The Winsock Kernel (WSK) Network Programming Interface (NPI) includes support for extension interfaces. The WSK subsystem can use extension interfaces to extend the functionality of WSK sockets beyond the set of socket functions and event callback functions currently defined by the WSK NPI. Each extension interface is defined by an NPI that is independent of the WSK NPI. Currently no extension interfaces have been defined.
A WSK application can register for an extension interface that is supported by the WSK subsystem by using the SIO_WSK_REGISTER_EXTENSION socket IOCTL operation. A WSK application registers for extension interfaces on a socket-by-socket basis.
For more information about registering an extension interface, see Registering an Extension Interface.