Bug 1772111 - Refine TRR skiped reasons for retry, r=necko-reviewers,dragana

Differential Revision: https://phabricator.services.mozilla.com/D148107

netwerk/dns/TRRSkippedReason.h

@@ -72,6 +72,29 @@ inline bool IsRelevantTRRSkipReason(TRRSkippedReason aReason) {
   return true;
 }
 
+inline bool IsBlockedTRRRequest(TRRSkippedReason aReason) {
+  // See TRR::MaybeBlockRequest. These are the reasons that could block sending
+  // TRR requests.
+  return (aReason == TRRSkippedReason::TRR_EXCLUDED ||
+          aReason == TRRSkippedReason::TRR_MODE_NOT_ENABLED ||
+          aReason == TRRSkippedReason::TRR_HOST_BLOCKED_TEMPORARY);
+}
+
+inline bool IsNonRecoverableTRRSkipReason(TRRSkippedReason aReason) {
+  // These are non-recoverable reasons and we'll fallback to native without
+  // retrying.
+  return (aReason == TRRSkippedReason::TRR_NXDOMAIN ||
+          aReason == TRRSkippedReason::TRR_NO_ANSWERS ||
+          aReason == TRRSkippedReason::TRR_DISABLED_FLAG ||
+          aReason == TRRSkippedReason::TRR_RCODE_FAIL);
+}
+
+inline bool IsFailedConfirmationOrNoConnectivity(TRRSkippedReason aReason) {
+  // TRR is in non-confirmed state now, so we don't try to use TRR at all.
+  return (aReason == TRRSkippedReason::TRR_NOT_CONFIRMED ||
+          aReason == TRRSkippedReason::TRR_NO_CONNECTIVITY);
+}
+
 }  // namespace net
 }  // namespace mozilla
 

netwerk/dns/nsHostResolver.cpp

@@ -1325,11 +1325,9 @@ bool nsHostResolver::MaybeRetryTRRLookup(
     return NS_SUCCEEDED(NativeLookup(aAddrRec, aLock));
   }
 
-  if (aFirstAttemptSkipReason == TRRSkippedReason::TRR_RCODE_FAIL ||
-      aFirstAttemptSkipReason == TRRSkippedReason::TRR_NO_ANSWERS ||
-      aFirstAttemptSkipReason == TRRSkippedReason::TRR_NXDOMAIN ||
-      aFirstAttemptSkipReason == TRRSkippedReason::TRR_DISABLED_FLAG ||
-      aFirstAttemptSkipReason == TRRSkippedReason::TRR_NOT_CONFIRMED) {
+  if (IsFailedConfirmationOrNoConnectivity(aFirstAttemptSkipReason) ||
+      IsNonRecoverableTRRSkipReason(aFirstAttemptSkipReason) ||
+      IsBlockedTRRRequest(aFirstAttemptSkipReason)) {
     LOG(
         ("nsHostResolver::MaybeRetryTRRLookup retrying with native in strict "
          "mode, skip reason was %d",