From 5c0537cfaf6734203f63e2f204df52b2d93ebcd4 Mon Sep 17 00:00:00 2001
From: Mark Andrews <marka@isc.org>
Date: Mon, 26 Feb 2007 23:20:52 +0000
Subject: [PATCH] 2150.   [bug]           'rrset-order cyclic' uniformly
 distribute the                         starting point for the first response
 for a given                         RRset. [RT #16655]

---
 CHANGES         |  6 +++++-
 lib/dns/rbtdb.c | 25 +++++++++++++++++++------
 2 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/CHANGES b/CHANGES
index dfbda09e56..5de071a6af 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,7 @@
+2150.	[bug]		'rrset-order cyclic' uniformly distribute the
+			starting point for the first response for a given
+			RRset. [RT #16655]
+
 2147.	[bug]		libbind: remove potential buffer overflow from
 			hmac_link.c. [RT #16437]
 
@@ -1355,7 +1359,7 @@
 			[RT #6427]
 
 1555.	[func]		'rrset-order cyclic' no longer has a random starting
-			point. [RT #7572]
+			point per query. [RT #7572]
 
 1554.	[bug]		dig, host, nslookup failed when no nameservers
 			were specified in /etc/resolv.conf. [RT #8232]
diff --git a/lib/dns/rbtdb.c b/lib/dns/rbtdb.c
index 8930d355fd..9d51bbaa3f 100644
--- a/lib/dns/rbtdb.c
+++ b/lib/dns/rbtdb.c
@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: rbtdb.c,v 1.168.2.11.2.26 2006/03/02 23:18:20 marka Exp $ */
+/* $Id: rbtdb.c,v 1.168.2.11.2.27 2007/02/26 23:20:52 marka Exp $ */
 
 /*
  * Principal Author: Bob Halley
@@ -352,6 +352,19 @@ typedef struct rbtdb_dbiterator {
 static void free_rbtdb(dns_rbtdb_t *rbtdb, isc_boolean_t log,
 		       isc_event_t *event);
 
+/*%
+ * 'init_count' is used to initialize 'newheader->count' which inturn
+ * is used to determine where in the cycle rrset-order cyclic starts.
+ * We don't lock this as we don't care about simultanious updates.
+ *
+ * Note:
+ *	Both init_count and header->count can be ISC_UINT32_MAX.
+ *      The count on the returned rdataset however can't be as
+ *	that indicates that the database does not implement cyclic
+ *	processing.
+ */
+static unsigned int init_count;
+
 /*
  * Locking
  *
@@ -1513,8 +1526,8 @@ bind_rdataset(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node,
 	raw = (unsigned char *)header + sizeof(*header);
 	rdataset->private3 = raw;
 	rdataset->count = header->count++;
-	if (header->count == ISC_UINT32_MAX)
-		header->count = 0;
+	if (rdataset->count == ISC_UINT32_MAX)
+		rdataset->count = 0;
 
 	/*
 	 * Reset iterator state.
@@ -4341,7 +4354,7 @@ addrdataset(dns_db_t *db, dns_dbnode_t *node, dns_dbversion_t *version,
 						rdataset->covers);
 	newheader->attributes = 0;
 	newheader->noqname = NULL;
-	newheader->count = 0;
+	newheader->count = init_count++;
 	newheader->trust = rdataset->trust;
 	if (rbtversion != NULL) {
 		newheader->serial = rbtversion->serial;
@@ -4422,7 +4435,7 @@ subtractrdataset(dns_db_t *db, dns_dbnode_t *node, dns_dbversion_t *version,
 	newheader->serial = rbtversion->serial;
 	newheader->trust = 0;
 	newheader->noqname = NULL;
-	newheader->count = 0;
+	newheader->count = init_count++;
 
 	LOCK(&rbtdb->node_locks[rbtnode->locknum].lock);
 
@@ -4655,7 +4668,7 @@ loading_addrdataset(void *arg, dns_name_t *name, dns_rdataset_t *rdataset) {
 	newheader->trust = rdataset->trust;
 	newheader->serial = 1;
 	newheader->noqname = NULL;
-	newheader->count = 0;
+	newheader->count = init_count++;
 
 	result = add(rbtdb, node, rbtdb->current_version, newheader,
 		     DNS_DBADD_MERGE, ISC_TRUE, NULL, 0);