From 43316a40a09c57cf16f8c8d0cbd1aa01616fd71f Mon Sep 17 00:00:00 2001
From: Mark Andrews <marka@isc.org>
Date: Wed, 27 Oct 2021 13:25:41 +1100
Subject: [PATCH] Record how often DNS_R_COVERINGNSEC is returned from the
 cache

reported as "covering nsec returned" when dumping cache stats
and as "CoveringNSEC" in json and xml cache statistics.
---
 lib/dns/cache.c             | 9 +++++++++
 lib/dns/include/dns/stats.h | 3 ++-
 lib/dns/rbtdb.c             | 5 ++++-
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/lib/dns/cache.c b/lib/dns/cache.c
index dbbe44e660..acf7767f1b 100644
--- a/lib/dns/cache.c
+++ b/lib/dns/cache.c
@@ -1260,6 +1260,9 @@ dns_cache_dumpstats(dns_cache_t *cache, FILE *fp) {
 	fprintf(fp, "%20" PRIu64 " %s\n",
 		values[dns_cachestatscounter_deletettl],
 		"cache records deleted due to TTL expiration");
+	fprintf(fp, "%20" PRIu64 " %s\n",
+		values[dns_cachestatscounter_coveringnsec],
+		"covering nsec returned");
 	fprintf(fp, "%20u %s\n", dns_db_nodecount(cache->db, dns_dbtree_main),
 		"cache database nodes");
 	fprintf(fp, "%20u %s\n", dns_db_nodecount(cache->db, dns_dbtree_nsec),
@@ -1328,6 +1331,8 @@ dns_cache_renderxml(dns_cache_t *cache, void *writer0) {
 			writer));
 	TRY0(renderstat("DeleteTTL", values[dns_cachestatscounter_deletettl],
 			writer));
+	TRY0(renderstat("CoveringNSEC",
+			values[dns_cachestatscounter_coveringnsec], writer));
 
 	TRY0(renderstat("CacheNodes",
 			dns_db_nodecount(cache->db, dns_dbtree_main), writer));
@@ -1393,6 +1398,10 @@ dns_cache_renderjson(dns_cache_t *cache, void *cstats0) {
 	CHECKMEM(obj);
 	json_object_object_add(cstats, "DeleteTTL", obj);
 
+	obj = json_object_new_int64(values[dns_cachestatscounter_coveringnsec]);
+	CHECKMEM(obj);
+	json_object_object_add(cstats, "CoveringNSEC", obj);
+
 	obj = json_object_new_int64(
 		dns_db_nodecount(cache->db, dns_dbtree_main));
 	CHECKMEM(obj);
diff --git a/lib/dns/include/dns/stats.h b/lib/dns/include/dns/stats.h
index 4342fe41c5..6e61d279b7 100644
--- a/lib/dns/include/dns/stats.h
+++ b/lib/dns/include/dns/stats.h
@@ -119,8 +119,9 @@ enum {
 	dns_cachestatscounter_querymisses = 4,
 	dns_cachestatscounter_deletelru = 5,
 	dns_cachestatscounter_deletettl = 6,
+	dns_cachestatscounter_coveringnsec = 7,
 
-	dns_cachestatscounter_max = 7,
+	dns_cachestatscounter_max = 8,
 
 	/*%
 	 * Query statistics counters (obsolete).
diff --git a/lib/dns/rbtdb.c b/lib/dns/rbtdb.c
index a7e2a654b1..4b954597dd 100644
--- a/lib/dns/rbtdb.c
+++ b/lib/dns/rbtdb.c
@@ -786,13 +786,16 @@ update_cachestats(dns_rbtdb_t *rbtdb, isc_result_t result) {
 	}
 
 	switch (result) {
+	case DNS_R_COVERINGNSEC:
+		isc_stats_increment(rbtdb->cachestats,
+				    dns_cachestatscounter_coveringnsec);
+		/* FALLTHROUGH */
 	case ISC_R_SUCCESS:
 	case DNS_R_CNAME:
 	case DNS_R_DNAME:
 	case DNS_R_DELEGATION:
 	case DNS_R_NCACHENXDOMAIN:
 	case DNS_R_NCACHENXRRSET:
-	case DNS_R_COVERINGNSEC:
 		isc_stats_increment(rbtdb->cachestats,
 				    dns_cachestatscounter_hits);
 		break;