[mod] Revision of the favicon solution

All favicons implementations have been documented and moved to the Python
package:

    searx.favicons

There is a configuration (based on Pydantic) for the favicons and all its
components:

    searx.favicons.config

A solution for caching favicons has been implemented:

    searx.favicon.cache

If the favicon is already in the cache, the returned URL is a data URL [1]
(something like `data:image/png;base64,...`).  By generating a data url from
the FaviconCache, additional HTTP roundtripps via the favicon_proxy are saved:

    favicons.proxy.favicon_url

The favicon proxy service now sets a HTTP header "Cache-Control: max-age=...":

    favicons.proxy.favicon_proxy

The resolvers now also provide the mime type (data, mime):

    searx.favicon.resolvers

[1] https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URLs

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

1 files changed, 62 insertions, 0 deletions

diff --git a/searx/favicons/config.py b/searx/favicons/config.py
new file mode 100644
index 000000000..1c18b1631
--- /dev/null
+++ b/searx/favicons/config.py
@@ -0,0 +1,62 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
+# pylint: disable=missing-module-docstring
+
+from __future__ import annotations
+
+import pathlib
+from pydantic import BaseModel
+
+from searx.compat import tomllib
+from .cache import FaviconCacheConfig
+from .proxy import FaviconProxyConfig
+
+CONFIG_SCHEMA: int = 1
+"""Version of the configuration schema."""
+
+TOML_CACHE: dict[str, "FaviconConfig"] = {}
+"""Cache config objects by TOML's filename."""
+
+DEFAULT_CFG_TOML = pathlib.Path(__file__).parent / "favicons.toml"
+
+
+class FaviconConfig(BaseModel):
+    """The class aggregates configurations of the favicon tools"""
+
+    cfg_schema: int
+    """Config's schema version.  The specification of the version of the schema
+    is mandatory, currently only version :py:obj:`CONFIG_SCHEMA` is supported.
+    By specifying a version, it is possible to ensure downward compatibility in
+    the event of future changes to the configuration schema"""
+
+    cache: FaviconCacheConfig = FaviconCacheConfig()
+    """Setup of the :py:obj:`.cache.FaviconCacheConfig`."""
+
+    proxy: FaviconProxyConfig = FaviconProxyConfig()
+    """Setup of the :py:obj:`.proxy.FaviconProxyConfig`."""
+
+    @classmethod
+    def from_toml_file(cls, cfg_file: pathlib.Path, use_cache: bool) -> "FaviconConfig":
+        """Create a config object from a TOML file, the ``use_cache`` argument
+        specifies whether a cache should be used.
+        """
+
+        cached = TOML_CACHE.get(str(cfg_file))
+        if use_cache and cached:
+            return cached
+
+        with cfg_file.open("rb") as f:
+
+            cfg = tomllib.load(f)
+            cfg = cfg.get("favicons", cfg)
+
+            schema = cfg.get("cfg_schema")
+            if schema != CONFIG_SCHEMA:
+                raise ValueError(
+                    f"config schema version {CONFIG_SCHEMA} is needed, version {schema} is given in {cfg_file}"
+                )
+
+            cfg = cls(**cfg)
+            if use_cache and cached:
+                TOML_CACHE[str(cfg_file.resolve())] = cfg
+
+            return cfg