hostapd: Use stations nsts capability in (Re)Association Response frame

Some deployed stations incorrectly consider nsts capability in
(Re)Association Response frame as required capability instead of maximum
capability and if it is greater than station's capability then beamform
will not happen in uplink traffic.

This commit adds support for an optional workaround to use station's
nsts capability in (Re)Association Response frame if the station's nsts
is less than AP by using the use_sta_nsts=1 configuration parameter.
This configuration is introduced in this commit and it is disabled by
default.

Signed-off-by: Tamizh chelvam <c_traja@qti.qualcomm.com>

hostapd/config_file.c

@@ -2895,6 +2895,8 @@ static int hostapd_config_fill(struct hostapd_config *conf,
 		conf->vht_oper_centr_freq_seg1_idx = atoi(pos);
 	} else if (os_strcmp(buf, "vendor_vht") == 0) {
 		bss->vendor_vht = atoi(pos);
+	} else if (os_strcmp(buf, "use_sta_nsts") == 0) {
+		bss->use_sta_nsts = atoi(pos);
 #endif /* CONFIG_IEEE80211AC */
 	} else if (os_strcmp(buf, "max_listen_interval") == 0) {
 		bss->max_listen_interval = atoi(pos);

hostapd/hostapd.conf

@@ -685,6 +685,13 @@ wmm_ac_vo_acm=0
 #
 #vht_oper_centr_freq_seg1_idx=159
 
+# Workaround to use station's nsts capability in (Re)Association Response frame
+# This may be needed with some deployed devices as an interoperability
+# workaround for beamforming if the AP's capability is greater than the
+# station's capability. This is disabled by default and can be enabled by
+# setting use_sta_nsts=1.
+#use_sta_nsts=0
+
 ##### IEEE 802.1X-2004 related configuration ##################################
 
 # Require IEEE 802.1X authorization

src/ap/ap_config.h

@@ -582,6 +582,7 @@ struct hostapd_bss_config {
 	u8 radio_measurements[RRM_CAPABILITIES_IE_LEN];
 
 	int vendor_vht;
+	int use_sta_nsts;
 
 	char *no_probe_resp_if_seen_on;
 	char *no_auth_if_seen_on;

src/ap/beacon.c

@@ -485,7 +485,7 @@ static u8 * hostapd_gen_probe_resp(struct hostapd_data *hapd,
 
 #ifdef CONFIG_IEEE80211AC
 	if (hapd->iconf->ieee80211ac && !hapd->conf->disable_11ac) {
-		pos = hostapd_eid_vht_capabilities(hapd, pos);
+		pos = hostapd_eid_vht_capabilities(hapd, pos, 0);
 		pos = hostapd_eid_vht_operation(hapd, pos);
 		pos = hostapd_eid_txpower_envelope(hapd, pos);
 		pos = hostapd_eid_wb_chsw_wrapper(hapd, pos);
@@ -1105,7 +1105,7 @@ int ieee802_11_build_ap_params(struct hostapd_data *hapd,
 
 #ifdef CONFIG_IEEE80211AC
 	if (hapd->iconf->ieee80211ac && !hapd->conf->disable_11ac) {
-		tailpos = hostapd_eid_vht_capabilities(hapd, tailpos);
+		tailpos = hostapd_eid_vht_capabilities(hapd, tailpos, 0);
 		tailpos = hostapd_eid_vht_operation(hapd, tailpos);
 		tailpos = hostapd_eid_txpower_envelope(hapd, tailpos);
 		tailpos = hostapd_eid_wb_chsw_wrapper(hapd, tailpos);

src/ap/ieee802_11.c

@@ -1944,7 +1944,23 @@ static u16 send_assoc_resp(struct hostapd_data *hapd, struct sta_info *sta,
 
 #ifdef CONFIG_IEEE80211AC
 	if (hapd->iconf->ieee80211ac && !hapd->conf->disable_11ac) {
-		p = hostapd_eid_vht_capabilities(hapd, p);
+		u32 nsts = 0, sta_nsts;
+
+		if (hapd->conf->use_sta_nsts && sta->vht_capabilities) {
+			struct ieee80211_vht_capabilities *capa;
+
+			nsts = (hapd->iface->conf->vht_capab >>
+				VHT_CAP_BEAMFORMEE_STS_OFFSET) & 7;
+			capa = sta->vht_capabilities;
+			sta_nsts = (le_to_host32(capa->vht_capabilities_info) >>
+				    VHT_CAP_BEAMFORMEE_STS_OFFSET) & 7;
+
+			if (nsts < sta_nsts)
+				nsts = 0;
+			else
+				nsts = sta_nsts;
+		}
+		p = hostapd_eid_vht_capabilities(hapd, p, nsts);
 		p = hostapd_eid_vht_operation(hapd, p);
 	}
 #endif /* CONFIG_IEEE80211AC */

src/ap/ieee802_11.h

@@ -50,7 +50,7 @@ u8 * hostapd_eid_ext_supp_rates(struct hostapd_data *hapd, u8 *eid);
 u8 * hostapd_eid_ht_capabilities(struct hostapd_data *hapd, u8 *eid);
 u8 * hostapd_eid_ht_operation(struct hostapd_data *hapd, u8 *eid);
 u8 * hostapd_eid_secondary_channel(struct hostapd_data *hapd, u8 *eid);
-u8 * hostapd_eid_vht_capabilities(struct hostapd_data *hapd, u8 *eid);
+u8 * hostapd_eid_vht_capabilities(struct hostapd_data *hapd, u8 *eid, u32 nsts);
 u8 * hostapd_eid_vht_operation(struct hostapd_data *hapd, u8 *eid);
 u8 * hostapd_eid_vendor_vht(struct hostapd_data *hapd, u8 *eid);
 u8 * hostapd_eid_wb_chsw_wrapper(struct hostapd_data *hapd, u8 *eid);

src/ap/ieee802_11_vht.c

@@ -20,7 +20,7 @@
 #include "dfs.h"
 
 
-u8 * hostapd_eid_vht_capabilities(struct hostapd_data *hapd, u8 *eid)
+u8 * hostapd_eid_vht_capabilities(struct hostapd_data *hapd, u8 *eid, u32 nsts)
 {
 	struct ieee80211_vht_capabilities *cap;
 	struct hostapd_hw_modes *mode = hapd->iface->current_mode;
@@ -50,6 +50,18 @@ u8 * hostapd_eid_vht_capabilities(struct hostapd_data *hapd, u8 *eid)
 	cap->vht_capabilities_info = host_to_le32(
 		hapd->iface->conf->vht_capab);
 
+	if (nsts != 0) {
+		u32 hapd_nsts;
+
+		hapd_nsts = le_to_host32(cap->vht_capabilities_info);
+		hapd_nsts = (hapd_nsts >> VHT_CAP_BEAMFORMEE_STS_OFFSET) & 7;
+		cap->vht_capabilities_info &=
+			~(host_to_le32(hapd_nsts <<
+				       VHT_CAP_BEAMFORMEE_STS_OFFSET));
+		cap->vht_capabilities_info |=
+			host_to_le32(nsts << VHT_CAP_BEAMFORMEE_STS_OFFSET);
+	}
+
 	/* Supported MCS set comes from hw */
 	os_memcpy(&cap->vht_supported_mcs_set, mode->vht_mcs_set, 8);
 
@@ -398,7 +410,7 @@ u8 * hostapd_eid_vendor_vht(struct hostapd_data *hapd, u8 *eid)
 	WPA_PUT_BE32(pos, (OUI_BROADCOM << 8) | VENDOR_VHT_TYPE);
 	pos += 4;
 	*pos++ = VENDOR_VHT_SUBTYPE;
-	pos = hostapd_eid_vht_capabilities(hapd, pos);
+	pos = hostapd_eid_vht_capabilities(hapd, pos, 0);
 	pos = hostapd_eid_vht_operation(hapd, pos);
 
 	return pos;

wpa_supplicant/mesh_mpm.c

@@ -348,7 +348,7 @@ static void mesh_mpm_send_plink_action(struct wpa_supplicant *wpa_s,
 	if (type != PLINK_CLOSE && wpa_s->mesh_vht_enabled) {
 		u8 vht_capa_oper[2 + 12 + 2 + 5];
 
-		pos = hostapd_eid_vht_capabilities(bss, vht_capa_oper);
+		pos = hostapd_eid_vht_capabilities(bss, vht_capa_oper, 0);
 		pos = hostapd_eid_vht_operation(bss, pos);
 		wpabuf_put_data(buf, vht_capa_oper, pos - vht_capa_oper);
 	}