tor

Foundation-Devices/tor as a multi-platform Flutter FFI plugin for starting and stopping the Tor daemon. Based on libtor-sys.

Getting started

Install rust

Install cargo ndk

cargo install cargo-ndk

Install dependencies

sudo apt install git build-essential cmake llvm clang pkg-config cargo rustc libssl-dev libc6-dev-i386

Run build scripts

Linux

Run build script

cd scripts/linux
./build_all.sh

Android

Run the NDK setup and build scripts

cd scripts/android
./install_ndk.sh
./build_all.sh

Development

To generate tor-ffi.h C bindings for Rust, cbindgen --config cbindgen.toml --crate tor-ffi --output target/tor-ffi.h or cargo build in native/tor-ffi to produce headers according to build.rs To generate tor_bindings_generated.dart Dart bindings for C, flutter pub run ffigen --config ffigen.yaml

Example app

flutter run in example to run the example app

See example/lib/main.dart for usage. Must run the build script for your platform first.

Flutter FFI plugin template

This project is a starting point for a Flutter FFI plugin, a specialized package that includes native code directly invoked with Dart FFI.

Project stucture

This template uses the following structure:

• src: Contains the native source code, and a CmakeFile.txt file for building that source code into a dynamic library.

• lib: Contains the Dart code that defines the API of the plugin, and which calls into the native code using dart:ffi.

• platform folders (android, ios, windows, etc.): Contains the build files for building and bundling the native code library with the platform application.

Buidling and bundling native code

The pubspec.yaml specifies FFI plugins as follows:

  plugin:
    platforms:
      some_platform:
        ffiPlugin: true

This configuration invokes the native build for the various target platforms and bundles the binaries in Flutter applications using these FFI plugins.

This can be combined with dartPluginClass, such as when FFI is used for the implementation of one platform in a federated plugin:

  plugin:
    implements: some_other_plugin
    platforms:
      some_platform:
        dartPluginClass: SomeClass
        ffiPlugin: true

A plugin can have both FFI and method channels:

  plugin:
    platforms:
      some_platform:
        pluginClass: SomeName
        ffiPlugin: true

The native build systems that are invoked by FFI (and method channel) plugins are:

• For Android: Gradle, which invokes the Android NDK for native builds.
  • See the documentation in android/build.gradle.
• For iOS and MacOS: Xcode, via CocoaPods.
  • See the documentation in ios/flutter_libtor.podspec.
  • See the documentation in macos/flutter_libtor.podspec.
• For Linux and Windows: CMake.
  • See the documentation in linux/CMakeLists.txt.
  • See the documentation in windows/CMakeLists.txt.

Binding to native code

To use the native code, bindings in Dart are needed. To avoid writing these by hand, they are generated from the header file (src/flutter_libtor.h) by package:ffigen. Regenerate the bindings by running flutter pub run ffigen --config ffigen.yaml.

Invoking native code

Very short-running native functions can be directly invoked from any isolate. For example, see sum in lib/flutter_libtor.dart.

Longer-running functions should be invoked on a helper isolate to avoid dropping frames in Flutter applications. For example, see sumAsync in lib/flutter_libtor.dart.

Flutter help

For help getting started with Flutter, view our online documentation, which offers tutorials, samples, guidance on mobile development, and a full API reference.