c# - In ASP.NET Core how do you check if request is local?

Question

In the regular ASP.NET you could do this in a view to determine if the current request was from localhost:

HttpContext.Current.Request.IsLocal

But I can't find something similar in ASP.NET 6/Core/whatever it is meant to be called.

Answer 1

UPDATE: ASP.NET Core 2.0 has a method called Url.IsLocalUrl (see this Microsoft Docs).

I think this code will work, but I haven't been able to test it completely

var callingUrl = Request.Headers["Referer"].ToString();
var isLocal = Url.IsLocalUrl(callingUrl);

But see Will Dean's comment below about this approach:

Anyone thinking about using the 'updated' version which checks the Referrer header should bear in mind that headers are extremely easy to spoof, to a degree that doesn't apply to loopback IP addresses.

---

Original solution

I came across this looking for a solution to knowing if a request is local. Unfortunately ASP.NET version 1.1.0 does not have a IsLocal method on a connection. I found one solution on a web site called Strathweb but that is out of date too.

I have created my own IsLocal extension, and it seems to work, but I can't say I have tested it in all circumstances, but you are welcome to try it.

public static class IsLocalExtension
{
    private const string NullIpAddress = "::1";

    public static bool IsLocal(this HttpRequest req)
    {
        var connection = req.HttpContext.Connection;
        if (connection.RemoteIpAddress.IsSet())
        {
            //We have a remote address set up
            return connection.LocalIpAddress.IsSet() 
                  //Is local is same as remote, then we are local
                ? connection.RemoteIpAddress.Equals(connection.LocalIpAddress) 
                  //else we are remote if the remote IP address is not a loopback address
                : IPAddress.IsLoopback(connection.RemoteIpAddress);
        }

        return true;
    }

    private static bool IsSet(this IPAddress address)
    {
        return address != null && address.ToString() != NullIpAddress;
    }
}

You call it in a controller action from using the Request property, i.e.

 public IActionResult YourAction()
 {
     var isLocal = Request.IsLocal();
     //... your code here
 }

I hope that helps someone.