AP: Use monotonic time for MMIC failure/TKIP countermeasures

Wall time jumps shouldn't affect MMIC failure/TKIP countermeasures,
so use monotonic time. Change the michael_mic_failure variable to
struct os_reltime for type-safety.

Signed-hostap: Johannes Berg <johannes.berg@intel.com>

src/ap/hostapd.h

@@ -146,7 +146,7 @@ struct hostapd_data {
 	struct eapol_authenticator *eapol_auth;
 
 	struct rsn_preauth_interface *preauth_iface;
-	time_t michael_mic_failure;
+	struct os_reltime michael_mic_failure;
 	int michael_mic_failures;
 	int tkip_countermeasures;
 

src/ap/tkip_countermeasures.c

@@ -68,7 +68,7 @@ void ieee80211_tkip_countermeasures_deinit(struct hostapd_data *hapd)
 
 int michael_mic_failure(struct hostapd_data *hapd, const u8 *addr, int local)
 {
-	struct os_time now;
+	struct os_reltime now;
 	int ret = 0;
 
 	if (addr && local) {
@@ -89,8 +89,8 @@ int michael_mic_failure(struct hostapd_data *hapd, const u8 *addr, int local)
 		}
 	}
 
-	os_get_time(&now);
-	if (now.sec > hapd->michael_mic_failure + 60) {
+	os_get_reltime(&now);
+	if (os_reltime_expired(&now, &hapd->michael_mic_failure, 60)) {
 		hapd->michael_mic_failures = 1;
 	} else {
 		hapd->michael_mic_failures++;
@@ -99,7 +99,7 @@ int michael_mic_failure(struct hostapd_data *hapd, const u8 *addr, int local)
 			ret = 1;
 		}
 	}
-	hapd->michael_mic_failure = now.sec;
+	hapd->michael_mic_failure = now;
 
 	return ret;
 }