From b6aeccf697729c4c721fc71da7063bb18a89c751 Mon Sep 17 00:00:00 2001
From: Aram Sargsyan <aram@isc.org>
Date: Tue, 18 Oct 2022 08:54:04 +0000
Subject: [PATCH] Fix ns_statscounter_recursclients counting bug

The incrementing and decrementing of 'ns_statscounter_recursclients'
were not properly balanced: for example, it would be incremented for
a prefetch query but not decremented if the query failed.

This commit ensures that the recursion quota and the recursive clients
counter are always in sync with each other.

(cherry picked from commit 82991451b41793af201d070aba654c4ea89819cb)
---
 lib/ns/client.c |  6 ++----
 lib/ns/query.c  | 28 +++++++++++++---------------
 2 files changed, 15 insertions(+), 19 deletions(-)

diff --git a/lib/ns/client.c b/lib/ns/client.c
index ce2f84cc430..6bd5ddfdefb 100644
--- a/lib/ns/client.c
+++ b/lib/ns/client.c
@@ -242,10 +242,8 @@ ns_client_endrequest(ns_client_t *client) {
 	 */
 	if (client->recursionquota != NULL) {
 		isc_quota_detach(&client->recursionquota);
-		if (client->query.prefetch == NULL) {
-			ns_stats_decrement(client->sctx->nsstats,
-					   ns_statscounter_recursclients);
-		}
+		ns_stats_decrement(client->sctx->nsstats,
+				   ns_statscounter_recursclients);
 	}
 
 	/*
diff --git a/lib/ns/query.c b/lib/ns/query.c
index 98cfffe8c36..43a0293d5d3 100644
--- a/lib/ns/query.c
+++ b/lib/ns/query.c
@@ -2486,11 +2486,10 @@ prefetch_done(isc_task_t *task, isc_event_t *event) {
 	 */
 	if (client->recursionquota != NULL) {
 		isc_quota_detach(&client->recursionquota);
+		ns_stats_decrement(client->sctx->nsstats,
+				   ns_statscounter_recursclients);
 	}
 
-	ns_stats_decrement(client->sctx->nsstats,
-			   ns_statscounter_recursclients);
-
 	free_devent(client, &event, &devent);
 	isc_nmhandle_detach(&client->prefetchhandle);
 }
@@ -2518,6 +2517,8 @@ query_prefetch(ns_client_t *client, dns_name_t *qname,
 					  &client->recursionquota);
 		switch (result) {
 		case ISC_R_SUCCESS:
+			ns_stats_increment(client->sctx->nsstats,
+					   ns_statscounter_recursclients);
 			break;
 		case ISC_R_SOFTQUOTA:
 			isc_quota_detach(&client->recursionquota);
@@ -2527,9 +2528,6 @@ query_prefetch(ns_client_t *client, dns_name_t *qname,
 		}
 	}
 
-	ns_stats_increment(client->sctx->nsstats,
-			   ns_statscounter_recursclients);
-
 	tmprdataset = ns_client_newrdataset(client);
 	if (tmprdataset == NULL) {
 		return;
@@ -2736,6 +2734,8 @@ query_rpzfetch(ns_client_t *client, dns_name_t *qname, dns_rdatatype_t type) {
 					  &client->recursionquota);
 		switch (result) {
 		case ISC_R_SUCCESS:
+			ns_stats_increment(client->sctx->nsstats,
+					   ns_statscounter_recursclients);
 			break;
 		case ISC_R_SOFTQUOTA:
 			isc_quota_detach(&client->recursionquota);
@@ -2745,9 +2745,6 @@ query_rpzfetch(ns_client_t *client, dns_name_t *qname, dns_rdatatype_t type) {
 		}
 	}
 
-	ns_stats_increment(client->sctx->nsstats,
-			   ns_statscounter_recursclients);
-
 	tmprdataset = ns_client_newrdataset(client);
 	if (tmprdataset == NULL) {
 		return;
@@ -6128,11 +6125,10 @@ fetch_callback(isc_task_t *task, isc_event_t *event) {
 
 	if (client->recursionquota != NULL) {
 		isc_quota_detach(&client->recursionquota);
+		ns_stats_decrement(client->sctx->nsstats,
+				   ns_statscounter_recursclients);
 	}
 
-	ns_stats_decrement(client->sctx->nsstats,
-			   ns_statscounter_recursclients);
-
 	LOCK(&client->manager->reclock);
 	if (ISC_LINK_LINKED(client, rlink)) {
 		ISC_LIST_UNLINK(client->manager->recursing, client, rlink);
@@ -6285,6 +6281,11 @@ ns_query_recurse(ns_client_t *client, dns_rdatatype_t qtype, dns_name_t *qname,
 	if (client->recursionquota == NULL) {
 		result = isc_quota_attach(&client->sctx->recursionquota,
 					  &client->recursionquota);
+		if (result == ISC_R_SUCCESS || result == ISC_R_SOFTQUOTA) {
+			ns_stats_increment(client->sctx->nsstats,
+					   ns_statscounter_recursclients);
+		}
+
 		if (result == ISC_R_SOFTQUOTA) {
 			isc_stdtime_t now;
 			isc_stdtime_get(&now);
@@ -6333,9 +6334,6 @@ ns_query_recurse(ns_client_t *client, dns_rdatatype_t qtype, dns_name_t *qname,
 		ns_client_recursing(client);
 	}
 
-	ns_stats_increment(client->sctx->nsstats,
-			   ns_statscounter_recursclients);
-
 	/*
 	 * Invoke the resolver.
 	 */
-- 
2.47.3