Error if signatures-refresh is too high

The signatures-refresh should not near the signatures-validity value,
to prevent operational instability. Same is true when checking against
signatures-validity-dnskey.

bin/tests/system/checkconf/kasp-bad-signatures-refresh.conf

@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ *
+ * 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.
+ */
+
+dnssec-policy "bad-sigrefresh" {
+	keys {
+		csk lifetime unlimited algorithm 13;
+	};
+
+	signatures-validity P10D;
+	signatures-validity-dnskey P20D;
+	signatures-refresh P9DT1S;
+};
+
+dnssec-policy "bad-sigrefresh-dnskey" {
+	keys {
+		csk lifetime unlimited algorithm 13;
+	};
+
+	signatures-validity P20D;
+	signatures-validity-dnskey P10D;
+	signatures-refresh P9DT1S;
+};
+
+zone "sigrefresh.example.net" {
+	type primary;
+	file "sigrefresh.example.db";
+	dnssec-policy "bad-sigrefresh";
+};
+
+zone "dnskey.example.net" {
+	type primary;
+	file "dnskey.example.db";
+	dnssec-policy "bad-sigrefresh-dnskey";
+};

bin/tests/system/checkconf/tests.sh

@@ -528,6 +528,17 @@ grep "dnssec-policy: key with algorithm rsasha1 has invalid key length 511" < ch
 if [ $ret != 0 ]; then echo_i "failed"; fi
 status=`expr $status + $ret`
 
+n=`expr $n + 1`
+echo_i "checking named-checkconf kasp signatures refresh errors ($n)"
+ret=0
+$CHECKCONF kasp-bad-signatures-refresh.conf > checkconf.out$n 2>&1 && ret=1
+grep "dnssec-policy: policy 'bad-sigrefresh' signatures-refresh must be at most 90% of the signatures-validity" < checkconf.out$n > /dev/null || ret=1
+grep "dnssec-policy: policy 'bad-sigrefresh-dnskey' signatures-refresh must be at most 90% of the signatures-validity-dnskey" < checkconf.out$n > /dev/null || ret=1
+lines=$(wc -l < "checkconf.out$n")
+if [ $lines != 2 ]; then ret=1; fi
+if [ $ret != 0 ]; then echo_i "failed"; fi
+status=`expr $status + $ret`
+
 n=`expr $n + 1`
 echo_i "checking named-checkconf kasp predefined key length ($n)"
 ret=0

lib/isccfg/kaspconf.c

@@ -268,6 +268,7 @@ cfg_kasp_fromconfig(const cfg_obj_t *config, const char *name, isc_mem_t *mctx,
 	const char *kaspname = NULL;
 	dns_kasp_t *kasp = NULL;
 	size_t i = 0;
+	uint32_t sigrefresh = 0, sigvalidity = 0;
 
 	REQUIRE(kaspp != NULL && *kaspp == NULL);
 
@@ -308,13 +309,36 @@ cfg_kasp_fromconfig(const cfg_obj_t *config, const char *name, isc_mem_t *mctx,
 	maps[i] = NULL;
 
 	/* Configuration: Signatures */
-	dns_kasp_setsigrefresh(kasp, get_duration(maps, "signatures-refresh",
+	sigrefresh = get_duration(maps, "signatures-refresh",
-						  DNS_KASP_SIG_REFRESH));
+				  DNS_KASP_SIG_REFRESH);
-	dns_kasp_setsigvalidity(kasp, get_duration(maps, "signatures-validity",
+	dns_kasp_setsigrefresh(kasp, sigrefresh);
-						   DNS_KASP_SIG_VALIDITY));
+
-	dns_kasp_setsigvalidity_dnskey(
+	sigvalidity = get_duration(maps, "signatures-validity",
-		kasp, get_duration(maps, "signatures-validity-dnskey",
+				   DNS_KASP_SIG_VALIDITY);
-				   DNS_KASP_SIG_VALIDITY_DNSKEY));
+	if (sigrefresh >= (sigvalidity * 0.9)) {
+		cfg_obj_log(config, logctx, ISC_LOG_ERROR,
+			    "dnssec-policy: policy '%s' signatures-refresh "
+			    "must be at most 90%% of the signatures-validity",
+			    kaspname);
+		result = ISC_R_FAILURE;
+	}
+	dns_kasp_setsigvalidity(kasp, sigvalidity);
+
+	sigvalidity = get_duration(maps, "signatures-validity-dnskey",
+				   DNS_KASP_SIG_VALIDITY_DNSKEY);
+	if (sigrefresh >= (sigvalidity * 0.9)) {
+		cfg_obj_log(
+			config, logctx, ISC_LOG_ERROR,
+			"dnssec-policy: policy '%s' signatures-refresh must be "
+			"at most 90%% of the signatures-validity-dnskey",
+			kaspname);
+		result = ISC_R_FAILURE;
+	}
+	dns_kasp_setsigvalidity_dnskey(kasp, sigvalidity);
+
+	if (result != ISC_R_SUCCESS) {
+		goto cleanup;
+	}
 
 	/* Configuration: Keys */
 	dns_kasp_setdnskeyttl(