Bug 1634462 - Add doh-rollout.mode pref check and mode change notification r=dragana,necko-reviewers

Differential Revision: https://phabricator.services.mozilla.com/D74316

netwerk/dns/ChildDNSService.cpp

@@ -373,6 +373,11 @@ ChildDNSService::GetCurrentTrrURI(nsACString& aURI) {
   return NS_ERROR_NOT_AVAILABLE;
 }
 
+NS_IMETHODIMP
+ChildDNSService::GetCurrentTrrMode(uint32_t* aMode) {
+  return NS_ERROR_NOT_AVAILABLE;
+}
+
 NS_IMETHODIMP
 ChildDNSService::GetMyHostName(nsACString& result) {
   // TODO: get value from parent during PNecko construction?

netwerk/dns/TRRService.cpp

@@ -26,6 +26,7 @@ static const char kDisableIpv6Pref[] = "network.dns.disableIPv6";
 static const char kPrefSkipTRRParentalControl[] =
     "network.dns.skipTRR-when-parental-control-enabled";
 static const char kRolloutURIPref[] = "doh-rollout.uri";
+static const char kRolloutModePref[] = "doh-rollout.mode";
 
 #define TRR_PREF_PREFIX "network.trr."
 #define TRR_PREF(x) TRR_PREF_PREFIX x
@@ -89,6 +90,7 @@ nsresult TRRService::Init() {
     prefBranch->AddObserver(kDisableIpv6Pref, this, true);
     prefBranch->AddObserver(kPrefSkipTRRParentalControl, this, true);
     prefBranch->AddObserver(kRolloutURIPref, this, true);
+    prefBranch->AddObserver(kRolloutModePref, this, true);
   }
   nsCOMPtr<nsICaptivePortalService> captivePortalService =
       do_GetService(NS_CAPTIVEPORTAL_CID);
@@ -274,6 +276,35 @@ void TRRService::CheckURIPrefs() {
   MaybeSetPrivateURI(mURIPref);
 }
 
+// static
+uint32_t TRRService::ModeFromPrefs() {
+  // 0 - off, 1 - reserved, 2 - TRR first, 3 - TRR only, 4 - reserved,
+  // 5 - explicit off
+
+  auto processPrefValue = [](uint32_t value) -> uint32_t {
+    if (value == MODE_RESERVED1 || value == MODE_RESERVED4 ||
+        value > MODE_TRROFF) {
+      return MODE_TRROFF;
+    }
+    return value;
+  };
+
+  uint32_t tmp = MODE_NATIVEONLY;
+  if (NS_SUCCEEDED(Preferences::GetUint(TRR_PREF("mode"), &tmp))) {
+    tmp = processPrefValue(tmp);
+  }
+
+  if (tmp != MODE_NATIVEONLY) {
+    return tmp;
+  }
+
+  if (NS_SUCCEEDED(Preferences::GetUint(kRolloutModePref, &tmp))) {
+    return processPrefValue(tmp);
+  }
+
+  return MODE_NATIVEONLY;
+}
+
 nsresult TRRService::ReadPrefs(const char* name) {
   MOZ_ASSERT(NS_IsMainThread(), "wrong thread");
 
@@ -281,21 +312,17 @@ nsresult TRRService::ReadPrefs(const char* name) {
   // we set this to true then do it at the end of the method.
   bool clearEntireCache = false;
 
-  if (!name || !strcmp(name, TRR_PREF("mode"))) {
-    // 0 - off, 1 - reserved, 2 - TRR first, 3 - TRR only, 4 - reserved,
-    // 5 - explicit off
-    uint32_t tmp;
-    if (NS_SUCCEEDED(Preferences::GetUint(TRR_PREF("mode"), &tmp))) {
-      if (tmp > MODE_TRROFF) {
-        tmp = MODE_TRROFF;
+  if (!name || !strcmp(name, TRR_PREF("mode")) ||
+      !strcmp(name, kRolloutModePref)) {
+    uint32_t oldMode = mMode;
+    mMode = ModeFromPrefs();
+    if (mMode != oldMode) {
+      nsCOMPtr<nsIObserverService> obs =
+          mozilla::services::GetObserverService();
+      if (obs) {
+        obs->NotifyObservers(nullptr, NS_NETWORK_TRR_MODE_CHANGED_TOPIC,
+                             nullptr);
       }
-      if (tmp == MODE_RESERVED1) {
-        tmp = MODE_TRROFF;
-      }
-      if (tmp == MODE_RESERVED4) {
-        tmp = MODE_TRROFF;
-      }
-      mMode = tmp;
     }
   }
   if (!name || !strcmp(name, TRR_PREF("uri")) ||

netwerk/dns/TRRService.h

@@ -107,6 +107,8 @@ class TRRService : public nsIObserver,
   void ProcessURITemplate(nsACString& aURI);
   void ClearEntireCache();
 
+  static uint32_t ModeFromPrefs();
+
   bool mInitialized;
   Atomic<uint32_t, Relaxed> mMode;
   Atomic<uint32_t, Relaxed> mTRRBlacklistExpireTime;

netwerk/dns/nsDNSService2.cpp

@@ -1371,6 +1371,15 @@ nsDNSService::GetCurrentTrrURI(nsACString& aURI) {
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsDNSService::GetCurrentTrrMode(uint32_t* aMode) {
+  *aMode = 0;  // The default mode.
+  if (mTrrService) {
+    *aMode = mTrrService->Mode();
+  }
+  return NS_OK;
+}
+
 size_t nsDNSService::SizeOfIncludingThis(
     mozilla::MallocSizeOf mallocSizeOf) const {
   // Measurement of the following members may be added later if DMD finds it

netwerk/dns/nsIDNSService.idl

@@ -318,6 +318,11 @@ interface nsIDNSService : nsISupports
      */
     readonly attribute AUTF8String currentTrrURI;
 
+    /**
+     * Returns the value of the TRR Service's current default mode.
+     */
+    readonly attribute unsigned long currentTrrMode;
+
     /**
      * @return the hostname of the operating system.
      */
@@ -417,5 +422,11 @@ interface nsIDNSService : nsISupports
  */
 #define NS_NETWORK_TRR_URI_CHANGED_TOPIC "network:trr-uri-changed"
 
+/**
+ * An observer notification for this topic is sent whenever the mode that the
+ * TRR service is using has changed.
+ */
+#define NS_NETWORK_TRR_MODE_CHANGED_TOPIC "network:trr-mode-changed"
+
 %}