From 2e10bf25d730018a0e6d93d80a4f217da9831679 Mon Sep 17 00:00:00 2001
From: Kershaw Chang <kershaw@mozilla.com>
Date: Fri, 21 Aug 2020 18:59:03 +0000
Subject: [PATCH] Bug 1652655 - P1: Sort HTTPSSVC records,
 r=dragana,necko-reviewers

Differential Revision: https://phabricator.services.mozilla.com/D85121
---
 netwerk/dns/HTTPSSVC.h |  3 +++
 netwerk/dns/TRR.cpp    | 10 ++++++++++
 2 files changed, 13 insertions(+)

diff --git a/netwerk/dns/HTTPSSVC.h b/netwerk/dns/HTTPSSVC.h
index 7c8184dd40c2..de757539bdda 100644
--- a/netwerk/dns/HTTPSSVC.h
+++ b/netwerk/dns/HTTPSSVC.h
@@ -82,6 +82,9 @@ struct SVCB {
            mSvcDomainName == aOther.mSvcDomainName &&
            mSvcFieldValue == aOther.mSvcFieldValue;
   }
+  bool operator<(const SVCB& aOther) const {
+    return mSvcFieldPriority < aOther.mSvcFieldPriority;
+  }
   uint16_t mSvcFieldPriority = 0;
   nsCString mSvcDomainName;
   CopyableTArray<SvcFieldValue> mSvcFieldValue;
diff --git a/netwerk/dns/TRR.cpp b/netwerk/dns/TRR.cpp
index 2933f8e5153d..3ab663c86a66 100644
--- a/netwerk/dns/TRR.cpp
+++ b/netwerk/dns/TRR.cpp
@@ -1197,6 +1197,16 @@ nsresult TRR::DohDecode(nsCString& aHost) {
     LOG(("TRR: No entries were stored!\n"));
     return NS_ERROR_FAILURE;
   }
+
+  // https://tools.ietf.org/html/draft-ietf-dnsop-svcb-httpssvc-03#page-14
+  // If one or more SVCB records of ServiceForm SvcRecordType are returned for
+  // HOST, clients should select the highest-priority option with acceptable
+  // parameters.
+  if (mResult.is<TypeRecordHTTPSSVC>()) {
+    auto& results = mResult.as<TypeRecordHTTPSSVC>();
+    results.Sort();
+  }
+
   return NS_OK;
 }