asp.net mvc Adding to the AUTHORIZE attribute

Question

How do I create a custom attribute to extend existing Authorize attribute in MVC?

Answer 1

Derive your class from AuthorizeAttribute. Override the OnAuthorization method. Add and set up a CacheValidationHandler.

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


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

    if (AuthorizeCore( filterContext.HttpContext ))
    {
       ... your custom code ...
       SetCachePolicy( filterContext );
    }
    else if (!filterContext.HttpContext.User.Identity.IsAuthenticated)
    {
        // auth failed, redirect to login page
        filterContext.Result = new HttpUnauthorizedResult();
    }
    else
    {
       ... handle a different case than not authenticated
    }
}


protected void SetCachePolicy( AuthorizationContext filterContext )
 {
     // ** IMPORTANT **
     // Since we're performing authorization at the action level, the authorization code runs
     // after the output caching module. In the worst case this could allow an authorized user
     // to cause the page to be cached, then an unauthorized user would later be served the
     // cached page. We work around this by telling proxies not to cache the sensitive page,
     // then we hook our custom authorization code into the caching mechanism so that we have
     // the final say on whether a page should be served from the cache.
     HttpCachePolicyBase cachePolicy = filterContext.HttpContext.Response.Cache;
     cachePolicy.SetProxyMaxAge( new TimeSpan( 0 ) );
     cachePolicy.AddValidationCallback( CacheValidationHandler, null /* data */);
 }