Add option to ignore Probe Request frames on 2.4 GHz from dualband STA

The new no_probe_resp_if_seen_on=<ifname> parameter can now be used to
configure hostapd to not reply to group-addressed Probe Request from a
station that was seen on another radio.

This can be used with enabled track_sta_max_num configuration on another
interface controlled by the same hostapd process to restrict Probe
Request frame handling from replying to group-addressed Probe Request
frames from a station that has been detected to be capable of operating
on another band, e.g., to try to reduce likelihood of the station
selecting a 2.4 GHz BSS when the AP operates both a 2.4 GHz and 5 GHz
BSS concurrently.

Note: Enabling this can cause connectivity issues and increase latency
for discovering the AP.

Signed-off-by: Jouni Malinen <j@w1.fi>

src/ap/ap_config.c

@@ -566,6 +566,8 @@ void hostapd_config_free_bss(struct hostapd_bss_config *conf)
 	wpabuf_free(conf->own_ie_override);
 #endif /* CONFIG_TESTING_OPTIONS */
 
+	os_free(conf->no_probe_resp_if_seen_on);
+
 	os_free(conf);
 }