MatrixSynapse/synapse/events/utils.py

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# Copyright 2014-2016 OpenMarket Ltd
# Copyright 2021 The Matrix.org Foundation C.I.C.
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#
# 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
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import re
from typing import (
TYPE_CHECKING,
Any,
Callable,
Dict,
Iterable,
List,
Mapping,
Match,
MutableMapping,
Optional,
Union,
)
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import attr
from canonicaljson import encode_canonical_json
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from synapse.api.constants import (
MAX_PDU_SIZE,
EventContentFields,
EventTypes,
RelationTypes,
)
from synapse.api.errors import Codes, SynapseError
from synapse.api.room_versions import RoomVersion
from synapse.types import JsonDict, Requester
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from . import EventBase
if TYPE_CHECKING:
from synapse.handlers.relations import BundledAggregations
# Split strings on "." but not "\." (or "\\\.").
SPLIT_FIELD_REGEX = re.compile(r"\\*\.")
# Find escaped characters, e.g. those with a \ in front of them.
ESCAPE_SEQUENCE_PATTERN = re.compile(r"\\(.)")
CANONICALJSON_MAX_INT = (2**53) - 1
CANONICALJSON_MIN_INT = -CANONICALJSON_MAX_INT
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def prune_event(event: EventBase) -> EventBase:
"""Returns a pruned version of the given event, which removes all keys we
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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
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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
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"""
allowed_keys = [
"event_id",
"sender",
"room_id",
"hashes",
"signatures",
"content",
"type",
"state_key",
"depth",
"prev_events",
"auth_events",
"origin_server_ts",
]
# Earlier room versions from had additional allowed keys.
if not room_version.updated_redaction_rules:
allowed_keys.extend(["prev_state", "membership", "origin"])
event_type = event_dict["type"]
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new_content = {}
def add_fields(*fields: str) -> None:
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for field in fields:
if field in event_dict["content"]:
new_content[field] = event_dict["content"][field]
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if event_type == EventTypes.Member:
add_fields("membership")
if room_version.restricted_join_rule_fix:
add_fields(EventContentFields.AUTHORISING_USER)
if room_version.updated_redaction_rules:
# Preserve the signed field under third_party_invite.
third_party_invite = event_dict["content"].get("third_party_invite")
if isinstance(third_party_invite, collections.abc.Mapping):
new_content["third_party_invite"] = {}
if "signed" in third_party_invite:
new_content["third_party_invite"]["signed"] = third_party_invite[
"signed"
]
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elif event_type == EventTypes.Create:
if room_version.updated_redaction_rules:
# MSC2176 rules state that create events cannot have their `content` redacted.
new_content = event_dict["content"]
elif not room_version.implicit_room_creator:
# Some room versions give meaning to `creator`
add_fields("creator")
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elif event_type == EventTypes.JoinRules:
add_fields("join_rule")
if room_version.restricted_join_rule:
add_fields("allow")
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elif event_type == EventTypes.PowerLevels:
add_fields(
"users",
"users_default",
"events",
"events_default",
"state_default",
"ban",
"kick",
"redact",
)
if room_version.updated_redaction_rules:
add_fields("invite")
elif event_type == EventTypes.Aliases and room_version.special_case_aliases_auth:
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add_fields("aliases")
elif event_type == EventTypes.RoomHistoryVisibility:
add_fields("history_visibility")
elif event_type == EventTypes.Redaction and room_version.updated_redaction_rules:
add_fields("redacts")
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# Protect the rel_type and event_id fields under the m.relates_to field.
if room_version.msc3389_relation_redactions:
relates_to = event_dict["content"].get("m.relates_to")
if isinstance(relates_to, collections.abc.Mapping):
new_relates_to = {}
for field in ("rel_type", "event_id"):
if field in relates_to:
new_relates_to[field] = relates_to[field]
# Only include a non-empty relates_to field.
if new_relates_to:
new_content["m.relates_to"] = new_relates_to
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allowed_fields = {k: v for k, v in event_dict.items() if k in allowed_keys}
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allowed_fields["content"] = new_content
unsigned: JsonDict = {}
allowed_fields["unsigned"] = unsigned
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event_unsigned = event_dict.get("unsigned", {})
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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 isinstance(
sub_dict[sub_field], collections.abc.Mapping
):
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:
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sub_out_dict = sub_out_dict.setdefault(sub_field, {})
sub_out_dict[key_to_move] = sub_dict[key_to_move]
def _escape_slash(m: Match[str]) -> str:
"""
Replacement function; replace a backslash-backslash or backslash-dot with the
second character. Leaves any other string alone.
"""
if m.group(1) in ("\\", "."):
return m.group(1)
return m.group(0)
def _split_field(field: str) -> List[str]:
"""
Splits strings on unescaped dots and removes escaping.
Args:
field: A string representing a path to a field.
Returns:
A list of nested fields to traverse.
"""
# Convert the field and remove escaping:
#
# 1. "content.body.thing\.with\.dots"
# 2. ["content", "body", "thing\.with\.dots"]
# 3. ["content", "body", "thing.with.dots"]
# Find all dots (and their preceding backslashes). If the dot is unescaped
# then emit a new field part.
result = []
prev_start = 0
for match in SPLIT_FIELD_REGEX.finditer(field):
# If the match is an *even* number of characters than the dot was escaped.
if len(match.group()) % 2 == 0:
continue
# Add a new part (up to the dot, exclusive) after escaping.
result.append(
ESCAPE_SEQUENCE_PATTERN.sub(
_escape_slash, field[prev_start : match.end() - 1]
)
)
prev_start = match.end()
# Add any part of the field after the last unescaped dot. (Note that if the
# character is a dot this correctly adds a blank string.)
result.append(re.sub(r"\\(.)", _escape_slash, field[prev_start:]))
return result
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.
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The entries may include '.' characters to indicate sub-fields.
So ['content.body'] will include the 'body' field of the 'content' object.
A literal '.' or '\' 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(f) for f in 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 = (
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"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 = (
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"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
# The entity that requested the event. This is used to determine whether to include
# the transaction_id in the unsigned section of the event.
requester: Optional[Requester] = 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()
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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.
"""
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# 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 = dict(e.get_dict().items())
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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"]
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if "redacted_because" in e.unsigned:
d["unsigned"]["redacted_because"] = serialize_event(
e.unsigned["redacted_because"],
time_now_ms,
config=config,
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)
# If we have a txn_id saved in the internal_metadata, we should include it in the
# unsigned section of the event if it was sent by the same session as the one
# requesting the event.
txn_id: Optional[str] = getattr(e.internal_metadata, "txn_id", None)
if (
txn_id is not None
and config.requester is not None
and config.requester.user.to_string() == e.sender
):
# Some events do not have the device ID stored in the internal metadata,
# this includes old events as well as those created by appservice, guests,
# or with tokens minted with the admin API. For those events, fallback
# to using the access token instead.
event_device_id: Optional[str] = getattr(e.internal_metadata, "device_id", None)
if event_device_id is not None:
if event_device_id == config.requester.device_id:
d["unsigned"]["transaction_id"] = txn_id
else:
# Fallback behaviour: only include the transaction ID if the event
# was sent from the same access token.
#
# For regular users, the access token ID can be used to determine this.
# This includes access tokens minted with the admin API.
#
# For guests and appservice users, we can't check the access token ID
# so assume it is the same session.
event_token_id: Optional[int] = getattr(
e.internal_metadata, "token_id", None
)
if (
(
event_token_id is not None
and config.requester.access_token_id is not None
and event_token_id == config.requester.access_token_id
)
or config.requester.is_guest
or config.requester.app_service
):
d["unsigned"]["transaction_id"] = txn_id
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# 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:
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d["unsigned"].pop("invite_room_state", None)
d["unsigned"].pop("knock_room_state", None)
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if config.as_client_event:
d = config.event_format(d)
# If the event is a redaction, the field with the redacted event ID appears
# in a different location depending on the room version. e.redacts handles
# fetching from the proper location; copy it to the other location for forwards-
# and backwards-compatibility with clients.
if e.type == EventTypes.Redaction and e.redacts is not None:
if e.room_version.updated_redaction_rules:
d["redacts"] = e.redacts
else:
d["content"] = dict(d["content"])
d["content"]["redacts"] = e.redacts
only_event_fields = config.only_event_fields
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if only_event_fields:
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if not isinstance(only_event_fields, list) or not all(
isinstance(f, str) for f in only_event_fields
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):
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raise TypeError("only_event_fields must be a list of strings")
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d = only_fields(d, only_event_fields)
return d
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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,
) -> 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.
Returns:
The serialized event
"""
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# To handle the case of presence events and the like
if not isinstance(event, EventBase):
return event
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serialized_event = serialize_event(event, time_now, config=config)
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# Check if there are any bundled aggregations to include with the event.
if bundle_aggregations:
if event.event_id in bundle_aggregations:
self._inject_bundled_aggregations(
event,
time_now,
config,
bundle_aggregations,
serialized_event,
)
return serialized_event
def _inject_bundled_aggregations(
self,
event: EventBase,
time_now: int,
config: SerializeEventConfig,
bundled_aggregations: Dict[str, "BundledAggregations"],
serialized_event: JsonDict,
) -> 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
config: Event serialization config
bundled_aggregations: Bundled aggregations to be injected.
A map from event_id to aggregation data. Must contain at least an
entry for `event`.
While serializing the bundled aggregations this map may be searched
again for additional events in a recursive manner.
serialized_event: The serialized event which may be modified.
"""
# We have already checked that aggregations exist for this event.
event_aggregations = bundled_aggregations[event.event_id]
# The JSON dictionary to be added under the unsigned property of the event
# being serialized.
serialized_aggregations = {}
if event_aggregations.references:
serialized_aggregations[
RelationTypes.REFERENCE
] = event_aggregations.references
if event_aggregations.replace:
# Include information about it in the relations dict.
#
# Matrix spec v1.5 (https://spec.matrix.org/v1.5/client-server-api/#server-side-aggregation-of-mreplace-relationships)
# said that we should only include the `event_id`, `origin_server_ts` and
# `sender` of the edit; however MSC3925 proposes extending it to the whole
# of the edit, which is what we do here.
serialized_aggregations[RelationTypes.REPLACE] = self.serialize_event(
event_aggregations.replace,
time_now,
config=config,
)
# Include any threaded replies to this event.
if event_aggregations.thread:
thread = event_aggregations.thread
serialized_latest_event = self.serialize_event(
thread.latest_event,
time_now,
config=config,
bundle_aggregations=bundled_aggregations,
)
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
]
_PowerLevel = Union[str, int]
PowerLevelsContent = Mapping[str, Union[_PowerLevel, Mapping[str, _PowerLevel]]]
def copy_and_fixup_power_levels_contents(
old_power_levels: PowerLevelsContent,
) -> Dict[str, Union[int, Dict[str, int]]]:
"""Copy the content of a power_levels event, unfreezing immutabledicts along the way.
We accept as input power level values which are strings, provided they represent an
integer, e.g. `"`100"` instead of 100. Such strings are converted to integers
in the returned dictionary (hence "fixup" in the function name).
Note that future room versions will outlaw such stringy power levels (see
https://github.com/matrix-org/matrix-spec/issues/853).
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, collections.abc.Mapping):
h: Dict[str, int] = {}
power_levels[k] = h
for k1, v1 in v.items():
_copy_power_level_value_as_integer(v1, h, k1)
else:
_copy_power_level_value_as_integer(v, power_levels, k)
return power_levels
def _copy_power_level_value_as_integer(
old_value: object,
power_levels: MutableMapping[str, Any],
key: str,
) -> None:
"""Set `power_levels[key]` to the integer represented by `old_value`.
:raises TypeError: if `old_value` is neither an integer nor a base-10 string
representation of an integer.
"""
if type(old_value) is int: # noqa: E721
power_levels[key] = old_value
return
if isinstance(old_value, str):
try:
parsed_value = int(old_value, base=10)
except ValueError:
# Fall through to the final TypeError.
pass
else:
power_levels[key] = parsed_value
return
raise TypeError(f"Invalid power_levels value for {key}: {old_value}")
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 type(value) is int: # noqa: E721
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, collections.abc.Mapping):
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)
def maybe_upsert_event_field(
event: EventBase, container: JsonDict, key: str, value: object
) -> bool:
"""Upsert an event field, but only if this doesn't make the event too large.
Returns true iff the upsert took place.
"""
if key in container:
old_value: object = container[key]
container[key] = value
# NB: here and below, we assume that passing a non-None `time_now` argument to
# get_pdu_json doesn't increase the size of the encoded result.
upsert_okay = len(encode_canonical_json(event.get_pdu_json())) <= MAX_PDU_SIZE
if not upsert_okay:
container[key] = old_value
else:
container[key] = value
upsert_okay = len(encode_canonical_json(event.get_pdu_json())) <= MAX_PDU_SIZE
if not upsert_okay:
del container[key]
return upsert_okay