From: George Thessalonikefs <yorgos@nlnetlabs.nl>
Date: Wed, 18 Oct 2023 09:59:41 +0000 (+0200)
Subject: Fixes for dns64 fallback to plain AAAA when no A records:
X-Git-Tag: release-1.19.0rc1~17
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=d5522c3480dc128dc8a5c84a4d7aea9c8d12e0f9;p=thirdparty%2Funbound.git

Fixes for dns64 fallback to plain AAAA when no A records:
- Cleanup if condition.
- Rename variable for readability.
---

diff --git a/dns64/dns64.c b/dns64/dns64.c
index 10e7512a9..83fb02779 100644
--- a/dns64/dns64.c
+++ b/dns64/dns64.c
@@ -633,7 +633,7 @@ handle_event_moddone(struct module_qstate* qstate, int id)
 	 * synthesis. We skip queries with DNSSEC enabled (!CD) and
 	 * ones generated by us to retrive the A/PTR record to use for
 	 * synth. */
-	int want_synth =
+	int could_synth =
 		qstate->qinfo.qtype == LDNS_RR_TYPE_AAAA &&
 		(!iq || iq->state != DNS64_INTERNAL_QUERY) &&
 		!(qstate->query_flags & BIT_CD);
@@ -643,7 +643,7 @@ handle_event_moddone(struct module_qstate* qstate, int id)
 		reply_find_answer_rrset(&qstate->qinfo, qstate->return_msg->rep);
 	int synth_qname = 0;
 
-	if(want_synth &&
+	if(could_synth &&
 		(!has_data ||
 		(synth_qname=dns64_always_synth_for_qname(qstate, id)))) {
 		if(synth_qname)
@@ -975,20 +975,18 @@ 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 &&
-	    qstate->return_rcode == LDNS_RCODE_NOERROR &&
-	    !( qstate->return_msg &&
-	       qstate->return_msg->rep &&
-	       reply_find_answer_rrset(&qstate->qinfo, qstate->return_msg->rep)))
-	{
+	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;
 	}