Add a none parameter to query-source[-v6]

This change adds a "none" parameter to the query-source[-v6]
options in named.conf, which forbid the usage of IPv4 or IPv6
addresses when doing upstream queries.

bin/tests/system/query-source/tests_querysource_none.py

@@ -0,0 +1,58 @@
+#!/usr/bin/python3
+
+# 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.
+
+import pytest
+import isctest
+
+pytest.importorskip("dns")
+import dns.message
+
+pytestmark = pytest.mark.extra_artifacts(
+    [
+        "ns*/named.pid",
+        "ns*/managed-keys.bind*",
+    ]
+)
+
+
+def test_querysource_none():
+    msg = dns.message.make_query("example.", "A", want_dnssec=False)
+
+    res = isctest.query.udp(msg, "10.53.0.2")
+    isctest.check.noerror(res)
+
+    res = isctest.query.udp(msg, "10.53.0.3")
+    isctest.check.noerror(res)
+
+    res = isctest.query.udp(msg, "10.53.0.4")
+    isctest.check.servfail(res)
+
+    res = isctest.query.udp(msg, "10.53.0.5")
+    isctest.check.servfail(res)
+
+    # using a different name below to make sure we don't use the
+    # resolver cache
+
+    msg = dns.message.make_query("exampletwo.", "A", want_dnssec=False)
+
+    res = isctest.query.udp(msg, "fd92:7065:b8e:ffff::2")
+    isctest.check.noerror(res)
+
+    res = isctest.query.udp(msg, "fd92:7065:b8e:ffff::3")
+    isctest.check.noerror(res)
+
+    res = isctest.query.udp(msg, "fd92:7065:b8e:ffff::4")
+    isctest.check.servfail(res)
+
+    res = isctest.query.udp(msg, "fd92:7065:b8e:ffff::5")
+    isctest.check.servfail(res)