Return an empty NOERROR response for non-AAAA records

Previously, we returned NXDOMAIN, which would cause host(1) from looking up an
AAAA record afterwards when using just 'host ipv6-…' (without -t AAAA).

lib/App/AllKnowingDNS/Handler.pm

@@ -79,6 +79,10 @@ sub handle_aaaa_query {
     my ($digits) = ($qname =~ /$regexp/);
     return ('NXDOMAIN', undef, undef, undef) unless defined($digits);
 
+    if ($qtype ne 'AAAA') {
+        return ('NOERROR', [ ], [], [], { aa => 1 });
+    }
+
     # Pad with zeros so that we can match 4 digits each.
     $digits = "0$digits" while (length($digits) % 4) != 0;
 
@@ -114,8 +118,7 @@ sub reply_handler {
         return handle_ptr_query($querylog, $zone, $qname, $qclass, $qtype);
     }
 
-    if ($qtype eq 'AAAA' &&
-        defined(my $zone = $config->zone_for_aaaa($qname))) {
+    if (defined(my $zone = $config->zone_for_aaaa($qname))) {
         return handle_aaaa_query($zone, $qname, $qclass, $qtype);
     }
 

t/004-handler.t

@@ -56,6 +56,18 @@ is(scalar @$ans, 1, 'one answer RR');
 is($rr->type, 'AAAA', 'RR type is AAAA');
 is($rr->rdatastr, '2001:4d88:100e:ccc0:219:dbff:fe43:2ec7', 'RR ok');
 
+################################################################################
+# Check resolving hostnames to A records
+################################################################################
+
+$qname = 'ipv6-0219dbfffe432ec7-blah.nutzer.raumzeitlabor.de';
+$qclass = 'IN';
+$qtype = 'A';
+$peerhost = 'testsuite';
+($rcode, $ans, $auth, $add) = reply_handler($config, 0, $qname, $qclass, $qtype, $peerhost);
+is($rcode, 'NOERROR', 'no error when handling query');
+is(scalar @$ans, 0, 'zero answer RRs');
+
 ################################################################################
 # A pathetic example for resolving hostname to AAAA record: a /112 net
 ################################################################################