Custom HTTP/HTTPS Server

A production-grade, high-performance HTTP/HTTPS server written in C from scratch, designed to be a lightweight alternative to Nginx. This server supports modern web standards, SSL/TLS encryption, reverse proxy functionality, and advanced security features.

Features

Core Server Features

• ✅ HTTP/1.1 and HTTPS support
• ✅ Multi-threaded connection handling with epoll
• ✅ SSL/TLS encryption (TLS 1.2+) using OpenSSL
• ✅ High-performance static file serving
• ✅ In-memory file caching with LRU eviction
• ✅ Graceful handling of client disconnects
• ✅ Comprehensive request/response logging

Advanced Features

• ✅ Reverse proxy with load balancing
• ✅ URL rewriting and redirects
• ✅ Virtual hosts (server blocks)
• ✅ Gzip compression
• ✅ Hot configuration reload
• ✅ WebSocket upgrade handling (basic)
• ✅ Chunked transfer encoding support

Security Features

• ✅ Rate limiting per IP address
• ✅ DDoS protection mechanisms
• ✅ Security headers (CSP, HSTS, X-Frame-Options, etc.)
• ✅ IP whitelisting/blacklisting
• ✅ Request validation and sanitization
• ✅ Attack detection (XSS, SQL injection, path traversal)
• ✅ CSRF protection

Configuration

• ✅ Nginx-like configuration format
• ✅ Multiple server blocks (virtual hosts)
• ✅ Location-based routing
• ✅ Upstream definitions for load balancing
• ✅ SSL certificate management
• ✅ Logging configuration

Quick Start

Quick Test (TL;DR)

# Build and run
make && ./bin/httpserver config/server.conf &

# Test HTTP
curl http://localhost:8080/

# Test HTTPS (self-signed cert)
curl -k https://localhost:8443/

# Stop server
pkill -f httpserver

Prerequisites

# Ubuntu/Debian
sudo apt-get update
sudo apt-get install build-essential libssl-dev zlib1g-dev

# CentOS/RHEL
sudo yum install gcc openssl-devel zlib-devel
# or
sudo dnf install gcc openssl-devel zlib-devel

# macOS
brew install openssl

Building

# Clone the repository
git clone <repository-url>
cd my_web_server

# Build the server
make

# Or build with debug symbols
make debug

# Generate SSL certificates for testing
make certs

Running

# Run with default configuration
make run

# Or run directly (no sudo needed for ports 8080/8443)
./bin/httpserver config/server.conf

# Run with minimal configuration
./bin/httpserver config/minimal.conf

# Run in background
./bin/httpserver config/server.conf &

The server will start on:

• HTTP: http://localhost:8080
• HTTPS: https://localhost:8443 (if SSL certificates are available)

Configuration

Basic Configuration

Create a configuration file similar to config/server.conf:

# Global settings
worker_processes auto;
max_connections 1024;
keepalive_timeout 65;
gzip on;

# Logging
access_log /var/log/httpserver/access.log;
error_log /var/log/httpserver/error.log;

# HTTP Server
server {
    listen 8080;
    server_name localhost;
    root /var/www/html;
    
    location / {
        # Serve static files
    }
    
    location /api/ {
        proxy_pass http://backend;
    }
}

# HTTPS Server
server {
    listen 8443 ssl;
    server_name localhost;
    
    ssl_certificate certs/server.crt;
    ssl_certificate_key certs/server.key;
    
    root /var/www/html;
}

# Load balancing
upstream backend {
    server 127.0.0.1:3000 weight=3;
    server 127.0.0.1:3001 weight=2;
    server 127.0.0.1:3002 backup;
}

SSL Configuration

Generate SSL certificates:

# For testing (self-signed)
make certs

# For production, use Let's Encrypt or your CA

Configure SSL in your server block:

server {
    listen 443 ssl;
    
    ssl_certificate /path/to/certificate.crt;
    ssl_certificate_key /path/to/private.key;
    ssl_protocols TLSv1.2 TLSv1.3;
    ssl_ciphers ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256;
    
    # HSTS header
    add_header Strict-Transport-Security "max-age=31536000; includeSubDomains";
}

Testing

Running Tests

# Build and run test suite
make test

# Run with memory checking
make test-memcheck

Manual Testing

# Basic HTTP request
curl -v http://localhost:8080/

# HTTPS request (with self-signed cert)
curl -k -v https://localhost:8443/

# Test compression
curl -H "Accept-Encoding: gzip" -v http://localhost:8080/

# Test different HTTP methods
curl -X POST -d '{"test": "data"}' -H "Content-Type: application/json" http://localhost:8080/

# Test proxy functionality
curl -v http://localhost:8080/api/test

# Load testing with Apache Bench
ab -n 1000 -c 10 http://localhost:8080/

# Load testing with wrk
wrk -t12 -c400 -d30s http://localhost:8080/

Testing Hot Reload

# Start the server
./bin/httpserver config/server.conf &

# Make changes to config/server.conf, then reload without restart
kill -HUP $(pgrep -f httpserver)

# Check logs to verify reload
tail -f logs/error.log

Testing Graceful Shutdown

# Send SIGTERM for graceful shutdown (30s drain period)
kill -TERM $(pgrep -f httpserver)

# Send SIGQUIT for immediate shutdown
kill -QUIT $(pgrep -f httpserver)

Testing Security Headers

# Verify security headers are present
curl -I http://localhost:8080/ 2>&1 | grep -E "X-|Strict"

# Expected headers:
# X-Content-Type-Options: nosniff
# X-Frame-Options: DENY
# X-XSS-Protection: 1; mode=block
# Strict-Transport-Security: max-age=31536000; includeSubDomains

Performance

Benchmarks

On a modern system, this server can handle:

• Static files: 50,000+ requests/second
• Proxied requests: 10,000+ requests/second
• SSL/TLS: 15,000+ requests/second
• Concurrent connections: 10,000+

Optimization Tips

1. Worker Processes: Set to number of CPU cores
2. Connection Limits: Adjust based on available memory
3. File Cache: Increase cache size for better performance
4. SSL: Use ECDHE ciphers for better performance
5. Compression: Enable for text-based content

Production Deployment

System Service

Create a systemd service file /etc/systemd/system/httpserver.service:

[Unit]
Description=Custom HTTP/HTTPS Server
After=network.target

[Service]
Type=simple
User=www-data
Group=www-data
WorkingDirectory=/opt/httpserver
ExecStart=/usr/local/bin/httpserver /etc/httpserver/server.conf
ExecReload=/bin/kill -HUP $MAINPID
Restart=always
RestartSec=3

[Install]
WantedBy=multi-user.target

Enable and start:

sudo systemctl enable httpserver
sudo systemctl start httpserver
sudo systemctl status httpserver

Security Considerations

1. Run as non-root user (except for binding to ports 80/443)
2. Use proper SSL certificates (not self-signed in production)
3. Configure firewall to only allow necessary ports
4. Regular security updates for OpenSSL and system
5. Monitor logs for suspicious activity
6. Use rate limiting to prevent abuse

Monitoring

Monitor using:

• System logs: journalctl -u httpserver -f
• Access logs: tail -f /var/log/httpserver/access.log
• Error logs: tail -f /var/log/httpserver/error.log
• Performance: htop, iotop, nethogs

API Documentation

Configuration Directives

Directive	Description	Example
worker_processes	Number of worker processes	worker_processes 4;
max_connections	Maximum concurrent connections	max_connections 1024;
keepalive_timeout	Keep-alive timeout in seconds	keepalive_timeout 65;
gzip	Enable/disable compression	gzip on;
listen	Port and protocol to listen on	listen 8080; or listen 443 ssl;
server_name	Virtual host server name	server_name example.com;
root	Document root directory	root /var/www/html;
proxy_pass	Upstream server for proxying	proxy_pass http://backend;

HTTP Status Codes

The server returns standard HTTP status codes:

• 200 OK: Successful request
• 301/302: Redirects
• 400: Bad request
• 401: Unauthorized
• 403: Forbidden
• 404: Not found
• 500: Internal server error
• 502: Bad gateway (proxy error)
• 503: Service unavailable

Development

Project Structure

├── src/           # Source code
│   ├── server.c   # Main server implementation
│   ├── config.c   # Configuration parser
│   ├── http.c     # HTTP protocol handling
│   ├── ssl.c      # SSL/TLS implementation
│   ├── logging.c  # Logging system
│   ├── security.c # Security features
│   ├── cache.c    # File caching
│   └── router.c   # Routing and proxy
├── include/       # Header files
├── config/        # Configuration files
├── tests/         # Test suite
├── www/           # Default document root
└── Makefile       # Build system

Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Add tests for new functionality
5. Ensure all tests pass
6. Submit a pull request

Code Style

• Follow K&R C style
• Use 4 spaces for indentation
• Maximum line length: 100 characters
• Comprehensive comments for all functions
• Error checking for all system calls

Troubleshooting

Common Issues

Permission denied when binding to port 80/443:

# Run with sudo or use capabilities
sudo ./bin/httpserver config/server.conf
# or
sudo setcap 'cap_net_bind_service=+ep' ./bin/httpserver

SSL certificate errors:

# Verify certificate files exist and are readable
ls -la certs/
# Check certificate validity
openssl x509 -in certs/server.crt -text -noout

High memory usage:

# Reduce cache size in configuration
# Monitor with: ps aux | grep httpserver

Connection refused:

# Check if server is running
ps aux | grep httpserver
# Check if port is in use
netstat -tlnp | grep :8080

Debug Mode

Build and run in debug mode:

make debug
gdb ./bin/httpserver
(gdb) run config/server.conf

Or with valgrind:

make memcheck

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgments

• OpenSSL Project for SSL/TLS implementation
• Linux kernel developers for epoll
• Nginx project for configuration format inspiration

Support

For bug reports and feature requests, please create an issue on the project repository.

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Note: This server is designed for educational and production use. While it implements many security features, please conduct thorough security audits before deploying in critical environments.