searxng/searx/botdetection/http_sec_fetch.py

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# SPDX-License-Identifier: AGPL-3.0-or-later
"""
Method ``http_sec_fetch``
-------------------------
The ``http_sec_fetch`` method protect resources from web attacks with `Fetch
Metadata`_. A request is filtered out in case of:
- http header Sec-Fetch-Mode_ is invalid
- http header Sec-Fetch-Dest_ is invalid
.. _Fetch Metadata:
https://developer.mozilla.org/en-US/docs/Glossary/Fetch_metadata_request_header
.. Sec-Fetch-Dest:
https://developer.mozilla.org/en-US/docs/Web/API/Request/destination
.. Sec-Fetch-Mode:
https://developer.mozilla.org/en-US/docs/Web/API/Request/mode
"""
# pylint: disable=unused-argument
from __future__ import annotations
from ipaddress import (
IPv4Network,
IPv6Network,
)
import flask
import werkzeug
from . import config
from ._helpers import logger
def filter_request(
network: IPv4Network | IPv6Network,
request: flask.Request,
cfg: config.Config,
) -> werkzeug.Response | None:
val = request.headers.get("Sec-Fetch-Mode", "")
if val != "navigate":
logger.debug("invalid Sec-Fetch-Mode '%s'", val)
return flask.redirect(flask.url_for('index'), code=302)
val = request.headers.get("Sec-Fetch-Site", "")
if val not in ('same-origin', 'same-site', 'none'):
logger.debug("invalid Sec-Fetch-Site '%s'", val)
flask.redirect(flask.url_for('index'), code=302)
val = request.headers.get("Sec-Fetch-Dest", "")
if val != "document":
logger.debug("invalid Sec-Fetch-Dest '%s'", val)
flask.redirect(flask.url_for('index'), code=302)
return None