pass the IP address

[checkmate1816]

Recently I'm reading the network part of this project and I just find out that creating a socket is following process like this (If thers is any error, just point it out! thx):

If I want to change the transport layer protocol to UDP protocol and customize something, which part should I focus on? Because every time I need to apparently mention the ip and port number when I use the "sendto" in UDP communication. It seems like that is a very huge change.