2049. [bug] Restore SOA before AXFR when falling back from

a attempted IXFR when transfering in a zone.
                        Allow a initial SOA query before attempting
                        a AXFR to be requested. [RT #16156]

CHANGES

@@ -1,3 +1,8 @@
+2049.	[bug]		Restore SOA before AXFR when falling back from
+			a attempted IXFR when transfering in a zone.
+			Allow a initial SOA query before attempting
+			a AXFR to be requested. [RT #16156]
+
 2048.	[bug]		It was possible to loop forever when using
 			avoid-v4-udp-ports / avoid-v6-udp-ports when
 			the OS always returned the same local port.

lib/dns/include/dns/xfrin.h

@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: xfrin.h,v 1.22 2005/04/29 00:23:06 marka Exp $ */
+/* $Id: xfrin.h,v 1.23 2006/07/19 00:53:42 marka Exp $ */
 
 #ifndef DNS_XFRIN_H
 #define DNS_XFRIN_H 1
@@ -77,10 +77,12 @@ dns_xfrin_create2(dns_zone_t *zone, dns_rdatatype_t xfrtype,
  * code as arguments when the transfer finishes.
  *
  * Requires:
- *\li	'xfrtype' is dns_rdatatype_axfr or dns_rdatatype_ixfr.
+ *\li	'xfrtype' is dns_rdatatype_axfr, dns_rdatatype_ixfr
+ *	of dns_rdatatype_soa (soa query followed by axfr if
+ *	serial is greater than current serial).
  *
- *\li	If 'xfrtype' is dns_rdatatype_ixfr, the zone has a
- * 	database.
+ *\li	If 'xfrtype' is dns_rdatatype_ixfr or dns_rdatatype_soa,
+ *	the zone has a database.
  */
 
 void

lib/dns/xfrin.c

@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: xfrin.c,v 1.146 2006/03/01 02:05:11 marka Exp $ */
+/* $Id: xfrin.c,v 1.147 2006/07/19 00:53:42 marka Exp $ */
 
 /*! \file */
 
@@ -75,6 +75,8 @@
  * when the first two (2) response RRs have already been received.
  */
 typedef enum {
+	XFRST_SOAQUERY,
+	XFRST_GOTSOA,
 	XFRST_INITIALSOA,
 	XFRST_FIRSTDATA,
 	XFRST_IXFR_DELSOA,
@@ -426,6 +428,30 @@ xfr_rr(dns_xfrin_ctx_t *xfr, dns_name_t *name, isc_uint32_t ttl,
 
  redo:
 	switch (xfr->state) {
+	case XFRST_SOAQUERY:
+		if (rdata->type != dns_rdatatype_soa) {
+			xfrin_log(xfr, ISC_LOG_ERROR,
+				  "non-SOA response to SOA query");
+			FAIL(DNS_R_FORMERR);
+		}
+		xfr->end_serial = dns_soa_getserial(rdata);
+		if (!DNS_SERIAL_GT(xfr->end_serial, xfr->ixfr.request_serial) &&
+		    !dns_zone_isforced(xfr->zone)) {
+			xfrin_log(xfr, ISC_LOG_DEBUG(3),
+				  "requested serial %u, "
+				  "master has %u, not updating",
+				  xfr->ixfr.request_serial, xfr->end_serial);
+			FAIL(DNS_R_UPTODATE);
+		}
+		xfr->state = XFRST_GOTSOA;
+		break;
+
+	case XFRST_GOTSOA:
+		/*
+		 * Skip other records in the answer section.
+		 */
+		break;
+
 	case XFRST_INITIALSOA:
 		if (rdata->type != dns_rdatatype_soa) {
 			xfrin_log(xfr, ISC_LOG_ERROR,
@@ -591,6 +617,9 @@ dns_xfrin_create2(dns_zone_t *zone, dns_rdatatype_t xfrtype,
 
 	(void)dns_zone_getdb(zone, &db);
 
+	if (xfrtype == dns_rdatatype_soa || xfrtype == dns_rdatatype_ixfr)
+		REQUIRE(db != NULL);
+
 	CHECK(xfrin_create(mctx, zone, db, task, timermgr, socketmgr, zonename,
 			   dns_zone_getclass(zone), xfrtype, masteraddr,
 			   sourceaddr, tsigkey, &xfr));
@@ -759,7 +788,10 @@ xfrin_create(isc_mem_t *mctx,
 	dns_diff_init(xfr->mctx, &xfr->diff);
 	xfr->difflen = 0;
 
-	xfr->state = XFRST_INITIALSOA;
+	if (reqtype == dns_rdatatype_soa)
+		xfr->state = XFRST_SOAQUERY;
+	else
+		xfr->state = XFRST_INITIALSOA;
 	/* end_serial */
 
 	xfr->nmsg = 0;
@@ -1005,7 +1037,9 @@ xfrin_send_request(dns_xfrin_ctx_t *xfr) {
 
 		CHECK(tuple2msgname(soatuple, msg, &msgsoaname));
 		dns_message_addname(msg, msgsoaname, DNS_SECTION_AUTHORITY);
-	}
+	} else if (xfr->reqtype == dns_rdatatype_soa)
+		CHECK(dns_db_getsoaserial(xfr->db, NULL,
+					  &xfr->ixfr.request_serial));
 
 	xfr->checkid = ISC_TRUE;
 	xfr->id++;
@@ -1166,8 +1200,8 @@ xfrin_recv_done(isc_task_t *task, isc_event_t *ev) {
  try_axfr:
 		dns_message_destroy(&msg);
 		xfrin_reset(xfr);
-		xfr->reqtype = dns_rdatatype_axfr;
-		xfr->state = XFRST_INITIALSOA;
+		xfr->reqtype = dns_rdatatype_soa;
+		xfr->state = XFRST_SOAQUERY;
 		(void)xfrin_start(xfr);
 		return;
 	}
@@ -1264,7 +1298,11 @@ xfrin_recv_done(isc_task_t *task, isc_event_t *ev) {
 
 	dns_message_destroy(&msg);
 
-	if (xfr->state == XFRST_END) {
+	if (xfr->state == XFRST_GOTSOA) {
+		xfr->reqtype = dns_rdatatype_axfr;
+		xfr->state = XFRST_INITIALSOA;
+		CHECK(xfrin_send_request(xfr));
+	} else if (xfr->state == XFRST_END) {
 		/*
 		 * Inform the caller we succeeded.
 		 */

lib/dns/zone.c

@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: zone.c,v 1.456 2006/06/04 23:17:06 marka Exp $ */
+/* $Id: zone.c,v 1.457 2006/07/19 00:53:42 marka Exp $ */
 
 /*! \file */
 
@@ -297,6 +297,7 @@ struct dns_zone {
 #define DNS_ZONEFLG_FLUSH	0x00200000U
 #define DNS_ZONEFLG_NOEDNS	0x00400000U
 #define DNS_ZONEFLG_USEALTXFRSRC 0x00800000U
+#define DNS_ZONEFLG_SOABEFOREAXFR 0x01000000U
 
 #define DNS_ZONE_OPTION(z,o) (((z)->options & (o)) != 0)
 
@@ -4286,8 +4287,13 @@ refresh_callback(isc_task_t *task, isc_event_t *event) {
 				     master, source);
 			/* Try with slave with TCP. */
 			if (zone->type == dns_zone_slave &&
-			    DNS_ZONE_OPTION(zone, DNS_ZONEOPT_TRYTCPREFRESH))
+			    DNS_ZONE_OPTION(zone, DNS_ZONEOPT_TRYTCPREFRESH)) {
+				LOCK_ZONE(zone);
+				DNS_ZONE_SETFLAG(zone,
+						 DNS_ZONEFLG_SOABEFOREAXFR);
+				UNLOCK_ZONE(zone);
 				goto tcp_transfer;
+			}
 		} else
 			dns_zone_log(zone, ISC_LOG_INFO,
 				     "refresh: failure trying master "
@@ -4354,6 +4360,9 @@ refresh_callback(isc_task_t *task, isc_event_t *event) {
 				     "initiating TCP zone xfer "
 				     "for master %s (source %s)",
 				     master, source);
+			LOCK_ZONE(zone);
+			DNS_ZONE_SETFLAG(zone, DNS_ZONEFLG_SOABEFOREAXFR);
+			UNLOCK_ZONE(zone);
 			goto tcp_transfer;
 		} else {
 			INSIST(zone->type == dns_zone_stub);
@@ -6334,6 +6343,7 @@ zone_xfrdone(dns_zone_t *zone, isc_result_t result) {
 	LOCK_ZONE(zone);
 	INSIST((zone->flags & DNS_ZONEFLG_REFRESH) != 0);
 	DNS_ZONE_CLRFLAG(zone, DNS_ZONEFLG_REFRESH);
+	DNS_ZONE_CLRFLAG(zone, DNS_ZONEFLG_SOABEFOREAXFR);
 
 	TIME_NOW(&now);
 	switch (result) {
@@ -6691,7 +6701,10 @@ got_transfer_quota(isc_task_t *task, isc_event_t *event) {
 				     "IXFR disabled, "
 				     "requesting AXFR from %s",
 				     mastertext);
-			xfrtype = dns_rdatatype_axfr;
+			if (DNS_ZONE_FLAG(zone, DNS_ZONEFLG_SOABEFOREAXFR))
+				xfrtype = dns_rdatatype_soa;
+			else
+				xfrtype = dns_rdatatype_axfr;
 		} else {
 			dns_zone_log(zone, ISC_LOG_DEBUG(1),
 				     "requesting IXFR from %s",