ConnectHub

A lightweight multiplayer TCP server that manages multiple user connections through organized socket pools and provides user authentication.

Tech Stack

Core Technologies

• C (C11 Standard)
• POSIX Threads (Pthread)
• Epoll Event Library
• TCP/IP Networking

Security

• Bcrypt Password Hashing
• Session-based Authentication
• Single-login Enforcement

Database

• SQLite3 for User Management
• In-memory Session Cache
• Prepared Statements for SQL Operations

Build Tools

• GNU Make
• GCC Compiler

Architecture

Router (Main Controller)

• Handles initial connections on port 8080
• Manages user authentication and registration
• Assigns authenticated users to available sockets
• Tracks active users and session management
• Non-blocking I/O with epoll

Socket Buckets

• Organizational units for socket management
• Manage socket lifecycles and resource allocation
• Enable modular server scaling and organization
• Independent socket operation within buckets

Sockets

• Handle multiple user connections
• Manage session verification and communication
• Operate independently regardless of bucket assignment
• Support TCP communication between any connected users
• Event-driven with epoll

Technical Details

Memory Management

• Dynamic memory allocation for socket pools
• Bit array for bucket status tracking
• Resource cleanup on shutdown

Threading Model

• Main router thread for authentication
• Individual threads per socket
• Thread-safe user cache operations

Network Configuration

NUMBER_OF_USERS = 10         // Maximum total users
SOCKETS_PER_BUCKET = 2       // Sockets in each bucket
USERS_PER_SOCKET = 5         // Users per socket
MAIN_SOCKET_PORT = 8080      // Router port
USER_SOCKET_PORT_START = 8081 // Starting port for user sockets

Features

• User authentication with bcrypt password hashing
• SQLite database for user management
• In-memory user session caching
• Dynamic socket assignment
• Session-based connection verification
• Epoll-based event handling
• Non-blocking I/O operations
• Graceful shutdown handling

Building and Running

System Requirements

• Linux-based OS (Epoll dependency)
• GCC Compiler
• Make build system
• Minimum 512MB RAM
• SQLite3 development libraries

Dependencies

• SQLite3 (libsqlite3-dev)
• Bcrypt
• Pthread
• Epoll (Linux)

Local Build

make clean
make
./bin/server

Deployment

For VM deployment:

./deploy.sh check  # Test connection
./deploy.sh deps   # Install dependencies
./deploy.sh all    # Deploy and run

Connection Flow

1. Client connects to router (MAIN_SOCKET_PORT)
2. Client registers or authenticates through router socket
3. Upon successful authentication:
   • Client receives assigned port number
   • Client receives unique session key
   • Server assigns client to available socket bucket/socket
4. Client connects to assigned port using session key
5. Socket verifies session key before allowing connection
6. Client can now communicate with server code base and other users

Project Structure

├── include/           # Header files
│   ├── db/           # Database headers
│   ├── server/       # Server component headers
│   └── util/         # Utility headers
├── server/
│   ├── core/         # Core server components
│   ├── db/           # Database implementation
│   └── util/         # Utility implementations
├── data/             # Database storage
└── bin/              # Compiled binaries

Development

Build System

• Makefile-based compilation
• Automatic dependency management
• Separate object file generation
• Clean build support

Testing

• Unity test framework integration
• Separate test suite for components
• Database operation testing
• Socket management testing

Code Style

• C11 Standard compliance
• POSIX compliance for portability
• Error handling for all operations
• Memory leak prevention
• Resource cleanup implementation

Usage

Start the server:

./bin/server

Server commands:

• Press 'Q' to gracefully shutdown the server

Server output provides:

• Connection status and information
• Error reporting
• Client connection tracking
• Resource usage information

Development Status

Current implementation focuses on:

• Basic connection handling
• User authentication
• Socket management
• Session verification
• Resource management
• Error handling

Future Enhancements Considered

• Configuration file support
• Enhanced monitoring capabilities
• Additional authentication methods
• Performance optimization
• Better framework for extendability for user socket endpoints
• Extended client protocol support