fixup! MB 234: Disable OS spoofing in HTTP User-Agent.

browser/app/profile/000-mullvad-browser.js

@@ -45,6 +45,3 @@ pref("app.releaseNotesURL", "https://github.com/mullvad/mullvad-browser/releases
 pref("app.releaseNotesURL.aboutDialog", "about:blank");
 // point to our feedback url rather than Mozilla's
 pref("app.feedback.baseURL", "https://mullvad.net/help/tag/browser/");
-
-// mullvad-browser#234: Do not spoof the OS in the User-Agent header
-pref("privacy.resistFingerprinting.spoofOsInUserAgentHeader", false);

netwerk/protocol/http/nsHttpHandler.cpp

@@ -482,9 +482,6 @@ nsresult nsHttpHandler::Init() {
     // obsService->AddObserver(this, "net:failed-to-process-uri-content", true);
   }
 
-  Preferences::AddWeakObserver(
-      this, "privacy.resistFingerprinting.spoofOsInUserAgentHeader"_ns);
-
   MakeNewRequestTokenBucket();
   mWifiTickler = new Tickler();
   if (NS_FAILED(mWifiTickler->Init())) mWifiTickler = nullptr;
@@ -2108,9 +2105,6 @@ nsHttpHandler::Observe(nsISupports* subject, const char* topic,
     // Inform nsIOService that network is tearing down.
     gIOService->SetHttpHandlerAlreadyShutingDown();
 
-    Preferences::RemoveObserver(
-        this, "privacy.resistFingerprinting.spoofOsInUserAgentHeader"_ns);
-
     ShutdownConnectionManager();
 
     // need to reset the session start time since cache validation may
@@ -2233,11 +2227,6 @@ nsHttpHandler::Observe(nsISupports* subject, const char* topic,
     ShutdownConnectionManager();
     mConnMgr = nullptr;
     Unused << InitConnectionMgr();
-  } else if (!strcmp(topic, "nsPref:changed") &&
-             !NS_strcmp(
-                 data,
-                 u"privacy.resistFingerprinting.spoofOsInUserAgentHeader")) {
-    nsRFPService::GetSpoofedUserAgent(mSpoofedUserAgent, true);
   }
 
   return NS_OK;

toolkit/components/resistfingerprinting/nsRFPService.cpp

@@ -904,16 +904,11 @@ void nsRFPService::GetSpoofedUserAgent(nsACString& userAgent,
   // https://developer.mozilla.org/en-US/docs/Web/API/NavigatorID/userAgent
   // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/User-Agent
 
-  const bool spoofOs =
-      isForHTTPHeader &&
-      Preferences::GetBool(
-          "privacy.resistFingerprinting.spoofOsInUserAgentHeader", true);
-
   // These magic numbers are the lengths of the UA string literals below.
   // Assume three-digit Firefox version numbers so we have room to grow.
   size_t preallocatedLength =
       13 +
-      (spoofOs ? mozilla::ArrayLength(SPOOFED_HTTP_UA_OS)
+      (isForHTTPHeader ? mozilla::ArrayLength(SPOOFED_HTTP_UA_OS)
                        : mozilla::ArrayLength(SPOOFED_UA_OS)) -
       1 + 5 + 3 + 10 + mozilla::ArrayLength(LEGACY_UA_GECKO_TRAIL) - 1 + 9 + 3 +
       2;
@@ -922,7 +917,7 @@ void nsRFPService::GetSpoofedUserAgent(nsACString& userAgent,
   // "Mozilla/5.0 (%s; rv:%d.0) Gecko/%d Firefox/%d.0"
   userAgent.AssignLiteral("Mozilla/5.0 (");
 
-  if (spoofOs) {
+  if (isForHTTPHeader) {
     userAgent.AppendLiteral(SPOOFED_HTTP_UA_OS);
   } else {
     userAgent.AppendLiteral(SPOOFED_UA_OS);