1 files changed, 17 insertions, 6 deletions
diff --git a/dom/xhr/XMLHttpRequest.cpp b/dom/xhr/XMLHttpRequest.cpp
index be94267d63..8807c5515a 100644
--- a/dom/xhr/XMLHttpRequest.cpp
+++ b/dom/xhr/XMLHttpRequest.cpp
@@ -7,7 +7,9 @@
 #include "XMLHttpRequest.h"
 #include "XMLHttpRequestMainThread.h"
 #include "XMLHttpRequestWorker.h"
+#include "mozilla/BasePrincipal.h"
 #include "mozilla/Logging.h"
+#include "mozilla/StaticPrefs_network.h"
 #include "mozilla/net/CookieJarSettings.h"
 
 mozilla::LazyLogModule gXMLHttpRequestLog("XMLHttpRequest");
@@ -21,15 +23,16 @@ already_AddRefed<XMLHttpRequest> XMLHttpRequest::Constructor(
   if (NS_IsMainThread()) {
     nsCOMPtr<nsIGlobalObject> global =
         do_QueryInterface(aGlobal.GetAsSupports());
-    nsCOMPtr<nsIScriptObjectPrincipal> principal =
+    nsCOMPtr<nsIScriptObjectPrincipal> scriptPrincipal =
         do_QueryInterface(aGlobal.GetAsSupports());
-    if (!global || !principal) {
+    if (!global || !scriptPrincipal) {
       aRv.Throw(NS_ERROR_FAILURE);
       return nullptr;
     }
 
     nsCOMPtr<nsICookieJarSettings> cookieJarSettings;
     nsCOMPtr<nsPIDOMWindowInner> window = do_QueryInterface(global);
+    nsCOMPtr<nsIPrincipal> principal = scriptPrincipal->GetPrincipal();
     if (window) {
       Document* document = window->GetExtantDoc();
       if (NS_WARN_IF(!document)) {
@@ -40,13 +43,21 @@ already_AddRefed<XMLHttpRequest> XMLHttpRequest::Constructor(
       cookieJarSettings = document->CookieJarSettings();
     } else {
       // We are here because this is a sandbox.
-      cookieJarSettings =
-          net::CookieJarSettings::Create(principal->GetPrincipal());
+      cookieJarSettings = net::CookieJarSettings::Create(principal);
     }
 
     RefPtr<XMLHttpRequestMainThread> req = new XMLHttpRequestMainThread(global);
-    req->Construct(principal->GetPrincipal(), cookieJarSettings, false);
-    req->InitParameters(aParams.mMozAnon, aParams.mMozSystem);
+    req->Construct(principal, cookieJarSettings, false);
+
+    bool isAnon = false;
+    if (aParams.mMozAnon.WasPassed()) {
+      isAnon = aParams.mMozAnon.Value();
+    } else {
+      isAnon =
+          StaticPrefs::network_fetch_systemDefaultsToOmittingCredentials() &&
+          (aParams.mMozSystem || principal->IsSystemPrincipal());
+    }
+    req->InitParameters(isAnon, aParams.mMozSystem);
     return req.forget();
   }