Tiny HTTP Server in C++ (Windows)

A minimal HTTP/1.1 server implemented entirely from scratch in C++ using raw TCP sockets via Windows Winsock.
This project intentionally avoids frameworks and third-party libraries to focus on core networking fundamentals and protocol behavior.

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Why This Project Exists

This project exists to deeply understand how an HTTP server actually works at the socket level on Windows.

Rather than abstracting networking behind libraries, it demonstrates:

• How TCP connections are established and terminated
• How HTTP is transmitted over raw byte streams
• How browsers behave when protocol expectations are not met
• How to correctly handle edge cases that are often hidden by frameworks

The goal is learning and correctness, not feature completeness or production readiness.

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What This Server Does

• Initializes the Windows Winsock subsystem
• Creates an IPv4 TCP socket
• Binds to port 8080
• Listens for incoming connections
• Accepts a client connection
• Reads raw TCP data using recv() in a loop
• Detects HTTP request boundaries using \r\n\r\n
• Correctly handles all recv() return values:
  • > 0 — data received
  • == 0 — graceful client disconnect
  • < 0 — socket error
• Parses the request path
• Sends valid HTTP/1.1 responses:
  • 200 OK for / with HTML content
  • 404 Not Found for all other paths
• Gracefully shuts down the connection using shutdown() to ensure browsers do not hang

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Socket Lifecycle

The server follows the classic blocking TCP socket lifecycle on Windows:

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Core Concepts Demonstrated

• Windows Winsock API usage
• TCP connection establishment and teardown
• Blocking socket behavior
• Partial TCP reads and stream reassembly
• HTTP request boundary detection
• Minimal HTTP/1.1 response formatting
• Proper use of shutdown() vs closesocket()
• Real browser interoperability considerations

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Error Handling and Edge Cases

This project explicitly handles common real-world failure modes:

• Winsock initialization failure
• Socket creation failure
• Bind failure (e.g., port already in use)
• Accept failure
• Partial TCP reads across multiple recv() calls
• Graceful client disconnect (recv() == 0)
• Socket errors (recv() < 0)
• Browser hanging due to missing TCP FIN (explicitly fixed using shutdown())

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How to Run

1. Build the project using a Windows C++ compiler (Visual Studio or equivalent).
2. Ensure no other service is using port 8080.
3. Run the executable.
4. The server will block and wait for an incoming connection.

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How to Test

Browser Test

Navigate to:

http://localhost:8080/

• / returns 200 OK with HTML content
• Any other path returns 404 Not Found

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curl Test

curl -v http://localhost:8080/

Non-existent path:

curl -v http://localhost:8080/does-not-exist

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Intentional Limitations

• Single-connection, blocking design
• No concurrency or threading
• No HTTP header parsing beyond the minimum required
• No request body handling
• No HTTPS / TLS
• No production performance optimizations

These limitations are intentional to preserve clarity and focus on fundamentals.

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Possible Extensions

• Multi-client support (threads or select())
• Robust HTTP header parsing
• Additional HTTP methods
• Keep-alive connections
• Logging and metrics
• IPv6 support

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Final Note

Understanding this project demonstrates practical knowledge of:

• TCP socket programming on Windows
• HTTP over raw TCP
• Correct connection termination semantics
• Browser behavior and protocol expectations
• What higher-level web frameworks abstract away

This is a foundational systems and networking exercise, not a production server.