feat: Implement unpublished MSC custom refresh token lifetime

lib/msc_extensions/msc_unpublished_custom_refresh_token_lifetime/msc_unpublished_custom_refresh_token_lifetime.dart

@@ -0,0 +1,56 @@
+import 'dart:convert';
+
+import 'package:http/http.dart';
+
+import 'package:matrix/matrix.dart';
+
+extension MscUnpublishedCustomRefreshTokenLifetime on MatrixApi {
+  static const String customFieldKey = 'com.famedly.refresh_token_lifetime_ms';
+
+  /// Refresh an access token. Clients should use the returned access token
+  /// when making subsequent API calls, and store the returned refresh token
+  /// (if given) in order to refresh the new access token when necessary.
+  ///
+  /// After an access token has been refreshed, a server can choose to
+  /// invalidate the old access token immediately, or can choose not to, for
+  /// example if the access token would expire soon anyways. Clients should
+  /// not make any assumptions about the old access token still being valid,
+  /// and should use the newly provided access token instead.
+  ///
+  /// The old refresh token remains valid until the new access token or refresh token
+  /// is used, at which point the old refresh token is revoked.
+  ///
+  /// Note that this endpoint does not require authentication via an
+  /// access token. Authentication is provided via the refresh token.
+  ///
+  /// Application Service identity assertion is disabled for this endpoint.
+  ///
+  /// [refreshToken] The refresh token
+  Future<RefreshResponse> refreshWithCustomRefreshTokenLifetime(
+    String refreshToken, {
+    /// This allows clients to pass an extra parameter when refreshing a token,
+    /// which overrides the configured refresh token timeout in the Synapse
+    /// config. This allows a client to opt into a shorter (or longer) lifetime
+    /// for their refresh token, which could be used to sign out web sessions
+    /// with a specific timeout.
+    ///
+    /// Experimental implementation in Synapse:
+    /// https://github.com/famedly/synapse/pull/10
+    int? refreshTokenLifetimeMs,
+  }) async {
+    final requestUri = Uri(path: '_matrix/client/v3/refresh');
+    final request = Request('POST', baseUri!.resolveUri(requestUri));
+    request.headers['content-type'] = 'application/json';
+    request.bodyBytes = utf8.encode(jsonEncode({
+      'refresh_token': refreshToken,
+      if (refreshTokenLifetimeMs != null)
+        customFieldKey: refreshTokenLifetimeMs,
+    }));
+    final response = await httpClient.send(request);
+    final responseBody = await response.stream.toBytes();
+    if (response.statusCode != 200) unexpectedResponse(response, responseBody);
+    final responseString = utf8.decode(responseBody);
+    final json = jsonDecode(responseString);
+    return RefreshResponse.fromJson(json as Map<String, Object?>);
+  }
+}

lib/src/client.dart

@@ -31,6 +31,7 @@ import 'package:random_string/random_string.dart';
 
 import 'package:matrix/encryption.dart';
 import 'package:matrix/matrix.dart';
+import 'package:matrix/msc_extensions/msc_unpublished_custom_refresh_token_lifetime/msc_unpublished_custom_refresh_token_lifetime.dart';
 import 'package:matrix/src/models/timeline_chunk.dart';
 import 'package:matrix/src/utils/cached_stream_controller.dart';
 import 'package:matrix/src/utils/client_init_exception.dart';
@@ -195,6 +196,11 @@ class Client extends MatrixApi {
     /// most common reason for soft logouts.
     /// You can also perform a new login here by passing the existing deviceId.
     this.onSoftLogout,
+
+    /// Experimental feature which allows to send a custom refresh token
+    /// lifetime to the server which overrides the default one. Needs server
+    /// support.
+    this.customRefreshTokenLifetime,
   })  : syncFilter = syncFilter ??
             Filter(
               room: RoomFilter(
@@ -238,6 +244,8 @@ class Client extends MatrixApi {
     registerDefaultCommands();
   }
 
+  Duration? customRefreshTokenLifetime;
+
   /// Fetches the refreshToken from the database and tries to get a new
   /// access token from the server and then stores it correctly. Unlike the
   /// pure API call of `Client.refresh()` this handles the complete soft
@@ -257,7 +265,10 @@ class Client extends MatrixApi {
       throw Exception('Cannot refresh access token when not logged in');
     }
 
-    final tokenResponse = await refresh(refreshToken);
+    final tokenResponse = await refreshWithCustomRefreshTokenLifetime(
+      refreshToken,
+      refreshTokenLifetimeMs: customRefreshTokenLifetime?.inMilliseconds,
+    );
 
     accessToken = tokenResponse.accessToken;
     final expiresInMs = tokenResponse.expiresInMs;