1 files changed, 57 insertions, 42 deletions

diff --git a/usr.sbin/unbound/dns64/dns64.c b/usr.sbin/unbound/dns64/dns64.c
index 1e31f51e831..83fb027790e 100644
--- a/usr.sbin/unbound/dns64/dns64.c
+++ b/usr.sbin/unbound/dns64/dns64.c
@@ -573,28 +573,29 @@ static enum module_ext_state
 handle_event_pass(struct module_qstate* qstate, int id)
 {
 	struct dns64_qstate* iq = (struct dns64_qstate*)qstate->minfo[id];
-	if (iq && iq->state == DNS64_NEW_QUERY
-            && qstate->qinfo.qtype == LDNS_RR_TYPE_PTR
-            && qstate->qinfo.qname_len == 74
-            && !strcmp((char*)&qstate->qinfo.qname[64], "\03ip6\04arpa"))
-        /* Handle PTR queries for IPv6 addresses. */
-        return handle_ipv6_ptr(qstate, id);
-
-	if (qstate->env->cfg->dns64_synthall &&
-	    iq && iq->state == DNS64_NEW_QUERY
-	    && qstate->qinfo.qtype == LDNS_RR_TYPE_AAAA)
-		return generate_type_A_query(qstate, id);
+	int synth_all_cfg = qstate->env->cfg->dns64_synthall;
+	int synth_qname = 0;
+
+	if(iq && iq->state == DNS64_NEW_QUERY
+		&& qstate->qinfo.qtype == LDNS_RR_TYPE_PTR
+		&& qstate->qinfo.qname_len == 74
+		&& !strcmp((char*)&qstate->qinfo.qname[64], "\03ip6\04arpa")) {
+		/* Handle PTR queries for IPv6 addresses. */
+		return handle_ipv6_ptr(qstate, id);
+	}
 
-	if(dns64_always_synth_for_qname(qstate, id) &&
-	    iq && iq->state == DNS64_NEW_QUERY
-	    && !(qstate->query_flags & BIT_CD)
-	    && qstate->qinfo.qtype == LDNS_RR_TYPE_AAAA) {
-		verbose(VERB_ALGO, "dns64: ignore-aaaa and synthesize anyway");
+	if(iq && iq->state == DNS64_NEW_QUERY &&
+		qstate->qinfo.qtype == LDNS_RR_TYPE_AAAA &&
+		(synth_all_cfg ||
+		(synth_qname=(dns64_always_synth_for_qname(qstate, id)
+			&& !(qstate->query_flags & BIT_CD))))) {
+		if(synth_qname)
+			verbose(VERB_ALGO, "dns64: ignore-aaaa and synthesize anyway");
 		return generate_type_A_query(qstate, id);
 	}
 
 	/* We are finished when our sub-query is finished. */
-	if (iq && iq->state == DNS64_SUBQUERY_FINISHED)
+	if(iq && iq->state == DNS64_SUBQUERY_FINISHED)
 		return module_finished;
 
 	/* Otherwise, pass request to next module. */
@@ -627,32 +628,37 @@ handle_event_moddone(struct module_qstate* qstate, int id)
      *        synthesize in (sec 5.1.2 of RFC6147).
      *   - A successful AAAA query with an answer.
      */
-	if((!iq || iq->state != DNS64_INTERNAL_QUERY)
-            && qstate->qinfo.qtype == LDNS_RR_TYPE_AAAA
-	    && !(qstate->query_flags & BIT_CD)
-	    && !(qstate->return_msg &&
-		    qstate->return_msg->rep &&
-		    reply_find_answer_rrset(&qstate->qinfo,
-			    qstate->return_msg->rep)))
-		/* not internal, type AAAA, not CD, and no answer RRset,
-		 * So, this is a AAAA noerror/nodata answer */
-		return generate_type_A_query(qstate, id);
 
-	if((!iq || iq->state != DNS64_INTERNAL_QUERY)
-	    && qstate->qinfo.qtype == LDNS_RR_TYPE_AAAA
-	    && !(qstate->query_flags & BIT_CD)
-	    && dns64_always_synth_for_qname(qstate, id)) {
-		/* if it is not internal, AAAA, not CD and listed domain,
-		 * generate from A record and ignore AAAA */
-		verbose(VERB_ALGO, "dns64: ignore-aaaa and synthesize anyway");
+	/* When an AAAA query completes check if we want to perform DNS64
+	 * synthesis. We skip queries with DNSSEC enabled (!CD) and
+	 * ones generated by us to retrive the A/PTR record to use for
+	 * synth. */
+	int could_synth =
+		qstate->qinfo.qtype == LDNS_RR_TYPE_AAAA &&
+		(!iq || iq->state != DNS64_INTERNAL_QUERY) &&
+		!(qstate->query_flags & BIT_CD);
+	int has_data = /* whether query returned non-empty rrset */
+		qstate->return_msg &&
+		qstate->return_msg->rep &&
+		reply_find_answer_rrset(&qstate->qinfo, qstate->return_msg->rep);
+	int synth_qname = 0;
+
+	if(could_synth &&
+		(!has_data ||
+		(synth_qname=dns64_always_synth_for_qname(qstate, id)))) {
+		if(synth_qname)
+			verbose(VERB_ALGO, "dns64: ignore-aaaa and synthesize anyway");
 		return generate_type_A_query(qstate, id);
 	}
 
 	/* Store the response in cache. */
-	if ( (!iq || !iq->started_no_cache_store) &&
-		qstate->return_msg && qstate->return_msg->rep &&
-		!dns_cache_store(qstate->env, &qstate->qinfo, qstate->return_msg->rep,
-		0, 0, 0, NULL, qstate->query_flags, qstate->qstarttime))
+	if( (!iq || !iq->started_no_cache_store) &&
+		qstate->return_msg &&
+		qstate->return_msg->rep &&
+		!dns_cache_store(
+			qstate->env, &qstate->qinfo, qstate->return_msg->rep,
+			0, 0, 0, NULL,
+			qstate->query_flags, qstate->qstarttime))
 		log_err("out of memory");
 
 	/* do nothing */
@@ -969,10 +975,19 @@ dns64_inform_super(struct module_qstate* qstate, int id,
 	}
 	super_dq->state = DNS64_SUBQUERY_FINISHED;
 
-	/* If there is no successful answer, we're done. */
-	if (qstate->return_rcode != LDNS_RCODE_NOERROR
-	    || !qstate->return_msg
-	    || !qstate->return_msg->rep) {
+	/* If there is no successful answer, we're done.
+	 * Guarantee that we have at least a NOERROR reply further on. */
+	if(qstate->return_rcode != LDNS_RCODE_NOERROR
+		|| !qstate->return_msg
+		|| !qstate->return_msg->rep) {
+		return;
+	}
+
+	/* When no A record is found for synthesis fall back to AAAA again. */
+	if(qstate->qinfo.qtype == LDNS_RR_TYPE_A &&
+		!reply_find_answer_rrset(&qstate->qinfo,
+			qstate->return_msg->rep)) {
+		super_dq->state = DNS64_INTERNAL_QUERY;
 		return;
 	}