notify/retry: use SOA retry for NOTIFY retry interval

src/knot/events/handlers/notify.c

@@ -195,7 +195,14 @@ int event_notify(conf_t *conf, zone_t *zone)
 
 	if (failed) {
 		notifailed_rmt_dynarray_sort_dedup(&zone->notifailed);
-		zone_events_schedule_at(zone, ZONE_EVENT_NOTIFY, time(NULL) + 10); // FIXME exponential backoff of NOTIFY retries
+
+		uint32_t retry_in = knot_soa_retry(soa.rrs.rdata);
+		conf_val_t val = conf_zone_get(conf, C_RETRY_MIN_INTERVAL, zone->name);
+		retry_in = MAX(retry_in, conf_int(&val));
+		val = conf_zone_get(conf, C_RETRY_MAX_INTERVAL, zone->name);
+		retry_in = MIN(retry_in, conf_int(&val));
+
+		zone_events_schedule_at(zone, ZONE_EVENT_NOTIFY, time(NULL) + retry_in);
 	}
 
 	return failed ? KNOT_ERROR : KNOT_EOK;

tests-extra/tests/notify/retry/test.py

@@ -17,6 +17,8 @@ t.link(zone, master, slave1)
 t.link(zone, master, slave2)
 t.link(zone, master, slave3)
 
+master.zones[zone[0].name].retry_max = 10
+
 t.start()
 
 serial = master.zone_wait(zone)