Getting the Client IP via ASP.NET Web API

I've seen some questions around the web regarding this, this version will return a string with the client IP. If it returns ::1 that means the client is requesting from the same computer as where the API is running. The query address will be something like http://yoursite/api/ip depending on your routing.

using System.Net.Http;
using System.ServiceModel.Channels;
using System.Web;
using System.Web.Http;
 
namespace Trikks.Controllers.Api
{
    public class IpController : ApiController
    {
        public string GetIp()
        {
            return GetClientIp();
        }
 
        private string GetClientIp(HttpRequestMessage request = null)
        {
            request = request ?? Request;
 
            if (request.Properties.ContainsKey("MS_HttpContext"))
            {
                return ((HttpContextWrapper)request.Properties["MS_HttpContext"]).Request.UserHostAddress;
            }
            else if (request.Properties.ContainsKey(RemoteEndpointMessageProperty.Name))
            {
                RemoteEndpointMessageProperty prop = (RemoteEndpointMessageProperty)this.Request.Properties[RemoteEndpointMessageProperty.Name];
                return prop.Address;
            }
            else if (HttpContext.Current != null)
            {
                return HttpContext.Current.Request.UserHostAddress;
            }
            else
            {
                return null;
            }
        }
    }
}