Siteminder注入了ASP.NET MVC站点找不到的自定义标头

Question

我有一个受Siteminder保护的ASP.NET MVC网站。验证后。 Siteminder注入自定义标头值并重定向到我的MVc网站。在这里，我试图解析Global.asax.cs中Application_AuthenticateRequest方法中的标题

 //Logging incoming request to check header for debug purposes
 protected void Application_BeginRequest(object sender, EventArgs e)
        {
            Elmah.ErrorSignal.FromCurrentContext().Raise(new ApplicationException("Begin Request. \n REQUEST HEADER =" + HttpContext.Current.Request.Headers.ToString() + " \n"));

        }

protected void Application_AuthenticateRequest(object sender, EventArgs e)
        {

            if (HttpContext.Current.User == null)
            {
                var smcred = ParseAuthorizationHeader(HttpContext.Current.Request);
                if (smcred.Username != null)
                {
                    if (Membership.ValidateUser(smcred.Username, null))
                    {
                        FormsAuthentication.SetAuthCookie(smcred.Username, false);
                        var identity = new GenericIdentity(smcred.Username);
                        string[] roles = null;// Roles.Provider.GetRolesForUser(smcred.SMUser);
                        var principal = new GenericPrincipal(identity, roles);

                        Thread.CurrentPrincipal = principal;
                        if (HttpContext.Current != null)
                        {
                            HttpContext.Current.User = principal;
                        }
                    }
                    else
                    {
                        Context.Response.StatusCode = 401;
                    }
                }   
            } 
        }

        /// <summary>
        /// Parses the Authorization header and creates user credentials
        /// </summary>
        /// <param name="actionContext"></param>
        protected virtual SiteminderCredentials ParseAuthorizationHeader(HttpRequest request)
        {
            string authHeader = null;
            var smcredential = new SiteminderCredentials();
            var auth = request.Headers.Keys; //request.ServerVariables.Keys;

            foreach (string LstrKey in auth)
            {
                switch (LstrKey.ToUpper())
                {
                    case "USER":
                        smcredential.Username = request.Headers[LstrKey].ToString();
                }
            }


                return smcredential;


        }

SiteminderCredentials.cs

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

namespace PerceptorWeb.Models
{
    public class SiteminderCredentials
    {

            public string Username;
            public string FirstName;
            public string LastName;
            public string EmailAddr;


    }
}

我在IIS上安装了高级日志记录，我看到自定义标头信息从Siteminder到我的IIS托管站点正常。但是，当我的authenticate_request尝试解析标头时，找不到这些自定义值。

任何帮助都将不胜感激。