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Iyas Altawil
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searx/favicons/proxy.py
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238
searx/favicons/proxy.py
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# SPDX-License-Identifier: AGPL-3.0-or-later
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"""Implementations for a favicon proxy"""
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from __future__ import annotations
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from typing import Callable
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import importlib
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import base64
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import pathlib
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import urllib.parse
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import flask
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from httpx import HTTPError
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import msgspec
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from searx import get_setting
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from searx.webutils import new_hmac, is_hmac_of
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from searx.exceptions import SearxEngineResponseException
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from searx.extended_types import sxng_request
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from .resolvers import DEFAULT_RESOLVER_MAP
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from . import cache
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DEFAULT_FAVICON_URL = {}
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CFG: FaviconProxyConfig = None # type: ignore
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def init(cfg: FaviconProxyConfig):
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global CFG # pylint: disable=global-statement
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CFG = cfg
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def _initial_resolver_map():
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d = {}
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name: str = get_setting("search.favicon_resolver", None) # type: ignore
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if name:
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func = DEFAULT_RESOLVER_MAP.get(name)
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if func:
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d = {name: f"searx.favicons.resolvers.{func.__name__}"}
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return d
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class FaviconProxyConfig(msgspec.Struct):
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"""Configuration of the favicon proxy."""
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max_age: int = 60 * 60 * 24 * 7 # seven days
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"""HTTP header Cache-Control_ ``max-age``
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.. _Cache-Control: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control
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"""
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secret_key: str = get_setting("server.secret_key") # type: ignore
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"""By default, the value from :ref:`server.secret_key <settings server>`
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setting is used."""
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resolver_timeout: int = get_setting("outgoing.request_timeout") # type: ignore
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"""Timeout which the resolvers should not exceed, is usually passed to the
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outgoing request of the resolver. By default, the value from
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:ref:`outgoing.request_timeout <settings outgoing>` setting is used."""
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resolver_map: dict[str, str] = msgspec.field(default_factory=_initial_resolver_map)
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"""The resolver_map is a key / value dictionary where the key is the name of
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the resolver and the value is the fully qualifying name (fqn) of resolver's
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function (the callable). The resolvers from the python module
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:py:obj:`searx.favicons.resolver` are available by default."""
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def get_resolver(self, name: str) -> Callable | None:
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"""Returns the callable object (function) of the resolver with the
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``name``. If no resolver is registered for the ``name``, ``None`` is
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returned.
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"""
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fqn = self.resolver_map.get(name)
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if fqn is None:
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return None
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mod_name, _, func_name = fqn.rpartition('.')
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mod = importlib.import_module(mod_name)
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func = getattr(mod, func_name)
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if func is None:
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raise ValueError(f"resolver {fqn} is not implemented")
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return func
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favicon_path: str = get_setting("ui.static_path") + "/themes/{theme}/img/empty_favicon.svg" # type: ignore
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favicon_mime_type: str = "image/svg+xml"
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def favicon(self, **replacements):
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"""Returns pathname and mimetype of the default favicon."""
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return (
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pathlib.Path(self.favicon_path.format(**replacements)),
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self.favicon_mime_type,
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)
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def favicon_data_url(self, **replacements):
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"""Returns data image URL of the default favicon."""
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cache_key = ", ".join(f"{x}:{replacements[x]}" for x in sorted(list(replacements.keys()), key=str))
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data_url = DEFAULT_FAVICON_URL.get(cache_key)
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if data_url is not None:
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return data_url
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fav, mimetype = CFG.favicon(**replacements)
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# hint: encoding utf-8 limits favicons to be a SVG image
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with fav.open("r", encoding="utf-8") as f:
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data_url = f.read()
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data_url = urllib.parse.quote(data_url)
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data_url = f"data:{mimetype};utf8,{data_url}"
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DEFAULT_FAVICON_URL[cache_key] = data_url
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return data_url
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def favicon_proxy():
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"""REST API of SearXNG's favicon proxy service
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::
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/favicon_proxy?authority=<...>&h=<...>
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``authority``:
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Domain name :rfc:`3986` / see :py:obj:`favicon_url`
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``h``:
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HMAC :rfc:`2104`, build up from the :ref:`server.secret_key <settings
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server>` setting.
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"""
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authority = sxng_request.args.get('authority')
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# malformed request or RFC 3986 authority
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if not authority or "/" in authority:
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return '', 400
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# malformed request / does not have authorisation
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if not is_hmac_of(
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CFG.secret_key,
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authority.encode(),
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sxng_request.args.get('h', ''),
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):
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return '', 400
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resolver = sxng_request.preferences.get_value('favicon_resolver') # type: ignore
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# if resolver is empty or not valid, just return HTTP 400.
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if not resolver or resolver not in CFG.resolver_map.keys():
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return "", 400
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data, mime = search_favicon(resolver, authority)
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if data is not None and mime is not None:
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resp = flask.Response(data, mimetype=mime) # type: ignore
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resp.headers['Cache-Control'] = f"max-age={CFG.max_age}"
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return resp
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# return default favicon from static path
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theme = sxng_request.preferences.get_value("theme") # type: ignore
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fav, mimetype = CFG.favicon(theme=theme)
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return flask.send_from_directory(fav.parent, fav.name, mimetype=mimetype)
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def search_favicon(resolver: str, authority: str) -> tuple[None | bytes, None | str]:
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"""Sends the request to the favicon resolver and returns a tuple for the
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favicon. The tuple consists of ``(data, mime)``, if the resolver has not
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determined a favicon, both values are ``None``.
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``data``:
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Binary data of the favicon.
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``mime``:
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Mime type of the favicon.
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"""
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data, mime = (None, None)
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func = CFG.get_resolver(resolver)
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if func is None:
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return data, mime
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# to avoid superfluous requests to the resolver, first look in the cache
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data_mime = cache.CACHE(resolver, authority)
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if data_mime is not None:
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return data_mime
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try:
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data, mime = func(authority, timeout=CFG.resolver_timeout)
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if data is None or mime is None:
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data, mime = (None, None)
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except (HTTPError, SearxEngineResponseException):
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pass
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cache.CACHE.set(resolver, authority, mime, data)
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return data, mime
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def favicon_url(authority: str) -> str:
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"""Function to generate the image URL used for favicons in SearXNG's result
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lists. The ``authority`` argument (aka netloc / :rfc:`3986`) is usually a
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(sub-) domain name. This function is used in the HTML (jinja) templates.
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.. code:: html
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<div class="favicon">
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<img src="{{ favicon_url(result.parsed_url.netloc) }}">
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</div>
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The returned URL is a route to :py:obj:`favicon_proxy` REST API.
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If the favicon is already in the cache, the returned URL is a `data URL`_
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(something like ``data:image/png;base64,...``). By generating a data url from
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the :py:obj:`.cache.FaviconCache`, additional HTTP roundtripps via the
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:py:obj:`favicon_proxy` are saved. However, it must also be borne in mind
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that data urls are not cached in the client (web browser).
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.. _data URL: https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URLs
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"""
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resolver = sxng_request.preferences.get_value('favicon_resolver') # type: ignore
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# if resolver is empty or not valid, just return nothing.
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if not resolver or resolver not in CFG.resolver_map.keys():
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return ""
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data_mime = cache.CACHE(resolver, authority)
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if data_mime == (None, None):
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# we have already checked, the resolver does not have a favicon
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theme = sxng_request.preferences.get_value("theme") # type: ignore
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return CFG.favicon_data_url(theme=theme)
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if data_mime is not None:
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data, mime = data_mime
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return f"data:{mime};base64,{str(base64.b64encode(data), 'utf-8')}" # type: ignore
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h = new_hmac(CFG.secret_key, authority.encode())
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proxy_url = flask.url_for('favicon_proxy')
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query = urllib.parse.urlencode({"authority": authority, "h": h})
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return f"{proxy_url}?{query}"
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