[API Proposal]: Expose response status code in WebSocketException for WebSocketError.NotAWebSocket case

[IlyaBiryukov]

Background and motivation

When client web socket connection fails to switch protocols, e.g. due to 401, 403, 429, or 500 errors, the client may want to know the details of the server response status code.

API Proposal

namespace System.Net.WebSockets;

public class WebSocketException : Win32Exception
{
    public int? ResponseStatusCode { get; internal set; }
}

API Usage

try
{
    var socket = new ClientWebSocket();
    await socket.ConnectAsync(uri, cancellation);
}
catch (WebSocketException wse) when (wse.WebSocketErrorCode == WebSocketError.NotAWebSocket)
{
    Console.WriteLine($"Couldn't connect to web socket service. Status code: {wse.ResponseStatusCode}");
}

Alternative Designs

Use WebSocketException constructors with nativeError and pass in the response status code as native error. The downside is that the native error is expected to be an HResult, not an HTTP response status code.

Risks

Low risks.

[ghost]

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Issue Details

---

Background and motivation

When client web socket connection fails to switch protocols, e.g. due to 401, 403, 429, or 500 errors, the client may want to know the details of the server response status code.

API Proposal

namespace System.Net.WebSockets;

public class WebSocketException : Win32Exception
{
    public int? ResponseStatusCode { get; internal set; }
}

API Usage

try
{
    var socket = new ClientWebSocket();
    await socket.ConnectAsync(uri, cancellation);
}
catch (WebSocketException wse) when (wse.WebSocketErrorCode == WebSocketError.NotAWebSocket)
{
    Console.WriteLine($"Couldn't connect to web socket service. Status code: {wse.ResponseStatusCode}");
}

Alternative Designs

Use WebSocketException constructors with nativeError and pass in the response status code as native error. The downside is that the native error is expected to be an HResult, not an HTTP response status code.

Risks

Low risks.

Author:	IlyaBiryukov
Assignees:	-
Labels:	api-suggestion, area-System.Net
Milestone:	-

[MihaZupan]

This has been added for 7.0 as part of #25918 (comment).

You have to set ClientWebSocketOptions.CollectHttpResponseDetails = true and then look at ClientWebSocket.HttpStatusCode.

[CarnaViire]

Duplicate of #25918