From ff5bacf17c2451e9d48c78a5ef96ec0c376ff33d Mon Sep 17 00:00:00 2001
From: Matthijs Mekking <matthijs@isc.org>
Date: Thu, 1 Jun 2023 10:03:48 +0200
Subject: [PATCH] Fix serve-stale hang at shutdown

The 'refresh_rrset' variable is used to determine if we can detach from
the client. This can cause a hang on shutdown. To fix this, move setting
of the 'nodetach' variable up to where 'refresh_rrset' is set (in
query_lookup(), and thus not in ns_query_done()), and set it to false
when actually refreshing the RRset, so that when this lookup is
completed, the client will be detached.
---
 lib/ns/query.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/lib/ns/query.c b/lib/ns/query.c
index 9fa8ee0f9a..64e9278307 100644
--- a/lib/ns/query.c
+++ b/lib/ns/query.c
@@ -5827,6 +5827,7 @@ query_refresh_rrset(query_ctx_t *orig_qctx) {
 	qctx.client->query.dboptions &= ~(DNS_DBFIND_STALETIMEOUT |
 					  DNS_DBFIND_STALEOK |
 					  DNS_DBFIND_STALEENABLED);
+	qctx.client->nodetach = false;
 
 	/*
 	 * We'll need some resources...
@@ -6100,7 +6101,14 @@ query_lookup(query_ctx_t *qctx) {
 					"%s stale answer used, an attempt to "
 					"refresh the RRset will still be made",
 					namebuf);
+
 				qctx->refresh_rrset = STALE(qctx->rdataset);
+				/*
+				 * If we are refreshing the RRSet, we must not
+				 * detach from the client in query_send().
+				 */
+				qctx->client->nodetach = qctx->refresh_rrset;
+
 				if (stale_found) {
 					ns_client_extendederror(
 						qctx->client, ede,
@@ -11961,12 +11969,7 @@ ns_query_done(query_ctx_t *qctx) {
 	/*
 	 * Client may have been detached after query_send(), so
 	 * we test and store the flag state here, for safety.
-	 * If we are refreshing the RRSet, we must not detach from the client
-	 * in the query_send(), so we need to override the flag.
 	 */
-	if (qctx->refresh_rrset) {
-		qctx->client->nodetach = true;
-	}
 	nodetach = qctx->client->nodetach;
 	query_send(qctx->client);