Show error on macOS if missing Local Network permissions #161846

loic-sharma · 2025-01-18T02:15:34Z

Background

macOS Sequoia requires the user's permission to do multicast operations, which the Flutter tool does to connect to the Dart VM. If the app does not have permission to communicate with devices on the local network, the following happens:

Flutter tool starts a multicast lookup
The mDNS client sends data on the socket
macOS blocks the operation. Dart's native socket implementation throws an OSError
Dart's Socket.send catches the OSError, wraps it in a SocketException, and schedules a microtask that reports the exception through the socket's stream (Socket is a Stream)
The mDNS client does not listen to the socket stream's errors, so the error is sent to the current Zone's uncaught error handler.

Reproduction

To reproduce this error on macOS...

Open System Settings > Privacy & Security > Local Network and toggle off Visual Studio Code
Run a Flutter app using a physical device

Fix

Ideally, we'd make MDnsClient.lookup throw an exception for this scenario. Unfortunately, the MDnsClient can have multiple lookup operations in parallel, and the SocketException doesn't give us enough information to match it back to a pending MDnsClient request. See flutter/packages#8450 as an attempt to solve this in the MDnsClient layer.

Instead, this fix introduces a Zone in the tool to catch the socket's uncaught exception.

Follow-up to #157638

See: #150131

Pre-launch Checklist

I read the Contributor Guide and followed the process outlined there for submitting PRs.
I read the Tree Hygiene wiki page, which explains my responsibilities.
I read and followed the Flutter Style Guide, including Features we expect every widget to implement.
I signed the CLA.
I listed at least one issue that this PR fixes in the description above.
I updated/added relevant documentation (doc comments with ///).
I added new tests to check the change I am making, or this PR is test-exempt.
I followed the breaking change policy and added Data Driven Fixes where supported.
All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel on Discord.

loic-sharma · 2025-01-18T02:16:16Z

packages/flutter_tools/lib/src/mdns_discovery.dart

+  }) async {
+    final Completer<List<MDnsVmServiceDiscoveryResult>> completer =
+        Completer<List<MDnsVmServiceDiscoveryResult>>();
+    unawaited(


If there's an error, the Future returned by runZonedGuarded never completes, hence the unawaited and Completer. See: https://dart.dev/libraries/async/zones#example-errors-cant-leave-error-zones

This is inspired by the tool's test context:

flutter/packages/flutter_tools/test/src/context.dart

Lines 130 to 175 in 9bf4e89

// To catch all errors thrown by the test, even uncaught async errors, we use a zone.

//

// Zones introduce their own event loop, so we do not await futures created inside

// the zone from outside the zone. Instead, we create a Completer outside the zone,

// and have the test complete it when the test ends (in success or failure), and we

// await that.

final Completer<void> completer = Completer<void>();

runZonedGuarded<Future<dynamic>>(

() async {

try {

return await context.run<dynamic>(

// Apply the overrides to the test context in the zone since their

// instantiation may reference items already stored on the context.

overrides: overrides,

name: 'test-specific overrides',

body: () async {

if (initializeFlutterRoot) {

// Provide a sane default for the flutterRoot directory. Individual

// tests can override this either in the test or during setup.

Cache.flutterRoot ??= getFlutterRoot();

}

return await testMethod();

},

);

} finally {

// We do not need a catch { ... } block because the error zone

// will catch all errors and send them to the completer below.

//

// See https://github.com/flutter/flutter/pull/141821/files#r1462288131.

if (!completer.isCompleted) {

completer.complete();

}

}

},

(Object error, StackTrace stackTrace) {

// When things fail, it's ok to print to the console!

print(error); // ignore: avoid_print

print(stackTrace); // ignore: avoid_print

_printBufferedErrors(context);

if (!completer.isCompleted) {

completer.completeError(error, stackTrace);

}

throw error; //ignore: only_throw_errors

},

);

return completer.future;

loic-sharma · 2025-01-21T19:42:05Z

packages/flutter_tools/lib/src/mdns_discovery.dart

+    bool useDeviceIPAsHost = false,
+    required Duration timeout,
+    bool quitOnFind = false,
+  }) async {


This diff is confusing. The only change to _pollingVmService's arguments is that deviceVmservicePort was renamed to deviceVmServicePort. _pollingVmService and _doPollingVmService have the same arguments.

loic-sharma · 2025-01-21T23:39:43Z

~~@jonahwilliams Jenn told me you actually understand Dart Zones and all their implications. Would you be able to review this to double-check I'm not doing anything horrible?~~

EDIT: @matanlurey spot-checked the Zone usage.

bkonyi

Excellent! I'm looking forward to this no longer being our top crasher!

We should consider cherry picking this into stable if we can.

andrewkolos

LGTM

flutteractionsbot · 2025-01-23T21:38:56Z

Failed to create CP due to merge conflicts.
You will need to create the PR manually. See the cherrypick wiki for more info.

…tter/flutter#161846)

…tter/flutter#161846)

Manual roll requested by [email protected] flutter/flutter@c1561a4...c1ffaa9 2025-01-24 [email protected] Fix link to hotfix documentation best practices (flutter/flutter#162116) 2025-01-24 [email protected] Add integration test for cutout rotation evaluation (flutter/flutter#160354) 2025-01-24 [email protected] Reland "[Impeller] Migrate unit tests off of Skia geometry classes (#161855)" (flutter/flutter#162146) 2025-01-24 [email protected] Fix TextField intrinsic width when hint is not visible (flutter/flutter#161235) 2025-01-24 [email protected] When parsing flavors, handle Xcode build configurations that are not lowercase (flutter/flutter#161455) 2025-01-24 [email protected] [Impeller] Fix source offset in PathBuilder::AddPath (flutter/flutter#162052) 2025-01-24 [email protected] Add to Setup Path Example to Engine README (flutter/flutter#162115) 2025-01-23 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Unskip test. (#162106)" (flutter/flutter#162122) 2025-01-23 [email protected] feat: Add `hint` (Widget) property to InputDecoration (flutter/flutter#161424) 2025-01-23 [email protected] Fix skwasm target in wasm_debug_unopt build. (flutter/flutter#162100) 2025-01-23 [email protected] Marks Linux_android_emu android views to be unflaky (flutter/flutter#160493) 2025-01-23 [email protected] Unskip test. (flutter/flutter#162106) 2025-01-23 [email protected] Add ability to maintain bottom view padding in `NavigationBar` safe area (flutter/flutter#162076) 2025-01-23 [email protected] Roll pub packages (flutter/flutter#162095) 2025-01-23 [email protected] Delete an unused (manual) workflow, added missing copyright headers. (flutter/flutter#162050) 2025-01-23 [email protected] Android templates: update default Kotlin from 1.8.22 to 2.1.0, update default Gradle from 8.9 to 8.12 (flutter/flutter#160974) 2025-01-23 [email protected] flutter_tools: flutter_tester is a host artifact (flutter/flutter#162047) 2025-01-23 [email protected] [Impeller] Make glIsTexture mockable for use by the ReactorGLES.NameUntrackedHandle test (flutter/flutter#162082) 2025-01-23 [email protected] Remove "Mac Designed for iPad" as a discoverable `flutter run` device (flutter/flutter#161459) 2025-01-23 [email protected] Show error on macOS if missing Local Network permissions (flutter/flutter#161846) 2025-01-23 [email protected] Autocomplete keyboard navigation (flutter/flutter#159455) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC [email protected],[email protected] on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

) ⚠️ This targets branch `flutter-3.29-candidate.0` for the Flutter beta. Cherrypicks #161846 to `flutter-3.29-candidate.0`. **Impacted Users**: Users that use macOS Sequoia and haven't turned on Local Network permissions for their IDE or terminal app. See: #150131 **Impact Description**: Without this improved error message, `flutter run` outputs this error: `SocketException: Send failed, OS Error: No route to host, errno = 65`. **Workaround**: Turn on Local Network permissions for your IDE or terminal app. However, it's difficult for customers to discover this from the error message. **Risk**: This change could regress the tool's Dart VM discovery. **Test Coverage**: Yes added tests **Validation Steps**: In System Settings > Privacy & Security > Local Network, toggle off Visual Studio Code. In VS Code, run a Flutter app on a physical device.

…ter#162119) ⚠️ This targets branch `flutter-3.29-candidate.0` for the Flutter beta. Cherrypicks flutter#161846 to `flutter-3.29-candidate.0`. **Impacted Users**: Users that use macOS Sequoia and haven't turned on Local Network permissions for their IDE or terminal app. See: flutter#150131 **Impact Description**: Without this improved error message, `flutter run` outputs this error: `SocketException: Send failed, OS Error: No route to host, errno = 65`. **Workaround**: Turn on Local Network permissions for your IDE or terminal app. However, it's difficult for customers to discover this from the error message. **Risk**: This change could regress the tool's Dart VM discovery. **Test Coverage**: Yes added tests **Validation Steps**: In System Settings > Privacy & Security > Local Network, toggle off Visual Studio Code. In VS Code, run a Flutter app on a physical device.

…119) ⚠️ This targets branch `flutter-3.29-candidate.0` for the Flutter beta. Cherrypicks flutter/flutter#161846 to `flutter-3.29-candidate.0`. **Impacted Users**: Users that use macOS Sequoia and haven't turned on Local Network permissions for their IDE or terminal app. See: flutter/flutter#150131 **Impact Description**: Without this improved error message, `flutter run` outputs this error: `SocketException: Send failed, OS Error: No route to host, errno = 65`. **Workaround**: Turn on Local Network permissions for your IDE or terminal app. However, it's difficult for customers to discover this from the error message. **Risk**: This change could regress the tool's Dart VM discovery. **Test Coverage**: Yes added tests **Validation Steps**: In System Settings > Privacy & Security > Local Network, toggle off Visual Studio Code. In VS Code, run a Flutter app on a physical device.

…tter/flutter#161846)

) Manual roll requested by [email protected] flutter/flutter@c1561a4...c1ffaa9 2025-01-24 [email protected] Fix link to hotfix documentation best practices (flutter/flutter#162116) 2025-01-24 [email protected] Add integration test for cutout rotation evaluation (flutter/flutter#160354) 2025-01-24 [email protected] Reland "[Impeller] Migrate unit tests off of Skia geometry classes (#161855)" (flutter/flutter#162146) 2025-01-24 [email protected] Fix TextField intrinsic width when hint is not visible (flutter/flutter#161235) 2025-01-24 [email protected] When parsing flavors, handle Xcode build configurations that are not lowercase (flutter/flutter#161455) 2025-01-24 [email protected] [Impeller] Fix source offset in PathBuilder::AddPath (flutter/flutter#162052) 2025-01-24 [email protected] Add to Setup Path Example to Engine README (flutter/flutter#162115) 2025-01-23 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Unskip test. (#162106)" (flutter/flutter#162122) 2025-01-23 [email protected] feat: Add `hint` (Widget) property to InputDecoration (flutter/flutter#161424) 2025-01-23 [email protected] Fix skwasm target in wasm_debug_unopt build. (flutter/flutter#162100) 2025-01-23 [email protected] Marks Linux_android_emu android views to be unflaky (flutter/flutter#160493) 2025-01-23 [email protected] Unskip test. (flutter/flutter#162106) 2025-01-23 [email protected] Add ability to maintain bottom view padding in `NavigationBar` safe area (flutter/flutter#162076) 2025-01-23 [email protected] Roll pub packages (flutter/flutter#162095) 2025-01-23 [email protected] Delete an unused (manual) workflow, added missing copyright headers. (flutter/flutter#162050) 2025-01-23 [email protected] Android templates: update default Kotlin from 1.8.22 to 2.1.0, update default Gradle from 8.9 to 8.12 (flutter/flutter#160974) 2025-01-23 [email protected] flutter_tools: flutter_tester is a host artifact (flutter/flutter#162047) 2025-01-23 [email protected] [Impeller] Make glIsTexture mockable for use by the ReactorGLES.NameUntrackedHandle test (flutter/flutter#162082) 2025-01-23 [email protected] Remove "Mac Designed for iPad" as a discoverable `flutter run` device (flutter/flutter#161459) 2025-01-23 [email protected] Show error on macOS if missing Local Network permissions (flutter/flutter#161846) 2025-01-23 [email protected] Autocomplete keyboard navigation (flutter/flutter#159455) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC [email protected],[email protected] on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

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Show error on macOS if missing Local Network permissions

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[beta] Show error on macOS if missing Local Network permissions #162119

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Roll Flutter from c1561a41c530 to bf7daf22a51e (19 revisions) flutter/packages#8495

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Roll Flutter from c1561a41c530 to 02e11f95a18a (20 revisions) flutter/packages#8496

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Roll Flutter from c1561a41c530 to c1ffaa9d9deb (21 revisions) flutter/packages#8497

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Add a test to run on iPhone 16 #166781

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	// To catch all errors thrown by the test, even uncaught async errors, we use a zone.
	//
	// Zones introduce their own event loop, so we do not await futures created inside
	// the zone from outside the zone. Instead, we create a Completer outside the zone,
	// and have the test complete it when the test ends (in success or failure), and we
	// await that.
	final Completer<void> completer = Completer<void>();
	runZonedGuarded<Future<dynamic>>(
	() async {
	try {
	return await context.run<dynamic>(
	// Apply the overrides to the test context in the zone since their
	// instantiation may reference items already stored on the context.
	overrides: overrides,
	name: 'test-specific overrides',
	body: () async {
	if (initializeFlutterRoot) {
	// Provide a sane default for the flutterRoot directory. Individual
	// tests can override this either in the test or during setup.
	Cache.flutterRoot ??= getFlutterRoot();
	}
	return await testMethod();
	},
	);
	} finally {
	// We do not need a catch { ... } block because the error zone
	// will catch all errors and send them to the completer below.
	//
	// See https://github.com/flutter/flutter/pull/141821/files#r1462288131.
	if (!completer.isCompleted) {
	completer.complete();
	}
	}
	},
	(Object error, StackTrace stackTrace) {
	// When things fail, it's ok to print to the console!
	print(error); // ignore: avoid_print
	print(stackTrace); // ignore: avoid_print
	_printBufferedErrors(context);
	if (!completer.isCompleted) {
	completer.completeError(error, stackTrace);
	}
	throw error; //ignore: only_throw_errors
	},
	);
	return completer.future;

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