Hello everybody

I may ask  a stupid question but I am completely new to QNX and I have a problem. I have to port a specific application 
which is currently running on Windows with the library Winpcap and aims at read and write AFDX datas on an ethernet 
adapter. 
I rewrote it so that it uses Libpcap, but If am able to read using the filter module nfm-bpf.so, I cannot find any 
module for writing operations.
So I have to write a specific filter module in order to write (playing the same role as nfm-nraw.so which is not open 
source).
I wonder if I can find the source code of a filter module so I can have
a start to write my own.
I could not find it on the site but I am a bit lost and don't know how i can dowload the necessary files.