first commit

searx/botdetection/_helpers.py

@@ -0,0 +1,137 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
+# pylint: disable=missing-module-docstring, invalid-name
+from __future__ import annotations
+
+from ipaddress import (
+    IPv4Network,
+    IPv6Network,
+    IPv4Address,
+    IPv6Address,
+    ip_network,
+    ip_address,
+)
+import flask
+import werkzeug
+
+from searx import logger
+from searx.extended_types import SXNG_Request
+
+from . import config
+
+logger = logger.getChild('botdetection')
+
+
+def dump_request(request: SXNG_Request):
+    return (
+        request.path
+        + " || X-Forwarded-For: %s" % request.headers.get('X-Forwarded-For')
+        + " || X-Real-IP: %s" % request.headers.get('X-Real-IP')
+        + " || 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" % request.headers.get('User-Agent')
+        + " || Sec-Fetch-Site: %s" % request.headers.get('Sec-Fetch-Site')
+        + " || Sec-Fetch-Mode: %s" % request.headers.get('Sec-Fetch-Mode')
+        + " || Sec-Fetch-Dest: %s" % request.headers.get('Sec-Fetch-Dest')
+    )
+
+
+def too_many_requests(network: IPv4Network | IPv6Network, log_msg: str) -> werkzeug.Response | None:
+    """Returns a HTTP 429 response object and writes a ERROR message to the
+    'botdetection' logger.  This function is used in part by the filter methods
+    to return the default ``Too Many Requests`` response.
+
+    """
+
+    logger.debug("BLOCK %s: %s", network.compressed, log_msg)
+    return flask.make_response(('Too Many Requests', 429))
+
+
+def get_network(real_ip: IPv4Address | IPv6Address, cfg: config.Config) -> IPv4Network | IPv6Network:
+    """Returns the (client) network of whether the real_ip is part of."""
+
+    if real_ip.version == 6:
+        prefix = cfg['real_ip.ipv6_prefix']
+    else:
+        prefix = cfg['real_ip.ipv4_prefix']
+    network = ip_network(f"{real_ip}/{prefix}", strict=False)
+    # logger.debug("get_network(): %s", network.compressed)
+    return network
+
+
+_logged_errors = []
+
+
+def _log_error_only_once(err_msg):
+    if err_msg not in _logged_errors:
+        logger.error(err_msg)
+        _logged_errors.append(err_msg)
+
+
+def get_real_ip(request: SXNG_Request) -> str:
+    """Returns real IP of the request.  Since not all proxies set all the HTTP
+    headers and incoming headers can be faked it may happen that the IP cannot
+    be determined correctly.
+
+    .. sidebar:: :py:obj:`flask.Request.remote_addr`
+
+       SearXNG uses Werkzeug's ProxyFix_ (with it default ``x_for=1``).
+
+    This function tries to get the remote IP in the order listed below,
+    additional some tests are done and if inconsistencies or errors are
+    detected, they are logged.
+
+    The remote IP of the request is taken from (first match):
+
+    - X-Forwarded-For_ header
+    - `X-real-IP header <https://github.com/searxng/searxng/issues/1237#issuecomment-1147564516>`__
+    - :py:obj:`flask.Request.remote_addr`
+
+    .. _ProxyFix:
+       https://werkzeug.palletsprojects.com/middleware/proxy_fix/
+
+    .. _X-Forwarded-For:
+      https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-For
+
+    """
+
+    forwarded_for = request.headers.get("X-Forwarded-For")
+    real_ip = request.headers.get('X-Real-IP')
+    remote_addr = request.remote_addr
+    # logger.debug(
+    #     "X-Forwarded-For: %s || X-Real-IP: %s || request.remote_addr: %s", forwarded_for, real_ip, remote_addr
+    # )
+
+    if not forwarded_for:
+        _log_error_only_once("X-Forwarded-For header is not set!")
+    else:
+        from . import cfg  # pylint: disable=import-outside-toplevel, cyclic-import
+
+        forwarded_for = [x.strip() for x in forwarded_for.split(',')]
+        x_for: int = cfg['real_ip.x_for']  # type: ignore
+        forwarded_for = forwarded_for[-min(len(forwarded_for), x_for)]
+
+    if not real_ip:
+        _log_error_only_once("X-Real-IP header is not set!")
+
+    if forwarded_for and real_ip and forwarded_for != real_ip:
+        logger.warning("IP from X-Real-IP (%s) is not equal to IP from X-Forwarded-For (%s)", real_ip, forwarded_for)
+
+    if forwarded_for and remote_addr and forwarded_for != remote_addr:
+        logger.warning(
+            "IP from WSGI environment (%s) is not equal to IP from X-Forwarded-For (%s)", remote_addr, forwarded_for
+        )
+
+    if real_ip and remote_addr and real_ip != remote_addr:
+        logger.warning("IP from WSGI environment (%s) is not equal to IP from X-Real-IP (%s)", remote_addr, real_ip)
+
+    request_ip = ip_address(forwarded_for or real_ip or remote_addr or '0.0.0.0')
+    if request_ip.version == 6 and request_ip.ipv4_mapped:
+        request_ip = request_ip.ipv4_mapped
+
+    # logger.debug("get_real_ip() -> %s", request_ip)
+    return str(request_ip)