⚙️ Simple HTTP Server from Scratch (Go)

A minimal yet fully functional HTTP/1.1 server built from scratch in Go, without using net/http for handling requests or responses. This project was inspired by the Codecrafters HTTP Server Challenge and rebuilt from the ground up to deepen understanding of low-level networking and the HTTP protocol.

🚀 Features

✅ Manual TCP Handling — Uses Go’s net package directly (net.Listen, net.Conn) to accept and manage client connections.

✅ HTTP/1.1 Parsing — Parses request lines, headers, and bodies manually via buffered I/O.

✅ Persistent Connections — Supports Connection: keep-alive and Connection: close.

✅ Custom Routing — Handles multiple routes without using frameworks:

• / — Simple health check.
• /echo/<text> — Responds with the given text.
• /user-agent — Returns the client’s User-Agent header.
• /files/<filename> — • GET: Serves static files from a provided directory. • POST: Writes file contents to disk.

✅ Gzip Compression — Compresses responses when the client includes Accept-Encoding: gzip.

✅ File I/O Handling — Secure path resolution and support for reading/writing binary files.

✅ Proper Status Codes — Returns 200 OK, 201 Created, 404 Not Found, 500 Internal Server Error, etc.

✅ Concurrent Connections — Handles multiple clients via goroutines.

✅ Verbose Logging — Logs request lifecycle and connection details.

🧩 Getting Started

1. Clone the repo

git clone https://github.com/humankernel/http-server.git
cd http-server

2. Run the server

You must provide a file directory path for /files route:

go run app/main.go ./tmp

3. Try some requests

# Echo
curl -v http://localhost:4221/echo/hello

# User-Agent
curl -v http://localhost:4221/user-agent

# Upload a file
curl -v -X POST --data-binary @example.txt http://localhost:4221/files/example.txt

# Download a file
curl -v http://localhost:4221/files/example.txt

4. Observe raw traffic (optional)

sudo tcpdump -i any -n host localhost

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📂 Example Response

> GET /echo/hi HTTP/1.1
> Host: localhost:4221

< HTTP/1.1 200 OK
< Content-Type: text/plain
< Content-Length: 2

hi

🧭 Project Structure

http-server/
├── app/
│   └── main.go        # Core server implementation
├── tmp/               # Example directory for /files route
└── README.md

💡 Future Improvements

• Add proper routing abstraction (similar to http.ServeMux)
• Implement chunked transfer encoding and streaming responses
• Improve security and header handling