webserv

A production-like HTTP/1.1 server built from scratch in C++ — handling multiple connections, CGI execution, and static file serving.

🇧🇷 Leia em Português

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Why this project matters

"This project taught me how web servers actually work — how HTTP requests are parsed byte by byte, how non-blocking I/O with select/poll allows a single process to handle thousands of simultaneous connections, and what CGI really is. After this project, concepts like Nginx config files, reverse proxies, and connection pooling stopped being magic — they became engineering decisions I now understand deeply."

This is one of the most demanding projects at 42. Building a functioning HTTP server from scratch — without any networking library — demonstrates a real understanding of the protocol and OS-level I/O that powers the entire web.

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What was built

An HTTP/1.1 server supporting:

Core HTTP

• GET, POST, DELETE methods
• Static file serving with correct MIME types
• Custom error pages (400, 403, 404, 405, 500...)
• Chunked transfer encoding
• Persistent connections (keep-alive)

Configuration

• NGINX-inspired configuration file parser
• Multiple virtual servers (different ports/host)
• Per-route configuration: allowed methods, redirects, root, index, autoindex
• Upload directory configuration
• Max body size limit

CGI

• Full CGI/1.1 execution — runs Python, PHP, or any script
• Environment variables set per the CGI spec
• POST body forwarded to CGI stdin
• CGI stdout returned as HTTP response

Connection management

• Non-blocking I/O with select()
• Multiple simultaneous client connections
• Graceful timeout and connection close

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A standout technical detail

The server is structured around a clear three-layer model: Webserv (event loop + socket management), Connection (per-client state machine), and Client + Request/Response (HTTP parsing and generation). This separation of concerns — where each class has a single, well-defined responsibility — is the same architecture pattern used by nginx and most production HTTP servers. It demonstrates mature software design thinking in C++.

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Getting Started

git clone https://github.com/gustavofsousa/webserv_42.git
cd webserv_42
make

Running

./webserv config/default.conf

Open your browser at http://localhost:8080

Configuration example

server {
    listen      8080;
    server_name localhost;
    root        ./static_pages;
    index       index.html;

    location / {
        allowed_methods GET POST;
        autoindex       on;
    }

    location /upload {
        allowed_methods POST;
        upload_dir      ./uploads;
    }

    location /cgi-bin {
        allowed_methods GET POST;
        cgi_extension   .py;
    }
}

Testing

# GET request
curl http://localhost:8080/

# POST request
curl -X POST -d "name=gustavo" http://localhost:8080/form

# DELETE request
curl -X DELETE http://localhost:8080/file.txt

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Project structure

webserv_42/
├── source/
│   ├── main.cpp
│   ├── core/
│   │   ├── Webserv.cpp       # Event loop (select), socket management
│   │   ├── Server.cpp        # Virtual server + config binding
│   │   └── Connection.cpp    # Per-client connection state
│   ├── http/
│   │   ├── Request.cpp       # HTTP request parser
│   │   ├── Response.cpp      # HTTP response builder
│   │   ├── Client.cpp        # Client state machine
│   │   ├── CGI.cpp           # CGI execution
│   │   └── cgi/              # CGI helper scripts
│   └── config/               # Config file parser
├── static_pages/             # Static HTML/CSS files
└── index.html

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Skills demonstrated

• HTTP/1.1 protocol implementation (parsing, headers, status codes)
• Non-blocking I/O with select() system call
• TCP socket programming (socket, bind, listen, accept)
• CGI/1.1 specification implementation
• NGINX-style configuration parsing
• Multi-client connection management
• Object-oriented design patterns in C++ (state machine, layered architecture)

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License

This project was developed as part of the 42 School curriculum.

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Made with ☕ at 42 Rio de Janeiro