Why would HttpContext not contain a "Host" header?

Question

In my MVC3 application I have a custom controller factory that has CreateController()method working as follows:

  public IController CreateController(RequestContext requestContext, string controllerName)
   {
       string host = requestContext.HttpContext.Request.Headers["Host"];
       if( !host.EndsWith( SomeHardcodedString ) ) { // FAILS HERE
           //some special action
       }
       //proceed with controller creation
   }

the problem is host is null sometimes - I see NullReferenceException for some requests and the exception stack trace points exactly at that line.

Why would null be retrieved here? How do I handle such cases?

Answer 1

Use string host = requestContext.HttpContext.Request.Url.Host;

Answer 2

To handle it, you might want to try something like:

var host = requestContext.HttpContext.Request.Url.Host;

if (host != null)
    if(!host.EndsWith("SomeHardcodedString")) 
else
   // Handle it