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