From 48840a82cdadc850606b0fbd18dd82c496c93912 Mon Sep 17 00:00:00 2001
From: Nihanth Subramanya <nhnt11@gmail.com>
Date: Sat, 6 Feb 2021 13:00:36 +0000
Subject: [PATCH] Bug 1688228 - Introduce TRR_NXDOMAIN skip reason and record
 it when an rcode value of 0x03 is received. r=valentin,necko-reviewers

Differential Revision: https://phabricator.services.mozilla.com/D102774
---
 netwerk/dns/DNSPacket.cpp    | 3 ++-
 netwerk/dns/nsHostResolver.h | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/netwerk/dns/DNSPacket.cpp b/netwerk/dns/DNSPacket.cpp
index 12f0018447d1..c3f94d00c81a 100644
--- a/netwerk/dns/DNSPacket.cpp
+++ b/netwerk/dns/DNSPacket.cpp
@@ -456,7 +456,8 @@ nsresult DNSPacket::DecodeInternal(
   LOG(("TRR Decode %s RCODE %d\n", aHost.get(), rcode));
   if (rcode) {
     if (aReason == nsHostRecord::TRR_UNSET) {
-      aReason = nsHostRecord::TRR_RCODE_FAIL;
+      aReason = rcode == 0x03 ? nsHostRecord::TRR_NXDOMAIN
+                              : nsHostRecord::TRR_RCODE_FAIL;
     }
   }
 
diff --git a/netwerk/dns/nsHostResolver.h b/netwerk/dns/nsHostResolver.h
index fe6ff3231c6d..f5054cd2cd9d 100644
--- a/netwerk/dns/nsHostResolver.h
+++ b/netwerk/dns/nsHostResolver.h
@@ -119,6 +119,7 @@ class nsHostRecord : public mozilla::LinkedListElement<RefPtr<nsHostRecord>>,
     TRR_SERVER_RESPONSE_ERR = 27,  // Server responded with non-200 code
     TRR_RCODE_FAIL = 28,           // DNS response contains a non-NOERROR rcode
     TRR_NO_CONNECTIVITY = 29,      // Not confirmed because of no connectivity
+    TRR_NXDOMAIN = 30,             // DNS response contains NXDOMAIN rcode (0x03)
   };
 
   // Records the first reason that caused TRR to be skipped or to fail.