AP: Add fuzz to idle-timer calculations

This should keep us from getting into a state where we bounce large
numbers of stations all at once. Spreading out the bounce should cause
less stress on the network as the idle stations won't all be trying to
reconnect at once.

Signed-hostap: Ben Greear <greearb@candelatech.com>

src/ap/sta_info.c

@@ -284,6 +284,12 @@ void ap_handle_timer(void *eloop_ctx, void *timeout_ctx)
 	    (sta->timeout_next == STA_NULLFUNC ||
 	     sta->timeout_next == STA_DISASSOC)) {
 		int inactive_sec;
+		/*
+		 * Add random value to timeout so that we don't end up bouncing
+		 * all stations at the same time if we have lots of associated
+		 * stations that are idle (but keep re-associating).
+		 */
+		int fuzz = os_random() % 20;
 		inactive_sec = hostapd_drv_get_inact_sec(hapd, sta->addr);
 		if (inactive_sec == -1) {
 			wpa_msg(hapd->msg_ctx, MSG_DEBUG,
@@ -295,7 +301,7 @@ void ap_handle_timer(void *eloop_ctx, void *timeout_ctx)
 			 * Anyway, try again after the next inactivity timeout,
 			 * but do not disconnect the station now.
 			 */
-			next_time = hapd->conf->ap_max_inactivity;
+			next_time = hapd->conf->ap_max_inactivity + fuzz;
 		} else if (inactive_sec < hapd->conf->ap_max_inactivity &&
 			   sta->flags & WLAN_STA_ASSOC) {
 			/* station activity detected; reset timeout state */
@@ -303,7 +309,7 @@ void ap_handle_timer(void *eloop_ctx, void *timeout_ctx)
 				"Station " MACSTR " has been active %is ago",
 				MAC2STR(sta->addr), inactive_sec);
 			sta->timeout_next = STA_NULLFUNC;
-			next_time = hapd->conf->ap_max_inactivity -
+			next_time = hapd->conf->ap_max_inactivity + fuzz -
 				inactive_sec;
 		} else {
 			wpa_msg(hapd->msg_ctx, MSG_DEBUG,