= 255)
+			slice_len = len;
+		else
+			slice_len = 255;
+
+		*pos++ = WLAN_EID_FRAGMENT;
+		*pos++ = slice_len;
+		os_memcpy(pos, ptr, slice_len);
+
+		ptr += slice_len;
+		pos += slice_len;
+		len -= slice_len;
+	}
+
+	wpabuf_free(buf);
+	return pos;
+}

src/ap/sta_info.h

@@ -69,6 +69,35 @@ struct pending_eapol_rx {
 	enum frame_encryption encrypted;
 };
 
+#define EHT_ML_MAX_STA_PROF_LEN 1024
+struct mld_info {
+	bool mld_sta;
+
+	struct ml_common_info {
+		u8 mld_addr[ETH_ALEN];
+		u16 medium_sync_delay;
+		u16 eml_capa;
+		u16 mld_capa;
+	} common_info;
+
+	struct mld_link_info {
+		u8 valid;
+		u8 local_addr[ETH_ALEN];
+		u8 peer_addr[ETH_ALEN];
+
+		size_t nstr_bitmap_len;
+		u8 nstr_bitmap[2];
+
+		u16 capability;
+
+		u16 status;
+		size_t resp_sta_profile_len;
+		u8 resp_sta_profile[EHT_ML_MAX_STA_PROF_LEN];
+
+		const u8 *rsne, *rsnxe;
+	} links[MAX_NUM_MLD_LINKS];
+};
+
 struct sta_info {
 	struct sta_info *next; /* next entry in sta list */
 	struct sta_info *hnext; /* next entry in hash table list */
@@ -299,6 +328,11 @@ struct sta_info {
 #ifdef CONFIG_PASN
 	struct pasn_data *pasn;
 #endif /* CONFIG_PASN */
+
+#ifdef CONFIG_IEEE80211BE
+	struct mld_info mld_info;
+	u8 mld_assoc_link_id;
+#endif /* CONFIG_IEEE80211BE */
 };
 
 

src/common/ieee802_11_defs.h

@@ -2660,6 +2660,16 @@ struct eht_ml_basic_common_info {
 #define EHT_ML_MLD_CAPA_FREQ_SEP_FOR_STR_MASK         0x0f80
 #define EHT_ML_MLD_CAPA_AAR_SUPP                      0x1000
 
+#define EHT_PER_STA_CTRL_LINK_ID_MSK                  0x000f
+#define EHT_PER_STA_CTRL_COMPLETE_PROFILE_MSK         0x0010
+#define EHT_PER_STA_CTRL_MAC_ADDR_PRESENT_MSK         0x0020
+#define EHT_PER_STA_CTRL_BEACON_INTERVAL_PRESENT_MSK  0x0040
+#define EHT_PER_STA_CTRL_TSF_OFFSET_PRESENT_MSK       0x0080
+#define EHT_PER_STA_CTRL_DTIM_INFO_PRESENT_MSK        0x0100
+#define EHT_PER_STA_CTRL_NSTR_LINK_PAIR_PRESENT_MSK   0x0200
+#define EHT_PER_STA_CTRL_NSTR_BM_SIZE_MSK             0x0400
+#define EHT_PER_STA_CTRL_BSS_PARAM_CNT_PRESENT_MSK    0x0800
+
 /* IEEE P802.11be/D2.0, 9.4.2.312.2.4 - Per-STA Profile subelement format */
 struct ieee80211_eht_per_sta_profile {
 	le16 sta_control;