redir.py

#!/usr/bin/env python3

import http.server
import socketserver

from http import HTTPStatus

PORT = 8000

class Handler(http.server.SimpleHTTPRequestHandler):
    def do_GET(self):
        self.send_response(HTTPStatus.FOUND)
        self.send_header("Location", "magnet:?xt=urn:btih:aa9dc8a79ddaba135a59966ecef849884a336f82&dn=hello.txt")
        self.end_headers()

with socketserver.TCPServer(("", PORT), Handler) as httpd:
    print("serving at port", PORT)
    httpd.serve_forever()