Remove support for silently ignoring 'no-change' deltas from BIND 8 when...

Remove support for silently ignoring 'no-change' deltas from BIND 8 when processing an IXFR stream. 'no-change' deltas will now trigger a fallback to AXFR as the recovery mechanism.

CHANGES

+4993.	[cleanup]	Remove support for silently ignoring 'no-change' deltas
+			from BIND 8 when processing an IXFR stream. 'no-change'
+			deltas will now trigger a fallback to AXFR as the
+			recovery mechanism. [GL #369]
+
 4992.	[bug]		The wrong address was being logged for trust anchor
 			telemetry queries. [GL #379]

doc/arm/notes.xml

@@ -241,6 +241,11 @@
 	  abundance of caution. DNS COOKIE is an important security mechanism,
 	  and should not be disabled unless absolutely necessary.
 	</para>
+	<para>
+	  Remove support for silently ignoring 'no-change' deltas from
+	  BIND 8 when processing an IXFR stream.  'no-change' deltas
+	  will now trigger a fallback to AXFR as the recovery mechanism.
+	</para>
       </listitem>
     </itemizedlist>
   </section>

lib/dns/journal.c

@@ -71,12 +71,6 @@
  *     the "end" position in the header.  The latter will
  *     be overwritten when new transactions are added.
  */
-/*%
- * When true, accept IXFR difference sequences where the
- * SOA serial number does not change (BIND 8 sends such
- * sequences).
- */
-static isc_boolean_t bind8_compat = ISC_TRUE; /* XXX config */
 
 /**************************************************************************/
 /*
@@ -1130,13 +1124,10 @@ dns_journal_commit(dns_journal_t *j) {
 			      j->filename, j->x.n_soa);
 		return (ISC_R_UNEXPECTED);
 	}
-	if (! (DNS_SERIAL_GT(j->x.pos[1].serial, j->x.pos[0].serial) ||
-	       (bind8_compat &&
-		j->x.pos[1].serial == j->x.pos[0].serial)))
-	{
+	if (! DNS_SERIAL_GT(j->x.pos[1].serial, j->x.pos[0].serial)) {
 		isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
 			      "%s: malformed transaction: serial number "
-			      "would decrease", j->filename);
+			      "did not increase", j->filename);
 		return (ISC_R_UNEXPECTED);
 	}
 	if (! JOURNAL_EMPTY(&j->header)) {