Merge pull request from GHSA-x345-32rc-8h85

* tests for push rule pattern matching

* tests for acl pattern matching

* factor out common `re.escape`

* Factor out common re.compile

* Factor out common anchoring code

* add word_boundary support to `glob_to_regex`

* Use `glob_to_regex` in push rule evaluator

NB that this drops support for character classes. I don't think anyone ever
used them.

* Improve efficiency of globs with multiple wildcards

The idea here is that we compress multiple `*` globs into a single `.*`. We
also need to consider `?`, since `*?*` is as hard to implement efficiently as
`**`.

* add assertion on regex pattern

* Fix mypy

* Simplify glob_to_regex

* Inline the glob_to_regex helper function

Signed-off-by: Dan Callahan <danc@element.io>

* Moar comments

Signed-off-by: Dan Callahan <danc@element.io>

Co-authored-by: Dan Callahan <danc@element.io>

tests/util/test_glob_to_regex.py

@@ -0,0 +1,59 @@
+# Copyright 2021 The Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from synapse.util import glob_to_regex
+
+from tests.unittest import TestCase
+
+
+class GlobToRegexTestCase(TestCase):
+    def test_literal_match(self):
+        """patterns without wildcards should match"""
+        pat = glob_to_regex("foobaz")
+        self.assertTrue(
+            pat.match("FoobaZ"), "patterns should match and be case-insensitive"
+        )
+        self.assertFalse(
+            pat.match("x foobaz"), "pattern should not match at word boundaries"
+        )
+
+    def test_wildcard_match(self):
+        pat = glob_to_regex("f?o*baz")
+
+        self.assertTrue(
+            pat.match("FoobarbaZ"),
+            "* should match string and pattern should be case-insensitive",
+        )
+        self.assertTrue(pat.match("foobaz"), "* should match 0 characters")
+        self.assertFalse(pat.match("fooxaz"), "the character after * must match")
+        self.assertFalse(pat.match("fobbaz"), "? should not match 0 characters")
+        self.assertFalse(pat.match("fiiobaz"), "? should not match 2 characters")
+
+    def test_multi_wildcard(self):
+        """patterns with multiple wildcards in a row should match"""
+        pat = glob_to_regex("**baz")
+        self.assertTrue(pat.match("agsgsbaz"), "** should match any string")
+        self.assertTrue(pat.match("baz"), "** should match the empty string")
+        self.assertEqual(pat.pattern, r"\A.{0,}baz\Z")
+
+        pat = glob_to_regex("*?baz")
+        self.assertTrue(pat.match("agsgsbaz"), "*? should match any string")
+        self.assertTrue(pat.match("abaz"), "*? should match a single char")
+        self.assertFalse(pat.match("baz"), "*? should not match the empty string")
+        self.assertEqual(pat.pattern, r"\A.{1,}baz\Z")
+
+        pat = glob_to_regex("a?*?*?baz")
+        self.assertTrue(pat.match("a g baz"), "?*?*? should match 3 chars")
+        self.assertFalse(pat.match("a..baz"), "?*?*? should not match 2 chars")
+        self.assertTrue(pat.match("a.gg.baz"), "?*?*? should match 4 chars")
+        self.assertEqual(pat.pattern, r"\Aa.{3,}baz\Z")