forked from zaclys/searxng
156 lines
4.5 KiB
Python
156 lines
4.5 KiB
Python
# SPDX-License-Identifier: AGPL-3.0-or-later
|
|
# lint: pylint
|
|
"""
|
|
Method ``link_token``
|
|
---------------------
|
|
|
|
The ``link_token`` method evaluates a request as :py:obj:`suspicious
|
|
<is_suspicious>` if the URL ``/client<token>.css`` is not requested by the
|
|
client. By adding a random component (the token) in the URL, a bot can not send
|
|
a ping by request a static URL.
|
|
|
|
.. note::
|
|
|
|
This method requires a redis DB and needs a HTTP X-Forwarded-For_ header.
|
|
|
|
To get in use of this method a flask URL route needs to be added:
|
|
|
|
.. code:: python
|
|
|
|
@app.route('/client<token>.css', methods=['GET', 'POST'])
|
|
def client_token(token=None):
|
|
link_token.ping(request, token)
|
|
return Response('', mimetype='text/css')
|
|
|
|
And in the HTML template from flask a stylesheet link is needed (the value of
|
|
``link_token`` comes from :py:obj:`get_token`):
|
|
|
|
.. code:: html
|
|
|
|
<link rel="stylesheet"
|
|
href="{{ url_for('client_token', token=link_token) }}"
|
|
type="text/css" />
|
|
|
|
.. _X-Forwarded-For:
|
|
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-For
|
|
|
|
"""
|
|
from __future__ import annotations
|
|
from ipaddress import (
|
|
IPv4Network,
|
|
IPv6Network,
|
|
ip_address,
|
|
)
|
|
|
|
import string
|
|
import random
|
|
import flask
|
|
|
|
from searx import logger
|
|
from searx import redisdb
|
|
from searx.redislib import secret_hash
|
|
|
|
from ._helpers import (
|
|
get_network,
|
|
get_real_ip,
|
|
)
|
|
|
|
TOKEN_LIVE_TIME = 600
|
|
"""Livetime (sec) of limiter's CSS token."""
|
|
|
|
PING_LIVE_TIME = 3600
|
|
"""Livetime (sec) of the ping-key from a client (request)"""
|
|
|
|
PING_KEY = 'SearXNG_limiter.ping'
|
|
"""Prefix of all ping-keys generated by :py:obj:`get_ping_key`"""
|
|
|
|
TOKEN_KEY = 'SearXNG_limiter.token'
|
|
"""Key for which the current token is stored in the DB"""
|
|
|
|
logger = logger.getChild('botdetection.link_token')
|
|
|
|
|
|
def is_suspicious(network: IPv4Network | IPv6Network, request: flask.Request, renew: bool = False):
|
|
"""Checks whether a valid ping is exists for this (client) network, if not
|
|
this request is rated as *suspicious*. If a valid ping exists and argument
|
|
``renew`` is ``True`` the expire time of this ping is reset to
|
|
:py:obj:`PING_LIVE_TIME`.
|
|
|
|
"""
|
|
redis_client = redisdb.client()
|
|
if not redis_client:
|
|
return False
|
|
|
|
ping_key = get_ping_key(network, request)
|
|
if not redis_client.get(ping_key):
|
|
logger.info("missing ping (IP: %s) / request: %s", network.compressed, ping_key)
|
|
return True
|
|
|
|
if renew:
|
|
redis_client.set(ping_key, 1, ex=PING_LIVE_TIME)
|
|
|
|
logger.debug("found ping for (client) network %s -> %s", network.compressed, ping_key)
|
|
return False
|
|
|
|
|
|
def ping(request: flask.Request, token: str):
|
|
"""This function is called by a request to URL ``/client<token>.css``. If
|
|
``token`` is valid a :py:obj:`PING_KEY` for the client is stored in the DB.
|
|
The expire time of this ping-key is :py:obj:`PING_LIVE_TIME`.
|
|
|
|
"""
|
|
from . import redis_client, cfg # pylint: disable=import-outside-toplevel, cyclic-import
|
|
|
|
if not redis_client:
|
|
return
|
|
if not token_is_valid(token):
|
|
return
|
|
|
|
real_ip = ip_address(get_real_ip(request))
|
|
network = get_network(real_ip, cfg)
|
|
|
|
ping_key = get_ping_key(network, request)
|
|
logger.debug("store ping_key for (client) network %s (IP %s) -> %s", network.compressed, real_ip, ping_key)
|
|
redis_client.set(ping_key, 1, ex=PING_LIVE_TIME)
|
|
|
|
|
|
def get_ping_key(network: IPv4Network | IPv6Network, request: flask.Request) -> str:
|
|
"""Generates a hashed key that fits (more or less) to a *WEB-browser
|
|
session* in a network."""
|
|
return (
|
|
PING_KEY
|
|
+ "["
|
|
+ secret_hash(
|
|
network.compressed + request.headers.get('Accept-Language', '') + request.headers.get('User-Agent', '')
|
|
)
|
|
+ "]"
|
|
)
|
|
|
|
|
|
def token_is_valid(token) -> bool:
|
|
valid = token == get_token()
|
|
logger.debug("token is valid --> %s", valid)
|
|
return valid
|
|
|
|
|
|
def get_token() -> str:
|
|
"""Returns current token. If there is no currently active token a new token
|
|
is generated randomly and stored in the redis DB.
|
|
|
|
- :py:obj:`TOKEN_LIVE_TIME`
|
|
- :py:obj:`TOKEN_KEY`
|
|
|
|
"""
|
|
redis_client = redisdb.client()
|
|
if not redis_client:
|
|
# This function is also called when limiter is inactive / no redis DB
|
|
# (see render function in webapp.py)
|
|
return '12345678'
|
|
token = redis_client.get(TOKEN_KEY)
|
|
if token:
|
|
token = token.decode('UTF-8')
|
|
else:
|
|
token = ''.join(random.choice(string.ascii_lowercase + string.digits) for _ in range(16))
|
|
redis_client.set(TOKEN_KEY, token, ex=TOKEN_LIVE_TIME)
|
|
return token
|