WinCap is a lightweight TCP/UDP packet sniffer for Windows. It will provide a library for C/C++ and eventually Python. There will also be a small GUI to easily observe packets.
WinCap can be installed as an unsigned driver. It has a basic C API. In lib/Example.c you can see how to print network packets. Take a look at lib/wincap.c and lib/wincap.h if you are interested in working with the network data.