NetworkChange NetworkAddressChanged event throws NetworkInformationException on Android

[chriskarlsson]

Description

NetworkInformationException is thrown when trying to subscribe to NetworkChange.NetworkAddressChanged on Android.

There is no indication in the source code that Android is UnsupportedOSPlatform but Android is not listed as supported in Microsoft Learn.

Reproduction Steps

Add the following to MainActivity of a clean Android or Maui application project:

NetworkChange.NetworkAddressChanged += (sender, args) =>
{
    Console.WriteLine($"Sender: {sender} args: {string.Join(", ", args.ToString())}");
};

Expected behavior

Console output when network address changes.

Actual behavior

NetworkInformationException is thrown with the quite cryptic exception message "Success".

Regression?

This was working fine when the application ran on Mono. It also works fine on .Net6-ios and .Net6-mac.

Known Workarounds

No response

Configuration

Which version of .NET is the code running on? - Behavior seen on both .Net6-android with and without Maui
What OS and version, and what distro if applicable? - Android 12/API 31
What is the architecture (x64, x86, ARM, ARM64)? - ARM

Other information

No response

[ghost]

Tagging subscribers to this area: @dotnet/ncl
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Description

NetworkInformationException is thrown when trying to subscribe to NetworkChange.NetworkAddressChanged on Android.

There is no indication in the source code that Android is UnsupportedOSPlatform but Android is not listed as supported in Microsoft Learn.

Reproduction Steps

Add the following to MainActivity of a clean Android or Maui application project:

NetworkChange.NetworkAddressChanged += (sender, args) =>
{
    Console.WriteLine($"Sender: {sender} args: {string.Join(", ", args.ToString())}");
};

Expected behavior

Console output when network address changes.

Actual behavior

NetworkInformationException is thrown with the quite cryptic exception message "Success".

Regression?

This was working fine when the application ran on Mono. It also works fine on .Net6-ios and .Net6-mac.

Known Workarounds

No response

Configuration

Which version of .NET is the code running on? - Behavior seen on both .Net6-android with and without Maui
What OS and version, and what distro if applicable? - Android 12/API 31
What is the architecture (x64, x86, ARM, ARM64)? - ARM

Other information

No response

Author:	chriskarlsson
Assignees:	-
Labels:	area-System.Net, untriaged
Milestone:	-

[ghost]

Tagging subscribers to 'arch-android': @steveisok, @akoeplinger
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Description

NetworkInformationException is thrown when trying to subscribe to NetworkChange.NetworkAddressChanged on Android.

There is no indication in the source code that Android is UnsupportedOSPlatform but Android is not listed as supported in Microsoft Learn.

Reproduction Steps

Add the following to MainActivity of a clean Android or Maui application project:

NetworkChange.NetworkAddressChanged += (sender, args) =>
{
    Console.WriteLine($"Sender: {sender} args: {string.Join(", ", args.ToString())}");
};

Expected behavior

Console output when network address changes.

Actual behavior

NetworkInformationException is thrown with the quite cryptic exception message "Success".

Regression?

This was working fine when the application ran on Mono. It also works fine on .Net6-ios and .Net6-mac.

Known Workarounds

No response

Configuration

Which version of .NET is the code running on? - Behavior seen on both .Net6-android with and without Maui
What OS and version, and what distro if applicable? - Android 12/API 31
What is the architecture (x64, x86, ARM, ARM64)? - ARM

Other information

No response

Author:	chriskarlsson
Assignees:	-
Labels:	area-System.Net, os-android, untriaged
Milestone:	-

[am11]

(aside from the NetworkAddressChanged event issue)

NetworkInformationException is thrown with the quite cryptic exception message "Success".

If this exception is thrown from

runtime/src/libraries/System.Net.NetworkInformation/src/System/Net/NetworkInformation/NetworkAddressChange.Unix.cs

Lines 172 to 176 in 13733cd

	if (result != Interop.Error.SUCCESS)
	{
	string message = Interop.Sys.GetLastErrorInfo().GetErrorMessage();
	sh.Dispose();
	throw new NetworkInformationException(message);

it shouldn't print "Success". @akoeplinger, looks like there is also something wrong in the error mapping? 🤔

[steveisok]

@simonrozsival, please take a look.

[simonrozsival]

I can reproduce the bug locally. I'll continue investigating the issue tomorrow.

[akoeplinger]

@simonrozsival did you happen to find out whether we could support this?

[simonrozsival]

@akoeplinger I looked into it and I didn't find a good 1:1 replacement Android API. There are some ConnectivityManager APIs that seemed promissing but they don't behave the same way (for example ConnectivityManager.registerNetworkCallback). I will need to revisit this and look for some alternative ways of implementing it if it's even possible with the current Android restrictions.

[akoeplinger]

I wonder if we could start a timer/polling loop whenever someone registers the event that would continuously look for network changes

[simonrozsival]

We could do that. It would certainly work but wouldn't that be quite inefficient to do on a mobile device?

[simonrozsival]

I'm experimenting with PeriodicTimer to poll network information. I'm still not convinced that this is the optimal implementation but it's likely good enough. I need to do more testing before I submit the PR for full review. For the time being I opened a draft PR and any suggestions are welcome.

[akoeplinger]

With #80548 being merged we should be done here right? I don't think it makes sense to backport this to 7.0

[simonrozsival]

I don't think we should backport the implementation. I think we can close this issue now.