SignIn Callback may drive to 404

[Han-O-Neam]

Hi.
We have configured an open id auth options in this way :

• OpenIdConnectAuthenticationOptions.Callback : "/signin-my-connector"
• in OpenIdConnectAuthenticationOptions OpenIdConnectAuthenticationNotifications, in RedirectToIdentityProvider :

  case OpenIdConnectRequestType.Authentication:
      context.ProtocolMessage.RedirectUri = $"{context.Request.Scheme}://{context.Request.Host}{context.Request.PathBase}{context.Options.CallbackPath}"

While debuging (on http://localhost:port/), everythings were going right.
But after having deployed in a platform, the app was published under a site name : http://domain/MyApp.
On that environnement, i got a 404 : The controller for path '/MyApp/signin-my-connector' was not found or does not implement IController.
I reproduced localy when i set my web site (VS2022) to be used throught http://localhost:port/MyApp/ instead of http://localhost:port/.

As a 'workaround', I had to change my settings :

• OpenIdConnectAuthenticationOptions.Callback : i have to combine(1) System.Web.HttpContext.Current.Request.ApplicationPath with "/signin-my-connector"
• in OpenIdConnectAuthenticationOptions OpenIdConnectAuthenticationNotifications, in RedirectToIdentityProvider :

  case OpenIdConnectRequestType.Authentication:
      //{context.Request.PathBase} removed, included in context.Options.CallbackPath
      context.ProtocolMessage.RedirectUri = $"{context.Request.Scheme}://{context.Request.Host}{context.Options.CallbackPath}"

(1) : i did a small split/join about '/' to manage the various cases singles/multiples '/' and to avoid any '//'

And then everything was working properly, no more errors.

I'm speaking about a workaround because i'm considering that the callback would have to be relative to the app's root, and the option to be the same even i'm deploying to host:port, host:port/AppName, host/AppName or anything else i havn't think about.

Maybe i'm wrong and it is the expected bahavior and i have to change my mind.
Am I ?

I tried to figure out where it is managed in the katana's source code in order to suggest a fix through a pull request but didn't get it :(
Neverthleless, here i provide a solution/workaround if it is never fixed...