From fce3c93ea2ac63cd06faf817abf3c775fe11a33d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20K=C4=99pie=C5=84?= <michal@isc.org>
Date: Thu, 31 Oct 2019 08:48:35 +0100
Subject: [PATCH 1/2] Prevent TCP failures from affecting EDNS stats

EDNS mechanisms only apply to DNS over UDP.  Thus, errors encountered
while sending DNS queries over TCP must not influence EDNS timeout
statistics.
---
 bin/tests/system/legacy/tests.sh | 12 ++++++++++++
 lib/dns/resolver.c               | 25 ++++++++++++++++++++-----
 2 files changed, 32 insertions(+), 5 deletions(-)

diff --git a/bin/tests/system/legacy/tests.sh b/bin/tests/system/legacy/tests.sh
index a7319840ddc..ed784d9615d 100755
--- a/bin/tests/system/legacy/tests.sh
+++ b/bin/tests/system/legacy/tests.sh
@@ -241,6 +241,18 @@ fi
 if [ $ret != 0 ]; then echo_i "failed"; fi
 status=`expr $status + $ret`
 
+n=`expr $n + 1`
+echo_i "checking that TCP failures do not influence EDNS statistics in the ADB ($n)"
+ret=0
+rndc_dumpdb ns1 -adb || ret=1
+timeouts512=`sed -n "s|.*10\.53\.0\.7.*\[edns \([0-9/][0-9/]*\).*|\1|p" ns1/named_dump.db.test$n | awk -F/ '{print $NF}'`
+if [ $timeouts512 -ne 0 ]; then
+	echo_i "512-byte EDNS timeouts according to ADB: $timeouts512, expected: 0"
+	ret=1
+fi
+if [ $ret != 0 ]; then echo_i "failed"; fi
+status=`expr $status + $ret`
+
 $PERL $SYSTEMTESTTOP/stop.pl --use-rndc --port ${CONTROLPORT} legacy ns1
 copy_setports ns1/named2.conf.in ns1/named.conf
 $PERL $SYSTEMTESTTOP/start.pl --noclean --restart --port ${PORT} legacy ns1
diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
index 11ef066608f..70bfa2232a7 100644
--- a/lib/dns/resolver.c
+++ b/lib/dns/resolver.c
@@ -1142,6 +1142,25 @@ resquery_destroy(resquery_t **queryp) {
 		empty_bucket(res);
 }
 
+/*%
+ * Update EDNS statistics for a server after not getting a response to a UDP
+ * query sent to it.
+ */
+static void
+update_edns_stats(resquery_t *query) {
+	fetchctx_t *fctx = query->fctx;
+
+	if ((query->options & DNS_FETCHOPT_TCP) != 0) {
+		return;
+	}
+
+	if ((query->options & DNS_FETCHOPT_NOEDNS0) == 0) {
+		dns_adb_ednsto(fctx->adb, query->addrinfo, query->udpsize);
+	} else {
+		dns_adb_timeout(fctx->adb, query->addrinfo);
+	}
+}
+
 static void
 fctx_cancelquery(resquery_t **queryp, dns_dispatchevent_t **deventp,
 		 isc_time_t *finish, bool no_response,
@@ -1202,11 +1221,7 @@ fctx_cancelquery(resquery_t **queryp, dns_dispatchevent_t **deventp,
 			uint32_t value;
 			uint32_t mask;
 
-			if ((query->options & DNS_FETCHOPT_NOEDNS0) == 0)
-				dns_adb_ednsto(fctx->adb, query->addrinfo,
-					       query->udpsize);
-			else
-				dns_adb_timeout(fctx->adb, query->addrinfo);
+			update_edns_stats(query);
 
 			/*
 			 * If "forward first;" is used and a forwarder timed
-- 
GitLab


From 36d3c66e4e139430e176da01f58b927fd572d64b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20K=C4=99pie=C5=84?= <michal@isc.org>
Date: Thu, 31 Oct 2019 08:48:35 +0100
Subject: [PATCH 2/2] Add CHANGES entry

5310.	[bug]		TCP failures were affecting EDNS statistics. [GL #1059]
---
 CHANGES | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/CHANGES b/CHANGES
index 7f421234148..7452a520e1e 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,5 @@
+5310.	[bug]		TCP failures were affecting EDNS statistics. [GL #1059]
+
 5309.	[placeholder]
 
 5308.	[bug]		Don't log DNS_R_UNCHANGED from sync_secure_journal()
-- 
GitLab