When migrating apps or libraries that use sockets to WinRT, the absence of Winsock is often one of the first hurdles for many C++ devs. The suggested alternative to Winsock is to use the
Windows.Networking.Sockets namespace. For a full list of alternate APIs that replace existing ones, see:
Be aware that you will most likely not get a one-to-one mapping for various API functions and structures. So you should fully expect to re-design and workaround that and use alternate approaches to achieving the same functionality/usability.