hostapd: Add support to send CW change notification

Add hostapd_cli command to notify channel width change to all
associated STAs.

Notify Channel Width frame for HT STAs.
(IEEE P802.11-REVme/D4.0, 9.6.11.2)

Operating Mode Notification frame for VHT STAs.
(IEEE P802.11-REVme/D4.0, 9.6.22.4)

Usage: hostapd_cli notify_cw_change <channel_width>
<channel_width> = 0 - 20 MHz, 1 - 40 MHz, 2 - 80 MHz, 3 - 160 MHz.

Co-developed-by: Bhagavathi Perumal S <quic_bperumal@quicinc.com>
Signed-off-by: Bhagavathi Perumal S <quic_bperumal@quicinc.com>
Signed-off-by: Vignesh C <quic_vignc@quicinc.com>

hostapd/ctrl_iface.c

@@ -2715,6 +2715,155 @@ static int hostapd_ctrl_iface_chan_switch(struct hostapd_iface *iface,
 }
 
 
+static u8 hostapd_maxnss(struct hostapd_data *hapd, struct sta_info *sta)
+{
+	u8 *mcs_set = NULL;
+	u16 mcs_map;
+	u8 ht_rx_nss = 0;
+	u8 vht_rx_nss = 1;
+	u8 mcs;
+	bool ht_supported = false;
+	bool vht_supported = false;
+	int i;
+
+	if (sta->ht_capabilities && (sta->flags & WLAN_STA_HT)) {
+		mcs_set = sta->ht_capabilities->supported_mcs_set;
+		ht_supported = true;
+	}
+
+	if (sta->vht_capabilities && (sta->flags & WLAN_STA_VHT)) {
+		mcs_map = le_to_host16(
+			sta->vht_capabilities->vht_supported_mcs_set.rx_map);
+		vht_supported = true;
+	}
+
+	if (ht_supported && mcs_set) {
+		if (mcs_set[0])
+			ht_rx_nss++;
+		if (mcs_set[1])
+			ht_rx_nss++;
+		if (mcs_set[2])
+			ht_rx_nss++;
+		if (mcs_set[3])
+			ht_rx_nss++;
+	}
+	if (vht_supported) {
+		for (i = 7; i >= 0; i--) {
+			mcs = (mcs_map >> (2 * i)) & 0x03;
+			if (mcs != 0x03) {
+				vht_rx_nss = i + 1;
+				break;
+			}
+		}
+	}
+
+	return ht_rx_nss > vht_rx_nss ? ht_rx_nss : vht_rx_nss;
+}
+
+
+static char hostapd_ctrl_iface_notify_cw_htaction(struct hostapd_data *hapd,
+						  const u8 *addr, u8 width)
+{
+	u8 buf[3];
+	char ret;
+
+	width = width >= 1 ? 1 : 0;
+
+	buf[0] = WLAN_ACTION_HT;
+	buf[1] = WLAN_HT_ACTION_NOTIFY_CHANWIDTH;
+	buf[2] = width;
+
+	ret = hostapd_drv_send_action(hapd, hapd->iface->freq, 0, addr,
+				      buf, sizeof(buf));
+	if (ret)
+		wpa_printf(MSG_DEBUG,
+			   "Failed to send Notify Channel Width frame to "
+			   MACSTR, MAC2STR(addr));
+
+	return ret;
+}
+
+
+static char hostapd_ctrl_iface_notify_cw_vhtaction(struct hostapd_data *hapd,
+						   const u8 *addr, u8 width)
+{
+	u8 buf[3];
+	char ret;
+
+	buf[0] = WLAN_ACTION_VHT;
+	buf[1] = WLAN_VHT_ACTION_OPMODE_NOTIF;
+	buf[2] = width;
+
+	ret = hostapd_drv_send_action(hapd, hapd->iface->freq, 0, addr,
+				      buf, sizeof(buf));
+	if (ret)
+		wpa_printf(MSG_DEBUG,
+			   "Failed to send Opeating Mode Notification frame to "
+			   MACSTR, MAC2STR(addr));
+
+	return ret;
+}
+
+
+static char hostapd_ctrl_iface_notify_cw_change(struct hostapd_data *hapd,
+						const char *cmd)
+{
+	u8 cw, operating_mode = 0, nss;
+	struct sta_info *sta;
+	enum hostapd_hw_mode hw_mode;
+
+	if (is_6ghz_freq(hapd->iface->freq)) {
+		wpa_printf(MSG_ERROR, "20/40 BSS coex not supported in 6 GHz");
+		return -1;
+	}
+
+	cw = atoi(cmd);
+	hw_mode = hapd->iface->current_mode->mode;
+	if ((hw_mode == HOSTAPD_MODE_IEEE80211G ||
+	     hw_mode == HOSTAPD_MODE_IEEE80211B) &&
+	    !(cw == 0 || cw == 1)) {
+		wpa_printf(MSG_ERROR,
+			   "Channel width should be either 20 MHz or 40 MHz for 2.4 GHz band");
+		return -1;
+	}
+
+	switch (cw) {
+	case 0:
+		operating_mode = 0;
+		break;
+	case 1:
+		operating_mode = VHT_OPMODE_CHANNEL_40MHZ;
+		break;
+	case 2:
+		operating_mode = VHT_OPMODE_CHANNEL_80MHZ;
+		break;
+	case 3:
+		operating_mode = VHT_OPMODE_CHANNEL_160MHZ;
+		break;
+	default:
+		wpa_printf(MSG_ERROR, "Channel width should be between 0 to 3");
+		return -1;
+	}
+
+	for (sta = hapd->sta_list; sta; sta = sta->next) {
+		if ((sta->flags & WLAN_STA_VHT) && sta->vht_capabilities) {
+			nss = hostapd_maxnss(hapd, sta) - 1;
+			hostapd_ctrl_iface_notify_cw_vhtaction(hapd, sta->addr,
+							       operating_mode |
+							       (u8) (nss << 4));
+			continue;
+		}
+
+		if ((sta->flags & (WLAN_STA_HT | WLAN_STA_VHT)) ==
+		    WLAN_STA_HT && sta->ht_capabilities)
+			hostapd_ctrl_iface_notify_cw_htaction(hapd, sta->addr,
+							      cw);
+	}
+
+	return 0;
+}
+
+
 static int hostapd_ctrl_iface_mib(struct hostapd_data *hapd, char *reply,
 				  int reply_size, const char *param)
 {
@@ -3561,6 +3710,9 @@ static int hostapd_ctrl_iface_receive_process(struct hostapd_data *hapd,
 	} else if (os_strncmp(buf, "CHAN_SWITCH ", 12) == 0) {
 		if (hostapd_ctrl_iface_chan_switch(hapd->iface, buf + 12))
 			reply_len = -1;
+	} else if (os_strncmp(buf, "NOTIFY_CW_CHANGE ", 17) == 0) {
+		if (hostapd_ctrl_iface_notify_cw_change(hapd, buf + 17))
+			reply_len = -1;
 	} else if (os_strncmp(buf, "VENDOR ", 7) == 0) {
 		reply_len = hostapd_ctrl_iface_vendor(hapd, buf + 7, reply,
 						      reply_size);

hostapd/hostapd_cli.c

@@ -1207,6 +1207,13 @@ static int hostapd_cli_cmd_chan_switch(struct wpa_ctrl *ctrl,
 }
 
 
+static int hostapd_cli_cmd_notify_cw_change(struct wpa_ctrl *ctrl,
+					    int argc, char *argv[])
+{
+	return hostapd_cli_cmd(ctrl, "NOTIFY_CW_CHANGE", 1, argc, argv);
+}
+
+
 static int hostapd_cli_cmd_enable(struct wpa_ctrl *ctrl, int argc,
 				      char *argv[])
 {
@@ -1679,6 +1686,8 @@ static const struct hostapd_cli_cmd hostapd_cli_commands[] = {
 	  "<cs_count> <freq> [sec_channel_offset=] [center_freq1=]\n"
 	  "  [center_freq2=] [bandwidth=] [blocktx] [ht|vht]\n"
 	  "  = initiate channel switch announcement" },
+	{ "notify_cw_change", hostapd_cli_cmd_notify_cw_change, NULL,
+	  "<channel_width> = 0 - 20 MHz, 1 - 40 MHz, 2 - 80 MHz, 3 - 160 MHz" },
 	{ "hs20_wnm_notif", hostapd_cli_cmd_hs20_wnm_notif, NULL,
 	  "<addr> <url>\n"
 	  "  = send WNM-Notification Subscription Remediation Request" },

src/common/ieee802_11_defs.h

@@ -678,6 +678,19 @@
 #define WLAN_PA_FILS_DISCOVERY 34
 #define WLAN_PA_LOCATION_MEASUREMENT_REPORT 47
 
+/* HT Action field values (IEEE P802.11-REVme/D4.0, 9.6.11.1, Table 9-491) */
+#define WLAN_HT_ACTION_NOTIFY_CHANWIDTH 0
+#define WLAN_HT_ACTION_SMPS 1
+#define WLAN_HT_ACTION_CSI 4
+#define WLAN_HT_ACTION_NONCOMPRESSED_BF 5
+#define WLAN_HT_ACTION_COMPRESSED_BF 6
+#define WLAN_HT_ACTION_ASEL_IDX_FEEDBACK 7
+
+/* VHT Action field values (IEEE P802.11-REVme/D4.0, 9.6.22.1, Table 9-579) */
+#define WLAN_VHT_ACTION_COMPRESSED_BF 0
+#define WLAN_VHT_ACTION_GROUP_ID_MGMT 1
+#define WLAN_VHT_ACTION_OPMODE_NOTIF 2
+
 /* Protected Dual of Public Action frames (IEEE Std 802.11-2016, 9.6.11,
  * Table 9-332) */
 #define WLAN_PROT_DSE_ENABLEMENT 1
@@ -1357,6 +1370,10 @@ struct ieee80211_ampe_ie {
 
 #define VHT_RX_NSS_MAX_STREAMS			    8
 
+#define VHT_OPMODE_CHANNEL_40MHZ		    ((u8) BIT(0))
+#define VHT_OPMODE_CHANNEL_80MHZ		    ((u8) BIT(1))
+#define VHT_OPMODE_CHANNEL_160MHZ		    ((u8) BIT(1) | BIT(2))
+
 /* VHT operation information - channel widths */
 #define CHANWIDTH_USE_HT	0
 #define CHANWIDTH_80MHZ		1