取客户端的IP地址：
var remote = System.ServiceModel.OperationContext.Current.IncomingMessageProperties[System.ServiceModel.Channels.RemoteEndpointMessageProperty.Name] as System.ServiceModel.Channels.RemoteEndpointMessageProperty;
var ip = remote.Address;
取请求流长度:
System.ServiceModel.Web.WebOperationContext.Current.IncomingRequest.ContentLength