From aa59465e46b6fd617bf992a80da400ae14fbb4ec Mon Sep 17 00:00:00 2001
From: Otto Moerbeek <otto.moerbeek@open-xchange.com>
Date: Mon, 14 Feb 2022 15:39:17 +0100
Subject: [PATCH] If we get NODATA on an AAAA in followCNAMERecords, try dns64

Fixes #11320
---
 pdns/pdns_recursor.cc | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/pdns/pdns_recursor.cc b/pdns/pdns_recursor.cc
index 9aad7e01ee..29298cd19c 100644
--- a/pdns/pdns_recursor.cc
+++ b/pdns/pdns_recursor.cc
@@ -613,6 +613,8 @@ static bool udrCheckUniqueDNSRecord(const shared_ptr<Logr::Logger>& nodlogger, c
 }
 #endif /* NOD_ENABLED */
 
+static bool answerIsNOData(uint16_t requestedType, int rcode, const std::vector<DNSRecord>& records);
+
 int followCNAMERecords(vector<DNSRecord>& ret, const QType qtype, int rcode)
 {
   vector<DNSRecord> resolved;
@@ -633,8 +635,14 @@ int followCNAMERecords(vector<DNSRecord>& ret, const QType qtype, int rcode)
 
   rcode = directResolve(target, qtype, QClass::IN, resolved, t_pdl);
 
+  if (g_dns64Prefix && qtype == QType::AAAA && answerIsNOData(qtype, rcode, resolved)) {
+    rcode = getFakeAAAARecords(target, *g_dns64Prefix, resolved);
+  }
+
   for (DNSRecord& rr : resolved) {
-    ret.push_back(std::move(rr));
+    if (rr.d_place == DNSResourceRecord::ANSWER) {
+      ret.push_back(std::move(rr));
+    }
   }
   return rcode;
 }
-- 
2.47.2