When lacking user-specified timer values from the SOA,

use a retry time that backs off exponentially from one minute up to
six hours.  This should allow the xferquota test to succeed [RT #337]
by allowing for one or more retries during the test, while keeping the
amount of SOA query traffic to dead masters reasonable for GNS.

CHANGES

@@ -1,3 +1,9 @@
+
+ 490.	[func]		When a slave/stub zone has not yet successfully
+			obtained an SOA containing the zone's configured
+			retry time, perform the SOA query retries using
+			exponential backoff. [RT #337]
+
  489.	[func]		The zone manager now has a "i/o" queue.
 
  488.	[bug]		Locks weren't properly destroyed in some cases.

lib/dns/include/dns/zone.h

@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: zone.h,v 1.76 2000/09/26 17:24:00 gson Exp $ */
+/* $Id: zone.h,v 1.77 2000/09/26 18:17:10 gson Exp $ */
 
 #ifndef DNS_ZONE_H
 #define DNS_ZONE_H 1
@@ -66,7 +66,8 @@ typedef enum {
 #define DNS_ZONE_MAXRETRY		1209600	/* 2 weeks */
 #endif
 #ifndef DNS_ZONE_DEFAULTRETRY
-#define DNS_ZONE_DEFAULTRETRY		   1800	/* 30 minutes */
+#define DNS_ZONE_DEFAULTRETRY		     60	/* 1 minute, subject to
+						   exponential backoff */
 #endif
 
 ISC_LANG_BEGINDECLS

lib/dns/zone.c

@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: zone.c,v 1.221 2000/09/26 17:28:13 gson Exp $ */
+/* $Id: zone.c,v 1.222 2000/09/26 18:17:09 gson Exp $ */
 
 #include <config.h>
 
@@ -205,6 +205,9 @@ struct dns_zone {
 						 * zone with no masters
 						 * occured */
 #define DNS_ZONEFLG_LOADING	0x00002000U	/* load from disk in progress */
+#define DNS_ZONEFLG_HAVETIMERS	0x00004000U	/* timer values have been set from
+						   SOA (if not set, we are still using
+						   default timer values) */
 
 #define DNS_ZONE_OPTION(z,o) (((z)->options & (o)) != 0)
 
@@ -1056,8 +1059,9 @@ zone_postload(dns_zone_t *zone, dns_db_t *db, isc_time_t loadtime,
 				    zone->minretry, zone->maxretry);
 		zone->expire = RANGE(expire, zone->refresh + zone->retry,
 				     DNS_MAX_EXPIRE);
-
 		zone->minimum = minimum;
+		zone->flags |= DNS_ZONEFLG_HAVETIMERS;
+
 		if (zone->type == dns_zone_slave ||
 		    zone->type == dns_zone_stub) {
 			isc_time_t t;
@@ -1741,6 +1745,7 @@ zone_expire(dns_zone_t *zone) {
 	zone->flags |= DNS_ZONEFLG_EXPIRED;
 	zone->refresh = DNS_ZONE_DEFAULTREFRESH;
 	zone->retry = DNS_ZONE_DEFAULTRETRY;
+	zone->flags &= ~DNS_ZONEFLG_HAVETIMERS;
 	zone_unload(zone);
 }
 
@@ -1787,6 +1792,14 @@ dns_zone_refresh(dns_zone_t *zone) {
 		 "refresh time (%u/%u), now %u",
 		 zone->refreshtime, zone->refresh, now);
 
+	/*
+	 * When lacking user-specified timer values from the SOA,
+	 * do exponential backoff of the retry time up to a 
+	 * maximum of six hours.
+	 */
+	if (! DNS_ZONE_FLAG(zone, DNS_ZONEFLG_HAVETIMERS))
+		zone->retry = ISC_MIN(zone->retry * 2, 6 * 3600);
+
 	zone->curmaster = 0;
 	/* initiate soa query */
 	queue_soa_query(zone);
@@ -2716,6 +2729,9 @@ stub_callback(isc_task_t *task, isc_event_t *event) {
 	return;
 }
 
+/*
+ * An SOA query has finished (successfully or not).
+ */
 static void
 refresh_callback(isc_task_t *task, isc_event_t *event) {
 	const char me[] = "refresh_callback";
@@ -4247,6 +4263,7 @@ zone_xfrdone(dns_zone_t *zone, isc_result_t result) {
 					     zone->refresh + zone->retry,
 					     DNS_MAX_EXPIRE);
 			zone->minimum = minimum;
+			zone->flags |= DNS_ZONEFLG_HAVETIMERS;
 		}
 
 		/*