nocdnbs/app.py

from flask import Flask, render_template, request, Response, abort
from werkzeug.exceptions import InternalServerError

from urllib.request import urlopen
from urllib.error import HTTPError
from urllib.parse import unquote

app = Flask(__name__)


@app.route("/")
def home():
    domain = request.url_root
    return render_template("index.html", domain=domain)


@app.route("/<path:url>")
def proxy(url):
    jsdelivr_url = f"https://cdnjs.cloudflare.com/{url}"

    def generate():
        # Subfunction to allow streaming the data instead of
        # downloading all of it at once
        try:
            with urlopen(unquote(url)) as data:
                while True:
                    chunk = data.read(1024 * 1024)
                    if not chunk:
                        break
                    yield chunk
        except HTTPError as e:
            abort(e.code)

    try:
        with urlopen(unquote(jsdelivr_url)) as data:
            content_type = data.headers["content-type"]
    except HTTPError as e:
        abort(e.code)
    except KeyError:
        raise InternalServerError()

    headers = dict()
    filename = url.split("/")[-1]
    headers["Content-Disposition"] = f'attachment; filename="{filename}"'

    return Response(generate(), content_type=content_type, headers=headers)


if __name__ == "__main__":
    app.run()