Client-Server Project

Overview

This project implements a basic client-server communication system using C. The client and server programs communicate over a network using a predefined protocol to exchange messages.

Structure

The project contains several key files that contribute to both the client and server sides of the application:

• my-client.c: Implements the client-side functionalities.
• my-server.c: Implements the server-side functionalities.
• client-helper.c, client-helper.h: Helper functions for the client.
• server-helper.c, server-helper.h: Helper functions for the server.
• protocol.h: Defines the communication protocol and message structure.
• msg-list.c, msg-list.h, user-list.c, user-list.h: Contains additional utility functions used by the server.

Features

• Socket Communication: The client and server use sockets for network communication.
• Protocol-based Message Handling: Communication is structured based on a custom protocol defined in protocol.h.

Missig non-functional features

• Race condition problems not solved yet.

Compilation

1. Compile the Server (must be on FreeBSD server):

   gcc -lcrypt -pthread -o server my-server.c server-helper.c user-list.c msg-list.c authentication.c

2. Compile the Client:

   gcc -o client my-client.c client-helper.c msg-list.c user-list.c auth-client.c

Usage

1. Start the Server:

   ./server <hostname> <port>

2. Run the Client:

   ./client <hostname> <port> server-helper.h

Running the Remote Server at AWS

Connect to the AWS VPN

Run the AWS VPN client and connect to the VPN

Test your connection by logging into the remote machine (a FreeBSD machine)

In a Terminal/PowerShell, enter the following. Replace the names with your real name.

ssh yourfirstname-yourlastname@<hostname>
exit

Secure-copying files to the remote machine

This step is to copy all the C code files for the app server to the remote FreeBSD machine.

In a Terminal/PowerShell, enter the following. Replace the names with your real name.

scp client-server/server* yourfirstname-yourlastname@<hostname>:/usr/home/yourfirstname-yourlastname/.

Compiling and starting the app server on the remote FreeBSD machine

In a Terminal/PowerShell, enter the following. Replace the names with your real name.

ssh yourfirstname-yourlastname@<hostname>

After logged into the FreeBSD machine, enter the following to compile and run the app server:

gcc -o server my-server.c server-helper.c user-list.c msg-list.c -lpthread
./server <hostname> <port>

Run the app client on a local Ubuntu

Start another Terminal/PowerShell on your local machine, enter:

docker compose run --rm --name remoteclient1 remoteclient

In the Ubuntu machine, enter the following to start the client:

gcc -o client my-client.c client-helper.c msg-list.c user-list.c
./client <hostname> <port> server-helper.h

exit from the remote machine

Kill the app server by pressing CTRL + c, and then enter the following to exit the FreeBSD machine.

exit