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# SPDX-License-Identifier: AGPL-3.0-or-later
# lint: pylint
# pyright: basic
"""Some bot protection / rate limitation
To monitor rate limits and protect privacy the IP addresses are getting stored
with a hash so the limiter plugin knows who to block. A redis database is
needed to store the hash values.
Enable the plugin in ``settings.yml``:
- ``server.limiter: true``
- ``redis.url: ...`` check the value, see :ref:`settings redis`
"""
import re
from flask import request
from searx import redisdb
from searx.plugins import logger
from searx.redislib import incr_sliding_window
name = "Request limiter"
description = "Limit the number of request"
default_on = False
preference_section = 'service'
logger = logger.getChild('limiter')
block_user_agent = re.compile(
r'('
+ r'unknown'
+ r'|[Cc][Uu][Rr][Ll]|[wW]get|Scrapy|splash|JavaFX|FeedFetcher|python-requests|Go-http-client|Java|Jakarta|okhttp'
+ r'|HttpClient|Jersey|Python|libwww-perl|Ruby|SynHttpClient|UniversalFeedParser|Googlebot|GoogleImageProxy'
+ r'|bingbot|Baiduspider|yacybot|YandexMobileBot|YandexBot|Yahoo! Slurp|MJ12bot|AhrefsBot|archive.org_bot|msnbot'
+ r'|MJ12bot|SeznamBot|linkdexbot|Netvibes|SMTBot|zgrab|James BOT|Sogou|Abonti|Pixray|Spinn3r|SemrushBot|Exabot'
+ r'|ZmEu|BLEXBot|bitlybot'
# unmaintained Farside instances
+ r'|'
+ re.escape(r'Mozilla/5.0 (compatible; Farside/0.1.0; +https://farside.link)')
+ r')'
)
def is_accepted_request() -> bool:
# pylint: disable=too-many-return-statements
redis_client = redisdb.client()
user_agent = request.headers.get('User-Agent', 'unknown')
x_forwarded_for = request.headers.get('X-Forwarded-For', '')
if request.path == '/healthz':
return True
if block_user_agent.match(user_agent):
logger.debug("BLOCK %s: %s --> detected User-Agent: %s" % (x_forwarded_for, request.path, user_agent))
return False
if request.path == '/search':
c_burst = incr_sliding_window(redis_client, 'IP limit, burst' + x_forwarded_for, 20)
c_10min = incr_sliding_window(redis_client, 'IP limit, 10 minutes' + x_forwarded_for, 600)
if c_burst > 15 or c_10min > 150:
logger.debug("BLOCK %s: to many request", x_forwarded_for)
return False
if len(request.headers.get('Accept-Language', '').strip()) == '':
logger.debug("BLOCK %s: missing Accept-Language", x_forwarded_for)
return False
if request.headers.get('Connection') == 'close':
logger.debug("BLOCK %s: got Connection=close", x_forwarded_for)
return False
accept_encoding_list = [l.strip() for l in request.headers.get('Accept-Encoding', '').split(',')]
if 'gzip' not in accept_encoding_list and 'deflate' not in accept_encoding_list:
logger.debug("BLOCK %s: suspicious Accept-Encoding", x_forwarded_for)
return False
if 'text/html' not in request.accept_mimetypes:
logger.debug("BLOCK %s: Accept-Encoding misses text/html", x_forwarded_for)
return False
if request.args.get('format', 'html') != 'html':
c = incr_sliding_window(redis_client, 'API limit' + x_forwarded_for, 3600)
if c > 4:
logger.debug("BLOCK %s: API limit exceeded", x_forwarded_for)
return False
logger.debug(
"OK %s: '%s'" % (x_forwarded_for, request.path)
+ " || form: %s" % request.form
+ " || Accept: %s" % request.headers.get('Accept', '')
+ " || Accept-Language: %s" % request.headers.get('Accept-Language', '')
+ " || Accept-Encoding: %s" % request.headers.get('Accept-Encoding', '')
+ " || Content-Type: %s" % request.headers.get('Content-Type', '')
+ " || Content-Length: %s" % request.headers.get('Content-Length', '')
+ " || Connection: %s" % request.headers.get('Connection', '')
+ " || User-Agent: %s" % user_agent
)
return True
def pre_request():
if not is_accepted_request():
return 'Too Many Requests', 429
return None
def init(app, settings):
if not settings['server']['limiter']:
return False
if not redisdb.client():
logger.error("The limiter requires Redis") # pylint: disable=undefined-variable
return False
app.before_request(pre_request)
return True
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