Merge branch '3026-premature-tcp-connection-closure-leaks-fetch-contexts-hang-on-shutdown' into 'main'

Shutdown all active TCP connections on error Closes #3026 See merge request isc-projects/bind9!5599
2025-08-29 21:47:59 +00:00 · 2021-12-01 20:10:44 +00:00 · 2021-12-01 20:10:44 +00:00 · 4ecbc3d09f
commit 4ecbc3d09f
parent 081e18edc8 4e779b11f6
14 changed files with 482 additions and 104 deletions
--- a/4
+++ b/4
@ -1,3 +1,7 @@
+5772.	[bug]		The resolver could hang on shutdown due to dispatch
+			resources not being cleaned up when a TCP connection
+			was reset. [GL #3026]
+
 5771.	[bug]		Use idn2 UseSTD3ASCIIRules=false to disable additional
 			unicode validity checks because enabling the additional
 			checks would break valid domain names that contains
--- a/bin/tests/system/Makefile.am
+++ b/bin/tests/system/Makefile.am
@ -213,7 +213,7 @@ if HAVE_PYTHON
 TESTS += kasp keymgr2kasp tcp pipelined

 if HAVE_PYMOD_DNS
-TESTS += checkds qmin cookie timeouts
+TESTS += checkds dispatch qmin cookie timeouts

 if HAVE_PERLMOD_NET_DNS
 TESTS += dnssec
--- a/bin/tests/system/dispatch/ans3/ans.py
+++ b/bin/tests/system/dispatch/ans3/ans.py
@ -0,0 +1,99 @@
+############################################################################
+# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, you can obtain one at https://mozilla.org/MPL/2.0/.
+#
+# See the COPYRIGHT file distributed with this work for additional
+# information regarding copyright ownership.
+############################################################################
+
+import os
+import select
+import signal
+import socket
+import sys
+import time
+
+import dns.flags
+import dns.message
+
+
+def port():
+    env_port = os.getenv("PORT")
+    if env_port is None:
+        env_port = 5300
+    else:
+        env_port = int(env_port)
+
+    return env_port
+
+
+def udp_listen(port):
+    udp = socket.socket(type=socket.SOCK_DGRAM)
+    udp.bind(('10.53.0.3', port))
+
+    return udp
+
+
+def tcp_listen(port):
+    tcp = socket.socket(type=socket.SOCK_STREAM)
+    tcp.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+    tcp.bind(('10.53.0.3', port))
+    tcp.listen(100)
+
+    return tcp
+
+
+def udp_tc_once(udp):
+    qrybytes, clientaddr = udp.recvfrom(65535)
+    qry = dns.message.from_wire(qrybytes)
+    answ = dns.message.make_response(qry)
+    answ.flags |= dns.flags.TC
+    answbytes = answ.to_wire()
+    udp.sendto(answbytes, clientaddr)
+
+
+def tcp_once(tcp):
+    csock, _clientaddr = tcp.accept()
+    time.sleep(5)
+    csock.close()
+
+
+def sigterm(signum, frame):
+    os.remove('ans.pid')
+    sys.exit(0)
+
+
+def write_pid():
+    with open('ans.pid', 'w') as f:
+        pid = os.getpid()
+        f.write("{}".format(pid))
+
+
+signal.signal(signal.SIGTERM, sigterm)
+write_pid()
+
+udp = udp_listen(port())
+tcp = tcp_listen(port())
+
+input = [udp, tcp]
+
+while True:
+    try:
+        inputready, outputready, exceptready = select.select(input, [], [])
+    except select.error:
+        break
+    except socket.error:
+        break
+    except KeyboardInterrupt:
+        break
+
+    for s in inputready:
+        if s == udp:
+            udp_tc_once(udp)
+        if s == tcp:
+            tcp_once(tcp)
+
+sigterm(signal.SIGTERM, 0)
--- a/bin/tests/system/dispatch/clean.sh
+++ b/bin/tests/system/dispatch/clean.sh
@ -0,0 +1,12 @@
+# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, you can obtain one at https://mozilla.org/MPL/2.0/.
+#
+# See the COPYRIGHT file distributed with this work for additional
+# information regarding copyright ownership.
+
+rm -f ns*/named.run ns*/named.conf ns*/named.pid ns*/managed-keys.bind*
+rm -f ans*/ans.run ans*/ans.pid
+rm -f ns*/named.memstats
--- a/bin/tests/system/dispatch/conftest.py
+++ b/bin/tests/system/dispatch/conftest.py
@ -0,0 +1,25 @@
+############################################################################
+# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, you can obtain one at https://mozilla.org/MPL/2.0/.
+#
+# See the COPYRIGHT file distributed with this work for additional
+# information regarding copyright ownership.
+############################################################################
+
+import os
+import pytest
+
+
+@pytest.fixture
+def port(request):
+    # pylint: disable=unused-argument
+    env_port = os.getenv("PORT")
+    if env_port is None:
+        env_port = 5300
+    else:
+        env_port = int(env_port)
+
+    return env_port
--- a/bin/tests/system/dispatch/ns1/named.conf.in
+++ b/bin/tests/system/dispatch/ns1/named.conf.in
@ -0,0 +1,42 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+key rndc_key {
+	secret "1234abcd8765";
+	algorithm hmac-sha256;
+};
+
+controls {
+	inet 10.53.0.1 port @CONTROLPORT@ allow { any; } keys { rndc_key; };
+};
+
+options {
+	port @PORT@;
+	pid-file "named.pid";
+
+	listen-on { 10.53.0.1; };
+	query-source address 10.53.0.1;
+	notify-source 10.53.0.1;
+	transfer-source 10.53.0.1;
+
+	listen-on-v6 { fd92:7065:b8e:ffff::1; };
+	query-source-v6 address fd92:7065:b8e:ffff::1;
+	notify-source-v6 fd92:7065:b8e:ffff::1;
+	transfer-source-v6 fd92:7065:b8e:ffff::1;
+
+	recursion no;
+	servfail-ttl 0;
+};
+
+zone "." {
+	type primary;
+	file "root.db";
+};
--- a/bin/tests/system/dispatch/ns1/root.db
+++ b/bin/tests/system/dispatch/ns1/root.db
@ -0,0 +1,14 @@
+; Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+;
+; This Source Code Form is subject to the terms of the Mozilla Public
+; License, v. 2.0. If a copy of the MPL was not distributed with this
+; file, You can obtain one at http://mozilla.org/MPL/2.0/.
+;
+; See the COPYRIGHT file distributed with this work for additional
+; information regarding copyright ownership.
+
+.		300	SOA	. . 0 0 0 0 0
+.		300	NS	ns.nil.
+ns.nil.		300	A	10.53.0.1
+example.	300	NS	ns.example.
+ns.example.	300	A	10.53.0.2
--- a/bin/tests/system/dispatch/ns2/example.db
+++ b/bin/tests/system/dispatch/ns2/example.db
@ -0,0 +1,6 @@
+example.		86400	IN	SOA	ns.example. root.example. 43 10800 900 604800 86400
+example.		86400	IN	NS	ns.example.
+ns.example.				A	10.53.0.2
+
+ns.sub.example.				A	10.53.0.3
+sub.example.				NS	ns.sub.example.
--- a/bin/tests/system/dispatch/ns2/named.conf.in
+++ b/bin/tests/system/dispatch/ns2/named.conf.in
@ -0,0 +1,47 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+key rndc_key {
+	secret "1234abcd8765";
+	algorithm hmac-sha256;
+};
+
+controls {
+	inet 10.53.0.2 port @CONTROLPORT@ allow { any; } keys { rndc_key; };
+};
+
+options {
+	port @PORT@;
+	pid-file "named.pid";
+
+	listen-on { 10.53.0.2; };
+	query-source address 10.53.0.2;
+	notify-source 10.53.0.2;
+	transfer-source 10.53.0.2;
+
+	listen-on-v6 { fd92:7065:b8e:ffff::2; };
+	query-source-v6 address fd92:7065:b8e:ffff::2;
+	notify-source-v6 fd92:7065:b8e:ffff::2;
+	transfer-source-v6 fd92:7065:b8e:ffff::2;
+
+	recursion yes;
+	servfail-ttl 0;
+};
+
+zone "." {
+	type hint;
+	file "../../common/root.hint";
+};
+
+zone "example" {
+	type primary;
+	file "example.db";
+};
--- a/bin/tests/system/dispatch/setup.sh
+++ b/bin/tests/system/dispatch/setup.sh
@ -0,0 +1,15 @@
+#!/bin/sh
+#
+# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, you can obtain one at https://mozilla.org/MPL/2.0/.
+#
+# See the COPYRIGHT file distributed with this work for additional
+# information regarding copyright ownership.
+
+. ../conf.sh
+
+copy_setports ns1/named.conf.in ns1/named.conf
+copy_setports ns2/named.conf.in ns2/named.conf
--- a/bin/tests/system/dispatch/tests-connreset.py
+++ b/bin/tests/system/dispatch/tests-connreset.py
@ -0,0 +1,25 @@
+#!/usr/bin/python3
+############################################################################
+# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, you can obtain one at https://mozilla.org/MPL/2.0/.
+#
+# See the COPYRIGHT file distributed with this work for additional
+# information regarding copyright ownership.
+############################################################################
+
+import pytest
+
+pytest.importorskip("dns")
+import dns.message
+import dns.query
+import dns.rcode
+
+
+def test_connreset(port):
+    msg = dns.message.make_query("sub.example.", "A", want_dnssec=True,
+                                 use_edns=0, payload=1232)
+    ans = dns.query.udp(msg, "10.53.0.2", timeout=10, port=port)
+    assert ans.rcode() == dns.rcode.SERVFAIL
--- a/doc/notes/notes-current.rst
+++ b/doc/notes/notes-current.rst
@ -56,3 +56,6 @@ Bug Fixes
  ``rndc reconfig``, then bringing back the removed ``catalog-zone`` clause and
  running ``rndc reconfig`` again caused ``named`` to crash. This has been fixed.
  :gl:`#1608`
+
+- The resolver could hang on shutdown due to dispatch resources not being
+  cleaned up when a TCP connection was reset. This has been fixed. :gl:`#3026`
--- a/lib/dns/dispatch.c
+++ b/lib/dns/dispatch.c
@ -134,6 +134,8 @@ struct dns_dispatch {

 	unsigned int requests;	 /*%< how many requests we have */
 	unsigned int tcpbuffers; /*%< allocated buffers */
+
+	unsigned int timedout;
 };

 #define QID_MAGIC    ISC_MAGIC('Q', 'i', 'd', ' ')
@ -595,6 +597,134 @@ done:
 	dispentry_detach(&resp);
 }

+static isc_result_t
+tcp_recv_timeout(dns_dispatch_t *disp, dns_dispentry_t **respp) {
+	dns_dispentry_t *resp = ISC_LIST_HEAD(disp->active);
+	if (resp != NULL) {
+		dispentry_attach(resp, &(dns_dispentry_t *){ NULL });
+		ISC_LIST_UNLINK(disp->active, resp, alink);
+		ISC_LIST_APPEND(disp->active, resp, alink);
+
+		disp->timedout++;
+
+		*respp = resp;
+		return (ISC_R_TIMEDOUT);
+	}
+
+	return (ISC_R_NOTFOUND);
+}
+
+static isc_result_t
+tcp_recv_success(dns_dispatch_t *disp, isc_region_t *region, dns_qid_t *qid,
+		 isc_sockaddr_t *peer, dns_dispentry_t **respp) {
+	isc_buffer_t source;
+	dns_messageid_t id;
+	unsigned int flags;
+	unsigned int bucket;
+	isc_result_t result = ISC_R_SUCCESS;
+	dns_dispentry_t *resp = NULL;
+
+	dispatch_log(disp, LVL(90), "success, length == %d, addr = %p",
+		     region->length, region->base);
+
+	/*
+	 * Peek into the buffer to see what we can see.
+	 */
+	isc_buffer_init(&source, region->base, region->length);
+	isc_buffer_add(&source, region->length);
+	result = dns_message_peekheader(&source, &id, &flags);
+	if (result != ISC_R_SUCCESS) {
+		dispatch_log(disp, LVL(10), "got garbage packet");
+		return (ISC_R_UNEXPECTED);
+	}
+
+	dispatch_log(disp, LVL(92),
+		     "got valid DNS message header, /QR %c, id %u",
+		     (((flags & DNS_MESSAGEFLAG_QR) != 0) ? '1' : '0'), id);
+
+	/*
+	 * Look at the message flags.  If it's a query, ignore it and keep
+	 * reading.
+	 */
+	if ((flags & DNS_MESSAGEFLAG_QR) == 0) {
+		dispatch_log(disp, LVL(10), "got DNS query instead of answer");
+		return (ISC_R_UNEXPECTED);
+	}
+
+	/*
+	 * We have a valid response; find the associated dispentry object
+	 * and call the caller back.
+	 */
+	bucket = dns_hash(qid, peer, id, disp->localport);
+	LOCK(&qid->lock);
+	resp = entry_search(qid, peer, id, disp->localport, bucket);
+	if (resp != NULL) {
+		dispentry_attach(resp, &(dns_dispentry_t *){ NULL });
+		*respp = resp;
+	} else if (disp->timedout > 0) {
+		/* There was active query that timed-out before */
+		disp->timedout--;
+
+		resp = ISC_LIST_HEAD(disp->active);
+		if (resp != NULL) {
+			/*
+			 * It's a DNS response, but didn't match any outstanding
+			 * queries. It's possible we would have timed out by
+			 * now, but non-matching responses prevented it, so we
+			 * check the age of the oldest active resp.
+			 */
+			int timeout = resp->timeout - dispentry_runtime(resp);
+			if (timeout <= 0) {
+				result = tcp_recv_timeout(disp, respp);
+			}
+		} else {
+			result = ISC_R_NOTFOUND;
+		}
+	} else {
+		/* We are not expecting this DNS message */
+		result = ISC_R_UNEXPECTED;
+	}
+	dispatch_log(disp, LVL(90), "search for response in bucket %d: %s",
+		     bucket, isc_result_totext(result));
+	UNLOCK(&qid->lock);
+
+	return (result);
+}
+
+static void
+tcp_recv_shutdown(dns_dispatch_t *disp, dns_displist_t *resps) {
+	dns_dispentry_t *resp = NULL, *next = NULL;
+
+	/*
+	 * If there are any active responses, shut them all down.
+	 */
+	for (resp = ISC_LIST_HEAD(disp->active); resp != NULL; resp = next) {
+		next = ISC_LIST_NEXT(resp, alink);
+		dispentry_attach(resp, &(dns_dispentry_t *){ NULL });
+		ISC_LIST_UNLINK(disp->active, resp, alink);
+		ISC_LIST_APPEND(*resps, resp, rlink);
+	}
+}
+
+static void
+tcp_recv_done(dns_dispentry_t *resp, isc_result_t eresult,
+	      isc_region_t *region) {
+	resp->response(eresult, region, resp->arg);
+	dispentry_detach(&resp);
+}
+
+static void
+tcp_recv_cancelall(dns_displist_t *resps, isc_region_t *region) {
+	dns_dispentry_t *resp = NULL, *next = NULL;
+
+	for (resp = ISC_LIST_HEAD(*resps); resp != NULL; resp = next) {
+		next = ISC_LIST_NEXT(resp, rlink);
+		ISC_LIST_UNLINK(*resps, resp, rlink);
+		resp->response(ISC_R_SHUTTINGDOWN, region, resp->arg);
+		dispentry_detach(&resp);
+	}
+}
+
 /*
 * General flow:
 *
@ -611,18 +741,12 @@ done:
 *	restart.
 */
 static void
-tcp_recv(isc_nmhandle_t *handle, isc_result_t eresult, isc_region_t *region,
+tcp_recv(isc_nmhandle_t *handle, isc_result_t result, isc_region_t *region,
 	 void *arg) {
 	dns_dispatch_t *disp = (dns_dispatch_t *)arg;
-	dns_dispentry_t *resp = NULL, *next = NULL;
-	dns_messageid_t id;
-	isc_result_t dres;
-	unsigned int flags;
-	unsigned int bucket;
+	dns_dispentry_t *resp = NULL;
 	dns_qid_t *qid = NULL;
-	int level;
 	char buf[ISC_SOCKADDR_FORMATSIZE];
-	isc_buffer_t source;
 	isc_sockaddr_t peer;
 	dns_displist_t resps;

@ -630,36 +754,26 @@ tcp_recv(isc_nmhandle_t *handle, isc_result_t eresult, isc_region_t *region,

 	qid = disp->mgr->qid;

+	ISC_LIST_INIT(resps);
+
 	LOCK(&disp->lock);

 	dispatch_log(disp, LVL(90), "TCP read:%s:requests %d, buffers %d",
-		     isc_result_totext(eresult), disp->requests,
+		     isc_result_totext(result), disp->requests,
 		     disp->tcpbuffers);

 	peer = isc_nmhandle_peeraddr(handle);
-	ISC_LIST_INIT(resps);
-
-	switch (eresult) {
-	case ISC_R_SUCCESS:
-		/* got our answer */
-		break;

+	switch (result) {
 	case ISC_R_SHUTTINGDOWN:
 	case ISC_R_CANCELED:
 	case ISC_R_EOF:
-		dispatch_log(disp, LVL(90), "shutting down: %s",
-			     isc_result_totext(eresult));
-		/*
-		 * If there are any active responses, shut them all down.
-		 */
-		for (resp = ISC_LIST_HEAD(disp->active); resp != NULL;
-		     resp = next) {
-			next = ISC_LIST_NEXT(resp, alink);
-			dispentry_attach(resp, &(dns_dispentry_t *){ NULL });
-			ISC_LIST_UNLINK(disp->active, resp, alink);
-			ISC_LIST_APPEND(resps, resp, rlink);
-		}
-		goto done;
+	case ISC_R_CONNECTIONRESET:
+		isc_sockaddr_format(&peer, buf, sizeof(buf));
+		dispatch_log(disp, LVL(90), "shutting down TCP: %s: %s", buf,
+			     isc_result_totext(result));
+		tcp_recv_shutdown(disp, &resps);
+		break;

 	case ISC_R_TIMEDOUT:
 		/*
@ -668,90 +782,55 @@ tcp_recv(isc_nmhandle_t *handle, isc_result_t eresult, isc_region_t *region,
 		 * active queue immediately, though, because the callback
 		 * might decide to keep waiting and leave it active.)
 		 */
-		resp = ISC_LIST_HEAD(disp->active);
-		if (resp != NULL) {
-			dispentry_attach(resp, &(dns_dispentry_t *){ NULL });
-			ISC_LIST_UNLINK(disp->active, resp, alink);
-			ISC_LIST_APPEND(disp->active, resp, alink);
-		}
-		goto done;
+		result = tcp_recv_timeout(disp, &resp);
+		break;

+	case ISC_R_SUCCESS:
+		/* We got an answer */
+		result = tcp_recv_success(disp, region, qid, &peer, &resp);
+		if (result != ISC_R_UNEXPECTED) {
+			/*
+			 * It's a valid DNS response, which may or may not
+			 * have matched an outstanding query.
+			 */
+
+			dispatch_getnext(disp, NULL, -1);
+			break;
+		}
+
+		/* Got an invalid DNS response, terminate the connection */
+		/* FALLTHROUGH */
 	default:
-		if (eresult == ISC_R_CONNECTIONRESET) {
-			level = ISC_LOG_INFO;
-		} else {
-			level = ISC_LOG_ERROR;
-		}
-
 		isc_sockaddr_format(&peer, buf, sizeof(buf));
-		dispatch_log(disp, level,
+		dispatch_log(disp, ISC_LOG_ERROR,
 			     "shutting down due to TCP "
 			     "receive error: %s: %s",
-			     buf, isc_result_totext(eresult));
-		goto done;
+			     buf, isc_result_totext(result));
+		tcp_recv_shutdown(disp, &resps);
+		break;
 	}

-	dispatch_log(disp, LVL(90), "success, length == %d, addr = %p",
-		     region->length, region->base);
-
-	/*
-	 * Peek into the buffer to see what we can see.
-	 */
-	isc_buffer_init(&source, region->base, region->length);
-	isc_buffer_add(&source, region->length);
-	dres = dns_message_peekheader(&source, &id, &flags);
-	if (dres != ISC_R_SUCCESS) {
-		dispatch_log(disp, LVL(10), "got garbage packet");
-		goto next;
-	}
-
-	dispatch_log(disp, LVL(92),
-		     "got valid DNS message header, /QR %c, id %u",
-		     (((flags & DNS_MESSAGEFLAG_QR) != 0) ? '1' : '0'), id);
-
-	/*
-	 * Look at the message flags.  If it's a query, ignore it
-	 * and keep reading.
-	 */
-	if ((flags & DNS_MESSAGEFLAG_QR) == 0) {
-		/*
-		 * Query.
-		 */
-		goto next;
-	}
-
-	/*
-	 * We have a valid response; find the associated dispentry object
-	 * and call the caller back.
-	 */
-	bucket = dns_hash(qid, &peer, id, disp->localport);
-	LOCK(&qid->lock);
-	resp = entry_search(qid, &peer, id, disp->localport, bucket);
-	if (resp != NULL) {
-		dispentry_attach(resp, &(dns_dispentry_t *){ NULL });
-	}
-	dispatch_log(disp, LVL(90), "search for response in bucket %d: %s",
-		     bucket, (resp == NULL ? "not found" : "found"));
-	UNLOCK(&qid->lock);
-
-next:
-	dispatch_getnext(disp, NULL, -1);
-
-done:
 	UNLOCK(&disp->lock);

-	if (resp != NULL) {
-		/* We got a matching response, or timed out */
-		resp->response(eresult, region, resp->arg);
-		dispentry_detach(&resp);
-	} else {
-		/* We're being shut down; cancel all outstanding resps */
-		for (resp = ISC_LIST_HEAD(resps); resp != NULL; resp = next) {
-			next = ISC_LIST_NEXT(resp, rlink);
-			ISC_LIST_UNLINK(resps, resp, rlink);
-			resp->response(ISC_R_SHUTTINGDOWN, region, resp->arg);
-			dispentry_detach(&resp);
-		}
+	switch (result) {
+	case ISC_R_SUCCESS:
+	case ISC_R_TIMEDOUT:
+		/*
+		 * Either we found a matching response, or we timed out
+		 * and canceled the oldest resp.
+		 */
+		INSIST(resp != NULL);
+		tcp_recv_done(resp, result, region);
+		break;
+	case ISC_R_NOTFOUND:
+		/*
+		 * Either we got a response that didn't match any active
+		 * resps, or we timed out but there *were* no active resps.
+		 */
+		break;
+	default:
+		/* We're being shut down; cancel all outstanding resps. */
+		tcp_recv_cancelall(&resps, region);
 	}

 	dns_dispatch_detach(&disp);
@ -1442,6 +1521,8 @@ dispatch_getnext(dns_dispatch_t *disp, dns_dispentry_t *resp, int32_t timeout) {

 	switch (disp->socktype) {
 	case isc_socktype_udp:
+		REQUIRE(resp != NULL);
+
 		dispentry_attach(resp, &(dns_dispentry_t *){ NULL });
 		if (timeout > 0) {
 			isc_nmhandle_settimeout(resp->handle, timeout);
--- a/util/copyrights
+++ b/util/copyrights
@ -228,6 +228,11 @@
 ./bin/tests/system/digdelv/setup.sh		SH	2018,2019,2020,2021
 ./bin/tests/system/digdelv/tests.sh		SH	2015,2016,2017,2018,2019,2020,2021
 ./bin/tests/system/digdelv/yamlget.py		PYTHON	2019,2020,2021
+./bin/tests/system/dispatch/ans3/ans.py		PYTHON	2021
+./bin/tests/system/dispatch/clean.sh		SH	2021
+./bin/tests/system/dispatch/conftest.py		PYTHON	2021
+./bin/tests/system/dispatch/setup.sh		SH	2021
+./bin/tests/system/dispatch/tests-connreset.py	PYTHON-BIN	2021
 ./bin/tests/system/ditch.pl			PERL	2015,2016,2018,2019,2020,2021
 ./bin/tests/system/dlzexternal/clean.sh		SH	2010,2012,2014,2015,2016,2018,2019,2020,2021
 ./bin/tests/system/dlzexternal/driver/driver.c	C	2011,2012,2013,2014,2015,2016,2017,2018,2019,2020,2021