Bug 1565022 - TRR: Check for NRPT on Windows to use platform DNS r=mayhemer

Differential Revision: https://phabricator.services.mozilla.com/D54093

--HG--
extra : moz-landing-system : lando

modules/libpref/init/StaticPrefList.yaml

@@ -6861,6 +6861,12 @@
   value: false
   mirror: always
 
+# This pref controls if TRR will still be enabled when NRPT rules are detected
+- name: network.trr.enable_when_nrpt_detected
+  type: RelaxedAtomicBool
+  value: false
+  mirror: always
+
 # Allow the network changed event to get sent when a network topology or setup
 # change is noticed while running.
 - name: network.notify.changed
@@ -6891,6 +6897,13 @@
   value: true
   mirror: always
 
+# Whether to check the registry for NRPT rules on network changes that
+# indicate that TRR should not be used.
+- name: network.notify.checkForNRPT
+  type: RelaxedAtomicBool
+  value: true
+  mirror: always
+
 #---------------------------------------------------------------------------
 # Prefs starting with "nglayout."
 #---------------------------------------------------------------------------

netwerk/base/nsINetworkLinkService.idl

@@ -60,6 +60,7 @@ interface nsINetworkLinkService : nsISupports
   const unsigned long NONE_DETECTED = 0;
   const unsigned long VPN_DETECTED = 1 << 0;
   const unsigned long PROXY_DETECTED = 1 << 1;
+  const unsigned long NRPT_DETECTED = 1 << 2;
 
   /**
    * A bitfield that encodes the platform attributes we detected which

netwerk/dns/TRRService.cpp

@@ -491,7 +491,9 @@ void TRRService::CheckPlatformDNSStatus(nsINetworkLinkService* aLinkService) {
       (!StaticPrefs::network_trr_enable_when_vpn_detected() &&
        (platformIndications & nsINetworkLinkService::VPN_DETECTED)) ||
       (!StaticPrefs::network_trr_enable_when_proxy_detected() &&
-       (platformIndications & nsINetworkLinkService::PROXY_DETECTED));
+       (platformIndications & nsINetworkLinkService::PROXY_DETECTED)) ||
+      (!StaticPrefs::network_trr_enable_when_nrpt_detected() &&
+       (platformIndications & nsINetworkLinkService::NRPT_DETECTED));
 }
 
 void TRRService::MaybeConfirm() {

netwerk/system/win32/nsNotifyAddrListener.cpp

@@ -542,31 +542,31 @@ nsNotifyAddrListener::CheckAdaptersAddresses(void) {
     checkRegistry();
   }
 
+  auto registryChildCount = [](const nsAString& aRegPath) -> uint32_t {
+    nsresult rv;
+    nsCOMPtr<nsIWindowsRegKey> regKey =
+        do_CreateInstance("@mozilla.org/windows-registry-key;1", &rv);
+    if (NS_FAILED(rv)) {
+      LOG(("  creating nsIWindowsRegKey failed\n"));
+      return 0;
+    }
+    rv = regKey->Open(nsIWindowsRegKey::ROOT_KEY_LOCAL_MACHINE, aRegPath,
+                      nsIWindowsRegKey::ACCESS_READ);
+    if (NS_FAILED(rv)) {
+      LOG(("  opening registry key failed\n"));
+      return 0;
+    }
+
+    uint32_t count = 0;
+    rv = regKey->GetChildCount(&count);
+    if (NS_FAILED(rv)) {
+      return 0;
+    }
+
+    return count;
+  };
+
   if (StaticPrefs::network_notify_checkForProxies()) {
-    auto registryChildCount = [](const nsAString& aRegPath) -> uint32_t {
-      nsresult rv;
-      nsCOMPtr<nsIWindowsRegKey> regKey =
-          do_CreateInstance("@mozilla.org/windows-registry-key;1", &rv);
-      if (NS_FAILED(rv)) {
-        LOG(("  creating nsIWindowsRegKey failed\n"));
-        return 0;
-      }
-      rv = regKey->Open(nsIWindowsRegKey::ROOT_KEY_LOCAL_MACHINE, aRegPath,
-                        nsIWindowsRegKey::ACCESS_READ);
-      if (NS_FAILED(rv)) {
-        LOG(("  opening registry key failed\n"));
-        return 0;
-      }
-
-      uint32_t count = 0;
-      rv = regKey->GetChildCount(&count);
-      if (NS_FAILED(rv)) {
-        return 0;
-      }
-
-      return count;
-    };
-
     if (registryChildCount(
             NS_LITERAL_STRING("SYSTEM\\CurrentControlSet\\Services\\Dnscache\\"
                               "Parameters\\DnsConnections")) > 0 ||
@@ -577,6 +577,17 @@ nsNotifyAddrListener::CheckAdaptersAddresses(void) {
     }
   }
 
+  if (StaticPrefs::network_notify_checkForNRPT()) {
+    if (registryChildCount(
+            NS_LITERAL_STRING("SYSTEM\\CurrentControlSet\\Services\\Dnscache\\"
+                              "Parameters\\DnsPolicyConfig")) > 0 ||
+        registryChildCount(
+            NS_LITERAL_STRING("SOFTWARE\\Policies\\Microsoft\\Windows NT\\"
+                              "DNSClient\\DnsPolicyConfig")) > 0) {
+      platformDNSIndications |= NRPT_DETECTED;
+    }
+  }
+
   {
     MutexAutoLock lock(mMutex);
     mDnsSuffixList.SwapElements(dnsSuffixList);