[mod] data: implement a simple tracker URL (SQL) database

On demand, the tracker data is loaded directly into the cache, so that the
maintenance of this data via PRs is no longer necessary.

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

searx/data/tracker_patterns.py

@@ -0,0 +1,142 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
+"""Simple implementation to store TrackerPatterns data in a SQL database."""
+
+from __future__ import annotations
+import typing
+
+__all__ = ["TrackerPatternsDB"]
+
+import re
+import pathlib
+from collections.abc import Iterator
+from urllib.parse import urlparse, urlunparse, parse_qsl, urlencode
+
+import httpx
+
+from searx.data.core import get_cache, log
+
+RuleType = tuple[str, list[str], list[str]]
+
+
+class TrackerPatternsDB:
+    # pylint: disable=missing-class-docstring
+
+    ctx_name = "data_tracker_patterns"
+    json_file = pathlib.Path(__file__).parent / "tracker_patterns.json"
+
+    CLEAR_LIST_URL = [
+        # ClearURL rule lists, the first one that responds HTTP 200 is used
+        "https://rules1.clearurls.xyz/data.minify.json",
+        "https://rules2.clearurls.xyz/data.minify.json",
+        "https://raw.githubusercontent.com/ClearURLs/Rules/refs/heads/master/data.min.json",
+    ]
+
+    class Fields:
+        # pylint: disable=too-few-public-methods, invalid-name
+        url_regexp: typing.Final = 0  # URL (regular expression) match condition of the link
+        url_ignore: typing.Final = 1  # URL (regular expression) to ignore
+        del_args: typing.Final = 2  # list of URL arguments (regular expression) to delete
+
+    def __init__(self):
+        self.cache = get_cache()
+
+    def init(self):
+        if self.cache.properties("tracker_patterns loaded") != "OK":
+            self.load()
+            self.cache.properties.set("tracker_patterns loaded", "OK")
+        # F I X M E:
+        #     do we need a maintenance .. rember: database is stored
+        #     in /tmp and will be rebuild during the reboot anyway
+
+    def load(self):
+        log.debug("init searx.data.TRACKER_PATTERNS")
+        for rule in self.iter_clear_list():
+            self.add(rule)
+
+    def add(self, rule: RuleType):
+        self.cache.set(
+            key=rule[self.Fields.url_regexp],
+            value=(
+                rule[self.Fields.url_ignore],
+                rule[self.Fields.del_args],
+            ),
+            ctx=self.ctx_name,
+            expire=None,
+        )
+
+    def rules(self) -> Iterator[RuleType]:
+        self.init()
+        for key, value in self.cache.pairs(ctx=self.ctx_name):
+            yield key, value[0], value[1]
+
+    def iter_clear_list(self) -> Iterator[RuleType]:
+        resp = None
+        for url in self.CLEAR_LIST_URL:
+            resp = httpx.get(url, timeout=3)
+            if resp.status_code == 200:
+                break
+            log.warning(f"TRACKER_PATTERNS: ClearURL ignore HTTP {resp.status_code} {url}")
+
+        if resp is None:
+            log.error("TRACKER_PATTERNS: failed fetching ClearURL rule lists")
+            return
+
+        for rule in resp.json()["providers"].values():
+            yield (
+                rule["urlPattern"].replace("\\\\", "\\"),  # fix javascript regex syntax
+                [exc.replace("\\\\", "\\") for exc in rule.get("exceptions", [])],
+                rule.get("rules", []),
+            )
+
+    def clean_url(self, url: str) -> bool | str:
+        """The URL arguments are normalized and cleaned of tracker parameters.
+
+        Returns bool ``True`` to use URL unchanged (``False`` to ignore URL).
+        If URL should be modified, the returned string is the new URL to use.
+        """
+
+        new_url = url
+        parsed_new_url = urlparse(url=new_url)
+
+        for rule in self.rules():
+
+            if not re.match(rule[self.Fields.url_regexp], new_url):
+                # no match / ignore pattern
+                continue
+
+            do_ignore = False
+            for pattern in rule[self.Fields.url_ignore]:
+                if re.match(pattern, new_url):
+                    do_ignore = True
+                    break
+
+            if do_ignore:
+                # pattern is in the list of exceptions / ignore pattern
+                # HINT:
+                #    we can't break the outer pattern loop since we have
+                #    overlapping urlPattern like ".*"
+                continue
+
+            # remove tracker arguments from the url-query part
+            query_args: list[tuple[str, str]] = list(parse_qsl(parsed_new_url.query))
+
+            for name, val in query_args.copy():
+                # remove URL arguments
+                for pattern in rule[self.Fields.del_args]:
+                    if re.match(pattern, name):
+                        log.debug("TRACKER_PATTERNS: %s remove tracker arg: %s='%s'", parsed_new_url.netloc, name, val)
+                        query_args.remove((name, val))
+
+            parsed_new_url = parsed_new_url._replace(query=urlencode(query_args))
+            new_url = urlunparse(parsed_new_url)
+
+        if new_url != url:
+            return new_url
+
+        return True
+
+
+if __name__ == "__main__":
+    db = TrackerPatternsDB()
+    for r in db.rules():
+        print(r)