diff --git a/changelog.d/4083.bugfix b/changelog.d/4083.bugfix
new file mode 100644
index 0000000000..b3b08cdfa6
--- /dev/null
+++ b/changelog.d/4083.bugfix
@@ -0,0 +1 @@
+Fix bug which prevented backslashes being used in event field filters
\ No newline at end of file
diff --git a/synapse/api/filtering.py b/synapse/api/filtering.py
index eed8c67e6a..677c0bdd4c 100644
--- a/synapse/api/filtering.py
+++ b/synapse/api/filtering.py
@@ -172,7 +172,10 @@ USER_FILTER_SCHEMA = {
# events a lot easier as we can then use a negative lookbehind
# assertion to split '\.' If we allowed \\ then it would
# incorrectly split '\\.' See synapse.events.utils.serialize_event
- "pattern": "^((?!\\\).)*$"
+ #
+ # Note that because this is a regular expression, we have to escape
+ # each backslash in the pattern.
+ "pattern": r"^((?!\\\\).)*$"
}
}
},
diff --git a/tests/api/test_filtering.py b/tests/api/test_filtering.py
index 48b2d3d663..2a7044801a 100644
--- a/tests/api/test_filtering.py
+++ b/tests/api/test_filtering.py
@@ -60,7 +60,7 @@ class FilteringTestCase(unittest.TestCase):
invalid_filters = [
{"boom": {}},
{"account_data": "Hello World"},
- {"event_fields": ["\\foo"]},
+ {"event_fields": [r"\\foo"]},
{"room": {"timeline": {"limit": 0}, "state": {"not_bars": ["*"]}}},
{"event_format": "other"},
{"room": {"not_rooms": ["#foo:pik-test"]}},
@@ -109,6 +109,16 @@ class FilteringTestCase(unittest.TestCase):
"event_format": "client",
"event_fields": ["type", "content", "sender"],
},
+
+ # a single backslash should be permitted (though it is debatable whether
+ # it should be permitted before anything other than `.`, and what that
+ # actually means)
+ #
+ # (note that event_fields is implemented in
+ # synapse.events.utils.serialize_event, and so whether this actually works
+ # is tested elsewhere. We just want to check that it is allowed through the
+ # filter validation)
+ {"event_fields": [r"foo\.bar"]},
]
for filter in valid_filters:
try:
|
