context.Request.User is null in OWIN OAuthAuthorizationServerProvider - iis

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
Pull the WindowsPrincipal out of the OWIN context
Use the SID from the WindowsPrincipal to look up some roles for this
user in a SQL table.
Create a new ClaimsIdentity that stores the username and roles
Turn that into a Json Web Token (JWT) that I sent bak
When I request a resource from my API using my token
Convert the JWT Bearer token back to the ClaimsIdentity
Use that ClaimsIdentity for authorizing requests to the resource by
role
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.