ASP.NET MVC - Set custom IIdentity or IPrincipal

Question

I need to do something fairly simple: in my ASP.NET MVC application, I want to set a custom IIdentity / IPrincipal. Whichever is easier / more suitable. I want to extend the default so that I can call something like User.Identity.Id and User.Identity.Role. Nothing fancy, just some extra properties.

I've read tons of articles and questions but I feel like I'm making it harder than it actually is. I thought it would be easy. If a user logs on, I want to set a custom IIdentity. So I thought, I will implement Application_PostAuthenticateRequest in my global.asax. However, that is called on every request, and I don't want to do a call to the database on every request which would request all the data from the database and put in a custom IPrincipal object. That also seems very unnecessary, slow, and in the wrong place (doing database calls there) but I could be wrong. Or where else would that data come from?

So I thought, whenever a user logs in, I can add some necessary variables in my session, which I add to the custom IIdentity in the Application_PostAuthenticateRequest event handler. However, my Context.Session is null there, so that is also not the way to go.

I've been working on this for a day now and I feel I'm missing something. This shouldn't be too hard to do, right? I'm also a bit confused by all the (semi)related stuff that comes with this. MembershipProvider, MembershipUser, RoleProvider, ProfileProvider, IPrincipal, IIdentity, FormsAuthentication.... Am I the only one who finds all this very confusing?

If someone could tell me a simple, elegant, and efficient solution to store some extra data on a IIdentity without all the extra fuzz.. that would be great! I know there are similar questions on SO but if the answer I need is in there, I must've overlooked.

Answer 1

All right, so i'm a serious cryptkeeper here by dragging up this very old question, but there is a much simpler approach to this, which was touched on by @Baserz above. And that is to use a combination of C# Extension methods and caching (Do NOT use session).

In fact, Microsoft has already provided a number of such extensions in the Microsoft.AspNet.Identity.IdentityExtensions namespace. For instance, GetUserId() is an extension method that returns the user Id. There is also GetUserName() and FindFirstValue(), which returns claims based on the IPrincipal.

So you need only include the namespace, and then call User.Identity.GetUserName() to get the users name as configured by ASP.NET Identity.

I'm not certain if this is cached, since the older ASP.NET Identity is not open sourced, and I haven't bothered to reverse engineer it. However, if it's not then you can write your own extension method, that will cache this result for a specific amount of time.

Answer 2

I can't speak directly for ASP.NET MVC, but for ASP.NET Web Forms, the trick is to create a FormsAuthenticationTicket and encrypt it into a cookie once the user has been authenticated. This way, you only have to call the database once (or AD or whatever you are using to perform your authentication), and each subsequent request will authenticate based on the ticket stored in the cookie.

A good article on this: http://www.ondotnet.com/pub/a/dotnet/2004/02/02/effectiveformsauth.html (broken link)

Edit:

Since the link above is broken, I would recommend LukeP's solution in his answer above: https://stackoverflow.com/a/10524305 - I would also suggest that the accepted answer be changed to that one.

Edit 2: An alternative for the broken link: https://web.archive.org/web/20120422011422/http://ondotnet.com/pub/a/dotnet/2004/02/02/effectiveformsauth.html

Answer 3

I tried the solution suggested by LukeP and found that it doesn't support the Authorize attribute. So, I modified it a bit.

public class UserExBusinessInfo
{
    public int BusinessID { get; set; }
    public string Name { get; set; }
}

public class UserExInfo
{
    public IEnumerable<UserExBusinessInfo> BusinessInfo { get; set; }
    public int? CurrentBusinessID { get; set; }
}

public class PrincipalEx : ClaimsPrincipal
{
    private readonly UserExInfo userExInfo;
    public UserExInfo UserExInfo => userExInfo;

    public PrincipalEx(IPrincipal baseModel, UserExInfo userExInfo)
        : base(baseModel)
    {
        this.userExInfo = userExInfo;
    }
}

public class PrincipalExSerializeModel
{
    public UserExInfo UserExInfo { get; set; }
}

public static class IPrincipalHelpers
{
    public static UserExInfo ExInfo(this IPrincipal @this) => (@this as PrincipalEx)?.UserExInfo;
}


    [HttpPost]
    [AllowAnonymous]
    [ValidateAntiForgeryToken]
    public async Task<ActionResult> Login(LoginModel details, string returnUrl)
    {
        if (ModelState.IsValid)
        {
            AppUser user = await UserManager.FindAsync(details.Name, details.Password);

            if (user == null)
            {
                ModelState.AddModelError("", "Invalid name or password.");
            }
            else
            {
                ClaimsIdentity ident = await UserManager.CreateIdentityAsync(user, DefaultAuthenticationTypes.ApplicationCookie);
                AuthManager.SignOut();
                AuthManager.SignIn(new AuthenticationProperties { IsPersistent = false }, ident);

                user.LastLoginDate = DateTime.UtcNow;
                await UserManager.UpdateAsync(user);

                PrincipalExSerializeModel serializeModel = new PrincipalExSerializeModel();
                serializeModel.UserExInfo = new UserExInfo()
                {
                    BusinessInfo = await
                        db.Businesses
                        .Where(b => user.Id.Equals(b.AspNetUserID))
                        .Select(b => new UserExBusinessInfo { BusinessID = b.BusinessID, Name = b.Name })
                        .ToListAsync()
                };

                JavaScriptSerializer serializer = new JavaScriptSerializer();

                string userData = serializer.Serialize(serializeModel);

                FormsAuthenticationTicket authTicket = new FormsAuthenticationTicket(
                         1,
                         details.Name,
                         DateTime.Now,
                         DateTime.Now.AddMinutes(15),
                         false,
                         userData);

                string encTicket = FormsAuthentication.Encrypt(authTicket);
                HttpCookie faCookie = new HttpCookie(FormsAuthentication.FormsCookieName, encTicket);
                Response.Cookies.Add(faCookie);

                return RedirectToLocal(returnUrl);
            }
        }
        return View(details);
    }

And finally in Global.asax.cs

    protected void Application_PostAuthenticateRequest(Object sender, EventArgs e)
    {
        HttpCookie authCookie = Request.Cookies[FormsAuthentication.FormsCookieName];

        if (authCookie != null)
        {
            FormsAuthenticationTicket authTicket = FormsAuthentication.Decrypt(authCookie.Value);
            JavaScriptSerializer serializer = new JavaScriptSerializer();
            PrincipalExSerializeModel serializeModel = serializer.Deserialize<PrincipalExSerializeModel>(authTicket.UserData);
            PrincipalEx newUser = new PrincipalEx(HttpContext.Current.User, serializeModel.UserExInfo);
            HttpContext.Current.User = newUser;
        }
    }

Now I can access the data in views and controllers simply by calling

User.ExInfo()

To log out I just call

AuthManager.SignOut();

where AuthManager is

HttpContext.GetOwinContext().Authentication