URL Parameter encoding in MVC .NET

Question

I have a controller in an MVC 4 .NET application that receives a string as a parameter from an URL. This comes from an aspx page redirected to the controller in Route.config.

If I send this value for the parameter in the client: fwdgerhb+bhrth+ftrgbhrt

I get the following value at the server: fwdgerhb bhrth ftrgbhrt

The server is interpreting the URL parameter value as an encoded URL and replaces + by . But it has not been URL encoded. This will occur for other combinations of special chars if they appear in the parameter value.

Is there a config parameter in IIS Server to configure the server to not try to URL-decode this value?

Example Request:

mypage.aspx?value=cat+dog    (NOT ENCODED)

Route Config

static void RegisterRoutes(RouteCollection routes)
{
    routes.MapRouteLowercase(
        name: "MyRouter",
        url: "mypage.aspx",
        defaults: new { controller = "My", action = "DoLog" }
    );
}

The controller:

public class MyController : Controller
{
    [AllowAnonymous]
    public ActionResult DoLog(string value)
    {
        //Here value has "cat dog"
    }
}

Answer 1

Yes, MVC automatically URL decodes action parameters, but you can still access the URL encoded version through a query string. As you can see in this question: Is MVC2 ASP.Net URLDecoding automatically?

You can also try to access a server variable named UNENCODED_URL. More information about this scenario can be found here: URL Rewrite Module Configuration Reference