Windows authentication/authorization - asp.net-core

Question

I am working on a website where I need to authorize the user through a service. I have managed to get windows authentication working if I use the AuthorizeAttribute (User.Identities will be set). My plan is to create a custom middleware that sets the roles/claims for the user but context.User is not set in the middleware. User.Identities will also not be set in the controllers where I don't add the AuthorizeAttribute.
My goal is to write a middleware that gets the windows username and calls a service with the username to get the roles the user has access to and then set the roles or claims for the user.
public class RoleMiddleware
{
private readonly RequestDelegate _next;
public RoleMiddleware(RequestDelegate next)
{
_next = next;
}
public async Task Invoke(HttpContext context)
{
if (!rolesSet)
{
var result = _service.GetRoles(context.User.Identity.Name);
//set roles
//set claims
}
await _next.Invoke(context);
}
}
Would a middleware be the correct place to do this and what do I need to do to get access to the username in the same way as I do when I use the AuthorizeAttribute in a controller?

Answer 1

In my opinion that's not the right way to do it. ASP.NET Identity provide rich set of classes which you can override and extend to fit your requirements.
If you want to inject roles bases on some custom service then you should override RoleStore (and maybe RoleManager too) and inject there your custom roles.
It will be also worth to take a look here: Using Role Claims in ASP.NET Identity Core

Answer 2

I solved it by using requirements
public class CustomFunctionRequirement : IAuthorizationRequirement
{
public CustomFunctionRequirement(string function)
{
Function = function;
}
public string Function { get; }
}
The handler
public class CustomFunctionHandler : AuthorizationHandler<CustomFunctionRequirement>
{
private readonly Service _service;
public CustomFunctionHandler(Service service)
{
_service = service;
}
protected override Task HandleRequirementAsync(AuthorizationHandlerContext context, CustomFunctionRequirement requirement)
{
var functions = _service.GetFunctions(context.User.Identity.Name);
if (functions.Any(x => x == requirement.Function))
{
context.Succeed(requirement);
}
return Task.CompletedTask;
}
}
Setup in ConfigureServices in Startup
services.AddMvc(
config =>
{
var policy = new AuthorizationPolicyBuilder()
.RequireAuthenticatedUser()
.Build();
config.Filters.Add(new AuthorizeFilter(policy));
});
services.AddAuthorization(
options =>
{
options.AddPolicy("User", policy => policy.Requirements.Add(new CustomRequirement("User")));
});
I can now in my controller specify the requirement by adding the authorize attribute [Authorize(Policy = "User")].