Copyright (c) 2022 Sabin Padurariu

━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━┏━━━┓┏━━━┓┏━━━┓━━━━┏┓━━┏┓┏━━━┓┏┓━┏┓━━━━┏━━━┓┏━━━┓┏━━━┓┏━━━┓┏━━┓┏━┓━┏┓┏━━━┓━━━ ━━━┃┏━┓┃┃┏━┓┃┃┏━━┛━━━━┃┗┓┏┛┃┃┏━┓┃┃┃━┃┃━━━━┃┏━┓┃┃┏━━┛┃┏━┓┃┗┓┏┓┃┗┫┣┛┃┃┗┓┃┃┃┏━┓┃━━━ ━━━┃┃━┃┃┃┗━┛┃┃┗━━┓━━━━┗┓┗┛┏┛┃┃━┃┃┃┃━┃┃━━━━┃┗━┛┃┃┗━━┓┃┃━┃┃━┃┃┃┃━┃┃━┃┏┓┗┛┃┃┃━┗┛━━━ ━━━┃┗━┛┃┃┏┓┏┛┃┏━━┛━━━━━┗┓┏┛━┃┃━┃┃┃┃━┃┃━━━━┃┏┓┏┛┃┏━━┛┃┗━┛┃━┃┃┃┃━┃┃━┃┃┗┓┃┃┃┃┏━┓━━━ ━━━┃┏━┓┃┃┃┃┗┓┃┗━━┓━━━━━━┃┃━━┃┗━┛┃┃┗━┛┃━━━━┃┃┃┗┓┃┗━━┓┃┏━┓┃┏┛┗┛┃┏┫┣┓┃┃━┃┃┃┃┗┻━┃━━━ ━━━┗┛━┗┛┗┛┗━┛┗━━━┛━━━━━━┗┛━━┗━━━┛┗━━━┛━━━━┗┛┗━┛┗━━━┛┗┛━┗┛┗━━━┛┗━━┛┗┛━┗━┛┗━━━┛━━━ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┏━┓┏━┓┏━━━┓━━━━┏━━━┓━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┃┃┗┛┃┃┃┏━━┛━━━━┃┏━┓┃━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┃┏┓┏┓┃┃┗━━┓━━━━┗┛┏┛┃━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┃┃┃┃┃┃┃┏━━┛━━━━━━┃┏┛━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┃┃┃┃┃┃┃┗━━┓━━━━━━┏┓━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┗┛┗┛┗┛┗━━━┛━━━━━━┗┛━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

TTY Chat

General Overview

A lightweight chat architecture written in C using POSIX libraries. Designed to be easy to use, very portable and easy to maintain.

Future Updates

• download and upload files to the server
• client commands
  • see people connected
  • create chat rooms
  • see uploaded media
• server commands
  • see people connected and ip address
  • see chat rooms
  • see uploaded files
  • see server up time
  • ban/kick clients

Functionality

Server

The server creates two log files in the directory it resides, one containing general information about the server's activity and one containing all messages that are sent across the connections.

The messages are encrypted using a simple xor key for a light security measure.

Currently the server supports only one command, closetower, that closes the server and all connections.

For more information or help use the "--help" flag.

Client

The client has a terminal user interface where messages are displayed and an input prompt for writing messages.

Currently, the client supports only normal messages and one command "/leave" that is used to leave the chat and close the connection.

For more information or help use the "--help" flag.

Usage

To start the server just run the executable:

user@hostname:~$ server 8192

To start the client and connect to the server just run the executable:

user@hostname:~$ client james 81.123.210.3 8192

Implementation

The asynchronous execution is what lies at the core of the implementation. The server listens for client connections and fowards traffic in an asynchronous manner which makes it fast and cheap in terms of resources.

File descriptor Group

The fd_group data structure is the working horse of the system. It manages connections by leveraging the multiplexing mechanism provided by the epoll kernel data struture in order to achieve fast response times.

By using multiplexing the server is able to listen to multiple connections at the same time and respond to each one of them.

It stores the sockets of the connections in static int array and broadcasts every message received from the clients.