DPP2: Fix channel 6 inclusion for chirping with non-2 GHz interfaces

When the driver provides a list of supported modes, hostapd ended up
adding channel 6 even if the 2.4 GHz mode was not included. This
resulted in incorrect behavior of trying to transmit on a not supported
channel in case of 5 GHz only radios.

Fix this by adding the channel 6 by default only if the driver does not
provide a list of supported modes. Whenever the supported modes are
available, only add this channel if it is explicitly listed as an
enabled channel.

This is similar to an earlier wpa_supplicant change in commit
8e5739c3ac ("DPP2: Check channel 6 validity before adding it to chirp
channel list").

Signed-off-by: Disha Das <dishad@codeaurora.org>

src/ap/dpp_hostapd.c

@@ -2387,6 +2387,7 @@ hostapd_dpp_chirp_scan_res_handler(struct hostapd_iface *iface)
 	unsigned int i;
 	struct hostapd_hw_modes *mode;
 	int c;
+	bool chan6 = hapd->iface->hw_features == NULL;
 
 	if (!bi)
 		return;
@@ -2406,7 +2407,21 @@ hostapd_dpp_chirp_scan_res_handler(struct hostapd_iface *iface)
 	}
 
 	/* Preferred chirping channels */
-	int_array_add_unique(&hapd->dpp_chirp_freqs, 2437);
+	mode = dpp_get_mode(hapd, HOSTAPD_MODE_IEEE80211G);
+	if (mode) {
+		for (c = 0; c < mode->num_channels; c++) {
+			struct hostapd_channel_data *chan = &mode->channels[c];
+
+			if (chan->flag & (HOSTAPD_CHAN_DISABLED |
+					  HOSTAPD_CHAN_RADAR) ||
+			    chan->freq != 2437)
+				continue;
+			chan6 = true;
+			break;
+		}
+	}
+	if (chan6)
+		int_array_add_unique(&hapd->dpp_chirp_freqs, 2437);
 
 	mode = dpp_get_mode(hapd, HOSTAPD_MODE_IEEE80211A);
 	if (mode) {