Added gRPC streaming for large file uploads

Author: Ojin13

.fvmrc

@@ -1,3 +1,3 @@
 {
-  "flutter": "3.32.8"
+  "flutter": "3.35.0"
 }

lib/view_model/app_view_model.dart

@@ -26,12 +26,11 @@ class TaskStream {
 }
 
 class AppViewModel with ChangeNotifier {
-  // Limit reduced from 8MB to 3MB to account for encryption overhead
-  // and stay under gRPC's 4MB message size limit.
-  // Currently it is not possible to configure dart's gRPC message size.
-  // TODO: Verify encryption overhead / JSON encoding overhead to find find optimal buffer.
-  // Please follow: https://github.com/grpc/grpc-dart/issues/551
-  static const maxDataSize = 3 * 1024 * 1024; // 3MB
+  // Be aware of the max gRPC message size limit:
+  // https://github.com/grpc/grpc-dart/issues/551
+
+  // For upload of large files (PDFs, images) use gRPC streaming!
+  static const maxDataSize = 8 * 1024 * 1024; // 8MB
   Device? device;
 
   final List<Task> allTasks = [];

meesign_core/lib/src/data/decrypt_repository.dart

@@ -1,4 +1,5 @@
 import 'package:drift/drift.dart';
+import 'package:fixnum/fixnum.dart';
 import 'package:meesign_native/meesign_native.dart';
 import 'package:meesign_network/grpc.dart' as rpc;
 
@@ -34,13 +35,51 @@ class DecryptRepository extends TaskRepository<Decrypt> {
     List<int> gid,
   ) async {
     final enc = ElGamalWrapper.encrypt(data, gid);
-    await _dispatcher.unauth.decrypt(
-      rpc.DecryptRequest()
-        ..groupId = gid
-        ..name = description
-        ..dataType = dataType.value
-        ..data = enc,
-    );
+
+    // Use streaming for large encrypted data (> 1MB)
+    if (enc.length > 1024 * 1024) {
+      await _encryptStreaming(description, dataType, enc, gid);
+    } else {
+      // Use regular RPC for small data
+      await _dispatcher.unauth.decrypt(
+        rpc.DecryptRequest()
+          ..groupId = gid
+          ..name = description
+          ..dataType = dataType.value
+          ..data = enc,
+      );
+    }
+  }
+
+  /// Stream large encrypted data in chunks to avoid gRPC message size limits.
+  Future<void> _encryptStreaming(
+    String description,
+    MimeType dataType,
+    List<int> encryptedData,
+    List<int> gid,
+  ) async {
+    const chunkSize = 256 * 1024; // 256KB chunks
+
+    Stream<rpc.DecryptRequestChunk> chunks() async* {
+      // First chunk: metadata
+      yield rpc.DecryptRequestChunk()
+        ..metadata = (rpc.DecryptMetadata()
+          ..name = description
+          ..groupId = gid
+          ..dataType = dataType.value
+          ..totalSize = Int64(encryptedData.length));
+
+      // Subsequent chunks: data
+      for (var i = 0; i < encryptedData.length; i += chunkSize) {
+        final end = (i + chunkSize < encryptedData.length)
+            ? i + chunkSize
+            : encryptedData.length;
+
+        yield rpc.DecryptRequestChunk()..chunk = encryptedData.sublist(i, end);
+      }
+    }
+
+    await _dispatcher.unauth.decryptStream(chunks());
   }
 
   @override

meesign_core/lib/src/data/file_repository.dart

@@ -1,4 +1,5 @@
 import 'package:drift/drift.dart';
+import 'package:fixnum/fixnum.dart';
 import 'package:meesign_core/src/model/group.dart';
 import 'package:meesign_native/meesign_native.dart';
 import 'package:meesign_network/grpc.dart' as rpc;
@@ -33,12 +34,45 @@ class FileRepository extends TaskRepository<File> {
   ) : super(rpc.TaskType.SIGN_PDF, taskSource, _taskDao);
 
   Future<void> sign(String name, List<int> data, List<int> gid) async {
-    await _dispatcher.unauth.sign(
-      rpc.SignRequest()
-        ..groupId = gid
-        ..name = name
-        ..data = data,
-    );
+    // Use streaming for large files (> 1MB)
+    if (data.length > 1024 * 1024) {
+      await _signStreaming(name, data, gid);
+    } else {
+      // Use regular RPC for small files
+      await _dispatcher.unauth.sign(
+        rpc.SignRequest()
+          ..groupId = gid
+          ..name = name
+          ..data = data,
+      );
+    }
+  }
+
+  /// Stream large PDF files in chunks to avoid gRPC message size limits.
+  Future<void> _signStreaming(
+    String name,
+    List<int> data,
+    List<int> gid,
+  ) async {
+    const chunkSize = 256 * 1024; // 256KB chunks
+
+    Stream<rpc.SignRequestChunk> chunks() async* {
+      // First chunk: metadata
+      yield rpc.SignRequestChunk()
+        ..metadata = (rpc.SignMetadata()
+          ..name = name
+          ..groupId = gid
+          ..totalSize = Int64(data.length));
+
+      // Subsequent chunks: data
+      for (var i = 0; i < data.length; i += chunkSize) {
+        final end = (i + chunkSize < data.length) ? i + chunkSize : data.length;
+
+        yield rpc.SignRequestChunk()..chunk = data.sublist(i, end);
+      }
+    }
+
+    await _dispatcher.unauth.signStream(chunks());
   }
 
   @override

meesign_core/pubspec.yaml

@@ -11,6 +11,7 @@ dependencies:
   collection: ^1.16.0
   convert: ^3.1.1
   drift: ^2.26.1
+  fixnum: ^1.0.1
   freezed_annotation: ^3.1.0
   meesign_native: {path: ../meesign_native}
   meesign_network: {path: ../meesign_network}