diff --git a/synapse/event_auth.py b/synapse/event_auth.py
index bab31e33c5..d437b7e5d1 100644
--- a/synapse/event_auth.py
+++ b/synapse/event_auth.py
@@ -52,6 +52,7 @@ from synapse.api.room_versions import (
KNOWN_ROOM_VERSIONS,
EventFormatVersions,
RoomVersion,
+ RoomVersions,
)
from synapse.storage.databases.main.events_worker import EventRedactBehaviour
from synapse.types import MutableStateMap, StateMap, UserID, get_domain_from_id
@@ -341,19 +342,80 @@ def check_state_dependent_auth_rules(
logger.debug("Allowing! %s", event)
+# Set of room versions where Synapse did not apply event key size limits
+# in bytes, but rather in codepoints.
+# In these room versions, we are more lenient with event size validation.
+LENIENT_EVENT_BYTE_LIMITS_ROOM_VERSIONS = {
+ RoomVersions.V1,
+ RoomVersions.V2,
+ RoomVersions.V3,
+ RoomVersions.V4,
+ RoomVersions.V5,
+ RoomVersions.V6,
+ RoomVersions.MSC2176,
+ RoomVersions.V7,
+ RoomVersions.V8,
+ RoomVersions.V9,
+ RoomVersions.MSC3787,
+ RoomVersions.V10,
+ RoomVersions.MSC2716v4,
+ RoomVersions.MSC1767v10,
+}
+
+
def _check_size_limits(event: "EventBase") -> None:
+ """
+ Checks the size limits in a PDU.
+
+ The entire size limit of the PDU is checked first.
+ Then the size of fields is checked, first in codepoints and then in bytes.
+
+ The codepoint size limits are only for Synapse compatibility.
+
+ Raises:
+ EventSizeError:
+ when a size limit has been violated.
+
+ unpersistable=True if Synapse never would have accepted the event and
+ the PDU must NOT be persisted.
+
+ unpersistable=False if a prior version of Synapse would have accepted the
+ event and so the PDU must be persisted as rejected to avoid
+ breaking the room.
+ """
+
+ # Whole PDU check
+ if len(encode_canonical_json(event.get_pdu_json())) > MAX_PDU_SIZE:
+ raise EventSizeError("event too large", unpersistable=True)
+
+ # Codepoint size check: Synapse always enforced these limits, so apply
+ # them strictly.
if len(event.user_id) > 255:
- raise EventSizeError("'user_id' too large")
+ raise EventSizeError("'user_id' too large", unpersistable=True)
if len(event.room_id) > 255:
- raise EventSizeError("'room_id' too large")
+ raise EventSizeError("'room_id' too large", unpersistable=True)
if event.is_state() and len(event.state_key) > 255:
- raise EventSizeError("'state_key' too large")
+ raise EventSizeError("'state_key' too large", unpersistable=True)
if len(event.type) > 255:
- raise EventSizeError("'type' too large")
+ raise EventSizeError("'type' too large", unpersistable=True)
if len(event.event_id) > 255:
- raise EventSizeError("'event_id' too large")
- if len(encode_canonical_json(event.get_pdu_json())) > MAX_PDU_SIZE:
- raise EventSizeError("event too large")
+ raise EventSizeError("'event_id' too large", unpersistable=True)
+
+ strict_byte_limits = (
+ event.room_version not in LENIENT_EVENT_BYTE_LIMITS_ROOM_VERSIONS
+ )
+
+ # Byte size check: if these fail, then be lenient to avoid breaking rooms.
+ if len(event.user_id.encode("utf-8")) > 255:
+ raise EventSizeError("'user_id' too large", unpersistable=strict_byte_limits)
+ if len(event.room_id.encode("utf-8")) > 255:
+ raise EventSizeError("'room_id' too large", unpersistable=strict_byte_limits)
+ if event.is_state() and len(event.state_key.encode("utf-8")) > 255:
+ raise EventSizeError("'state_key' too large", unpersistable=strict_byte_limits)
+ if len(event.type.encode("utf-8")) > 255:
+ raise EventSizeError("'type' too large", unpersistable=strict_byte_limits)
+ if len(event.event_id.encode("utf-8")) > 255:
+ raise EventSizeError("'event_id' too large", unpersistable=strict_byte_limits)
def _check_create(event: "EventBase") -> None:
|
