hostapd: report bssid, ssid and channel over ubus

Imports a function from iw to convert frequencies to channel numbers.

Co-authored-by: David Bauer <mail@david-bauer.net>
Signed-off-by: Martin Weinelt <hexa@darmstadt.ccc.de>
[fix potential out of bounds read]
Signed-off-by: David Bauer <mail@david-bauer.net>

package/network/services/hostapd/src/src/ap/ubus.c

@@ -372,6 +372,32 @@ hostapd_bss_get_features(struct ubus_context *ctx, struct ubus_object *obj,
 	return 0;
 }
 
+/* Imported from iw/util.c
+ *  https://git.kernel.org/pub/scm/linux/kernel/git/jberg/iw.git/tree/util.c?id=4b25ae3537af48dbf9d0abf94132e5ba01b32c18#n200
+ */
+int ieee80211_frequency_to_channel(int freq)
+{
+	/* see 802.11-2007 17.3.8.3.2 and Annex J */
+	if (freq == 2484)
+		return 14;
+	/* see 802.11ax D6.1 27.3.23.2 and Annex E */
+	else if (freq == 5935)
+		return 2;
+	else if (freq < 2484)
+		return (freq - 2407) / 5;
+	else if (freq >= 4910 && freq <= 4980)
+		return (freq - 4000) / 5;
+	else if (freq < 5950)
+		return (freq - 5000) / 5;
+	else if (freq <= 45000) /* DMG band lower limit */
+		/* see 802.11ax D6.1 27.3.23.2 */
+		return (freq - 5950) / 5;
+	else if (freq >= 58320 && freq <= 70200)
+		return (freq - 56160) / 2160;
+	else
+		return 0;
+}
+
 static int
 hostapd_bss_get_status(struct ubus_context *ctx, struct ubus_object *obj,
 		       struct ubus_request_data *req, const char *method,
@@ -380,12 +406,24 @@ hostapd_bss_get_status(struct ubus_context *ctx, struct ubus_object *obj,
 	struct hostapd_data *hapd = container_of(obj, struct hostapd_data, ubus.obj);
 	void *airtime_table, *dfs_table;
 	struct os_reltime now;
+	char ssid[SSID_MAX_LEN + 1];
 	char phy_name[17];
 	char mac_buf[20];
+	size_t ssid_len = SSID_MAX_LEN;
+
+	if (hapd->conf->ssid.ssid_len < SSID_MAX_LEN)
+		ssid_len = hapd->conf->ssid.ssid_len;
 
 	blob_buf_init(&b, 0);
 	blobmsg_add_string(&b, "status", hostapd_state_text(hapd->iface->state));
+	blobmsg_printf(&b, "bssid", MACSTR, MAC2STR(hapd->conf->bssid));
+
+	memset(ssid, 0, SSID_MAX_LEN + 1);
+	memcpy(ssid, hapd->conf->ssid.ssid, ssid_len);
+	blobmsg_add_string(&b, "ssid", ssid);
+
 	blobmsg_add_u32(&b, "freq", hapd->iface->freq);
+	blobmsg_add_u32(&b, "channel", ieee80211_frequency_to_channel(hapd->iface->freq));
 
 	snprintf(phy_name, 17, "%s", hapd->iface->phy);
 	blobmsg_add_string(&b, "phy", phy_name);