My Client/Server Internet created with Dlang

[Energo Koder]

Please answer me for these questions:

1. I can see in linked file one function conecta() (beside 
main()). This drive me to question: Is conecta() act one time as 
server and another time as client?

2. Do you introduce you app with:
import core.stdc.stdlib;
This drive me to question: Is the C API the the only way do 
access Internet?