context.Request.User is null in OWIN OAuthAuthorizationServerProvider

Question

I'm trying to implement OAuth using OWIN for a Web API v2 endpoint on my local intranet. The API is hosted in IIS using built-in Windows Authentication. In short, this is what I want to happen.

When I ask for my Token at /token

1. Pull the WindowsPrincipal out of the OWIN context

2. Use the SID from the WindowsPrincipal to look up some roles for this user in a SQL table.

3. Create a new ClaimsIdentity that stores the username and roles

4. Turn that into a Json Web Token (JWT) that I sent bak

When I request a resource from my API using my token

1. Convert the JWT Bearer token back to the ClaimsIdentity

2. Use that ClaimsIdentity for authorizing requests to the resource by role

3. This way I don't have to do a database lookup for user roles on each request. It's just baked into the JWT.

I think I'm setting everything up correctly. My Startup.Configuration method looks like this.

public void Configuration(IAppBuilder app)
{

    // token generation
    // This is what drives the action when a client connects to the /token route
    app.UseOAuthAuthorizationServer(new OAuthAuthorizationServerOptions
    {
        // for demo purposes
        AllowInsecureHttp = true,

        TokenEndpointPath = new PathString("/token"),
        AccessTokenExpireTimeSpan = TimeSpan.FromHours(8),
        AccessTokenFormat = GetMyJwtTokenFormat(),
        Provider = new MyAuthorizationServerProvider()
    });



    //// token consumption
    app.UseOAuthBearerAuthentication(
        new OAuthBearerAuthenticationOptions()
        {
            Realm = "http://www.ccl.org",
            Provider = new OAuthBearerAuthenticationProvider(),
            AccessTokenFormat = GetMyJwtTokenFormat()
        }
    );


    app.UseWebApi(WebApiConfig.Register());

}

MyAuthorizationServerProvider looks like this...

    public class MyAuthorizationServerProvider : OAuthAuthorizationServerProvider
    {

        public override async Task GrantResourceOwnerCredentials(OAuthGrantResourceOwnerCredentialsContext context)
        {

            // Since I'm hosting in IIS with Windows Auth enabled
            // I'm expecting my WindowsPrincipal to be here, but it's null  :(
            var windowsPrincipal = context.OwinContext.Request.User.Identity;

            // windowsPrincipal is null here.  Why?

            // Call SQL to get roles for this user

            // create the identity with the roles
            var id = new ClaimsIdentity(stuff, more stuff);

            context.Validated(id);
        }
    }

My problem is that context.Request.User is null here. I can't get to my WindowsPrincipal. If I create some other dummy middleware, I can get to the WindowsPrincipal without issue. Why is it null in this context? Am I doing something wrong?

Answer 1

Swap the order of UseOAuthAuthorizationServer and UseOAuthBearerAuthentication. UseOAuthBearerAuthentication calls UseStageMarker(PipelineStage.Authenticate); to make it (and everything before it) run earlier in the ASP.NET pipeline. User is null when you run during the Authenticate stage.