Custom HTTP/1.1 Server in Go

A complete HTTP/1.1 server implementation written in Go from scratch. This project demonstrates understanding of HTTP protocol fundamentals while providing a functional web server with advanced features like chunked transfer encoding and proxy functionality.

🚀 Features

• Complete HTTP/1.1 Protocol: Full implementation of HTTP/1.1 with proper request/response handling
• Custom TCP Listener: Built-in TCP server with connection management
• Proxy Functionality: Forward requests to external services (httpbin.org)
• File Serving: Serve static files (videos, HTML, etc.)
• Chunked Transfer Encoding: Support for streaming responses
• Graceful Shutdown: Proper server shutdown handling
• UDP Testing Client: Included UDP sender for development/testing
• Standalone TCP Listener: Dedicated tool for testing request parsing

📋 Requirements

• Go 1.19 or higher
• No external dependencies (standard library only)

🛠️ Installation

1. Clone the repository:

git clone <repository-url>
cd http_server

2. Build the applications:

# Build the main HTTP server
go build -o httpserver cmd/httpserver/main.go

# Build the TCP listener (for testing)
go build -o tcplistener cmd/tcplistener/main.go

# Build the UDP sender (for testing)
go build -o udpsender cmd/udpsender/main.go

🎮 Usage

Main HTTP Server

./httpserver

The server starts on port 42069 with the following endpoints:

• /yourproblem - Returns 400 Bad Request
• /myproblem - Returns 500 Internal Server Error
• /video - Serves assets/vim.mp4
• /httpbin/* - Proxies requests to httpbin.org with chunked encoding

TCP Listener (Testing Tool)

./tcplistener

Standalone TCP listener for testing HTTP request parsing without running the full server.

UDP Sender (Testing Tool)

./udpsender

Simple UDP client to send test messages to the HTTP server on localhost:42069.

📁 Project Structure

├── cmd/
│   ├── httpserver/     # Main HTTP server application
│   ├── tcplistener/    # TCP testing tool
│   └── udpsender/      # UDP testing tool
├── internal/
│   ├── server/         # Server management and connections
│   ├── request/        # HTTP request parsing
│   ├── response/       # HTTP response handling
│   └── headers/        # HTTP header management
└── assets/             # Static files (videos, etc.)

⚠️ Limitations

Security Concerns

• Path Traversal Risk: Static file serving uses relative paths without validation
• No Input Validation: Request targets are not sanitized
• SSRF Vulnerability: Proxy functionality could be abused for server-side request forgery
• No HTTPS Support: Only HTTP protocol implemented

Performance Issues

• Memory Inefficiency: Entire request bodies loaded into memory instead of streaming
• Fixed Buffer Size: Uses static 1024-byte buffers without dynamic resizing
• No Connection Pooling: Unlimited connections without proper limits

Code Quality

• Error Handling: Mix of log.Fatalf and error returning (can crash server)
• Complex State Management: Manual state manipulation prone to errors
• Limited Testing: Minimal test coverage for error scenarios
• TODO Items: Several incomplete features and potential bugs

Missing Features

• No authentication or authorization
• No rate limiting
• No structured logging
• No metrics or monitoring
• No configuration management
• No middleware support

🐛 TODO / Future Improvements

High Priority

• Implement proper error handling (replace log.Fatalf)
• Add input validation and sanitization
• Implement HTTPS support with TLS
• Add path validation for file serving

Medium Priority

• Implement streaming request/response handling
• Add connection pooling and limits
• Implement structured logging
• Add comprehensive test coverage

Low Priority

• Add configuration management (environment variables)
• Implement middleware pattern
• Add rate limiting
• Create proper documentation with examples
• Add benchmark tests

🧪 Testing

Run tests using:

go test ./...

📝 License

This project is for educational purposes. Not recommended for production use due to security and performance limitations.

🤝 Contributing

Feel free to submit issues and enhancement requests. Please ensure:

• Code follows Go best practices
• All TODO items are addressed before production use
• Security considerations are thoroughly reviewed

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Note: This is a learning project demonstrating HTTP protocol implementation. For production use, consider using established HTTP servers like Go's standard net/http package or other battle-tested solutions.