From: Remi Gacogne <remi.gacogne@powerdns.com>
Date: Tue, 27 May 2025 14:23:39 +0000 (+0200)
Subject: dnsdist: Do not replace EDNS in answers self-generated from a packet
X-Git-Tag: dnsdist-2.0.0-beta1~23^2~2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=07b66aead5dda1accd299941d3ab233db0750924;p=thirdparty%2Fpdns.git

dnsdist: Do not replace EDNS in answers self-generated from a packet

While it makes sense to add/remove EDNS when the answer was generated
from the query itself, we should not be doing that when it has been
generated from a whole DNS packet, as it probably contains exactly
what the user intended it to.

Signed-off-by: Remi Gacogne <remi.gacogne@powerdns.com>
---

diff --git a/pdns/dnsdistdist/dnsdist-self-answers.cc b/pdns/dnsdistdist/dnsdist-self-answers.cc
index dd0ff0b119..4e0b66084e 100644
--- a/pdns/dnsdistdist/dnsdist-self-answers.cc
+++ b/pdns/dnsdistdist/dnsdist-self-answers.cc
@@ -233,6 +233,7 @@ bool generateAnswerFromRawPacket(DNSQuestion& dnsQuestion, const PacketBuffer& p
 {
   auto questionId = dnsQuestion.getHeader()->id;
   dnsQuestion.getMutableData() = packet;
+  dnsQuestion.d_selfGeneratedFromPacket = 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 4c9d596724..b96617e0a5 100644
--- a/pdns/dnsdistdist/dnsdist.cc
+++ b/pdns/dnsdistdist/dnsdist.cc
@@ -326,6 +326,9 @@ static bool fixUpQueryTurnedResponse(DNSQuestion& dnsQuestion, const uint16_t or
     return true;
   });
 
+  if (dnsQuestion.d_selfGeneratedFromPacket) {
+    return true;
+  }
   return addEDNSToQueryTurnedResponse(dnsQuestion);
 }
 
diff --git a/pdns/dnsdistdist/dnsdist.hh b/pdns/dnsdistdist/dnsdist.hh
index 6624e86a45..06b32ade6f 100644
--- a/pdns/dnsdistdist/dnsdist.hh
+++ b/pdns/dnsdistdist/dnsdist.hh
@@ -184,6 +184,7 @@ public:
   bool ecsOverride;
   bool useECS{true};
   bool asynchronous{false};
+  bool d_selfGeneratedFromPacket{false};
 };
 
 struct DownstreamState;