OCE: Add RSSI based association rejection support (AP)

An AP might reject a STA association request due to low RSSI. In such
case, the AP informs the STA the desired RSSI improvement and a retry
timeout. The STA might retry to associate even if the RSSI hasn't
improved if the retry timeout expired.

Signed-off-by: Beni Lev <beni.lev@intel.com>

hostapd/config_file.c

@@ -4156,6 +4156,10 @@ static int hostapd_config_fill(struct hostapd_config *conf,
 		}
 
 		bss->multi_ap = val;
+	} else if (os_strcmp(buf, "rssi_reject_assoc_rssi") == 0) {
+		conf->rssi_reject_assoc_rssi = atoi(pos);
+	} else if (os_strcmp(buf, "rssi_reject_assoc_timeout") == 0) {
+		conf->rssi_reject_assoc_timeout = atoi(pos);
 	} else {
 		wpa_printf(MSG_ERROR,
 			   "Line %d: unknown configuration item '%s'",

hostapd/hostapd.conf

@@ -2295,6 +2295,21 @@ own_ip_addr=127.0.0.1
 # Default is 0 = OCE disabled
 #oce=0
 
+# RSSI-based assocition rejection
+#
+# Reject STA association if RSSI is below given threshold (in dBm)
+# Allowed range: -60 to -90 dBm; default = 0 (rejection disabled)
+# Note: This rejection happens based on a signal strength detected while
+# receiving a single frame and as such, there is significant risk of the value
+# not being accurate and this resulting in valid stations being rejected. As
+# such, this functionality is not recommended to be used for purposes other than
+# testing.
+#rssi_reject_assoc_rssi=-75
+#
+# Association retry delay in seconds allowed by the STA if RSSI has not met the
+# threshold (range: 0..255, default=30).
+#rssi_reject_assoc_timeout=30
+
 ##### Fast Session Transfer (FST) support #####################################
 #
 # The options in this section are only available when the build configuration

src/ap/ap_config.c

@@ -241,6 +241,9 @@ struct hostapd_config * hostapd_config_defaults(void)
 	 * environments for the current frequency band in the country. */
 	conf->country[2] = ' ';
 
+	conf->rssi_reject_assoc_rssi = 0;
+	conf->rssi_reject_assoc_timeout = 30;
+
 	return conf;
 }
 

src/ap/ap_config.h

@@ -849,6 +849,9 @@ struct hostapd_config {
 #define CH_SWITCH_VHT_ENABLED BIT(0)
 #define CH_SWITCH_VHT_DISABLED BIT(1)
 	unsigned int ch_switch_vht_config;
+
+	int rssi_reject_assoc_rssi;
+	int rssi_reject_assoc_timeout;
 };
 
 

src/ap/ieee802_11.c

@@ -2976,7 +2976,7 @@ static int add_associated_sta(struct hostapd_data *hapd,
 
 static u16 send_assoc_resp(struct hostapd_data *hapd, struct sta_info *sta,
 			   const u8 *addr, u16 status_code, int reassoc,
-			   const u8 *ies, size_t ies_len)
+			   const u8 *ies, size_t ies_len, int rssi)
 {
 	int send_len;
 	u8 *buf;
@@ -3021,6 +3021,16 @@ static u16 send_assoc_resp(struct hostapd_data *hapd, struct sta_info *sta,
 	/* Extended supported rates */
 	p = hostapd_eid_ext_supp_rates(hapd, p);
 
+#ifdef CONFIG_MBO
+	if (status_code == WLAN_STATUS_DENIED_POOR_CHANNEL_CONDITIONS &&
+	    rssi != 0) {
+		int delta = hapd->iconf->rssi_reject_assoc_rssi - rssi;
+
+		p = hostapd_eid_mbo_rssi_assoc_rej(hapd, p, buf + buflen - p,
+						   delta);
+	}
+#endif /* CONFIG_MBO */
+
 #ifdef CONFIG_IEEE80211R_AP
 	if (sta && status_code == WLAN_STATUS_SUCCESS) {
 		/* IEEE 802.11r: Mobility Domain Information, Fast BSS
@@ -3292,7 +3302,7 @@ void fils_hlp_finish_assoc(struct hostapd_data *hapd, struct sta_info *sta)
 	reply_res = send_assoc_resp(hapd, sta, sta->addr, WLAN_STATUS_SUCCESS,
 				    sta->fils_pending_assoc_is_reassoc,
 				    sta->fils_pending_assoc_req,
-				    sta->fils_pending_assoc_req_len);
+				    sta->fils_pending_assoc_req_len, 0);
 	os_free(sta->fils_pending_assoc_req);
 	sta->fils_pending_assoc_req = NULL;
 	sta->fils_pending_assoc_req_len = 0;
@@ -3329,7 +3339,7 @@ void fils_hlp_timeout(void *eloop_ctx, void *eloop_data)
 
 static void handle_assoc(struct hostapd_data *hapd,
 			 const struct ieee80211_mgmt *mgmt, size_t len,
-			 int reassoc)
+			 int reassoc, int rssi)
 {
 	u16 capab_info, listen_interval, seq_ctrl, fc;
 	u16 resp = WLAN_STATUS_SUCCESS, reply_res;
@@ -3512,6 +3522,12 @@ static void handle_assoc(struct hostapd_data *hapd,
 		resp = WLAN_STATUS_AP_UNABLE_TO_HANDLE_NEW_STA;
 		goto fail;
 	}
+
+	if (hapd->iconf->rssi_reject_assoc_rssi && rssi &&
+	    rssi < hapd->iconf->rssi_reject_assoc_rssi) {
+		resp = WLAN_STATUS_DENIED_POOR_CHANNEL_CONDITIONS;
+		goto fail;
+	}
 #endif /* CONFIG_MBO */
 
 	/*
@@ -3710,7 +3726,7 @@ static void handle_assoc(struct hostapd_data *hapd,
 #endif /* CONFIG_FILS */
 
 	reply_res = send_assoc_resp(hapd, sta, mgmt->sa, resp, reassoc, pos,
-				    left);
+				    left, rssi);
 	os_free(tmp);
 
 	/*
@@ -4155,12 +4171,12 @@ int ieee802_11_mgmt(struct hostapd_data *hapd, const u8 *buf, size_t len,
 		break;
 	case WLAN_FC_STYPE_ASSOC_REQ:
 		wpa_printf(MSG_DEBUG, "mgmt::assoc_req");
-		handle_assoc(hapd, mgmt, len, 0);
+		handle_assoc(hapd, mgmt, len, 0, ssi_signal);
 		ret = 1;
 		break;
 	case WLAN_FC_STYPE_REASSOC_REQ:
 		wpa_printf(MSG_DEBUG, "mgmt::reassoc_req");
-		handle_assoc(hapd, mgmt, len, 1);
+		handle_assoc(hapd, mgmt, len, 1, ssi_signal);
 		ret = 1;
 		break;
 	case WLAN_FC_STYPE_DISASSOC:

src/ap/ieee802_11.h

@@ -122,6 +122,9 @@ u8 * hostapd_eid_mbo(struct hostapd_data *hapd, u8 *eid, size_t len);
 
 u8 hostapd_mbo_ie_len(struct hostapd_data *hapd);
 
+u8 * hostapd_eid_mbo_rssi_assoc_rej(struct hostapd_data *hapd, u8 *eid,
+				    size_t len, int delta);
+
 #else /* CONFIG_MBO */
 
 static inline u8 * hostapd_eid_mbo(struct hostapd_data *hapd, u8 *eid,

src/ap/ieee802_11_shared.c

@@ -682,6 +682,22 @@ u8 * hostapd_eid_bss_max_idle_period(struct hostapd_data *hapd, u8 *eid)
 
 #ifdef CONFIG_MBO
 
+u8 * hostapd_eid_mbo_rssi_assoc_rej(struct hostapd_data *hapd, u8 *eid,
+				    size_t len, int delta)
+{
+	u8 mbo[4];
+
+	mbo[0] = OCE_ATTR_ID_RSSI_BASED_ASSOC_REJECT;
+	mbo[1] = 2;
+	/* Delta RSSI */
+	mbo[2] = delta;
+	/* Retry delay */
+	mbo[3] = hapd->iconf->rssi_reject_assoc_timeout;
+
+	return eid + mbo_add_ie(eid, len, mbo, 4);
+}
+
+
 u8 * hostapd_eid_mbo(struct hostapd_data *hapd, u8 *eid, size_t len)
 {
 	u8 mbo[9], *mbo_pos = mbo;