SpaProxy WebSocket protocol forwarding

[stephtr]

Describe the bug

When using SpaProxy for proxying a Websocket request/server which uses the Sec-WebSocket-Protocol header (in my case Snowpack), connecting to the server fails with: "ws failed: The WebSocket client request requested '' protocol(s), but server is only accepting 'esm-hmr' protocol(s)."

The reason for this is that the Sec-WebSocket-Protocol header gets copied via client.Options.SetRequestHeader, but in case the response contains the Sec-WebSocket-Protocol header, the implementation of WebSocketHandle checks whether the protocol had been set using client.Options.AddSubProtocol, which obviously wasn't the case.

To Reproduce

MVC Core app:

public void Configure(IApplicationBuilder app)
{
    ...
    app.UseSpa(spa => spa.UseProxyToSpaDevelopmentServer("http://localhost:8080"));
}

With a snowpack app listening on Port 8080. When necessary, I could create a sample repo.

Exceptions (if any)

Catched exception (SpaProxy#L246): "The WebSocket client request requested '' protocol(s), but server is only accepting 'esm-hmr' protocol(s)."

Fixed by

#23250

Further technical details

dotnet --info

.NET Core SDK (gemäß "global.json"): Version: 5.0.100-preview.5.20279.10 Commit: 8139f1b74e

Laufzeitumgebung:
OS Name: Windows
OS Version: 10.0.19041
OS Platform: Windows
RID: win10-x64
Base Path: C:\Program Files\dotnet\sdk\5.0.100-preview.5.20279.10\

Host (useful for support):
Version: 5.0.0-preview.5.20278.1
Commit: 4ae4e2fe08

.NET SDKs installed:
3.1.100 [C:\Program Files\dotnet\sdk]
3.1.300 [C:\Program Files\dotnet\sdk]
3.1.400-preview-015151 [C:\Program Files\dotnet\sdk]
5.0.100-preview.5.20279.10 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
Microsoft.AspNetCore.All 2.1.16 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.App 2.1.16 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.1.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.1.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.1.4 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 5.0.0-preview.5.20279.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 2.1.16 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 3.1.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 3.1.2 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 3.1.4 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 5.0.0-preview.5.20278.1 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 3.1.0 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 3.1.2 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 3.1.4 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 5.0.0-preview.5.20278.3 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

To install additional .NET runtimes or SDKs:
https://aka.ms/dotnet-download

[mkArtakMSFT]

Thanks for contacting us.
We're moving this issue to the Next sprint planning milestone for future evaluation / consideration. We will evaluate the request when we will planning the work for the next milestone. To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.

[stephtr]

I'm closing it, since the fix is already merged.