C HTTP Server

A lightweight, fully functional HTTP/1.1 server written from scratch in C for POSIX/Linux environments.

Features

• Static File Serving: Serves static assets (.html, .css, .js, .png, .jpg, .txt) with correct MIME types.
• CGI (Common Gateway Interface): Executes CGI scripts and pipes their output directly to the HTTP response.
• File Uploads: Supports multipart/form-data parsing for uploading files directly to the server.
• Configurable: Driven by a simple server.conf file to configure ports and directory roots.
• Non-blocking / Signal Handling: Ignores SIGPIPE to prevent crashes on premature client disconnects.

Project Structure

• src/ - Contains the C source code.
  • main.c - Entry point, configuration loading, and server initialization.
  • server.c / server.h - Core socket programming, connection handling, and event loop.
  • http.c / http.h - HTTP request parsing and response formatting.
  • handlers.c / handlers.h - Logic for static files, CGI execution, and file uploads.
• www/ - The document root for serving static files.
• cgi-bin/ - Directory for executable CGI scripts.
• uploads/ - Destination directory for uploaded files.
• server.conf - Configuration file.

Requirements

This project relies on POSIX-specific system calls (<sys/wait.h>, <arpa/inet.h>, fork(), pipe()). It requires a Linux environment or Windows Subsystem for Linux (WSL) to compile and run.

• GCC or Clang compiler
• Make (optional, but a Makefile is provided)

Building the Server

To build the project, simply use make in the root directory:

make

This will compile the source files and generate an executable named http_server.

Running the Server

Start the server by executing the compiled binary:

./http_server

The server will read server.conf to determine the listening port and root directories.

Configuration (server.conf)

The server is configured using a simple key-value format in server.conf:

port=8080
document_root=./www
cgi_root=./cgi-bin

Supported Endpoints

• GET / -> Serves index.html from the document root.
• GET /* -> Serves static files from the document root.
• GET /cgi-bin/* or POST /cgi-bin/* -> Executes the specified script in the CGI root.
• POST /upload -> Handles multipart/form-data uploads and saves them to the uploads/ directory.

Known Limitations

• Buffer Size: The server reads incoming requests into a fixed-size BUFFER_SIZE array (64KB). Requests or uploads larger than this limit are not properly handled because the read loop expects the full request to fit into this initial buffer.

License

MIT