[mod] limiter -> botdetection: modularization and documentation

In order to be able to meet the outstanding requirements, the implementation is
modularized and supplemented with documentation.

This patch does not contain functional change, except it fixes issue #2455

----

Aktivate limiter in the settings.yml and simulate a bot request by::

    curl -H 'Accept-Language: de-DE,en-US;q=0.7,en;q=0.3' \
         -H 'Accept: text/html'
         -H 'User-Agent: xyz' \
         -H 'Accept-Encoding: gzip' \
         'http://127.0.0.1:8888/search?q=foo'

In the LOG:

    DEBUG   searx.botdetection.link_token : missing ping for this request: .....

Since ``BURST_MAX_SUSPICIOUS = 2`` you can repeat the query above two time
before you get a "Too Many Requests" response.

Closes: https://github.com/searxng/searxng/issues/2455
Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

1 files changed, 6 insertions, 6 deletions

diff --git a/searx/webapp.py b/searx/webapp.py
index 815bfcabd..d6322447a 100755
--- a/searx/webapp.py
+++ b/searx/webapp.py
@@ -93,7 +93,8 @@ from searx.utils import (
 )
 from searx.version import VERSION_STRING, GIT_URL, GIT_BRANCH
 from searx.query import RawTextQuery
-from searx.plugins import limiter, Plugin, plugins, initialize as plugin_initialize
+from searx.plugins import Plugin, plugins, initialize as plugin_initialize
+from searx.botdetection import link_token
 from searx.plugins.oa_doi_rewrite import get_doi_resolver
 from searx.preferences import (
     Preferences,
@@ -416,7 +417,7 @@ def render(template_name: str, **kwargs):
     kwargs['endpoint'] = 'results' if 'q' in kwargs else request.endpoint
     kwargs['cookies'] = request.cookies
     kwargs['errors'] = request.errors
-    kwargs['limiter_token'] = limiter.get_token()
+    kwargs['link_token'] = link_token.get_token()
 
     # values from the preferences
     kwargs['preferences'] = request.preferences
@@ -643,10 +644,9 @@ def health():
     return Response('OK', mimetype='text/plain')
 
 
-@app.route('/limiter<token>.css', methods=['GET', 'POST'])
-def limiter_css(token=None):
-    if limiter.token_is_valid(token):
-        limiter.ping()
+@app.route('/client<token>.css', methods=['GET', 'POST'])
+def client_token(token=None):
+    link_token.ping(request, token)
     return Response('', mimetype='text/css')