Functions
	is_suspicious (IPv4Network\|IPv6Network network, flask.Request request, bool renew=False)

	ping (flask.Request request, str token)

str	get_ping_key (IPv4Network\|IPv6Network network, flask.Request request)

bool	token_is_valid (token)

str	get_token ()

Variables
int	TOKEN_LIVE_TIME = 600

int	PING_LIVE_TIME = 3600

str	PING_KEY = 'SearXNG_limiter.ping'

str	TOKEN_KEY = 'SearXNG_limiter.token'

	logger = logger.getChild('botdetection.link_token')

Detailed Description

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

Function Documentation

◆ get_ping_key()

str searx.botdetection.link_token.get_ping_key	(	IPv4Network \| IPv6Network	network,
		flask.Request	request )

Generates a hashed key that fits (more or less) to a *WEB-browser
session* in a network.

Definition at line 116 of file link_token.py.

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', '')
        )
        + "]"
    )
 
 

Referenced by searx.botdetection.link_token.is_suspicious(), and searx.botdetection.link_token.ping().

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◆ get_token()

str searx.botdetection.link_token.get_token ( )

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`

Definition at line 135 of file link_token.py.

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

Referenced by searx.botdetection.link_token.token_is_valid().

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◆ is_suspicious()

searx.botdetection.link_token.is_suspicious	(	IPv4Network \| IPv6Network	network,
		flask.Request	request,
		bool	renew = 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`.

Definition at line 72 of file link_token.py.

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
 
 

References searx.botdetection.link_token.get_ping_key().

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◆ ping()

searx.botdetection.link_token.ping	(	flask.Request	request,
		str	token )

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`.

Definition at line 95 of file link_token.py.

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)
 
 

References searx.botdetection.link_token.get_ping_key(), and searx.botdetection.link_token.token_is_valid().

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◆ token_is_valid()

bool searx.botdetection.link_token.token_is_valid ( token )

Definition at line 129 of file link_token.py.

def token_is_valid(token) -> bool:
    valid = token == get_token()
    logger.debug("token is valid --> %s", valid)
    return valid
 
 

References searx.botdetection.link_token.get_token().

Referenced by searx.botdetection.link_token.ping().

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Variable Documentation

◆ logger

searx.botdetection.link_token.logger = logger.getChild('botdetection.link_token')

Definition at line 69 of file link_token.py.

◆ PING_KEY

str searx.botdetection.link_token.PING_KEY = 'SearXNG_limiter.ping'

Definition at line 63 of file link_token.py.

◆ PING_LIVE_TIME

int searx.botdetection.link_token.PING_LIVE_TIME = 3600

Definition at line 60 of file link_token.py.

◆ TOKEN_KEY

str searx.botdetection.link_token.TOKEN_KEY = 'SearXNG_limiter.token'

Definition at line 66 of file link_token.py.

◆ TOKEN_LIVE_TIME

int searx.botdetection.link_token.TOKEN_LIVE_TIME = 600

Definition at line 57 of file link_token.py.

Functions

Variables

Detailed Description

Function Documentation

◆ get_ping_key()

◆ get_token()

◆ is_suspicious()

◆ ping()

◆ token_is_valid()

Variable Documentation

◆ logger

◆ PING_KEY

◆ PING_LIVE_TIME

◆ TOKEN_KEY

◆ TOKEN_LIVE_TIME