From 41147d678b30612d2431b59a898879368f1c4b06 Mon Sep 17 00:00:00 2001
From: Mark Zealey <mark@markandruth.co.uk>
Date: Wed, 10 Jul 2019 14:17:32 +0300
Subject: [PATCH] Fix SERVFAIL when backend returns empty DNSName

According to the documentation on UeberBackend::getAuth(), a backend
returning an empty DNSName should signal that no matching parent zone
exists in this backend. However commit ae14c1f36a raises an exception if
isPartOf() is called on an empty DNSName so we need to switch the order
of the logic to prevent a SERVFAIL as a result.
---
 pdns/ueberbackend.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pdns/ueberbackend.cc b/pdns/ueberbackend.cc
index 2c3dd363b0..e33b9030ea 100644
--- a/pdns/ueberbackend.cc
+++ b/pdns/ueberbackend.cc
@@ -330,7 +330,7 @@ bool UeberBackend::getAuth(const DNSName &target, const QType& qtype, SOAData* s
           DLOG(g_log<<Logger::Error<<"lookup: "<<shorter<<endl);
           if((*i)->getAuth(shorter, sd)) {
             DLOG(g_log<<Logger::Error<<"got: "<<sd->qname<<endl);
-            if(!shorter.isPartOf(sd->qname) && !sd->qname.empty()) {
+            if(!sd->qname.empty() && !shorter.isPartOf(sd->qname)) {
               throw PDNSException("getAuth() returned an SOA for the wrong zone. Zone '"+sd->qname.toLogString()+"' is not part of '"+shorter.toLogString()+"'");
             }
             j->first = sd->qname.wirelength();
-- 
2.47.2