using System.Net;
using Microsoft.AspNetCore.Http;

  
//https://stackoverflow.com/a/41242493/8939
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;
    }    
}