forked from zaclys/searxng
244 lines
6.9 KiB
Python
244 lines
6.9 KiB
Python
# SPDX-License-Identifier: AGPL-3.0-or-later
|
|
# lint: pylint
|
|
"""Bot protection / IP rate limitation. The intention of rate limitation is to
|
|
limit suspicious requests from an IP. The motivation behind this is the fact
|
|
that SearXNG passes through requests from bots and is thus classified as a bot
|
|
itself. As a result, the SearXNG engine then receives a CAPTCHA or is blocked
|
|
by the search engine (the origin) in some other way.
|
|
|
|
To avoid blocking, the requests from bots to SearXNG must also be blocked, this
|
|
is the task of the limiter. To perform this task, the limiter uses the methods
|
|
from the :ref:`botdetection`:
|
|
|
|
- Analysis of the HTTP header in the request / :ref:`botdetection probe headers`
|
|
can be easily bypassed.
|
|
|
|
- Block and pass lists in which IPs are listed / :ref:`botdetection ip_lists`
|
|
are hard to maintain, since the IPs of bots are not all known and change over
|
|
the time.
|
|
|
|
- Detection & dynamically :ref:`botdetection rate limit` of bots based on the
|
|
behavior of the requests. For dynamically changeable IP lists a Redis
|
|
database is needed.
|
|
|
|
The prerequisite for IP based methods is the correct determination of the IP of
|
|
the client. The IP of the client is determined via the X-Forwarded-For_ HTTP
|
|
header.
|
|
|
|
.. attention::
|
|
|
|
A correct setup of the HTTP request headers ``X-Forwarded-For`` and
|
|
``X-Real-IP`` is essential to be able to assign a request to an IP correctly:
|
|
|
|
- `NGINX RequestHeader`_
|
|
- `Apache RequestHeader`_
|
|
|
|
.. _X-Forwarded-For:
|
|
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-For
|
|
.. _NGINX RequestHeader:
|
|
https://docs.searxng.org/admin/installation-nginx.html#nginx-s-searxng-site
|
|
.. _Apache RequestHeader:
|
|
https://docs.searxng.org/admin/installation-apache.html#apache-s-searxng-site
|
|
|
|
Enable Limiter
|
|
==============
|
|
|
|
To enable the limiter activate:
|
|
|
|
.. code:: yaml
|
|
|
|
server:
|
|
...
|
|
limiter: true # rate limit the number of request on the instance, block some bots
|
|
|
|
and set the redis-url connection. Check the value, it depends on your redis DB
|
|
(see :ref:`settings redis`), by example:
|
|
|
|
.. code:: yaml
|
|
|
|
redis:
|
|
url: unix:///usr/local/searxng-redis/run/redis.sock?db=0
|
|
|
|
|
|
Configure Limiter
|
|
=================
|
|
|
|
The methods of :ref:`botdetection` the limiter uses are configured in a local
|
|
file ``/etc/searxng/limiter.toml``. The defaults are shown in limiter.toml_ /
|
|
Don't copy all values to your local configuration, just enable what you need by
|
|
overwriting the defaults. For instance to activate the ``link_token`` method in
|
|
the :ref:`botdetection.ip_limit` you only need to set this option to ``true``:
|
|
|
|
.. code:: toml
|
|
|
|
[botdetection.ip_limit]
|
|
link_token = true
|
|
|
|
.. _limiter.toml:
|
|
|
|
``limiter.toml``
|
|
================
|
|
|
|
In this file the limiter finds the configuration of the :ref:`botdetection`:
|
|
|
|
- :ref:`botdetection ip_lists`
|
|
- :ref:`botdetection rate limit`
|
|
- :ref:`botdetection probe headers`
|
|
|
|
.. kernel-include:: $SOURCEDIR/limiter.toml
|
|
:code: toml
|
|
|
|
Implementation
|
|
==============
|
|
|
|
"""
|
|
|
|
from __future__ import annotations
|
|
import sys
|
|
|
|
from pathlib import Path
|
|
from ipaddress import ip_address
|
|
import flask
|
|
import werkzeug
|
|
|
|
from searx import (
|
|
logger,
|
|
redisdb,
|
|
)
|
|
from searx import botdetection
|
|
from searx.botdetection import (
|
|
config,
|
|
http_accept,
|
|
http_accept_encoding,
|
|
http_accept_language,
|
|
http_user_agent,
|
|
ip_limit,
|
|
ip_lists,
|
|
get_network,
|
|
get_real_ip,
|
|
dump_request,
|
|
)
|
|
|
|
# the configuration are limiter.toml and "limiter" in settings.yml so, for
|
|
# coherency, the logger is "limiter"
|
|
logger = logger.getChild('limiter')
|
|
|
|
CFG: config.Config = None # type: ignore
|
|
_INSTALLED = False
|
|
|
|
LIMITER_CFG_SCHEMA = Path(__file__).parent / "limiter.toml"
|
|
"""Base configuration (schema) of the botdetection."""
|
|
|
|
LIMITER_CFG = Path('/etc/searxng/limiter.toml')
|
|
"""Local Limiter configuration."""
|
|
|
|
CFG_DEPRECATED = {
|
|
# "dummy.old.foo": "config 'dummy.old.foo' exists only for tests. Don't use it in your real project config."
|
|
}
|
|
|
|
|
|
def get_cfg() -> config.Config:
|
|
global CFG # pylint: disable=global-statement
|
|
if CFG is None:
|
|
CFG = config.Config.from_toml(LIMITER_CFG_SCHEMA, LIMITER_CFG, CFG_DEPRECATED)
|
|
return CFG
|
|
|
|
|
|
def filter_request(request: flask.Request) -> werkzeug.Response | None:
|
|
# pylint: disable=too-many-return-statements
|
|
|
|
cfg = get_cfg()
|
|
real_ip = ip_address(get_real_ip(request))
|
|
network = get_network(real_ip, cfg)
|
|
|
|
if request.path == '/healthz':
|
|
return None
|
|
|
|
# link-local
|
|
|
|
if network.is_link_local:
|
|
return None
|
|
|
|
# block- & pass- lists
|
|
#
|
|
# 1. The IP of the request is first checked against the pass-list; if the IP
|
|
# matches an entry in the list, the request is not blocked.
|
|
# 2. If no matching entry is found in the pass-list, then a check is made against
|
|
# the block list; if the IP matches an entry in the list, the request is
|
|
# blocked.
|
|
# 3. If the IP is not in either list, the request is not blocked.
|
|
|
|
match, msg = ip_lists.pass_ip(real_ip, cfg)
|
|
if match:
|
|
logger.warning("PASS %s: matched PASSLIST - %s", network.compressed, msg)
|
|
return None
|
|
|
|
match, msg = ip_lists.block_ip(real_ip, cfg)
|
|
if match:
|
|
logger.error("BLOCK %s: matched BLOCKLIST - %s", network.compressed, msg)
|
|
return flask.make_response(('IP is on BLOCKLIST - %s' % msg, 429))
|
|
|
|
# methods applied on /
|
|
|
|
for func in [
|
|
http_user_agent,
|
|
]:
|
|
val = func.filter_request(network, request, cfg)
|
|
if val is not None:
|
|
return val
|
|
|
|
# methods applied on /search
|
|
|
|
if request.path == '/search':
|
|
|
|
for func in [
|
|
http_accept,
|
|
http_accept_encoding,
|
|
http_accept_language,
|
|
http_user_agent,
|
|
ip_limit,
|
|
]:
|
|
val = func.filter_request(network, request, cfg)
|
|
if val is not None:
|
|
return val
|
|
logger.debug(f"OK {network}: %s", dump_request(flask.request))
|
|
return None
|
|
|
|
|
|
def pre_request():
|
|
"""See :py:obj:`flask.Flask.before_request`"""
|
|
return filter_request(flask.request)
|
|
|
|
|
|
def is_installed():
|
|
"""Returns ``True`` if limiter is active and a redis DB is available."""
|
|
return _INSTALLED
|
|
|
|
|
|
def initialize(app: flask.Flask, settings):
|
|
"""Install the limiter"""
|
|
global _INSTALLED # pylint: disable=global-statement
|
|
|
|
if not (settings['server']['limiter'] or settings['server']['public_instance']):
|
|
return
|
|
|
|
redis_client = redisdb.client()
|
|
if not redis_client:
|
|
logger.error(
|
|
"The limiter requires Redis, please consult the documentation: "
|
|
"https://docs.searxng.org/admin/searx.limiter.html"
|
|
)
|
|
if settings['server']['public_instance']:
|
|
sys.exit(1)
|
|
return
|
|
|
|
_INSTALLED = True
|
|
|
|
cfg = get_cfg()
|
|
if settings['server']['public_instance']:
|
|
# overwrite limiter.toml setting
|
|
cfg.set('botdetection.ip_limit.link_token', True)
|
|
|
|
botdetection.init(cfg, redis_client)
|
|
app.before_request(pre_request)
|