mirror of
https://github.com/searxng/searxng
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149 lines
5.2 KiB
Python
149 lines
5.2 KiB
Python
# SPDX-License-Identifier: AGPL-3.0-or-later
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# lint: pylint
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""".. _botdetection.ip_limit:
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Method ``ip_limit``
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-------------------
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The ``ip_limit`` method counts request from an IP in *sliding windows*. If
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there are to many requests in a sliding window, the request is evaluated as a
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bot request. This method requires a redis DB and needs a HTTP X-Forwarded-For_
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header. To take privacy only the hash value of an IP is stored in the redis DB
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and at least for a maximum of 10 minutes.
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The :py:obj:`.link_token` method can be used to investigate whether a request is
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*suspicious*. To activate the :py:obj:`.link_token` method in the
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:py:obj:`.ip_limit` method add the following to your
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``/etc/searxng/limiter.toml``:
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.. code:: toml
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[botdetection.ip_limit]
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link_token = true
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If the :py:obj:`.link_token` method is activated and a request is *suspicious*
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the request rates are reduced:
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- :py:obj:`BURST_MAX` -> :py:obj:`BURST_MAX_SUSPICIOUS`
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- :py:obj:`LONG_MAX` -> :py:obj:`LONG_MAX_SUSPICIOUS`
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To intercept bots that get their IPs from a range of IPs, there is a
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:py:obj:`SUSPICIOUS_IP_WINDOW`. In this window the suspicious IPs are stored
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for a longer time. IPs stored in this sliding window have a maximum of
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:py:obj:`SUSPICIOUS_IP_MAX` accesses before they are blocked. As soon as the IP
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makes a request that is not suspicious, the sliding window for this IP is
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dropped.
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.. _X-Forwarded-For:
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https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-For
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"""
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from __future__ import annotations
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from ipaddress import (
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IPv4Network,
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IPv6Network,
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)
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import flask
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import werkzeug
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from searx.tools import config
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from searx import redisdb
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from searx.redislib import incr_sliding_window, drop_counter
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from . import link_token
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from ._helpers import (
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too_many_requests,
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logger,
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)
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logger = logger.getChild('ip_limit')
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BURST_WINDOW = 20
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"""Time (sec) before sliding window for *burst* requests expires."""
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BURST_MAX = 15
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"""Maximum requests from one IP in the :py:obj:`BURST_WINDOW`"""
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BURST_MAX_SUSPICIOUS = 2
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"""Maximum of suspicious requests from one IP in the :py:obj:`BURST_WINDOW`"""
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LONG_WINDOW = 600
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"""Time (sec) before the longer sliding window expires."""
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LONG_MAX = 150
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"""Maximum requests from one IP in the :py:obj:`LONG_WINDOW`"""
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LONG_MAX_SUSPICIOUS = 10
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"""Maximum suspicious requests from one IP in the :py:obj:`LONG_WINDOW`"""
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API_WONDOW = 3600
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"""Time (sec) before sliding window for API requests (format != html) expires."""
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API_MAX = 4
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"""Maximum requests from one IP in the :py:obj:`API_WONDOW`"""
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SUSPICIOUS_IP_WINDOW = 3600 * 24 * 30
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"""Time (sec) before sliding window for one suspicious IP expires."""
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SUSPICIOUS_IP_MAX = 3
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"""Maximum requests from one suspicious IP in the :py:obj:`SUSPICIOUS_IP_WINDOW`."""
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def filter_request(
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network: IPv4Network | IPv6Network,
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request: flask.Request,
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cfg: config.Config,
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) -> werkzeug.Response | None:
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# pylint: disable=too-many-return-statements
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redis_client = redisdb.client()
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if network.is_link_local and not cfg['botdetection.ip_limit.filter_link_local']:
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logger.debug("network %s is link-local -> not monitored by ip_limit method", network.compressed)
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return None
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if request.args.get('format', 'html') != 'html':
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c = incr_sliding_window(redis_client, 'ip_limit.API_WONDOW:' + network.compressed, API_WONDOW)
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if c > API_MAX:
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return too_many_requests(network, "too many request in API_WINDOW")
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if cfg['botdetection.ip_limit.link_token']:
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suspicious = link_token.is_suspicious(network, request, True)
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if not suspicious:
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# this IP is no longer suspicious: release ip again / delete the counter of this IP
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drop_counter(redis_client, 'ip_limit.SUSPICIOUS_IP_WINDOW' + network.compressed)
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return None
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# this IP is suspicious: count requests from this IP
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c = incr_sliding_window(
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redis_client, 'ip_limit.SUSPICIOUS_IP_WINDOW' + network.compressed, SUSPICIOUS_IP_WINDOW
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)
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if c > SUSPICIOUS_IP_MAX:
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logger.error("BLOCK: too many request from %s in SUSPICIOUS_IP_WINDOW (redirect to /)", network)
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return flask.redirect(flask.url_for('index'), code=302)
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c = incr_sliding_window(redis_client, 'ip_limit.BURST_WINDOW' + network.compressed, BURST_WINDOW)
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if c > BURST_MAX_SUSPICIOUS:
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return too_many_requests(network, "too many request in BURST_WINDOW (BURST_MAX_SUSPICIOUS)")
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c = incr_sliding_window(redis_client, 'ip_limit.LONG_WINDOW' + network.compressed, LONG_WINDOW)
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if c > LONG_MAX_SUSPICIOUS:
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return too_many_requests(network, "too many request in LONG_WINDOW (LONG_MAX_SUSPICIOUS)")
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return None
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# vanilla limiter without extensions counts BURST_MAX and LONG_MAX
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c = incr_sliding_window(redis_client, 'ip_limit.BURST_WINDOW' + network.compressed, BURST_WINDOW)
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if c > BURST_MAX:
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return too_many_requests(network, "too many request in BURST_WINDOW (BURST_MAX)")
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c = incr_sliding_window(redis_client, 'ip_limit.LONG_WINDOW' + network.compressed, LONG_WINDOW)
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if c > LONG_MAX:
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return too_many_requests(network, "too many request in LONG_WINDOW (LONG_MAX)")
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return None
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