Linux Portal implementation for connectivity_plus

A Linux implementation of connectivity_plus that uses XDG Desktop Portal (org.freedesktop.portal.NetworkMonitor) for sandbox compliance (e.g., Flathub/Flatpak).

Getting Started

Call ConnectivityPlusLinuxPortalPlugin.registerWith() either for all Linux desktops or only under certain conditions (i.e., Flatpak detection):

import 'dart:io';

import 'package:connectivity_plus_linux_portal/connectivity_plus_linux_portal.dart';

void main() {
  if (Platform.isLinux) {
    final isFlatpak =
        Platform.environment.containsKey('FLATPAK_ID') ||
        Platform.environment['container'] == 'flatpak';
    final backend = Platform.environment['CONNECTIVITY_BACKEND'];
    final usePortal = isFlatpak || backend == 'portal';

    if (usePortal) {
      ConnectivityPlusLinuxPortalPlugin.registerWith();
    }
  }
}

The connectivity_plus plugin will now use the portal when running the Flatpak version of the app:

import 'package:connectivity_plus/connectivity_plus.dart';

Future<void> main() async {
  final result = await Connectivity().checkConnectivity();
  print(result); // Typically [ConnectivityResult.none] or [ConnectivityResult.other].
}

Manual testing

CONNECTIVITY_BACKEND=portal flutter run -d linux

Flatpak manifest

Pass the environment variable in the Flatpak manifest (optional fallback in case FLATPAK_ID env variable was not found):

finish-args:
  - --env=CONNECTIVITY_BACKEND=portal

Motivation

Address upstream issue.

The default connectivity_plus Linux implementation uses nm, which uses org.freedesktop.NetworkManager, which causes:

Unhandled Exception: org.freedesktop.DBus.Error.ServiceUnknown: org.freedesktop.DBus.Error.ServiceUnknown

While you you can add (last resort):

finish-args:
  - --talk-name=org.freedesktop.NetworkManager

This approach is often discouraged when submitting an app to Flathub (example comment).

This package uses xdg_desktop_portal. Both xdg_desktop_portal and nm uses the dbus package. All three packages are maintained by Canonical.

Limitations

This package uses org.freedesktop.portal.NetworkMonitor instead of org.freedesktop.NetworkManager.

As a result, fewer ConnectivityResult types are supported (by design for sandbox/privacy reasons):

• No network: ConnectivityResult.none
• Connected to a network: ConnectivityResult.other (still unknown)
• Captive portal: Assumes ConnectivityResult.wifi
• Network is metered: Assumes ConnectivityResult.mobile

You can use the portal implementation only for the Flatpak version (e.g., via environment variable or argument) and keep the default implementation (as shown in this section).

Acknowledgement

• @sgehrman for sharing the approach
• xdg_desktop_portal by Canonical