Custom SSRS Authentication Extended

One of the limitations of SSRS is that it cannot be used outside of a Windows environment (security is all dependent on Active Directory and Windows User accounts). Unfortunately app impersonation does not work cleanly enough as it will prompt users for credentials when they 1st authenticate to the Report Server. That doesn't cut the mustard for user expectations of public-facing apps.

Authentication only works as far its interoperability can reach (needs to reach beyond Windows Auth)

So, to get around this, Microsoft has provided a workaround in the form of the CustomAuthentication example. It provides a basic way to authenticate using forms-based authentication with a login page. This does work, "technically". But this also will not work if we want our report authentication to be invisible/seamless to a user who is already authenticated to the main app (that provides SSRS-based reporting features).

Why make a user auth 2x? 

So.... (and this isn't incredibly clever but it's useful): enter this extension of the CustomAuthentication example that is Local-only access by default, but suggests several overrides for authentication.

Here is the crux of how the CustomAuth can work in many different ways simply via modifying Login.aspx.cs of the Microsoft example:

        private void Page_Load(object sender, EventArgs e)
        {
            //Your secret authentication sauce goes here..
            //appHash should get dynamically generated from the app calling SSRS (ideally for each request if performant enough)
            //ie. 
            //if (CheckAuth(System.Web.HttpContext.Current.Request.Cookies["origAppHash"].ToString()))
            //if (CheckAuth(System.Web.HttpContext.Current.Session["otroAppHash"].ToString()))
            if (System.Web.HttpContext.Current.Request.IsLocal)
                FormsAuthentication.RedirectFromLoginPage("daylite", true);
        }

        private bool CheckAuth(string appHash)
        {
            //DecodeAndCryptoChecks on appHash
            return true;
        }

 MS' Example uses Page_Load(); presumably Page_PreLoad() or Page_Init() would also work here- 'just an HttpRequest eval

The idea behind this branch (closed as soon as PR'd as I don't expect MS to integrate this but I did want to not-so-subtly nudge them to explain SSRS' custom extensibility better) is not a defined solution- it is to demonstrate how you can interface with the authentication and authorization operations of SSRS service to achieve virtually any kind of custom security behavior or compatibility that you require.

GitHub (my sonrai LLC is my contractor/consultant LLC): https://github.com/sonrai-LLC/ExtRSAuth