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# Copyright 2014-2016 OpenMarket Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from typing import Union
from synapse.api.constants import MAX_ALIAS_LENGTH, EventTypes, Membership
from synapse.api.errors import Codes, SynapseError
from synapse.api.room_versions import EventFormatVersions
from synapse.config.homeserver import HomeServerConfig
from synapse.events import EventBase
from synapse.events.builder import EventBuilder
from synapse.events.utils import validate_canonicaljson
from synapse.federation.federation_server import server_matches_acl_event
from synapse.types import EventID, RoomID, UserID
class EventValidator:
def validate_new(self, event: EventBase, config: HomeServerConfig):
"""Validates the event has roughly the right format
Args:
event: The event to validate.
config: The homeserver's configuration.
"""
self.validate_builder(event)
if event.format_version == EventFormatVersions.V1:
EventID.from_string(event.event_id)
required = [
"auth_events",
"content",
"hashes",
"origin",
"prev_events",
"sender",
"type",
]
for k in required:
if not hasattr(event, k):
raise SynapseError(400, "Event does not have key %s" % (k,))
# Check that the following keys have string values
event_strings = ["origin"]
for s in event_strings:
if not isinstance(getattr(event, s), str):
raise SynapseError(400, "'%s' not a string type" % (s,))
# Depending on the room version, ensure the data is spec compliant JSON.
if event.room_version.strict_canonicaljson:
# Note that only the client controlled portion of the event is
# checked, since we trust the portions of the event we created.
validate_canonicaljson(event.content)
if event.type == EventTypes.Aliases:
if "aliases" in event.content:
for alias in event.content["aliases"]:
if len(alias) > MAX_ALIAS_LENGTH:
raise SynapseError(
400,
(
"Can't create aliases longer than"
" %d characters" % (MAX_ALIAS_LENGTH,)
),
Codes.INVALID_PARAM,
)
if event.type == EventTypes.Retention:
self._validate_retention(event)
if event.type == EventTypes.ServerACL:
if not server_matches_acl_event(config.server_name, event):
raise SynapseError(
400, "Can't create an ACL event that denies the local server"
)
def _validate_retention(self, event: EventBase):
"""Checks that an event that defines the retention policy for a room respects the
format enforced by the spec.
Args:
event: The event to validate.
"""
if not event.is_state():
raise SynapseError(code=400, msg="must be a state event")
min_lifetime = event.content.get("min_lifetime")
max_lifetime = event.content.get("max_lifetime")
if min_lifetime is not None:
if not isinstance(min_lifetime, int):
raise SynapseError(
code=400,
msg="'min_lifetime' must be an integer",
errcode=Codes.BAD_JSON,
)
if max_lifetime is not None:
if not isinstance(max_lifetime, int):
raise SynapseError(
code=400,
msg="'max_lifetime' must be an integer",
errcode=Codes.BAD_JSON,
)
if (
min_lifetime is not None
and max_lifetime is not None
and min_lifetime > max_lifetime
):
raise SynapseError(
code=400,
msg="'min_lifetime' can't be greater than 'max_lifetime",
errcode=Codes.BAD_JSON,
)
def validate_builder(self, event: Union[EventBase, EventBuilder]):
"""Validates that the builder/event has roughly the right format. Only
checks values that we expect a proto event to have, rather than all the
fields an event would have
"""
strings = ["room_id", "sender", "type"]
if hasattr(event, "state_key"):
strings.append("state_key")
for s in strings:
if not isinstance(getattr(event, s), str):
raise SynapseError(400, "Not '%s' a string type" % (s,))
RoomID.from_string(event.room_id)
UserID.from_string(event.sender)
if event.type == EventTypes.Message:
strings = ["body", "msgtype"]
self._ensure_strings(event.content, strings)
elif event.type == EventTypes.Topic:
self._ensure_strings(event.content, ["topic"])
self._ensure_state_event(event)
elif event.type == EventTypes.Name:
self._ensure_strings(event.content, ["name"])
self._ensure_state_event(event)
elif event.type == EventTypes.Member:
if "membership" not in event.content:
raise SynapseError(400, "Content has not membership key")
if event.content["membership"] not in Membership.LIST:
raise SynapseError(400, "Invalid membership key")
self._ensure_state_event(event)
elif event.type == EventTypes.Tombstone:
if "replacement_room" not in event.content:
raise SynapseError(400, "Content has no replacement_room key")
if event.content["replacement_room"] == event.room_id:
raise SynapseError(
400, "Tombstone cannot reference the room it was sent in"
)
self._ensure_state_event(event)
def _ensure_strings(self, d, keys):
for s in keys:
if s not in d:
raise SynapseError(400, "'%s' not in content" % (s,))
if not isinstance(d[s], str):
raise SynapseError(400, "'%s' not a string type" % (s,))
def _ensure_state_event(self, event):
if not event.is_state():
raise SynapseError(400, "'%s' must be state events" % (event.type,))
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