ClientWebSocket.ConnectAsync() does not work on Mac

[linkaiyu]

Description

in a simple MAUI test app, call to ClientWebSocket.ConnectAsync() on Mac does not return.
some experimental work suggests that MAUI is defaulting to HttpNoProxy:
when we don’t set proxy to ClientWebSocket Option the MAUI ClientWebSocket is defaulting to NoProxy and the connect fails. I checked the values of HttpClient.DefaultProxy:
In MAUI app:

  HttpClient.DefaultProxy    {System.Net.Http.HttpNoProxy}

comparing that to .Net7 App, it's set to MacProxy:

  HttpClient.DefaultProxy    {System.Net.Http.MacProxy}  

for reference:
https://github.com/dotnet/dotnet/blob/main/src/runtime/src/libraries/System.Net.WebSockets.Client/src/System/Net/WebSockets/WebSocketHandle.Managed.cs#L35

in customer situation, WPAD (Web Proxy Auto-Discovery) is used to configure internal laptops.
while testing on MS VPN, the code works. It's worth considering whether the MS VPN proxy setup differs from WPAD,

we need to get Proxy Url/object into MAUI app for all different VPN configuration and create WebProxy object and set it to ClientWebSocket.

Steps to Reproduce

download the repro to Mac connected via VPN with WPAD configured.
in the repro app, click on button to start test. the call to ClientWebSocket.ConnectAsync() will be stuck

Link to public reproduction project repository

https://github.com/linkaiyu/ClientWebSocket

Version with bug

7.0.49

Last version that worked well

Unknown/Other

Affected platforms

macOS

Affected platform versions

No response

Did you find any workaround?

short term workaround is to create a webproxy for the connection, but for long term when the app is going to be released to the public, the short term solution won't meet the needs

Relevant log output

No response

[drasticactions]

I don't think this is an Essentials issue. This is runtime code and not specific to MAUI UI. IMO it would be more appropriate for this to go to dotnet/runtime instead.

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

Issue Details

---

Description

in a simple MAUI test app, call to ClientWebSocket.ConnectAsync() on Mac does not return.
some experimental work suggests that MAUI is defaulting to HttpNoProxy:
when we don’t set proxy to ClientWebSocket Option the MAUI ClientWebSocket is defaulting to NoProxy and the connect fails. I checked the values of HttpClient.DefaultProxy:
In MAUI app:
HttpClient.DefaultProxy {System.Net.Http.HttpNoProxy}

comparing that to .Net7 App, it's set to MacProxy:
HttpClient.DefaultProxy {System.Net.Http.MacProxy}
for reference:
https://github.com/dotnet/dotnet/blob/main/src/runtime/src/libraries/System.Net.WebSockets.Client/src/System/Net/WebSockets/WebSocketHandle.Managed.cs#L35

in customer situation, WPAD (Web Proxy Auto-Discovery) is used to configure internal laptops.
while testing on MS VPN, the code works. It's worth considering whether the MS VPN proxy setup differs from WPAD,

we need to get Proxy Url/object into MAUI app for all different VPN configuration and create WebProxy object and set it to ClientWebSocket.

Steps to Reproduce

download the repro to Mac connected via VPN with WPAD configured.
in the repro app, click on button to start test. the call to ClientWebSocket.ConnectAsync() will be stuck

Link to public reproduction project repository

https://github.com/linkaiyu/ClientWebSocket

Version with bug

7.0.49

Last version that worked well

Unknown/Other

Affected platforms

macOS

Affected platform versions

No response

Did you find any workaround?

short term workaround is to create a webproxy for the connection, but for long term when the app is going to be released to the public, the short term solution won't meet the needs

Relevant log output

No response

Author:	linkaiyu
Assignees:	-
Labels:	area-System.Net
Milestone:	-

[CarnaViire]

From the issue:

I checked the values of HttpClient.DefaultProxy:
In MAUI app:
HttpClient.DefaultProxy {System.Net.Http.HttpNoProxy}

comparing that to .Net7 App, it's set to MacProxy:
HttpClient.DefaultProxy {System.Net.Http.MacProxy}

This doesn't look like a runtime issue, since it seems like either MAUI or something else is overriding the defaults somehow. @drasticactions @samhouts @linkaiyu

From what I see, on macOS, iOS and tvOS we use MacProxy by default:

runtime/src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/SystemProxyInfo.OSX.cs

Line 11 in 943af3a

return HttpEnvironmentProxy.TryCreate(out IWebProxy? proxy) ? proxy : new MacProxy();

Details

runtime/src/libraries/System.Net.Http/src/System.Net.Http.csproj

Lines 323 to 325 in 943af3a

	<ItemGroup Condition="'$(TargetPlatformIdentifier)' == 'osx' or '$(TargetPlatformIdentifier)' == 'ios' or '$(TargetPlatformIdentifier)' == 'tvos'">
	<Compile Include="System\Net\Http\SocketsHttpHandler\SystemProxyInfo.OSX.cs" />
	<Compile Include="System\Net\Http\SocketsHttpHandler\MacProxy.cs" />

while on other Unixes we use HttpNoProxy:

runtime/src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/SystemProxyInfo.Unix.cs

Line 13 in 943af3a

return HttpEnvironmentProxy.TryCreate(out IWebProxy? proxy) ? proxy : new HttpNoProxy();

Details

runtime/src/libraries/System.Net.Http/src/System.Net.Http.csproj

Lines 319 to 321 in 943af3a

	<ItemGroup Condition="'$(TargetPlatformIdentifier)' != '' and '$(TargetPlatformIdentifier)' != 'windows' and '$(TargetPlatformIdentifier)' != 'browser' and '$(TargetPlatformIdentifier)' != 'osx' and '$(TargetPlatformIdentifier)' != 'ios' and '$(TargetPlatformIdentifier)' != 'tvos'">
	<Compile Include="System\Net\Http\SocketsHttpHandler\HttpNoProxy.cs" />
	<Compile Include="System\Net\Http\SocketsHttpHandler\SystemProxyInfo.Unix.cs" />

It also shows that it can be overridden by an environmental value, so it is another potential culprit.

[CarnaViire]

cc @wfurt @MihaZupan

[wfurt]

It would be good to get packet captures @linkaiyu and verify where this code is trying to connect to.
AFAIK the discovery does not work on macOS e.g. you will either need to set the environment or use the system proxy config. It may be best to try very simple project with HttpCLient to peel off all the extra layers.

This issue has been marked needs-author-action and may be missing some important information.

[linkaiyu]

customer experimented with pre .net7 app and it works.
the problem happens with MAUI app.
will reach out to customer for network trace, not sure if they can provide useful info.

@drasticactions @CarnaViire @wfurt you are all added access to the repro app. very simple code, just a button click to invoke the API.