forked-synapse/synapse/events/utils.py
2022-04-19 16:42:19 +01:00

636 lines
21 KiB
Python

# Copyright 2014-2016 OpenMarket Ltd
# Copyright 2021 The Matrix.org Foundation C.I.C.
#
# 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.
import collections.abc
import re
from typing import (
TYPE_CHECKING,
Any,
Callable,
Dict,
Iterable,
List,
Mapping,
Optional,
Union,
)
import attr
from frozendict import frozendict
from synapse.api.constants import EventContentFields, EventTypes, RelationTypes
from synapse.api.errors import Codes, SynapseError
from synapse.api.room_versions import RoomVersion
from synapse.types import JsonDict
from synapse.util.frozenutils import unfreeze
from . import EventBase
if TYPE_CHECKING:
from synapse.handlers.relations import BundledAggregations
# Split strings on "." but not "\." This uses a negative lookbehind assertion for '\'
# (?<!stuff) matches if the current position in the string is not preceded
# by a match for 'stuff'.
# TODO: This is fast, but fails to handle "foo\\.bar" which should be treated as
# the literal fields "foo\" and "bar" but will instead be treated as "foo\\.bar"
SPLIT_FIELD_REGEX = re.compile(r"(?<!\\)\.")
CANONICALJSON_MAX_INT = (2**53) - 1
CANONICALJSON_MIN_INT = -CANONICALJSON_MAX_INT
def prune_event(event: EventBase) -> EventBase:
"""Returns a pruned version of the given event, which removes all keys we
don't know about or think could potentially be dodgy.
This is used when we "redact" an event. We want to remove all fields that
the user has specified, but we do want to keep necessary information like
type, state_key etc.
"""
pruned_event_dict = prune_event_dict(event.room_version, event.get_dict())
from . import make_event_from_dict
pruned_event = make_event_from_dict(
pruned_event_dict, event.room_version, event.internal_metadata.get_dict()
)
# copy the internal fields
pruned_event.internal_metadata.stream_ordering = (
event.internal_metadata.stream_ordering
)
pruned_event.internal_metadata.outlier = event.internal_metadata.outlier
# Mark the event as redacted
pruned_event.internal_metadata.redacted = True
return pruned_event
def prune_event_dict(room_version: RoomVersion, event_dict: JsonDict) -> JsonDict:
"""Redacts the event_dict in the same way as `prune_event`, except it
operates on dicts rather than event objects
Returns:
A copy of the pruned event dict
"""
allowed_keys = [
"event_id",
"sender",
"room_id",
"hashes",
"signatures",
"content",
"type",
"state_key",
"depth",
"prev_events",
"auth_events",
"origin",
"origin_server_ts",
]
# Room versions from before MSC2176 had additional allowed keys.
if not room_version.msc2176_redaction_rules:
allowed_keys.extend(["prev_state", "membership"])
event_type = event_dict["type"]
new_content = {}
def add_fields(*fields: str) -> None:
for field in fields:
if field in event_dict["content"]:
new_content[field] = event_dict["content"][field]
if event_type == EventTypes.Member:
add_fields("membership")
if room_version.msc3375_redaction_rules:
add_fields(EventContentFields.AUTHORISING_USER)
elif event_type == EventTypes.Create:
# MSC2176 rules state that create events cannot be redacted.
if room_version.msc2176_redaction_rules:
return event_dict
add_fields("creator")
elif event_type == EventTypes.JoinRules:
add_fields("join_rule")
if room_version.msc3083_join_rules:
add_fields("allow")
elif event_type == EventTypes.PowerLevels:
add_fields(
"users",
"users_default",
"events",
"events_default",
"state_default",
"ban",
"kick",
"redact",
)
if room_version.msc2176_redaction_rules:
add_fields("invite")
if room_version.msc2716_historical:
add_fields("historical")
elif event_type == EventTypes.Aliases and room_version.special_case_aliases_auth:
add_fields("aliases")
elif event_type == EventTypes.RoomHistoryVisibility:
add_fields("history_visibility")
elif event_type == EventTypes.Redaction and room_version.msc2176_redaction_rules:
add_fields("redacts")
elif room_version.msc2716_redactions and event_type == EventTypes.MSC2716_INSERTION:
add_fields(EventContentFields.MSC2716_NEXT_BATCH_ID)
elif room_version.msc2716_redactions and event_type == EventTypes.MSC2716_BATCH:
add_fields(EventContentFields.MSC2716_BATCH_ID)
elif room_version.msc2716_redactions and event_type == EventTypes.MSC2716_MARKER:
add_fields(EventContentFields.MSC2716_MARKER_INSERTION)
allowed_fields = {k: v for k, v in event_dict.items() if k in allowed_keys}
allowed_fields["content"] = new_content
unsigned: JsonDict = {}
allowed_fields["unsigned"] = unsigned
event_unsigned = event_dict.get("unsigned", {})
if "age_ts" in event_unsigned:
unsigned["age_ts"] = event_unsigned["age_ts"]
if "replaces_state" in event_unsigned:
unsigned["replaces_state"] = event_unsigned["replaces_state"]
return allowed_fields
def _copy_field(src: JsonDict, dst: JsonDict, field: List[str]) -> None:
"""Copy the field in 'src' to 'dst'.
For example, if src={"foo":{"bar":5}} and dst={}, and field=["foo","bar"]
then dst={"foo":{"bar":5}}.
Args:
src: The dict to read from.
dst: The dict to modify.
field: List of keys to drill down to in 'src'.
"""
if len(field) == 0: # this should be impossible
return
if len(field) == 1: # common case e.g. 'origin_server_ts'
if field[0] in src:
dst[field[0]] = src[field[0]]
return
# Else is a nested field e.g. 'content.body'
# Pop the last field as that's the key to move across and we need the
# parent dict in order to access the data. Drill down to the right dict.
key_to_move = field.pop(-1)
sub_dict = src
for sub_field in field: # e.g. sub_field => "content"
if sub_field in sub_dict and type(sub_dict[sub_field]) in [dict, frozendict]:
sub_dict = sub_dict[sub_field]
else:
return
if key_to_move not in sub_dict:
return
# Insert the key into the output dictionary, creating nested objects
# as required. We couldn't do this any earlier or else we'd need to delete
# the empty objects if the key didn't exist.
sub_out_dict = dst
for sub_field in field:
sub_out_dict = sub_out_dict.setdefault(sub_field, {})
sub_out_dict[key_to_move] = sub_dict[key_to_move]
def only_fields(dictionary: JsonDict, fields: List[str]) -> JsonDict:
"""Return a new dict with only the fields in 'dictionary' which are present
in 'fields'.
If there are no event fields specified then all fields are included.
The entries may include '.' characters to indicate sub-fields.
So ['content.body'] will include the 'body' field of the 'content' object.
A literal '.' character in a field name may be escaped using a '\'.
Args:
dictionary: The dictionary to read from.
fields: A list of fields to copy over. Only shallow refs are
taken.
Returns:
A new dictionary with only the given fields. If fields was empty,
the same dictionary is returned.
"""
if len(fields) == 0:
return dictionary
# for each field, convert it:
# ["content.body.thing\.with\.dots"] => [["content", "body", "thing\.with\.dots"]]
split_fields = [SPLIT_FIELD_REGEX.split(f) for f in fields]
# for each element of the output array of arrays:
# remove escaping so we can use the right key names.
split_fields[:] = [
[f.replace(r"\.", r".") for f in field_array] for field_array in split_fields
]
output: JsonDict = {}
for field_array in split_fields:
_copy_field(dictionary, output, field_array)
return output
def format_event_raw(d: JsonDict) -> JsonDict:
return d
def format_event_for_client_v1(d: JsonDict) -> JsonDict:
d = format_event_for_client_v2(d)
sender = d.get("sender")
if sender is not None:
d["user_id"] = sender
copy_keys = (
"age",
"redacted_because",
"replaces_state",
"prev_content",
"invite_room_state",
"knock_room_state",
)
for key in copy_keys:
if key in d["unsigned"]:
d[key] = d["unsigned"][key]
return d
def format_event_for_client_v2(d: JsonDict) -> JsonDict:
drop_keys = (
"auth_events",
"prev_events",
"hashes",
"signatures",
"depth",
"origin",
"prev_state",
)
for key in drop_keys:
d.pop(key, None)
return d
def format_event_for_client_v2_without_room_id(d: JsonDict) -> JsonDict:
d = format_event_for_client_v2(d)
d.pop("room_id", None)
return d
@attr.s(slots=True, frozen=True, auto_attribs=True)
class SerializeEventConfig:
as_client_event: bool = True
# Function to convert from federation format to client format
event_format: Callable[[JsonDict], JsonDict] = format_event_for_client_v1
# ID of the user's auth token - used for namespacing of transaction IDs
token_id: Optional[int] = None
# List of event fields to include. If empty, all fields will be returned.
only_event_fields: Optional[List[str]] = None
# Some events can have stripped room state stored in the `unsigned` field.
# This is required for invite and knock functionality. If this option is
# False, that state will be removed from the event before it is returned.
# Otherwise, it will be kept.
include_stripped_room_state: bool = False
_DEFAULT_SERIALIZE_EVENT_CONFIG = SerializeEventConfig()
def serialize_event(
e: Union[JsonDict, EventBase],
time_now_ms: int,
*,
config: SerializeEventConfig = _DEFAULT_SERIALIZE_EVENT_CONFIG,
) -> JsonDict:
"""Serialize event for clients
Args:
e
time_now_ms
config: Event serialization config
Returns:
The serialized event dictionary.
"""
# FIXME(erikj): To handle the case of presence events and the like
if not isinstance(e, EventBase):
return e
time_now_ms = int(time_now_ms)
# Should this strip out None's?
d = {k: v for k, v in e.get_dict().items()}
d["event_id"] = e.event_id
if "age_ts" in d["unsigned"]:
d["unsigned"]["age"] = time_now_ms - d["unsigned"]["age_ts"]
del d["unsigned"]["age_ts"]
if "redacted_because" in e.unsigned:
d["unsigned"]["redacted_because"] = serialize_event(
e.unsigned["redacted_because"], time_now_ms, config=config
)
if config.token_id is not None:
if config.token_id == getattr(e.internal_metadata, "token_id", None):
txn_id = getattr(e.internal_metadata, "txn_id", None)
if txn_id is not None:
d["unsigned"]["transaction_id"] = txn_id
# invite_room_state and knock_room_state are a list of stripped room state events
# that are meant to provide metadata about a room to an invitee/knocker. They are
# intended to only be included in specific circumstances, such as down sync, and
# should not be included in any other case.
if not config.include_stripped_room_state:
d["unsigned"].pop("invite_room_state", None)
d["unsigned"].pop("knock_room_state", None)
if config.as_client_event:
d = config.event_format(d)
only_event_fields = config.only_event_fields
if only_event_fields:
if not isinstance(only_event_fields, list) or not all(
isinstance(f, str) for f in only_event_fields
):
raise TypeError("only_event_fields must be a list of strings")
d = only_fields(d, only_event_fields)
return d
class EventClientSerializer:
"""Serializes events that are to be sent to clients.
This is used for bundling extra information with any events to be sent to
clients.
"""
def serialize_event(
self,
event: Union[JsonDict, EventBase],
time_now: int,
*,
config: SerializeEventConfig = _DEFAULT_SERIALIZE_EVENT_CONFIG,
bundle_aggregations: Optional[Dict[str, "BundledAggregations"]] = None,
apply_edits: bool = True,
) -> JsonDict:
"""Serializes a single event.
Args:
event: The event being serialized.
time_now: The current time in milliseconds
config: Event serialization config
bundle_aggregations: A map from event_id to the aggregations to be bundled
into the event.
apply_edits: Whether the content of the event should be modified to reflect
any replacement in `bundle_aggregations[<event_id>].replace`.
Returns:
The serialized event
"""
# To handle the case of presence events and the like
if not isinstance(event, EventBase):
return event
serialized_event = serialize_event(event, time_now, config=config)
# Check if there are any bundled aggregations to include with the event.
if bundle_aggregations:
event_aggregations = bundle_aggregations.get(event.event_id)
if event_aggregations:
self._inject_bundled_aggregations(
event,
time_now,
config,
event_aggregations,
serialized_event,
apply_edits=apply_edits,
)
return serialized_event
def _apply_edit(
self, orig_event: EventBase, serialized_event: JsonDict, edit: EventBase
) -> None:
"""Replace the content, preserving existing relations of the serialized event.
Args:
orig_event: The original event.
serialized_event: The original event, serialized. This is modified.
edit: The event which edits the above.
"""
# Ensure we take copies of the edit content, otherwise we risk modifying
# the original event.
edit_content = edit.content.copy()
# Unfreeze the event content if necessary, so that we may modify it below
edit_content = unfreeze(edit_content)
serialized_event["content"] = edit_content.get("m.new_content", {})
# Check for existing relations
relates_to = orig_event.content.get("m.relates_to")
if relates_to:
# Keep the relations, ensuring we use a dict copy of the original
serialized_event["content"]["m.relates_to"] = relates_to.copy()
else:
serialized_event["content"].pop("m.relates_to", None)
def _inject_bundled_aggregations(
self,
event: EventBase,
time_now: int,
config: SerializeEventConfig,
aggregations: "BundledAggregations",
serialized_event: JsonDict,
apply_edits: bool,
) -> None:
"""Potentially injects bundled aggregations into the unsigned portion of the serialized event.
Args:
event: The event being serialized.
time_now: The current time in milliseconds
aggregations: The bundled aggregation to serialize.
serialized_event: The serialized event which may be modified.
config: Event serialization config
apply_edits: Whether the content of the event should be modified to reflect
any replacement in `aggregations.replace`.
"""
serialized_aggregations = {}
if aggregations.annotations:
serialized_aggregations[RelationTypes.ANNOTATION] = aggregations.annotations
if aggregations.references:
serialized_aggregations[RelationTypes.REFERENCE] = aggregations.references
if aggregations.replace:
# If there is an edit, optionally apply it to the event.
edit = aggregations.replace
if apply_edits:
self._apply_edit(event, serialized_event, edit)
# Include information about it in the relations dict.
serialized_aggregations[RelationTypes.REPLACE] = {
"event_id": edit.event_id,
"origin_server_ts": edit.origin_server_ts,
"sender": edit.sender,
}
# If this event is the start of a thread, include a summary of the replies.
if aggregations.thread:
thread = aggregations.thread
# Don't bundle aggregations as this could recurse forever.
serialized_latest_event = serialize_event(
thread.latest_event, time_now, config=config
)
# Manually apply an edit, if one exists.
if thread.latest_edit:
self._apply_edit(
thread.latest_event, serialized_latest_event, thread.latest_edit
)
thread_summary = {
"latest_event": serialized_latest_event,
"count": thread.count,
"current_user_participated": thread.current_user_participated,
}
serialized_aggregations[RelationTypes.THREAD] = thread_summary
# Include the bundled aggregations in the event.
if serialized_aggregations:
# There is likely already an "unsigned" field, but a filter might
# have stripped it off (via the event_fields option). The server is
# allowed to return additional fields, so add it back.
serialized_event.setdefault("unsigned", {}).setdefault(
"m.relations", {}
).update(serialized_aggregations)
def serialize_events(
self,
events: Iterable[Union[JsonDict, EventBase]],
time_now: int,
*,
config: SerializeEventConfig = _DEFAULT_SERIALIZE_EVENT_CONFIG,
bundle_aggregations: Optional[Dict[str, "BundledAggregations"]] = None,
) -> List[JsonDict]:
"""Serializes multiple events.
Args:
event
time_now: The current time in milliseconds
config: Event serialization config
bundle_aggregations: Whether to include the bundled aggregations for this
event. Only applies to non-state events. (State events never include
bundled aggregations.)
Returns:
The list of serialized events
"""
return [
self.serialize_event(
event,
time_now,
config=config,
bundle_aggregations=bundle_aggregations,
)
for event in events
]
def copy_power_levels_contents(
old_power_levels: Mapping[str, Union[int, Mapping[str, int]]]
) -> Dict[str, Union[int, Dict[str, int]]]:
"""Copy the content of a power_levels event, unfreezing frozendicts along the way
Raises:
TypeError if the input does not look like a valid power levels event content
"""
if not isinstance(old_power_levels, collections.abc.Mapping):
raise TypeError("Not a valid power-levels content: %r" % (old_power_levels,))
power_levels: Dict[str, Union[int, Dict[str, int]]] = {}
for k, v in old_power_levels.items():
if isinstance(v, int):
power_levels[k] = v
continue
if isinstance(v, collections.abc.Mapping):
h: Dict[str, int] = {}
power_levels[k] = h
for k1, v1 in v.items():
# we should only have one level of nesting
if not isinstance(v1, int):
raise TypeError(
"Invalid power_levels value for %s.%s: %r" % (k, k1, v1)
)
h[k1] = v1
continue
raise TypeError("Invalid power_levels value for %s: %r" % (k, v))
return power_levels
def validate_canonicaljson(value: Any) -> None:
"""
Ensure that the JSON object is valid according to the rules of canonical JSON.
See the appendix section 3.1: Canonical JSON.
This rejects JSON that has:
* An integer outside the range of [-2 ^ 53 + 1, 2 ^ 53 - 1]
* Floats
* NaN, Infinity, -Infinity
"""
if isinstance(value, int):
if value < CANONICALJSON_MIN_INT or CANONICALJSON_MAX_INT < value:
raise SynapseError(400, "JSON integer out of range", Codes.BAD_JSON)
elif isinstance(value, float):
# Note that Infinity, -Infinity, and NaN are also considered floats.
raise SynapseError(400, "Bad JSON value: float", Codes.BAD_JSON)
elif isinstance(value, (dict, frozendict)):
for v in value.values():
validate_canonicaljson(v)
elif isinstance(value, (list, tuple)):
for i in value:
validate_canonicaljson(i)
elif not isinstance(value, (bool, str)) and value is not None:
# Other potential JSON values (bool, None, str) are safe.
raise SynapseError(400, "Unknown JSON value", Codes.BAD_JSON)