Concurrent Server Chatroom

A high-performance, multi-user chat server implemented in C. This project features a custom shell environment for users, a concurrent networking architecture, and a persistent database backend for managing messages, users, and groups.

Project Overview

The system is designed in three integrated layers:

1. Custom Shell & Command Execution: A sophisticated command parser that handles standard UNIX-style execution (fork + exec), basic pipes (|), and specialized "numbered pipes" for advanced redirection.
2. Concurrent Socket Networking: A TCP server architecture allowing multiple concurrent clients to connect via telnet or similar socket clients.
3. Data Persistence: A structured backend (using file-based or SQL-style logic) to manage user registration, login sessions, mail (messages), and group memberships.

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Directory Structure

Directory	Description
bin/	Compiled executable binaries for client-side tools and commands.
bsrc/	Source code for individual command utilities (e.g., mailto, login, createGroup).
include/	Header files (.h) defining data structures, signals, and networking protocols.
obj/	Compiled object files (.o) used during the linking process.
src/	The core server logic divided into db (database), network, and shell.
tmp/	Temporary storage for session buffers and user lists.

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Core Features

1. Shell & IPC (Inter-Process Communication)

The server provides each connected user with a shell-like interface.

• Command Execution: Uses fork() and execvp() to run binaries found in the bin/ directory.
• Piping: Supports standard piping (ls | cat).
• Numbered Pipes: (As indicated by exe_numpipe.c) Supports sending command output to a future command in the sequence, allowing complex multi-step workflows.

2. Networking & Concurrency

• TCP/IP Sockets: Built on the standard Berkeley Sockets API.
• Multi-User Support: Handles multiple connections simultaneously using a concurrent execution model (process-per-client or multiplexing).
• Telnet Compatible: No custom client is required; users can connect using standard telnet protocols.

3. Database & Management

The src/db and bsrc/ modules handle the state of the chatroom:

• User Management: register, login, and remove.
• Messaging: mailto for sending messages and listMail / delMail for inbox management.
• Group Chat: Features to createGroup, listGroup, addTo (add members), and leaveGroup.

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Getting Started

Prerequisites

• GCC or Clang compiler
• make build utility
• A Unix-like environment (Linux/macOS)
• MySQL Client Library: Required for database connectivity. On macOS (Homebrew), install via:

brew install mysql

Building the Project

To compile the server and all associated command binaries:

make

Running the Server

Start the main server process:

./myserver 127.0.0.1 [port]

Connecting as a Client

Open a new terminal and connect via telnet:

telnet 127.0.0.1 [port]

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Available Commands

Once connected, the following commands are available within the shell:

• login: Authenticate your session.
• register: Create a new user account.
• mailto [user]: Send a message to a specific user.
• createGroup [name]: Start a new chat group.
• listGroup: Show all available groups.
• number: A utility to add line numbers to output (useful for piping).