[API Proposal]: Provide tunnel status code for proxy exceptions

[jgilbert2017]

Background and motivation

API user would like to have specific information about why a proxy connection failed without the need to parse a text based error message.

Dotnet 6 altered how proxy errors were handled as part of #48679. Rather than the proxy response being returned to the user, an error message is returned. This was done to distinguish proxy related errors from upstream errors.

I have a need to distinguish proxy errors based upon the status code the proxy returned. This information is conveyed as part of the error message "The proxy tunnel request to proxy {proxyUri} failed with status code {statusCode}."

Please make the proxy status code somehow directly available to the user rather than by parsing a text string.

API Proposal

TBD

API Usage

TBD

Alternative Designs

No response

Risks

No response

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Issue Details

---

Background and motivation

API user would like to have specific information about why a proxy connection failed without the need to parse a text based error message.

Dotnet 6 altered how proxy errors were handled as part of #48679. Rather than the proxy response being returned to the user, an error message is returned. This was done to distinguish proxy related errors from upstream errors.

I have a need to distinguish proxy errors based upon the status code the proxy returned. This information is conveyed as part of the error message "The proxy tunnel request to proxy {proxyUri} failed with status code {statusCode}."

Please make the proxy status code somehow directly available to the user rather than by parsing a text string.

API Proposal

TBD

API Usage

TBD

Alternative Designs

No response

Risks

No response

Author:	jgilbert2017
Assignees:	-
Labels:	api-suggestion, area-System.Net.Http, untriaged
Milestone:	-

[wfurt]

Triage: looks reasonable. We should look at it at some point.

This is a huge issue to our team because we used the status code in combination with a default proxy property to determine whether we need to retry a request with a proxy server authentication.

There's currently no way to tell whether proxy required authentication, other than comparing an exception message which is not an acceptable workaround, especially in localized environments.

What are your suggestions to mitigate it in the current version of .NET 6?