Allow events to be created with no `prev_events` (MSC2716) (#11243)

The event still needs to have `auth_events` defined to be valid.

Split out from https://github.com/matrix-org/synapse/pull/11114
pull/11565/head
Eric Eastwood 2021-12-10 23:08:51 -06:00 committed by GitHub
parent 8391bd6ab5
commit aa8708ebed
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4 changed files with 124 additions and 7 deletions

1
changelog.d/11243.misc Normal file
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@ -0,0 +1 @@
Allow specific, experimental events to be created without `prev_events`. Used by [MSC2716](https://github.com/matrix-org/matrix-doc/pull/2716).

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@ -496,6 +496,7 @@ class EventCreationHandler:
require_consent: bool = True,
outlier: bool = False,
historical: bool = False,
allow_no_prev_events: bool = False,
depth: Optional[int] = None,
) -> Tuple[EventBase, EventContext]:
"""
@ -607,6 +608,7 @@ class EventCreationHandler:
prev_event_ids=prev_event_ids,
auth_event_ids=auth_event_ids,
depth=depth,
allow_no_prev_events=allow_no_prev_events,
)
# In an ideal world we wouldn't need the second part of this condition. However,
@ -882,6 +884,7 @@ class EventCreationHandler:
prev_event_ids: Optional[List[str]] = None,
auth_event_ids: Optional[List[str]] = None,
depth: Optional[int] = None,
allow_no_prev_events: bool = False,
) -> Tuple[EventBase, EventContext]:
"""Create a new event for a local client
@ -912,6 +915,7 @@ class EventCreationHandler:
full_state_ids_at_event = None
if auth_event_ids is not None:
# If auth events are provided, prev events must be also.
# prev_event_ids could be an empty array though.
assert prev_event_ids is not None
# Copy the full auth state before it stripped down
@ -943,14 +947,22 @@ class EventCreationHandler:
else:
prev_event_ids = await self.store.get_prev_events_for_room(builder.room_id)
# we now ought to have some prev_events (unless it's a create event).
#
# do a quick sanity check here, rather than waiting until we've created the
# Do a quick sanity check here, rather than waiting until we've created the
# event and then try to auth it (which fails with a somewhat confusing "No
# create event in auth events")
assert (
builder.type == EventTypes.Create or len(prev_event_ids) > 0
), "Attempting to create an event with no prev_events"
if allow_no_prev_events:
# We allow events with no `prev_events` but it better have some `auth_events`
assert (
builder.type == EventTypes.Create
# Allow an event to have empty list of prev_event_ids
# only if it has auth_event_ids.
or auth_event_ids
), "Attempting to create a non-m.room.create event with no prev_events or auth_event_ids"
else:
# we now ought to have some prev_events (unless it's a create event).
assert (
builder.type == EventTypes.Create or prev_event_ids
), "Attempting to create a non-m.room.create event with no prev_events"
event = await builder.build(
prev_event_ids=prev_event_ids,

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@ -658,7 +658,8 @@ class RoomMemberHandler(metaclass=abc.ABCMeta):
if block_invite:
raise SynapseError(403, "Invites have been disabled on this server")
if prev_event_ids:
# An empty prev_events list is allowed as long as the auth_event_ids are present
if prev_event_ids is not None:
return await self._local_membership_update(
requester=requester,
target=target,

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@ -23,6 +23,7 @@ from synapse.types import create_requester
from synapse.util.stringutils import random_string
from tests import unittest
from tests.test_utils.event_injection import create_event
logger = logging.getLogger(__name__)
@ -51,6 +52,24 @@ class EventCreationTestCase(unittest.HomeserverTestCase):
self.requester = create_requester(self.user_id, access_token_id=self.token_id)
def _create_and_persist_member_event(self) -> Tuple[EventBase, EventContext]:
# Create a member event we can use as an auth_event
memberEvent, memberEventContext = self.get_success(
create_event(
self.hs,
room_id=self.room_id,
type="m.room.member",
sender=self.requester.user.to_string(),
state_key=self.requester.user.to_string(),
content={"membership": "join"},
)
)
self.get_success(
self.persist_event_storage.persist_event(memberEvent, memberEventContext)
)
return memberEvent, memberEventContext
def _create_duplicate_event(self, txn_id: str) -> Tuple[EventBase, EventContext]:
"""Create a new event with the given transaction ID. All events produced
by this method will be considered duplicates.
@ -156,6 +175,90 @@ class EventCreationTestCase(unittest.HomeserverTestCase):
self.assertEqual(len(events), 2)
self.assertEqual(events[0].event_id, events[1].event_id)
def test_when_empty_prev_events_allowed_create_event_with_empty_prev_events(self):
"""When we set allow_no_prev_events=True, should be able to create a
event without any prev_events (only auth_events).
"""
# Create a member event we can use as an auth_event
memberEvent, _ = self._create_and_persist_member_event()
# Try to create the event with empty prev_events bit with some auth_events
event, _ = self.get_success(
self.handler.create_event(
self.requester,
{
"type": EventTypes.Message,
"room_id": self.room_id,
"sender": self.requester.user.to_string(),
"content": {"msgtype": "m.text", "body": random_string(5)},
},
# Empty prev_events is the key thing we're testing here
prev_event_ids=[],
# But with some auth_events
auth_event_ids=[memberEvent.event_id],
# Allow no prev_events!
allow_no_prev_events=True,
)
)
self.assertIsNotNone(event)
def test_when_empty_prev_events_not_allowed_reject_event_with_empty_prev_events(
self,
):
"""When we set allow_no_prev_events=False, shouldn't be able to create a
event without any prev_events even if it has auth_events. Expect an
exception to be raised.
"""
# Create a member event we can use as an auth_event
memberEvent, _ = self._create_and_persist_member_event()
# Try to create the event with empty prev_events but with some auth_events
self.get_failure(
self.handler.create_event(
self.requester,
{
"type": EventTypes.Message,
"room_id": self.room_id,
"sender": self.requester.user.to_string(),
"content": {"msgtype": "m.text", "body": random_string(5)},
},
# Empty prev_events is the key thing we're testing here
prev_event_ids=[],
# But with some auth_events
auth_event_ids=[memberEvent.event_id],
# We expect the test to fail because empty prev_events are not
# allowed here!
allow_no_prev_events=False,
),
AssertionError,
)
def test_when_empty_prev_events_allowed_reject_event_with_empty_prev_events_and_auth_events(
self,
):
"""When we set allow_no_prev_events=True, should be able to create a
event without any prev_events or auth_events. Expect an exception to be
raised.
"""
# Try to create the event with empty prev_events and empty auth_events
self.get_failure(
self.handler.create_event(
self.requester,
{
"type": EventTypes.Message,
"room_id": self.room_id,
"sender": self.requester.user.to_string(),
"content": {"msgtype": "m.text", "body": random_string(5)},
},
prev_event_ids=[],
# The event should be rejected when there are no auth_events
auth_event_ids=[],
# Allow no prev_events!
allow_no_prev_events=True,
),
AssertionError,
)
class ServerAclValidationTestCase(unittest.HomeserverTestCase):
servlets = [