feat: cache .well-known data

- BREAKING: create `DatabaseApi.storeWellKnown` method
- BREAKING: create `DatabaseApi.getWellKnown` method
- add new getter `Client.wellKnown` containing cached `DiscoveryInformation`
- override `Client.homeserver` to invalidate `Client.wellKnown` in case the domain changed
- override `Client.getWellknown` to cache the resolved `DiscoveryInformation`
- add tests for well-known cache

Fixes: #1865

Signed-off-by: The one with the braid <info@braid.business>

lib/src/client.dart

@@ -25,7 +25,6 @@ import 'dart:typed_data';
 import 'package:async/async.dart';
 import 'package:collection/collection.dart' show IterableExtension;
 import 'package:http/http.dart' as http;
-import 'package:http/http.dart';
 import 'package:mime/mime.dart';
 import 'package:olm/olm.dart' as olm;
 import 'package:random_string/random_string.dart';
@@ -124,6 +123,24 @@ class Client extends MatrixApi {
   /// The timeout until a typing indicator gets removed automatically.
   final Duration typingIndicatorTimeout;
 
+  DiscoveryInformation? _wellKnown;
+
+  /// the cached .well-known file updated using [getWellknown]
+  DiscoveryInformation? get wellKnown => _wellKnown;
+
+  /// The homeserver this client is communicating with.
+  ///
+  /// In case the [homeserver]'s host differs from the previous value, the
+  /// [wellKnown] cache will be invalidated.
+  @override
+  set homeserver(Uri? homeserver) {
+    if (homeserver?.host != this.homeserver?.host) {
+      _wellKnown = null;
+      unawaited(database?.storeWellKnown(null));
+    }
+    super.homeserver = homeserver;
+  }
+
   Future<MatrixImageFileResizedResponse?> Function(
       MatrixImageFileResizeArguments)? customImageResizer;
 
@@ -531,6 +548,27 @@ class Client extends MatrixApi {
     }
   }
 
+  /// Gets discovery information about the domain. The file may include
+  /// additional keys, which MUST follow the Java package naming convention,
+  /// e.g. `com.example.myapp.property`. This ensures property names are
+  /// suitably namespaced for each application and reduces the risk of
+  /// clashes.
+  ///
+  /// Note that this endpoint is not necessarily handled by the homeserver,
+  /// but by another webserver, to be used for discovering the homeserver URL.
+  ///
+  /// The result of this call is stored in [wellKnown] for later use at runtime.
+  @override
+  Future<DiscoveryInformation> getWellknown() async {
+    final wellKnown = await super.getWellknown();
+
+    // do not reset the well known here, so super call
+    super.homeserver = wellKnown.mHomeserver.baseUrl.stripTrailingSlash();
+    _wellKnown = wellKnown;
+    await database?.storeWellKnown(wellKnown);
+    return wellKnown;
+  }
+
   /// Checks to see if a username is available, and valid, for the server.
   /// Returns the fully-qualified Matrix user ID (MXID) that has been registered.
   /// You have to call [checkHomeserver] first to set a homeserver.
@@ -1196,7 +1234,7 @@ class Client extends MatrixApi {
       path = '_matrix/media/v3/config';
     }
     final requestUri = Uri(path: path);
-    final request = Request('GET', baseUri!.resolveUri(requestUri));
+    final request = http.Request('GET', baseUri!.resolveUri(requestUri));
     request.headers['authorization'] = 'Bearer ${bearerToken!}';
     final response = await httpClient.send(request);
     final responseBody = await response.stream.toBytes();
@@ -1236,7 +1274,7 @@ class Client extends MatrixApi {
         // removed with msc3916, so just to be explicit
         'allow_remote': allowRemote.toString(),
     });
-    final request = Request('GET', baseUri!.resolveUri(requestUri));
+    final request = http.Request('GET', baseUri!.resolveUri(requestUri));
     request.headers['authorization'] = 'Bearer ${bearerToken!}';
     final response = await httpClient.send(request);
     final responseBody = await response.stream.toBytes();
@@ -1279,7 +1317,7 @@ class Client extends MatrixApi {
         // removed with msc3916, so just to be explicit
         'allow_remote': allowRemote.toString(),
     });
-    final request = Request('GET', baseUri!.resolveUri(requestUri));
+    final request = http.Request('GET', baseUri!.resolveUri(requestUri));
     request.headers['authorization'] = 'Bearer ${bearerToken!}';
     final response = await httpClient.send(request);
     final responseBody = await response.stream.toBytes();
@@ -1315,7 +1353,7 @@ class Client extends MatrixApi {
       'url': url.toString(),
       if (ts != null) 'ts': ts.toString(),
     });
-    final request = Request('GET', baseUri!.resolveUri(requestUri));
+    final request = http.Request('GET', baseUri!.resolveUri(requestUri));
     request.headers['authorization'] = 'Bearer ${bearerToken!}';
     final response = await httpClient.send(request);
     final responseBody = await response.stream.toBytes();
@@ -1369,7 +1407,7 @@ class Client extends MatrixApi {
         'allow_remote': allowRemote.toString(),
     });
 
-    final request = Request('GET', baseUri!.resolveUri(requestUri));
+    final request = http.Request('GET', baseUri!.resolveUri(requestUri));
     request.headers['authorization'] = 'Bearer ${bearerToken!}';
     final response = await httpClient.send(request);
     final responseBody = await response.stream.toBytes();
@@ -1956,12 +1994,16 @@ class Client extends MatrixApi {
           _accountData = data;
           _updatePushrules();
         });
+        _discoveryDataLoading = database.getWellKnown().then((data) {
+          _wellKnown = data;
+        });
         // ignore: deprecated_member_use_from_same_package
         presences.clear();
         if (waitUntilLoadCompletedLoaded) {
           await userDeviceKeysLoading;
           await roomsLoading;
           await _accountDataLoading;
+          await _discoveryDataLoading;
         }
       }
       _initLock = false;
@@ -2784,10 +2826,13 @@ class Client extends MatrixApi {
   Future? userDeviceKeysLoading;
   Future? roomsLoading;
   Future? _accountDataLoading;
+  Future? _discoveryDataLoading;
   Future? firstSyncReceived;
 
   Future? get accountDataLoading => _accountDataLoading;
 
+  Future? get wellKnownLoading => _discoveryDataLoading;
+
   /// A map of known device keys per user.
   Map<String, DeviceKeysList> get userDeviceKeys => _userDeviceKeys;
   Map<String, DeviceKeysList> _userDeviceKeys = {};
@@ -3593,6 +3638,7 @@ class SdkError {
 
 class SyncConnectionException implements Exception {
   final Object originalException;
+
   SyncConnectionException(this.originalException);
 }
 

lib/src/database/database_api.dart

@@ -27,7 +27,9 @@ import 'package:matrix/src/utils/queued_to_device_event.dart';
 
 abstract class DatabaseApi {
   int get maxFileSize => 1 * 1024 * 1024;
+
   bool get supportsFileStoring => false;
+
   Future<Map<String, dynamic>?> getClient(String name);
 
   Future updateClient(
@@ -334,6 +336,10 @@ abstract class DatabaseApi {
 
   Future<CachedPresence?> getPresence(String userId);
 
+  Future<void> storeWellKnown(DiscoveryInformation? discoveryInformation);
+
+  Future<DiscoveryInformation?> getWellKnown();
+
   /// Deletes the whole database. The database needs to be created again after
   /// this.
   Future<void> delete();

lib/src/database/hive_collections_database.dart

@@ -1595,6 +1595,25 @@ class HiveCollectionsDatabase extends DatabaseApi {
     }
   }
 
+  @override
+  Future<void> storeWellKnown(DiscoveryInformation? discoveryInformation) {
+    if (discoveryInformation == null) {
+      return _clientBox.delete('discovery_information');
+    }
+    return _clientBox.put(
+      'discovery_information',
+      jsonEncode(discoveryInformation.toJson()),
+    );
+  }
+
+  @override
+  Future<DiscoveryInformation?> getWellKnown() async {
+    final rawDiscoveryInformation =
+        await _clientBox.get('discovery_information');
+    if (rawDiscoveryInformation == null) return null;
+    return DiscoveryInformation.fromJson(jsonDecode(rawDiscoveryInformation));
+  }
+
   @override
   Future<void> delete() => _collection.deleteFromDisk();
 

lib/src/database/hive_database.dart

@@ -1401,6 +1401,25 @@ class FamedlySdkHiveDatabase extends DatabaseApi with ZoneTransactionMixin {
     throw UnimplementedError();
   }
 
+  @override
+  Future<void> storeWellKnown(DiscoveryInformation? discoveryInformation) {
+    if (discoveryInformation == null) {
+      return _clientBox.delete('discovery_information');
+    }
+    return _clientBox.put(
+      'discovery_information',
+      jsonEncode(discoveryInformation.toJson()),
+    );
+  }
+
+  @override
+  Future<DiscoveryInformation?> getWellKnown() async {
+    final rawDiscoveryInformation =
+        await _clientBox.get('discovery_information');
+    if (rawDiscoveryInformation == null) return null;
+    return DiscoveryInformation.fromJson(jsonDecode(rawDiscoveryInformation));
+  }
+
   @override
   Future<void> delete() => Hive.deleteFromDisk();
 

lib/src/database/matrix_sdk_database.dart

@@ -1623,6 +1623,25 @@ class MatrixSdkDatabase extends DatabaseApi with DatabaseFileStorage {
     return CachedPresence.fromJson(copyMap(rawPresence));
   }
 
+  @override
+  Future<void> storeWellKnown(DiscoveryInformation? discoveryInformation) {
+    if (discoveryInformation == null) {
+      return _clientBox.delete('discovery_information');
+    }
+    return _clientBox.put(
+      'discovery_information',
+      jsonEncode(discoveryInformation.toJson()),
+    );
+  }
+
+  @override
+  Future<DiscoveryInformation?> getWellKnown() async {
+    final rawDiscoveryInformation =
+        await _clientBox.get('discovery_information');
+    if (rawDiscoveryInformation == null) return null;
+    return DiscoveryInformation.fromJson(jsonDecode(rawDiscoveryInformation));
+  }
+
   @override
   Future<void> delete() async {
     // database?.path is null on web

test/client_test.dart

@@ -175,6 +175,7 @@ void main() {
           matrix.userDeviceKeys['@alice:example.com']?.deviceKeys['JLAFKJWSCS']
               ?.verified,
           false);
+      expect(matrix.wellKnown, isNull);
 
       await matrix.handleSync(SyncUpdate.fromJson({
         'next_batch': 'fakesync',
@@ -1168,6 +1169,13 @@ void main() {
       await client.dispose(closeDatabase: true);
     });
 
+    test('wellKnown cache', () async {
+      final client = await getClient();
+      expect(client.wellKnown, null);
+      await client.getWellknown();
+      expect(client.wellKnown?.mHomeserver.baseUrl.host, 'matrix.example.com');
+    });
+
     test('refreshAccessToken', () async {
       final client = await getClient();
       expect(client.accessToken, 'abcd');