Bug 1610741 - Allow setting invalid URL in TRRService and show it in settings r=Gijs,fluent-reviewers,settings-reviewers,flod

- Patch changes TRRService::MaybeSetPrivateURI so that it doesn't bail
  if the URL is invalid. That could lead us into a state where the
  network.trr.uri pref has been set to some invalid URL, but we continue
  using the previous domain (or even the default TRR provider) instead.
- Updates the DoH settings UI to not set the network.trr.uri pref to "",
  as that will cause the TRRService to use the value of
  the network.trr.default_provider_uri pref instead.

Differential Revision: https://phabricator.services.mozilla.com/D174111

browser/components/preferences/privacy.js

@@ -563,10 +563,24 @@ var gPrivacyPane = {
     this.updateDoHResolverList(mode);
 
     let customInput = document.getElementById(`${mode}InputField`);
+
+    function updateURIPref() {
+      if (customInput.value == "") {
+        // Setting the pref to empty string will make it have the default
+        // pref value which makes us fallback to using the default TRR
+        // resolver in network.trr.default_provider_uri.
+        // If the input is empty we set it to "(space)" which is essentially
+        // the same.
+        Services.prefs.setStringPref("network.trr.uri", " ");
+      } else {
+        Services.prefs.setStringPref("network.trr.uri", customInput.value);
+      }
+    }
+
     menu.addEventListener("command", () => {
       if (menu.value == "custom") {
         customInput.hidden = false;
-        Services.prefs.setStringPref("network.trr.uri", customInput.value);
+        updateURIPref();
       } else {
         customInput.hidden = true;
         if (
@@ -589,16 +603,18 @@ var gPrivacyPane = {
 
     // Change the URL when you press ENTER in the input field it or loses focus
     customInput.addEventListener("change", () => {
-      Services.prefs.setStringPref("network.trr.uri", customInput.value);
+      updateURIPref();
     });
   },
 
-  updateDoHStatus() {
+  async updateDoHStatus() {
     let trrURI = Services.dns.currentTrrURI;
     let hostname = "";
     try {
       hostname = new URL(trrURI).hostname;
-    } catch (e) {}
+    } catch (e) {
+      hostname = await document.l10n.formatValue("preferences-doh-bad-url");
+    }
 
     let steering = document.getElementById("dohSteeringStatus");
     steering.hidden = true;

browser/locales/en-US/browser/preferences/preferences.ftl

@@ -1478,6 +1478,9 @@ preferences-doh-status = Status: { $status }
 # Variables:
 #   $name (string) - The name of the DNS over HTTPS resolver. If a custom resolver is used, the name will be the domain of the URL.
 preferences-doh-resolver = Provider: { $name }
+# This is displayed instead of $name in preferences-doh-resolver
+# when the DoH URL is not a valid URL
+preferences-doh-bad-url = Invalid URL
 preferences-doh-steering-status = Using local provider
 
 preferences-doh-status-active = Active

netwerk/dns/TRRService.cpp

@@ -294,19 +294,12 @@ bool TRRService::MaybeSetPrivateURI(const nsACString& aURI) {
       clearCache = true;
     }
 
-    nsCOMPtr<nsIURI> url;
-    nsresult rv = NS_MutateURI(NS_STANDARDURLMUTATOR_CONTRACTID)
-                      .Apply(&nsIStandardURLMutator::Init,
-                             nsIStandardURL::URLTYPE_STANDARD, 443, newURI,
-                             nullptr, nullptr, nullptr)
-                      .Finalize(url);
-    if (NS_FAILED(rv)) {
-      LOG(("TRRService::MaybeSetPrivateURI failed to create URI!\n"));
-      return false;
-    }
-
     nsAutoCString host;
-    url->GetHost(host);
+
+    nsCOMPtr<nsIURI> url;
+    if (NS_SUCCEEDED(NS_NewURI(getter_AddRefs(url), newURI))) {
+      url->GetHost(host);
+    }
 
     SetProviderDomain(host);
 

netwerk/dns/nsDNSService2.cpp

@@ -1499,6 +1499,7 @@ nsDNSService::GetCurrentTrrConfirmationState(uint32_t* aConfirmationState) {
 
 NS_IMETHODIMP
 nsDNSService::GetTrrDomain(nsACString& aTRRDomain) {
+  aTRRDomain.Truncate();
   nsAutoCString url;
   if (mTrrService) {
     mTrrService->GetURI(url);
@@ -1506,7 +1507,8 @@ nsDNSService::GetTrrDomain(nsACString& aTRRDomain) {
   nsCOMPtr<nsIURI> uri;
   nsresult rv = NS_NewURI(getter_AddRefs(uri), url);
   if (NS_FAILED(rv)) {
-    return rv;
+    // An empty TRR domain in case of invalid URL.
+    return NS_OK;
   }
   return uri->GetHost(aTRRDomain);
 }