HttpHandlerDiagnosticListener does not send second chain of events if the request was autoredirected on netfx in W3C mode

[eduard-bystrov]

Here from #38152

Request with status code 401(Unauthorized) can be autoredirected, which leads to the execution of the second request on the same object HttpWebRequest (may be HttpRequestMessage too).

If this happens we have the following chain of events:

1. System.Net.Http.Desktop.HttpRequestOut.Start
2. System.Net.Http.Desktop.HttpRequestOut.Ex.Stop (got 401)
3. System.Net.Http.Desktop.HttpRequestOut.Stop (success)

it's a bit strange... hardly anyone expects to get Stop and Stop.Ex for one request.

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

[karelz]

@eduard-bystrov were you able to reproduce it also on .NET Core?
Or is the report only about .NET Framework?

[eduard-bystrov]

@eduard-bystrov were you able to reproduce it also on .NET Core?
Or is the report only about .NET Framework?

only about .NET Framework
I have no information about .NET Core

[karelz]

We won't be able to fix .NET Framework, unless it has high business impact. (just to set the expectation -- the bar for .NET Framework fixes is pretty high in general)

Triage: It will likely repro in .NET Core as well, we should think about it in our DiagnosticHandler changes in 6.0. We may decide it is by design potentially.

[MihaZupan]

Note: the issue here is that DiagnosticHandler was wrapping the underlying handler and as such could never intercept redirects.

#55392 fixes that by moving DiagnosticHandler to the start of the chain so that any redirect flows through it again and can be instrumented.
With this, automatic redirects will light up in 6.0 like any other regular request.