ACS: Fix VHT80 segment picking

For example, the previous implementation considered [44, 48, 52, 56] to
be a valid VHT80 channel -- which it is not. This resulted in, e.g.,
failure to start CAC when channels on overlapped segments included DFS
channels.

Add a check similar to the HT40 one to prevent that. The check is
performed this way as the ACS implementation assumes the primary channel
to be the first channel in a given segment.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>

src/ap/acs.c

@@ -367,6 +367,19 @@ static int acs_usable_ht40_chan(struct hostapd_channel_data *chan)
 }
 
 
+static int acs_usable_vht80_chan(struct hostapd_channel_data *chan)
+{
+	const int allowed[] = { 36, 52, 100, 116, 132, 149 };
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(allowed); i++)
+		if (chan->chan == allowed[i])
+			return 1;
+
+	return 0;
+}
+
+
 static int acs_survey_is_sufficient(struct freq_survey *survey)
 {
 	if (!(survey->filled & SURVEY_HAS_NF)) {
@@ -541,6 +554,15 @@ acs_find_ideal_chan(struct hostapd_iface *iface)
 			continue;
 		}
 
+		if (iface->current_mode->mode == HOSTAPD_MODE_IEEE80211A &&
+		    iface->conf->ieee80211ac &&
+		    iface->conf->vht_oper_chwidth == 1 &&
+		    !acs_usable_vht80_chan(chan)) {
+			wpa_printf(MSG_DEBUG, "ACS: Channel %d: not allowed as primary channel for VHT80",
+				   chan->chan);
+			continue;
+		}
+
 		factor = 0;
 		if (acs_usable_chan(chan))
 			factor = chan->interference_factor;