Bug 1678614 - Don't try to resolve the host name again when trr mode is trr only r=necko-reviewers,dragana

Differential Revision: https://phabricator.services.mozilla.com/D98024

netwerk/base/nsSocketTransport2.cpp

@@ -1944,6 +1944,11 @@ bool nsSocketTransport::RecoverFromError() {
               mNetAddr.inet6.ip.u64[1] == 0))) {
           SOCKET_LOG(("  TRR returned 0.0.0.0 and there are no other IPs"));
         } else if (trrEnabled) {
+          nsCOMPtr<nsIDNSService> dns = do_GetService(kDNSServiceCID);
+          uint32_t trrMode = 0;
+          // If current trr mode is trr only, we should not retry.
+          if (dns && NS_SUCCEEDED(dns->GetCurrentTrrMode(&trrMode)) &&
+              trrMode != 3) {
             // Drop state to closed.  This will trigger a new round of
             // DNS resolving. Bypass the cache this time since the
             // cached data came from TRR and failed already!
@@ -1955,6 +1960,7 @@ bool nsSocketTransport::RecoverFromError() {
         }
       }
     }
+  }
 
   // prepare to try again.
   if (tryAgain) {