SPA proxying breaks with double-slash at beginning of path

[jez9999]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

When running an ASP.NET SPA site which uses .UseProxyToSpaDevelopmentServer(), the following kind of URL breaks the proxying:

https://localhost:44381//foo/bar

This is because internally, SpaProxy is constructing a Uri like this:

var targetUri = new Uri(
            baseUri,
            context.Request.Path + context.Request.QueryString);

If the second argument begins //, Uri treats it as an absolute path and throws away baseUri. A period . needs to be prefixed to the relative URI to avoid this behaviour.

Expected Behavior

The URL will proxy successfully and not break.

Steps To Reproduce

Setup an ASP.NET SPA site, and try to access any path on the local server beginning with a double-slash. eg. https://localhost:44381//foo/bar

Exceptions (if any)

System.Net.Http.HttpRequestException

Failed to proxy the request to http://aa/b, because the request to the proxy target failed. Check that the proxy target server is running and accepting requests to http://localhost:3000/.\n\nThe underlying exception message was 'No such host is known. (aa:80)'.Check the InnerException for more details.

.NET Version

5.0.411

Anything else?

No response

[javiercn]

@jez9999 thanks for contacting us.

.NET 5.0 is out of support, as per our support policy we will recommend that as a first step you update to .NET 6.0. We have changed the approach we use for SPAs in .NET 6.0 to use the SPA proxy in front of the ASP.NET backend as that's the canonical approach SPA frontends recommend.

[jez9999]

@javiercn Is having the ASP.NET app in front of the SPA app now a completely unsupported use-case? That's really quite annoying if so.

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