I'm working on an ASP.NET Core MVC application and I want to be able to better handle what happens when an unauthenticated user runs an action through AJAX.
I found this solution that essentially extends the Authorize attribute's logic and sets an AJAX request's status code to 401 when user is no longer authenticated. The status code is returned to a global AJAX error handler and the appropriate action can be performed.
I'm trying to create the attribute in Core 3.1 but I cannot find a way to first run the base logic of the filter. base.OnAuthorization method is not there. I specifically don't want to rewrite the Authorize attribute's functionality - only to extend it.
How can I extend the Authorize attribute's logic in Core 3.1?
The authorize attribute I'm writing:
public class AuthorizeUserAttribute : AuthorizeAttribute, IAuthorizationFilter
{
public void OnAuthorization(AuthorizationFilterContext context)
{
base.OnAuthorization(context); //method does not exist
OnAjaxAuthorization(context);
}
internal void OnAjaxAuthorization(AuthorizationFilterContext context)
{
if (context.HttpContext.User.Identity.IsAuthenticated == false)
{
if (context.HttpContext.Request.IsAjaxRequest())
{
context.HttpContext.Response.StatusCode = (int)HttpStatusCode.Unauthorized;
}
}
}
}
Just as a side note, I was thinking of writing a ActionFilterAttribute to run the additional code instead, but I can't do that because the Authorize attribute always runs first.
So, say I have an existing, working page Display Cashier, which displays information about a cashier in a shop. Now, I add a button to this page that looks like:
Manager
The request-mapping for this URL maps it (successfully) to a controller: HandleGetManager
the HandleGetManager controller looks like this:
#Controller
public class HandleGetManager{
private employeeBO employeeBO; //BO handles all business logic
//spring hooks
public HandleGetManager(){}
public void setemployeeBo(employeeBO employeeBO){
this.employeeBO = employeeBO;
}
//get controller
#RequestMapping(method=RequestMethod.GET)
public String getManager(#RequestParam String cashierId){
Long managerId = employeeBO.getManagerByCashierId(cashierId);
String redirectUrl = "/displayManager.ctl?managerId=" + managerId.toString();
return redirectUrl;
}
}
Here's what happens when I try it:
I hit the new button on the Display Cashier page, I expect the following to happen:
The browser sends a get request to the indicated URL
The spring request-mapping ensures that the flow of control is passed to this class.
the #RequestMapping(method=RequestMethod.GET) piece ensures that this method is evoked
The #RequestParam String cashierId instructs Spring to parse the URL and pass the cashierId value into this method as a parameter.
The EmployeeBo has been injected into the controller via spring.
The Business logic takes place, envoking the BO and the managerId var is populated with the correct value.
The method returns the name of a different view, with a new managerId URL arg appended
Now, up until this point, everything goes to plan. What I expect to happen next is:
the browsers is directed to that URL
whereupon it will send a get request to that url,
the whole process will start again in another controller, with a different URL and a different URL arg.
instead what happens is:
this controller returns the name of a different view
The browser is redirected to a half-right, half wrong URL: handleGetManager.ctl?managerId=12345
The URL argument changes, but the name of the controller does not, despite my explicitly returning it
I get an error
What am I doing wrong? Have I missed something?
Assuming you have a UrlBasedViewResolver in your MVC configuration, the String value you return is a View name. The ViewResolver will take that name and try to resolve a View for it.
What you seem to want to do is to have a 301 response with a redirect. With view names, you do that by specifying a redirect: prefix in your view name. It's described in the documentation, here.
Here's a question/answer explaining all the (default) ways you can perform a redirect:
How can I prevent Spring MVC from doing a redirect?
I'm creating a CMS using ASP.NET MVC, and by design, I've decided that each plugin (add-on) should have a key in the incoming HTTP request. Thus, I have this general route in my host application:
{pluginKey}/{controller}/{action}/{id}
I've created a custom controller factory which implements IControllerFactory and of course, it has a method to create controllers base on the ReqeustContext and controller name. However, I want to create an artificial HttpContext (alongside all other relevant objects like HttpRequest, RequestContext, RouteData, etc.) so that controllers of plugins won't misinterpret these URL segments wrongly. In other words, I want to cut the first part of the incoming URL, and make plugins think that they're processing this URL:
{controller}/{action}/{id}
How can I achieve this?
While you could create a new implementation of all the context classes, it seems like a bit of overkill. Why not use a derived Route Handler that applies the filtering functionality before returning the HttpHandler? Here's an example:
// To avoid conflicts with similarly named controllers, I find it to be good practice
// to create a route constraint with the set of all plugin names. If you don't have
// this function already, you should be able to access it with reflection (one time
// per app lifecycle) or you hard-code them. The point is to have a regex which ensures
// only valid plugins will get selected
string[] pluginNames = GetPluginNames();
string pluginNameRegex = string.Join("|",pluginNames);
Route pluginRoute = new Route (
url: "{pluginKey}/{controller}/{action}/{id}",
defaults: null,
constraints: new RouteValueDictionary(new { pluginKey = pluginNameRegex }),
routeHandler: new PluginRouteHandler()
});
// The custom route handler can modify your route data after receiving the RequestContext
// and then send it to the appropriate location. Here's an example (markdown code/untested)
// Note: You don't have to inherit from MvcRouteHandler (you could just implement IRouteHandler
// but I'm assuming you want Mvc functionality as the fallback)
public class PluginRouteHandler : MvcRouteHandler
{
public PluginRouteHandler(IControllerFactory controllerFactory)
: base(controllerFactory)
{}
protected override IHttpHandler GetHttpHandler(RequestContext requestContext){
if(ValidatePluginRoute(requestContext))
{
// we are going to remove the pluginKey from the RequestContext, It's probably wise
// to go ahead and add it to HttpContext.Items, in case you need the data later
requestContext.HttpContext.Items["pluginKey"] = requestContext.RouteData.Values["pluginKey"];
// now let's get ride of it, so your controller factory will process the
// requestContext as you have described.
requestContext.Values.Remove("pluginKey");
// the route will now be interpreted as described so let the flow go to the MvcRouteHandler's method
}
return base.GetHttpHandler(requestContext);
}
static bool ValidatePluginRoute(RequestContext requestContext){
return requestContext.RouteData.ContainsKey("pluginKey");
}
}
Using Windows Azure's Microsoft.Web.DistributedCache.DistributedCacheOutputCacheProvider as the outputCache provider for an MVC3 app. Here is the relevant action method:
[ActionName("sample-cached-page")]
[OutputCache(Duration = 300, VaryByCustom = "User",
Location = OutputCacheLocation.Server)]
[Authorize(Users = "me#mydomain.tld,another#otherdomain.tld")]
public virtual ActionResult SampleCachedPage()
{
return View();
}
I get the following exception when loading this view from a web browser:
System.Configuration.Provider.ProviderException: When using a custom output cache provider like 'DistributedCache', only the following expiration policies and cache features are supported: file dependencies, absolute expirations, static validation callbacks and static substitution callbacks.
System.Configuration.Provider.ProviderException: When using a custom output cache provider like 'DistributedCache', only the following expiration policies and cache features are supported: file dependencies, absolute expirations, static validation callbacks and static substitution callbacks.
at System.Web.Caching.OutputCache.InsertResponse(String cachedVaryKey, CachedVary cachedVary, String rawResponseKey, CachedRawResponse rawResponse, CacheDependency dependencies, DateTime absExp, TimeSpan slidingExp)
at System.Web.Caching.OutputCacheModule.OnLeave(Object source, EventArgs eventArgs)
at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
If I remove the [Authorize] attribute, the view caches as would be expected. Does this mean I cannot put [OutputCache] on an action method that must have [Authorize]? Or, do I need to override AuthorizeAttribute with a custom implementation that uses a static validation callback method for the cache?
Update 1
After Evan's answer, I tested the above action method in IIS Express (outside of Azure). Here is my override for the VaryByCustom = "User" property on the OutputCache attribute:
public override string GetVaryByCustomString(HttpContext context, string custom)
{
return "User".Equals(custom, StringComparison.OrdinalIgnoreCase)
? Thread.CurrentPrincipal.Identity.Name
: base.GetVaryByCustomString(context, custom);
}
When I visit the sample cached page as me#mydomain.tld, the output of the page is cached, and the view displays "This page was cached at 12/31/2011 11:06:12 AM (UTC)". If I then sign out and sign in as another#otherdomain.tld and visit the page, it displays "This page was cached at 12/31/2011 11:06:38 AM (UTC)". Signing back in as me#mydomain.tld and revisiting the page causes the cache to display "This page was cached at 12/31/2011 11:06:12 AM (UTC)" again. Further sign in/out attempts show that different output is being cached & returned depending on the user.
This is leading me to believe that the output is being cached separately based on the user, which is the intention with my VaryByCustom = "User" setting & override. The problem is that it doesn't work with Azure's distributed cache provider. Evan, does you answer about only caching public content still stand?
Update 2
I dug up the source, and found that the out-of-box AuthorizeAttribute does in fact have a non-static validation callback. Here is an excerpt from OnAuthorization:
if (AuthorizeCore(filterContext.HttpContext)) {
// ** 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(CacheValidateHandler, null /* data */);
}
else {
HandleUnauthorizedRequest(filterContext);
}
CacheValidationHandler delegates the cache validation to protected virtual HttpValidationStatus OnCacheAuthorization(HttpContextBase), which of course is not static. One reason why it is not static is because, as noted in the IMPORTANT comment above, it invokes protected virtual bool AuthorizeCore(HttpContextBase).
In order to do any of the AuthorizeCore logic from a static cache validation callback method, it would need to know the Users and Roles properties of the AuthorizeAttribute instance. However there doesn't seem to be an easy way to plug in. I would have to override OnAuthorization to put these 2 values into the HttpContext (Items collection?) and then override OnCacheAuthorization to get them back out. But that smells dirty.
If we are careful to use the VaryByCustom = "User" property in the OutputCache attribute, can we just override OnCacheAuthorization to always return HttpValidationStatus.Valid? When the action method does not have an OutputCache attribute, we would not need to worry about this callback ever being invoked, correct? And if we do have an OutputCache attribute without VaryByCustom = "User", then it should be obvious that the page could return any cached version regardless of which user request created the cached copy. How risky is this?
Caching happens before the Action. You will likely need to customize your authorization mechanics to handle cache scenarios.
Check out a question I posted a while back - MVC Custom Authentication, Authorization, and Roles Implementation.
The part I think would help you is a custom Authorize Attribute who's OnAuthorize() method deals with caching.
Below is a code block for example:
/// <summary>
/// Uses injected authorization service to determine if the session user
/// has necessary role privileges.
/// </summary>
/// <remarks>As authorization code runs at the action level, after the
/// caching module, our authorization code is hooked into the caching
/// mechanics, to ensure unauthorized users are not served up a
/// prior-authorized page.
/// Note: Special thanks to TheCloudlessSky on StackOverflow.
/// </remarks>
public void OnAuthorization(AuthorizationContext filterContext)
{
// User must be authenticated and Session not be null
if (!filterContext.HttpContext.User.Identity.IsAuthenticated || filterContext.HttpContext.Session == null)
HandleUnauthorizedRequest(filterContext);
else {
// if authorized, handle cache validation
if (_authorizationService.IsAuthorized((UserSessionInfoViewModel)filterContext.HttpContext.Session["user"], _authorizedRoles)) {
var cache = filterContext.HttpContext.Response.Cache;
cache.SetProxyMaxAge(new TimeSpan(0));
cache.AddValidationCallback((HttpContext context, object o, ref HttpValidationStatus status) => AuthorizeCache(context), null);
}
else
HandleUnauthorizedRequest(filterContext);
}
}
/// <summary>
/// Ensures that authorization is checked on cached pages.
/// </summary>
/// <param name="httpContext"></param>
/// <returns></returns>
public HttpValidationStatus AuthorizeCache(HttpContext httpContext)
{
if (httpContext.Session == null)
return HttpValidationStatus.Invalid;
return _authorizationService.IsAuthorized((UserSessionInfoViewModel) httpContext.Session["user"], _authorizedRoles)
? HttpValidationStatus.Valid
: HttpValidationStatus.IgnoreThisRequest;
}
I've come back to this issue and, after a bit of tinkering, have concluded that you cannot use the out of the box System.Web.Mvc.AuthorizeAttribute along with the out of the box System.Web.Mvc.OutputCacheAttribute when using the Azure DistributedCache. The main reason is because, as the error message in the original question states, the validation callback method must be static in order to use it with Azure's DistributedCache. The cache callback method in the MVC Authorize attribute is an instance method.
I went about trying to figure out how to make it work by making a copy of the AuthorizeAttribute from the MVC source, renaming it, hooking it up to an action with OutputCache connected to Azure, and debugging. The reason the cache callback method is not static is because, in order to authorize, the attribute needs to check the HttpContext's User against the Users and Roles property values that are set when the attribute is constructed. Here is the relevant code:
OnAuthorization
public virtual void OnAuthorization(AuthorizationContext filterContext) {
//... code to check argument and child action cache
if (AuthorizeCore(filterContext.HttpContext)) {
// 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(CacheValidateHandler, null /* data */);
}
else {
HandleUnauthorizedRequest(filterContext);
}
}
Cache Validation Callback
private void CacheValidateHandler(HttpContext context, object data,
ref HttpValidationStatus validationStatus) {
validationStatus = OnCacheAuthorization(new HttpContextWrapper(context));
}
// This method must be thread-safe since it is called by the caching module.
protected virtual HttpValidationStatus OnCacheAuthorization
(HttpContextBase httpContext) {
if (httpContext == null) {
throw new ArgumentNullException("httpContext");
}
bool isAuthorized = AuthorizeCore(httpContext);
return (isAuthorized)
? HttpValidationStatus.Valid
: HttpValidationStatus.IgnoreThisRequest;
}
As you can see, the cache validation callback ultimately invokes AuthorizeCore, which is another instance method (protected virtual). AuthorizeCore, which was also called during OnAuthorization, does 3 main things:
Checks that the HttpContextBase.User.Identity.IsAuthenticated == true
If the attribute has a non-empty Users string property, checks that the HttpContextBase.User.Identity.Name matches one of the comma-separated values.
If the attribute has a non-empty Roles string property, checks that the HttpContextBase.User.IsInRole for one of the comma-separated values.
AuthorizeCore
// This method must be thread-safe since it is called by the thread-safe
// OnCacheAuthorization() method.
protected virtual bool AuthorizeCore(HttpContextBase httpContext) {
if (httpContext == null) {
throw new ArgumentNullException("httpContext");
}
IPrincipal user = httpContext.User;
if (!user.Identity.IsAuthenticated) {
return false;
}
if (_usersSplit.Length > 0 && !_usersSplit.Contains
(user.Identity.Name, StringComparer.OrdinalIgnoreCase)) {
return false;
}
if (_rolesSplit.Length > 0 && !_rolesSplit.Any(user.IsInRole)) {
return false;
}
return true;
}
When you simply try to make the validation callback method static, the code won't compile because it needs access to these _rolesSplit and _usersSplit fields, which are based on the public Users and Roles properties.
My first attempt was to pass these values to the callback using the object data argument of the CacheValidateHandler. Even after introducing static methods, this still did not work, and resulted in the same exception. I was hoping that the object data would be serialized, then passed back to the validate handler during the callback. Apparently this is not the case, and when you try to do this, Azure's DistributedCache still considers it a non-static callback, resulting in the same exception & message.
// this won't work
cachePolicy.AddValidationCallback(CacheValidateHandler, new object() /* data */);
My second attempt was to add the values to the HttpContext.Items collection, since an instance of HttpContext is automatically passed to the handler. This didn't work either. The HttpContext that is passed to the CacheValidateHandler is not the same instance that existed on the filterContext.HttpContext property. In fact, when the CacheValidateHandler executes, it has a null Session and always has an empty Items collection.
// this won't work
private void CacheValidateHandler(HttpContext context, object data,
ref HttpValidationStatus validationStatus) {
Debug.Assert(!context.Items.Any()); // even after I put items into it
validationStatus = OnCacheAuthorization(new HttpContextWrapper(context));
}
However...
Even though there seems to be no way to pass the Users & Roles property values back to the cache validation callback handler, the HttpContext passed to it does in fact have the correct User Principal. Also, none of the actions where I currently want to combine [Authorize] and [OutputCache] ever pass a Users or Roles property to the AuthorizeAttribute constructor.
So, it is possible to create a custom AuthenticateAttribute which ignores these properties, and only checks to make sure the User.Identity.IsAuthenticated == true. If you need to authenticate against a specific role, you could also do so and combine with OutputCache... however, you would need a distinct attribute for each (set of) Role(s) in order to make the cache validation callback method static. I will come back and post the code after I've polished it a bit.
You are correct olive. Caching works by caching the entire output of the Action (including all attributes) then returning the result to subsequent calls without actually calling any of your code.
Because of this you cannot cache and check authorization because by caching you are not going to call any of your code (including authorization). Therefore anything that is cached must be public.
I'm using MVC3 and want to create a route to an ashx file. I've created an Generic Handler with this code in:
public IHttpHandler GetHttpHandler(RequestContext requestContext)
{
var handler = new TileHandler();
handler.ProcessRequest(requestContext);
return handler;
}
I've set a route up in the Global.asax which works fine. However my TileHandler which is an ashx page expects a HttpContext to be passed to it not a RequestContext. I can overload the method, but it obviously still wants the standard method invoked on call.
My question is therefore how can you use an ashx page passing in a RequestContext object?
Thanks in advance.
Change your TileHandler to inherit from System.Web.Mvc.MvcHandler instead.
Example.