HttpBasic Auth for GitDotAspx

HttpBasicAuthorizeAttribute.cs

// License: Apache License Version 2.0
// Author: Prabir Shrestha (http://www.prabir.me) https://github.com/prabirshrestha
// Description: HttpBasic Authentication support for https://github.com/jeremyskinner/git-dot-aspx

// Usage:
// 1. Add this file in the git-dot-aspx project
// 2. Add the following line in Application_Start
//    GlobalFilters.Filters.Add(new HttpBasicAuthorizeAttribute());  
// 3. In web.config in <appSettings>
//    add users and passwords (users seperated by semicolon, username and password sepearted by colon)
//    <add key="Users" value="user1:pass1;user2:pass2"/>

namespace GitAspx
{
    using System;
    using System.Collections.Concurrent;
    using System.Collections.Generic;
    using System.Configuration;
    using System.Security.Principal;
    using System.Text;
    using System.Web;
    using System.Web.Mvc;

    public class HttpBasicAuthorizeAttribute : AuthorizeAttribute {
        static readonly IDictionary<string, string> UserPass;

        static HttpBasicAuthorizeAttribute() {
            UserPass = new ConcurrentDictionary<string, string>();
            var users = ConfigurationManager.AppSettings["Users"].Split(new[] {';'}, StringSplitOptions.RemoveEmptyEntries);

            foreach (var user in users) {
                var userPass = user.Split(':');
                UserPass.Add(userPass[0],userPass[1]);
            }
        }

        public override void OnAuthorization(AuthorizationContext filterContext)
        {
            if (filterContext == null) {
                throw new ArgumentNullException("filterContext");
            }

            string auth = filterContext.HttpContext.Request.Headers["authorization"];

            if (!string.IsNullOrEmpty(auth))
            {
                byte[] encodedDataAsBytes = Convert.FromBase64String(auth.Replace("Basic ", ""));
                string val = Encoding.ASCII.GetString(encodedDataAsBytes);
                string userpass = val;
                string user = userpass.Substring(0, userpass.IndexOf(':'));
                string pass = userpass.Substring(userpass.IndexOf(':') + 1);

                if (Validate(filterContext, user, pass)) {
                    filterContext.HttpContext.User =  new GenericPrincipal(new GenericIdentity(user), null);
                    HttpCachePolicyBase cachePolicy = filterContext.HttpContext.Response.Cache; 
                    cachePolicy.SetProxyMaxAge(new TimeSpan(0)); 
                    cachePolicy.AddValidationCallback(CacheValidateHandler, null /* data */);            
                }
                else {
                    filterContext.Result = new HttpUnauthorizedResult();
                }
            }
            else
            {
                // auth failed, redirect to login page
                filterContext.HttpContext.Response.Clear();
                filterContext.HttpContext.Response.StatusCode = 401;
                filterContext.HttpContext.Response.StatusDescription = "Unauthorized";
                filterContext.HttpContext.Response.AddHeader("WWW-Authenticate", "Basic realm=\"Secure Area\"");
                filterContext.HttpContext.Response.Write("401, please authenticate");
                filterContext.HttpContext.Response.End();
            }
        }

        protected bool Validate(ControllerContext context, string user, string pass) {
            return UserPass.ContainsKey(user) && UserPass[user] == pass;
        }

        private void CacheValidateHandler(HttpContext context, object data, ref HttpValidationStatus validationStatus)
        {
            validationStatus = OnCacheAuthorization(new HttpContextWrapper(context));
        }
    }
}