public static class HttpRequestMessageExtensions    {        private const string HttpContext = "MS_HttpContext";        private const string RemoteEndpointMessage =            "System.ServiceModel.Channels.RemoteEndpointMessageProperty";        private const string OwinContext = "MS_OwinContext";        public static string GetClientIpAddress(this HttpRequestMessage request)        {            // Web-hosting. Needs reference to System.Web.dll            if (request.Properties.ContainsKey(HttpContext))            {                dynamic ctx = request.Properties[HttpContext];                if (ctx != null)                {                    return ctx.Request.UserHostAddress;                }            }            // Self-hosting. Needs reference to System.ServiceModel.dll.             if (request.Properties.ContainsKey(RemoteEndpointMessage))            {                dynamic remoteEndpoint = request.Properties[RemoteEndpointMessage];                if (remoteEndpoint != null)                {                    return remoteEndpoint.Address;                }            }            // Self-hosting using Owin. Needs reference to Microsoft.Owin.dll.             if (request.Properties.ContainsKey(OwinContext))            {                dynamic owinContext = request.Properties[OwinContext];                if (owinContext != null)                {                    return owinContext.Request.RemoteIpAddress;                }            }            return null;        }    }