From 190db5c21945d2aec18692978abfe60bd460732a Mon Sep 17 00:00:00 2001
From: Remi Gacogne <remi.gacogne@powerdns.com>
Date: Fri, 6 Jun 2025 15:14:13 +0200
Subject: [PATCH] dnsdist: Do not waste CPU cycles handling EDNS twice on
 self-generated answers

Signed-off-by: Remi Gacogne <remi.gacogne@powerdns.com>
---
 pdns/dnsdistdist/dnsdist-self-answers.cc | 5 ++++-
 pdns/dnsdistdist/dnsdist.cc              | 2 +-
 pdns/dnsdistdist/dnsdist.hh              | 2 +-
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/pdns/dnsdistdist/dnsdist-self-answers.cc b/pdns/dnsdistdist/dnsdist-self-answers.cc
index 4e0b66084e..be608fbd6e 100644
--- a/pdns/dnsdistdist/dnsdist-self-answers.cc
+++ b/pdns/dnsdistdist/dnsdist-self-answers.cc
@@ -94,6 +94,7 @@ bool generateAnswerFromCNAME(DNSQuestion& dnsQuestion, const DNSName& cname, con
     addEDNS(dnsQuestion.getMutableData(), dnsQuestion.getMaximumSize(), dnssecOK, dnsdist::configuration::getCurrentRuntimeConfiguration().d_payloadSizeSelfGenAnswers, 0);
   }
 
+  dnsQuestion.d_selfGeneratedHandledEDNS = true;
   return true;
 }
 
@@ -164,6 +165,7 @@ bool generateAnswerFromIPAddresses(DNSQuestion& dnsQuestion, const std::vector<C
     addEDNS(dnsQuestion.getMutableData(), dnsQuestion.getMaximumSize(), dnssecOK, dnsdist::configuration::getCurrentRuntimeConfiguration().d_payloadSizeSelfGenAnswers, 0);
   }
 
+  dnsQuestion.d_selfGeneratedHandledEDNS = true;
   return true;
 }
 
@@ -226,6 +228,7 @@ bool generateAnswerFromRDataEntries(DNSQuestion& dnsQuestion, const std::vector<
     addEDNS(dnsQuestion.getMutableData(), dnsQuestion.getMaximumSize(), dnssecOK, dnsdist::configuration::getCurrentRuntimeConfiguration().d_payloadSizeSelfGenAnswers, 0);
   }
 
+  dnsQuestion.d_selfGeneratedHandledEDNS = true;
   return true;
 }
 
@@ -233,7 +236,7 @@ bool generateAnswerFromRawPacket(DNSQuestion& dnsQuestion, const PacketBuffer& p
 {
   auto questionId = dnsQuestion.getHeader()->id;
   dnsQuestion.getMutableData() = packet;
-  dnsQuestion.d_selfGeneratedFromPacket = true;
+  dnsQuestion.d_selfGeneratedHandledEDNS = true;
   dnsdist::PacketMangling::editDNSHeaderFromPacket(dnsQuestion.getMutableData(), [questionId](dnsheader& header) {
     header.id = questionId;
     return true;
diff --git a/pdns/dnsdistdist/dnsdist.cc b/pdns/dnsdistdist/dnsdist.cc
index b96617e0a5..ff05ffdc21 100644
--- a/pdns/dnsdistdist/dnsdist.cc
+++ b/pdns/dnsdistdist/dnsdist.cc
@@ -326,7 +326,7 @@ static bool fixUpQueryTurnedResponse(DNSQuestion& dnsQuestion, const uint16_t or
     return true;
   });
 
-  if (dnsQuestion.d_selfGeneratedFromPacket) {
+  if (dnsQuestion.d_selfGeneratedHandledEDNS) {
     return true;
   }
   return addEDNSToQueryTurnedResponse(dnsQuestion);
diff --git a/pdns/dnsdistdist/dnsdist.hh b/pdns/dnsdistdist/dnsdist.hh
index 06b32ade6f..2d10591eab 100644
--- a/pdns/dnsdistdist/dnsdist.hh
+++ b/pdns/dnsdistdist/dnsdist.hh
@@ -184,7 +184,7 @@ public:
   bool ecsOverride;
   bool useECS{true};
   bool asynchronous{false};
-  bool d_selfGeneratedFromPacket{false};
+  bool d_selfGeneratedHandledEDNS{false};
 };
 
 struct DownstreamState;
-- 
2.47.2