From: Michał Kępień <michal@isc.org>
Date: Thu, 31 Oct 2019 07:48:35 +0000 (+0100)
Subject: Prevent TCP failures from affecting EDNS stats
X-Git-Tag: v9.15.6~42^2~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fce3c93ea2ac63cd06faf817abf3c775fe11a33d;p=thirdparty%2Fbind9.git

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.
---

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