OIDC - Setting the proxy to BackchannelHttpHandler does not make all calls pass through the proxy

[mouldt]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

same as issue #45688. Which was closed without resolution.

Expected Behavior

I expect that setting the proxy to the BackchannelHttpHandler would suffice, and I should not be required to also set HttpClient.DefaultProxy

Steps To Reproduce

You can find the steps in the following repo: https://github.com/samusaran/BackchannelHttpHandlerIssue

Exceptions (if any)

   ---> System.Net.Http.HttpRequestException: Name or service not known (XXX.b2clogin.com:443)
   ---> System.Net.Sockets.SocketException (0xFFFDFFFF): Name or service not known
     at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.ThrowException(SocketError error, CancellationToken cancellationToken)
     at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.System.Threading.Tasks.Sources.IValueTaskSource.GetResult(Int16 token)
     at System.Net.Sockets.Socket.<ConnectAsync>g__WaitForConnectWithCancellation|285_0(AwaitableSocketAsyncEventArgs saea, ValueTask connectTask, CancellationToken cancellationToken)
     at System.Net.Http.HttpConnectionPool.ConnectToTcpHostAsync(String host, Int32 port, HttpRequestMessage initialRequest, Boolean async, CancellationToken cancellationToken)
     --- End of inner exception stack trace ---
     at System.Net.Http.HttpConnectionPool.ConnectToTcpHostAsync(String host, Int32 port, HttpRequestMessage initialRequest, Boolean async, CancellationToken cancellationToken)
     at System.Net.Http.HttpConnectionPool.ConnectAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
     at System.Net.Http.HttpConnectionPool.CreateHttp11ConnectionAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
     at System.Net.Http.HttpConnectionPool.AddHttp11ConnectionAsync(QueueItem queueItem)
     at System.Threading.Tasks.TaskCompletionSourceWithCancellation`1.WaitWithCancellationAsync(CancellationToken cancellationToken)
     at System.Net.Http.HttpConnectionPool.SendWithVersionDetectionAndRetryAsync(HttpRequestMessage request, Boolean async, Boolean doRequestAuth, CancellationToken cancellationToken)
     at System.Net.Http.DiagnosticsHandler.SendAsyncCore(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
     at System.Net.Http.RedirectHandler.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
     at System.Net.Http.HttpClient.<SendAsync>g__Core|83_0(HttpRequestMessage request, HttpCompletionOption completionOption, CancellationTokenSource cts, Boolean disposeCts, CancellationTokenSource pendingRequestsCts, CancellationToken originalCancellationToken)
     at Microsoft.IdentityModel.Protocols.HttpDocumentRetriever.SendAndRetryOnNetworkErrorAsync(HttpClient httpClient, Uri uri)
     at Microsoft.IdentityModel.Protocols.HttpDocumentRetriever.GetDocumentAsync(String address, CancellationToken cancel)
     --- End of inner exception stack trace ---
     at Microsoft.IdentityModel.Protocols.HttpDocumentRetriever.GetDocumentAsync(String address, CancellationToken cancel)
     at Microsoft.IdentityModel.Protocols.OpenIdConnect.OpenIdConnectConfigurationRetriever.GetAsync(String address, IDocumentRetriever retriever, CancellationToken cancel)
     at Microsoft.IdentityModel.Protocols.ConfigurationManager`1.GetConfigurationAsync(CancellationToken cancel)., InnerException: System.IO.IOException.

.NET Version

8.0

Anything else?

Microsoft.Identity.Web 3.10.0