Redirect to the original page after a sign-in

[premun]

Context

When user signs in BarViz, they get routed back to the / address. This is because the allowed redirectUri is configured in the Entra app and cannot be dynamic.
To make this work, we will probably store the original URI in the state: https://learn.microsoft.com/en-us/entra/identity-platform/reply-url#use-a-state-parameter and then read it after the return and redirect there.

Goal

• Store the current URI in the state field before redirecting to the login page
• Read the state after the user comes back signed in
• Redirect the user to the original URI

Notes

Copilot says something like this:

Save the original URL: When a user tries to access a protected resource and gets redirected to the Microsoft login page, save the original URL they were trying to access. You can do this in a middleware or in the OnRedirectToIdentityProvider event.

options.Events = new OpenIdConnectEvents
{
    OnRedirectToIdentityProvider = context =>
    {
        var originalUrl = context.Request.Path + context.Request.QueryString;
        context.ProtocolMessage.State = ... // Encode the original URL in the state parameter
        return Task.CompletedTask;
    }
};

Retrieve the state parameter: After the user signs in, the Microsoft identity platform will redirect them back to your specified redirect URI with the state parameter. You will need to decode this state parameter to redirect the user back to the original URL.

options.Events = new OpenIdConnectEvents
{
    OnMessageReceived = context =>
    {
        ... // Decode the state parameter to get the original URL
        return Task.CompletedTask;
    }
};

Redirect the user back: Once you have retrieved the original URL from the state parameter, you can redirect the user back to that URL.

options.Events = new OpenIdConnectEvents
{
    OnTicketReceived = context =>
    {
        var originalUrl = ... // Retrieve the original URL from the context or session
        context.Properties.RedirectUri = originalUrl;
        return Task.CompletedTask;
    }
};