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_minimal_parse_stripped_room_state

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This commit is contained in:
Eric Eastwood
2026-05-22 20:14:43 -05:00
parent 4598a43364
commit fbff6859e3
1 changed files with 91 additions and 28 deletions
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synapse/handlers/federation.py
+91 -28
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@@ -30,6 +30,7 @@ from http import HTTPStatus
from typing import (
TYPE_CHECKING,
AbstractSet,
Any,
Iterable,
)
@@ -119,11 +120,6 @@ The number of events we try to backfill from other servers in a single request.
"""
class StrippedRoomStateType(enum.Enum):
INVITE = "invite_room_state"
KNOCK = "knock_room_state"
# TODO: We can refactor this away now that there is only one backfill point again
class _BackfillPointType(Enum):
# a regular backwards extremity (ie, an event which we don't yet have, but which
@@ -907,15 +903,45 @@ class FederationHandler:
# This is a bit of a hack and is cribbing off of invites. Basically we
# store the room state here and retrieve it again when this event appears
# in the invitee's sync stream. It is stripped out for all other local users.
stripped_room_state = knock_response.get("knock_room_state")
#
# Parse/validate `knock_room_state`
try:
stripped_room_state = await self._parse_stripped_room_state(
stripped_room_state=knock_response.get("knock_room_state"),
room_id=event.room_id,
room_version=event_format_version,
)
# Replace with our sanitized `knock_room_state`
event.unsigned["knock_room_state"] = [
serialize_stripped_state_event(stripped_state_event)
for stripped_state_event in stripped_room_state
]
except Exception as exc:
# FIXME(MSC4311): Apply this validation for all room versions after 2027-06-01 (to allow
# some time for the ecosystem to adapt and support MSC4311).
if event_format_version.msc4311_stripped_state:
# FIXME(MSC4311): Instead of logging, reject with 400 `M_MISSING_PARAM`
# after 2027-06-01. Given Synapse claimed to support room version 12 but
# didn't adhere to this behavior until 2026-06-01, we will only warn for
# now.
logger.warning(
"Continuing anyway but failed to validate `knock_room_state` on knock %s (room_version=%s): %s",
event,
event_format_version,
exc,
)
if stripped_room_state is None:
raise KeyError("Missing 'knock_room_state' field in send_knock response")
if not isinstance(stripped_room_state, list):
raise TypeError("'knock_room_state' has wrong type")
event.unsigned["knock_room_state"] = stripped_room_state
# FIXME(MSC4311): Remove this whole block after we always enforce the
# validation above. The only reason this is here is because the validation
# can fail for non-compliant servers but we should still use stripped state.
stripped_room_state = self._minimal_parse_stripped_room_state(
stripped_room_state=event.unsigned.get("knock_room_state"),
)
# Replace with our sanitized `knock_room_state`
event.unsigned["knock_room_state"] = [
serialize_stripped_state_event(stripped_state_event)
for stripped_state_event in stripped_room_state
]
context = EventContext.for_outlier(self._storage_controllers)
stream_id = await self._federation_event_handler.persist_events_and_notify(
@@ -1076,10 +1102,35 @@ class FederationHandler:
await self._event_auth_handler.check_auth_rules_from_context(event)
return event
def _minimal_parse_stripped_room_state(
self,
*,
stripped_room_state: Any,
) -> list[StrippedStateEvent]:
"""
The minimum amount of parsing necessary to ensure
`invite_room_state`/`knock_room_state` is at-least a list of stripped state events.
"""
# Scrutinize JSON values
if not isinstance(stripped_room_state, list):
raise TypeError("Stripped state must be a list of PDU's")
parsed_stripped_room_state = []
for raw_stripped_event in stripped_room_state:
# Parse and serialize to strip the events down to only the necessary fields
parsed_stripped_event = parse_stripped_state_event(raw_stripped_event)
if parsed_stripped_event is None:
raise ValueError("Unable to parse as stripped event")
parsed_stripped_room_state.append(parsed_stripped_event)
return parsed_stripped_room_state
async def _parse_stripped_room_state(
self,
stripped_room_state_type: StrippedRoomStateType,
event: EventBase,
*,
stripped_room_state: Any,
room_id: str,
room_version: RoomVersion,
) -> list[StrippedStateEvent]:
"""
@@ -1096,18 +1147,21 @@ class FederationHandler:
the events contained within can be full PDU's or stripped state events (older
version of the Matrix spec).
Args:
stripped_room_state: The raw `invite_room_state`/`knock_room_state` JSON
room_id: The room ID the invite/knock is happening in
room_version: The version of the room the invite/knock is happening in
Returns:
A list of parsed `StrippedStateEvent`
Raises:
`TypeError`/`ValueError` when the stripped room state is invalid
"""
stripped_room_state = event.unsigned.get(stripped_room_state_type.value)
# Scrutinize JSON values
if not isinstance(stripped_room_state, list):
raise TypeError(
f"`{stripped_room_state_type.value}` must be a list of PDU's that includes the `m.room.create` event"
"Stripped state must be a list of PDU's that includes the `m.room.create` event"
)
parsed_stripped_room_state = []
@@ -1118,13 +1172,13 @@ class FederationHandler:
pdu = event_from_pdu_json(raw_stripped_event, room_version)
except Exception as exc:
raise ValueError(
f"Unable to parse one of the `{stripped_room_state_type.value}` event's as a PDU"
"Unable to parse one of the stripped state events as a PDU"
) from exc
# Validate that it's from the same room
if pdu.room_id != event.room_id:
if pdu.room_id != room_id:
raise ValueError(
f"PDU from {stripped_room_state_type.value} must be from the room ID specified in the `/invite` request"
"PDU from stripped state must be from the room ID specified in the request"
)
# Validate signature/hashes
try:
@@ -1133,7 +1187,7 @@ class FederationHandler:
)
except InvalidEventSignatureError as exc:
raise ValueError(
f"PDU from {stripped_room_state_type.value} must pass signature/hash checks"
"PDU from stripped state must pass signature/hash checks"
) from exc
# Mark down whether we saw the create event which we will validate just below
@@ -1152,7 +1206,7 @@ class FederationHandler:
# Validate `m.room.create` event is included
if not includes_create_event:
raise ValueError(
f"`{stripped_room_state_type.value}` must include `m.room.create` event"
"Stripped state must include `m.room.create` event (MSC4311)"
)
return parsed_stripped_room_state
@@ -1238,7 +1292,9 @@ class FederationHandler:
# Parse/validate `invite_room_state`
try:
stripped_room_state = await self._parse_stripped_room_state(
StrippedRoomStateType.INVITE, event, room_version
stripped_room_state=event.unsigned.get("invite_room_state"),
room_id=event.room_id,
room_version=room_version,
)
# Replace with our sanitized `invite_room_state`
event.unsigned["invite_room_state"] = [
@@ -1260,10 +1316,17 @@ class FederationHandler:
exc,
)
# We did our best to sanitize `event.unsigned["invite_room_state"]` but
# ultimately failed. Leave it as-is for the client to interpret. Another
# valid decision would be to strip it from `unsigned` but this is more
# forwards compatible.
# FIXME(MSC4311): Remove this whole block after we always enforce the
# validation above. The only reason this is here is because the validation
# can fail for non-compliant servers but we should still use stripped state.
stripped_room_state = self._minimal_parse_stripped_room_state(
stripped_room_state=event.unsigned.get("invite_room_state"),
)
# Replace with our sanitized `invite_room_state`
event.unsigned["invite_room_state"] = [
serialize_stripped_state_event(stripped_state_event)
for stripped_state_event in stripped_room_state
]
event.internal_metadata.outlier = True
event.internal_metadata.out_of_band_membership = True