Fix updating summary RPZ DB for mixed-case RPZs

Each dns_rpz_zone_t structure keeps a hash table of the names this RPZ
database contains.  Here is what happens when an RPZ is updated:

  - a new hash table is prepared for the new version of the RPZ by
    iterating over it; each name found is added to the summary RPZ
    database,

  - every name added to the new hash table is searched for in the old
    hash table; if found, it is removed from the old hash table,

  - the old hash table is iterated over; all names found in it are
    removed from the summary RPZ database (because at that point the old
    hash table should only contain names which are not present in the
    new version of the RPZ),

  - the new hash table replaces the old hash table.

When the new version of the RPZ is iterated over, if a given name is
spelled using a different letter case than in the old version of the
RPZ, the new variant will hash to a different value than the old
variant, which means it will not be removed from the old hash table.
When the old hash table is subsequently iterated over to remove
seemingly deleted names, the old variant of the name will still be
there, causing the name to be deleted from the summary RPZ database
(which effectively causes a given rule to be ignored).

The issue can be triggered not just by altering the case of existing
names in an RPZ, but also by adding sibling names spelled with a
different letter case.  This is because RBT code preserves case when
node splitting occurs.  The end result is that when the RPZ is iterated
over, a given name may be using a different case than in the zone file
(or XFR contents).

Fix by downcasing all names found in the RPZ database before adding them
to the summary RPZ database.

bin/tests/system/rpz/clean.sh

@@ -31,6 +31,7 @@ rm -f ns*/*.key ns*/*.private
 rm -f ns2/tld2s.db ns2/bl.tld2.db
 rm -f ns3/bl*.db ns3/fast-expire.db ns*/empty.db
 rm -f ns3/manual-update-rpz.db
+rm -f ns3/mixed-case-rpz.db
 rm -f ns5/example.db ns5/bl.db ns5/fast-expire.db ns5/expire.conf
 rm -f ns8/manual-update-rpz.db
 rm -f */policy2.db

bin/tests/system/rpz/ns3/mixed-case-rpz-1.db.in

@@ -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.
+
+$TTL 300
+@		SOA	mixed-case-rpz.  hostmaster.ns.mixed-case-rpz. ( 1 3600 1200 604800 60 )
+		NS	ns.tld3.
+
+A6-2.TLD2	CNAME	.

bin/tests/system/rpz/ns3/mixed-case-rpz-2.db.in

@@ -0,0 +1,15 @@
+; 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.
+
+$TTL 300
+@		SOA	mixed-case-rpz.  hostmaster.ns.mixed-case-rpz. ( 2 3600 1200 604800 60 )
+		NS	ns.tld3.
+
+a6-1.tld2	CNAME	.
+A6-2.TLD2	CNAME	.

bin/tests/system/rpz/ns3/named.conf.in

@@ -48,6 +48,7 @@ options {
 	    zone "bl-tcp-only"	policy tcp-only;
 	    zone "bl.tld2";
 	    zone "manual-update-rpz";
+	    zone "mixed-case-rpz";
 	}
 	add-soa yes
 	min-ns-dots 0
@@ -114,6 +115,12 @@ zone "manual-update-rpz." {
 	notify no;
 };
 
+zone "mixed-case-rpz." {
+	type primary;
+	file "mixed-case-rpz.db";
+	notify no;
+};
+
 zone "fast-expire." {
 	type secondary;
 	file "fast-expire.db";

bin/tests/system/rpz/setup.sh

@@ -73,6 +73,8 @@ done
 cp ns3/manual-update-rpz.db.in ns3/manual-update-rpz.db
 cp ns8/manual-update-rpz.db.in ns8/manual-update-rpz.db
 
+cp ns3/mixed-case-rpz-1.db.in ns3/mixed-case-rpz.db
+
 # a zone that expires quickly and then can't be refreshed
 cp ns5/fast-expire.db.in ns5/fast-expire.db
 cp ns5/expire.conf.in ns5/expire.conf

bin/tests/system/rpz/tests.sh

@@ -823,6 +823,24 @@ EOF
     # ensure previous RPZ rules still apply.
     $DIG -p ${PORT} @$ns3 walled.tld2 > dig.out.$t.after
     grep "walled\.tld2\..*IN.*A.*10\.0\.0\.1" dig.out.$t.after > /dev/null || setret "failed"
+
+    t=`expr $t + 1`
+    echo_i "checking reload of a mixed-case RPZ zone (${t})"
+    # First, a sanity check: the A6-2.TLD2.mixed-case-rpz RPZ record should
+    # cause a6-2.tld2 NOERROR answers to be rewritten to NXDOMAIN answers.
+    $DIG -p ${PORT} @$ns3 a6-2.tld2. A > dig.out.$t.before
+    grep "status: NXDOMAIN" dig.out.$t.before >/dev/null || setret "failed"
+    # Add a sibling name (a6-1.tld2.mixed-case-rpz, with "tld2" in lowercase
+    # rather than uppercase) before A6-2.TLD.mixed-case-rpz.
+    nextpart ns3/named.run > /dev/null
+    cp ns3/mixed-case-rpz-2.db.in ns3/mixed-case-rpz.db
+    rndc_reload ns3 $ns3 mixed-case-rpz
+    wait_for_log 20 "rpz: mixed-case-rpz: reload done" ns3/named.run
+    # a6-2.tld2 NOERROR answers should still be rewritten to NXDOMAIN answers.
+    # (The bug we try to trigger here caused a6-2.tld2.mixed-case-rpz to be
+    # erroneously removed from the summary RPZ database after reload.)
+    $DIG -p ${PORT} @$ns3 a6-2.tld2. A > dig.out.$t.after
+    grep "status: NXDOMAIN" dig.out.$t.after >/dev/null || setret "failed"
   fi
 
   t=`expr $t + 1`

lib/dns/rpz.c

@@ -2008,6 +2008,7 @@ update_quantum(isc_task_t *task, isc_event_t *event) {
 			continue;
 		}
 
+		dns_name_downcase(name, name, NULL);
 		result = isc_ht_add(rpz->newnodes, name->ndata, name->length,
 				    rpz);
 		if (result != ISC_R_SUCCESS) {