Authenticate asp.net MVC with Shibboleth

Question

Shibboleth is SSO authentication that is added to IIS as a "plugin". After the user has logged in, there are headers showing the Shibboleth session: ShibSessionID ShibIdentityProvider eppn joining unscopedaffiliation right ... more

So, I can extract the username and role from the headers. so far so good.

Question: How can I implement a handler that reads the headers and sets the status that the user is allowed to? The idea is to use the [Log In] attribute and method of Roles.IsUserInRole. All of the headers, no database, no user management.

Update

Implementation According to @Pharylon's answer

There is nothing new in this update, just help for copies and friends. Of course, you must configure the properties and names of the header fields according to the Shibboleth setting.

File: ShibbolethPrincipal.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Security.Principal; //GenericPrincipal

namespace Shibboleth
{
    public class ShibbolethPrincipal : GenericPrincipal
    {
        public string username
        {
            get { return this.Identity.Name.Replace("@ksz.ch", ""); }
        }

        public string firstname
        {
            get { return HttpContext.Current.Request.Headers["givenName"]; }
        }

        public string lastname
        {
            get { return HttpContext.Current.Request.Headers["surname"]; }
        }

        public string phone
        {
            get { return HttpContext.Current.Request.Headers["telephoneNumber"]; }
        }

        public string mobile
        {
            get { return HttpContext.Current.Request.Headers["mobile"]; }
        }

        public string entitlement
        {
            get { return HttpContext.Current.Request.Headers["eduzgEntitlement"]; }            
        }

        public string homeOrganization
        {
            get { return HttpContext.Current.Request.Headers["homeOrganization"]; }            
        }

        public DateTime birthday
        {
            get
            {
                DateTime dtHappy = DateTime.MinValue;
                try
                {
                    dtHappy = DateTime.Parse(HttpContext.Current.Request.Headers["dateOfBirth"]);
                }
                finally
                {                    

                }

                return dtHappy;
            }
            set {}
        }

        public ShibbolethPrincipal()
            : base(new GenericIdentity(GetUserIdentityFromHeaders()), GetRolesFromHeader())
        {
        }

        public static string GetUserIdentityFromHeaders()
        {            
            //return HttpContext.Current.Request.Headers["eppn"];            
            return HttpContext.Current.Request.Headers["principalName"];                        
        }

        public static string[] GetRolesFromHeader()
        {
            string[] roles = null;
            //string rolesheader = HttpContext.Current.Request.Headers["affiliation"];
            string rolesheader = HttpContext.Current.Request.Headers["eduzgEntitlement"];
            if (rolesheader != null)
            {
                roles = rolesheader.Split(';');
            }
            return roles; 
        }
    }
}

File: ShibbolethController.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;

namespace Shibboleth
{
    public class ShibbolethController : Controller
    {
        protected new ShibbolethPrincipal User
        {
            get
            {
                return (base.User as ShibbolethPrincipal) ?? null; //CustomPrincipal.GetUnauthorizedPrincipal();
            }
        }
    }
}

File: Global.asax

void Application_PostAuthenticateRequest(object sender, EventArgs e)
        {
            var ctx = HttpContext.Current;

            var principal = new ShibbolethPrincipal();
            HttpContext.Current.User = principal;            
        }

Using examples:

 namespace itservices.Controllers
    {
        [Authorize] //examples : [Authorize(Roles="Administrators")], [Authorize(Users="Alice,Bob")]
        public class PasswordMailController : ShibbolethController
        {

---

    if(User.IsInRole("staff"))
    {

Answer 1

You want to create a method in Global.asax.cs that has the following signature

protected void Application_PostAuthenticateRequest()
{
    //Your code here.
}

, - (MVC , , " " ), . , , RolesHeader, , UserId, (duh) .

:

protected void Application_PostAuthenticateRequest()
{
    var rolesheader = Context.Request.Headers["RolesHeader"];
    var userId = Context.Request.Headers["UserId"];
    var roles = rolesheader.Split(',');
    var principal = new GenericPrincipal(new GenericIdentity(userId), roles);
    Context.User = principal;
}

/, [Authorize], , [Authorize] .

, :

, IPrincipal IIdentity GenericPrincipal GenericIdentity, . Principal Identity , ​​ - .

BaseController,

protected new CustomPrincipal User
{
    get
    {
        return (base.User as CustomPrincipal) ?? CustomPrincipal.GetUnauthorizedPrincipal();
    }
}

, , IPrincipal. BaseController, Controller.

, Application_PostAuthenticateRequest() Context.User CustomPrincipal GenericPrincipal.