Webbol
A minimal static web server written in COBOL using GnuCOBOL.
Features
Serves static files from the current directory
Automatic MIME type detection for common file types
HTTP status codes: 200 (OK), 403 (Forbidden), 404 (Not Found), 413 (Payload Too Large)
Path traversal attack prevention
Clean request logging with full HTTP headers
Defaults to index.html for root path requests
Requirements
GnuCOBOL (cobc) compiler
POSIX-compatible operating system (Linux, macOS, BSD)
make
Installing GnuCOBOL
macOS:
Ubuntu/Debian:
sudo apt-get install gnucobol
Fedora/RHEL:
sudo dnf install gnucobol
Building
Clone or download the repository, then compile:
This will compile all modules and create the webserver executable.
To clean build artifacts:
Usage
Start the server from the directory you want to serve:
The server will start on port 8080 and serve files from the current directory.
Example
# Create a test HTML file
echo “Hello from COBOL!” > index.html
# Start the server
./webserver
# In another terminal, test it
curl http://localhost:8080/
Accessing the Server
Once running, you can access files via:
http://localhost:8080/ – serves index.html from the current directory
http://localhost:8080/filename.html – serves the specified file
http://localhost:8080/path/to/file.txt – serves files from subdirectories
Press Ctrl+C to stop the server.
Configuration
To change the server port, edit config.cpy and modify the SERVER-PORT value:
01 SERVER-PORT PIC 9(5) VALUE 8080.
Then recompile with make.
Project Structure
webbol/
├── Makefile # Build configuration
├── README.md # This file
├── config.cpy # Server configuration
├── socket-defs.cpy # Socket structure definitions
├── http-structs.cpy # HTTP data structures
├── file-structs.cpy # File handling structures
├── path-utils.cbl # Path validation and sanitization
├── mime-types.cbl # MIME type detection
├── file-ops.cbl # File reading operations
├── http-handler.cbl # HTTP request/response handling
└── webserver.cbl # Main server program
Supported MIME Types
HTML: text/html
CSS: text/css
JavaScript: application/javascript
JSON: application/json
XML: application/xml
Plain text: text/plain
PNG: image/png
JPEG: image/jpeg
GIF: image/gif
SVG: image/svg+xml
ICO: image/x-icon
PDF: application/pdf
Additional MIME types can be added by editing mime-types.cbl.
Security Features
Path traversal prevention: Blocks requests containing .. sequences
Directory access restriction: Only serves files from the current directory and subdirectories
Safe file handling: Validates all paths before file system access
Limitations
Single-threaded: Handles one request at a time
No SSL/TLS support
Maximum file size: 64KB
Line sequential file organization only (text files)
No caching or compression
No range requests or partial content support
Troubleshooting
Port already in use:
Bind failed – check if port is in use
Another process is using port 8080. Either stop that process or change the port in config.cpy.
Permission denied:
Ensure the files you’re trying to serve have read permissions and the current user can access them.
File not found (404):
Verify the file exists in the current directory where the server is running. File paths are case-sensitive.
License
This project is released into the public domain. Use it however you’d like.
Acknowledgments
Built with GnuCOBOL, demonstrating that COBOL can still be used for modern systems programming tasks.
