hostapd: implement fallback for incomplete survey data

Signed-off-by: Felix Fietkau <[email protected]>

package/network/services/hostapd/patches/470-survey_data_fallback.patch

@@ -0,0 +1,45 @@
+--- a/src/ap/acs.c
++++ b/src/ap/acs.c
+@@ -292,18 +292,12 @@ static void acs_fail(struct hostapd_ifac
+ static long double
+ acs_survey_interference_factor(struct freq_survey *survey, s8 min_nf)
+ {
+-	long double factor, busy, total;
++	long double factor, busy = 0, total;
+ 
+ 	if (survey->filled & SURVEY_HAS_CHAN_TIME_BUSY)
+ 		busy = survey->channel_time_busy;
+ 	else if (survey->filled & SURVEY_HAS_CHAN_TIME_RX)
+ 		busy = survey->channel_time_rx;
+-	else {
+-		/* This shouldn't really happen as survey data is checked in
+-		 * acs_sanity_check() */
+-		wpa_printf(MSG_ERROR, "ACS: Survey data missing");
+-		return 0;
+-	}
+ 
+ 	total = survey->channel_time;
+ 
+@@ -395,20 +389,19 @@ static int acs_usable_vht80_chan(struct
+ static int acs_survey_is_sufficient(struct freq_survey *survey)
+ {
+ 	if (!(survey->filled & SURVEY_HAS_NF)) {
++		survey->nf = -95;
+ 		wpa_printf(MSG_INFO, "ACS: Survey is missing noise floor");
+-		return 0;
+ 	}
+ 
+ 	if (!(survey->filled & SURVEY_HAS_CHAN_TIME)) {
++		survey->channel_time = 0;
+ 		wpa_printf(MSG_INFO, "ACS: Survey is missing channel time");
+-		return 0;
+ 	}
+ 
+ 	if (!(survey->filled & SURVEY_HAS_CHAN_TIME_BUSY) &&
+ 	    !(survey->filled & SURVEY_HAS_CHAN_TIME_RX)) {
+ 		wpa_printf(MSG_INFO,
+ 			   "ACS: Survey is missing RX and busy time (at least one is required)");
+-		return 0;
+ 	}
+ 
+ 	return 1;