These applications were developed as proof-of-concept for functionality which will possibly be included in a satellite command and data handling system running NASA's Core Flight Executive (cFE).
The applications provide functionality for UDP multi-port processing. The router.c application acts as a server which uses the select() functionality to wait for readable input from multiple UDP sockets. A timeout is set in the server so that other work could be done in the loop if a packet had not been received within the time limit. The client application forks an additional process and both the parent and child processes create their own socket which addresses the server application. Each process has a unique port to send messages to the server application.
To build the applications in Linux using gcc, run make in the terminal. The files will be executable via ./router and ./client. The router application should be executed before the client application.