Do not reject /sync requests with unrecognised filter fields

[squahtx]

For forward compatibility, Synapse needs to ignore fields it does not
recognise instead of raising an error.

Fixes #14365.

Signed-off-by: Sean Quah seanq@matrix.org

[reivilibre]

without wanting to ask the annoying question, should this have a Complement test or something that sends a bogus field? (potentially not TBH since you could say the same about every single endpoint ever)

Other annoying question: did this JSON schema come from the spec's JSON schema? Does that need to be fixed?

[squahtx]

should this have a Complement test or something that sends a bogus field?

It turns out we have existing trial tests that this change has broken:

synapse/tests/api/test_filtering.py

Lines 48 to 60 in 4283bd1

	def test_errors_on_invalid_filters(self):
	invalid_filters = [
	{"boom": {}},
	{"account_data": "Hello World"},
	{"event_fields": [r"\\foo"]},
	{"room": {"timeline": {"limit": 0}, "state": {"not_bars": ["*"]}}},
	{"event_format": "other"},
	{"room": {"not_rooms": ["#foo:pik-test"]}},
	{"presence": {"senders": ["@bar;pik.test.com"]}},
	]
	for filter in invalid_filters:
	with self.assertRaises(SynapseError):
	self.filtering.check_valid_filter(filter)

I'm minded to flip the expectations around in the failing test cases.

did this JSON schema come from the spec's JSON schema? Does that need to be fixed?

Good question. The schema in the spec don't specify additionalProperties for sync filters. I think that means it defaults to true?

https://github.com/matrix-org/matrix-spec/blob/main/data/api/client-server/definitions/event_filter.yaml
https://github.com/matrix-org/matrix-spec/blob/main/data/api/client-server/definitions/sync_filter.yaml
https://github.com/matrix-org/matrix-spec/blob/main/data/api/client-server/definitions/room_event_filter.yaml

[squahtx]

I've fixed the failing test and adapted it to create a test for unknown filter fields.

[reivilibre]

Good question. The schema in the spec don't specify additionalProperties for sync filters. I think that means it defaults to true?

AFAICT you are correct.