298 lines
9.5 KiB
Python
298 lines
9.5 KiB
Python
# Copyright 2014-2016 OpenMarket Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import logging
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from typing import TYPE_CHECKING, Any, Dict, List, Optional, Tuple, Union
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import attr
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from signedjson.types import SigningKey
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from synapse.api.constants import MAX_DEPTH
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from synapse.api.room_versions import (
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KNOWN_EVENT_FORMAT_VERSIONS,
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EventFormatVersions,
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RoomVersion,
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)
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from synapse.crypto.event_signing import add_hashes_and_signatures
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from synapse.event_auth import auth_types_for_event
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from synapse.events import EventBase, _EventInternalMetadata, make_event_from_dict
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from synapse.state import StateHandler
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from synapse.storage.databases.main import DataStore
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from synapse.storage.state import StateFilter
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from synapse.types import EventID, JsonDict
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from synapse.util import Clock
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from synapse.util.stringutils import random_string
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if TYPE_CHECKING:
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from synapse.handlers.event_auth import EventAuthHandler
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from synapse.server import HomeServer
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logger = logging.getLogger(__name__)
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@attr.s(slots=True, cmp=False, frozen=True, auto_attribs=True)
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class EventBuilder:
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"""A format independent event builder used to build up the event content
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before signing the event.
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(Note that while objects of this class are frozen, the
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content/unsigned/internal_metadata fields are still mutable)
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Attributes:
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room_version: Version of the target room
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room_id
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type
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sender
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content
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unsigned
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internal_metadata
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_state
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_auth
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_store
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_clock
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_hostname: The hostname of the server creating the event
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_signing_key: The signing key to use to sign the event as the server
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"""
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_state: StateHandler
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_event_auth_handler: "EventAuthHandler"
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_store: DataStore
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_clock: Clock
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_hostname: str
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_signing_key: SigningKey
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room_version: RoomVersion
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room_id: str
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type: str
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sender: str
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content: JsonDict = attr.Factory(dict)
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unsigned: JsonDict = attr.Factory(dict)
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# These only exist on a subset of events, so they raise AttributeError if
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# someone tries to get them when they don't exist.
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_state_key: Optional[str] = None
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_redacts: Optional[str] = None
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_origin_server_ts: Optional[int] = None
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internal_metadata: _EventInternalMetadata = attr.Factory(
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lambda: _EventInternalMetadata({})
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)
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@property
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def state_key(self) -> str:
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if self._state_key is not None:
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return self._state_key
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raise AttributeError("state_key")
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def is_state(self) -> bool:
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return self._state_key is not None
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async def build(
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self,
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prev_event_ids: List[str],
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auth_event_ids: Optional[List[str]],
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depth: Optional[int] = None,
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) -> EventBase:
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"""Transform into a fully signed and hashed event
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Args:
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prev_event_ids: The event IDs to use as the prev events
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auth_event_ids: The event IDs to use as the auth events.
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Should normally be set to None, which will cause them to be calculated
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based on the room state at the prev_events.
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depth: Override the depth used to order the event in the DAG.
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Should normally be set to None, which will cause the depth to be calculated
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based on the prev_events.
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Returns:
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The signed and hashed event.
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"""
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if auth_event_ids is None:
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state_ids = await self._state.compute_state_after_events(
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self.room_id,
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prev_event_ids,
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state_filter=StateFilter.from_types(
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auth_types_for_event(self.room_version, self)
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),
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)
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auth_event_ids = self._event_auth_handler.compute_auth_events(
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self, state_ids
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)
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format_version = self.room_version.event_format
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# The types of auth/prev events changes between event versions.
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prev_events: Union[List[str], List[Tuple[str, Dict[str, str]]]]
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auth_events: Union[List[str], List[Tuple[str, Dict[str, str]]]]
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if format_version == EventFormatVersions.ROOM_V1_V2:
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auth_events = await self._store.add_event_hashes(auth_event_ids)
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prev_events = await self._store.add_event_hashes(prev_event_ids)
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else:
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auth_events = auth_event_ids
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prev_events = prev_event_ids
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# Otherwise, progress the depth as normal
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if depth is None:
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(
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_,
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most_recent_prev_event_depth,
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) = await self._store.get_max_depth_of(prev_event_ids)
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depth = most_recent_prev_event_depth + 1
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# we cap depth of generated events, to ensure that they are not
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# rejected by other servers (and so that they can be persisted in
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# the db)
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depth = min(depth, MAX_DEPTH)
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event_dict: Dict[str, Any] = {
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"auth_events": auth_events,
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"prev_events": prev_events,
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"type": self.type,
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"room_id": self.room_id,
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"sender": self.sender,
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"content": self.content,
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"unsigned": self.unsigned,
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"depth": depth,
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}
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if self.is_state():
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event_dict["state_key"] = self._state_key
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if self._redacts is not None:
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event_dict["redacts"] = self._redacts
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if self._origin_server_ts is not None:
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event_dict["origin_server_ts"] = self._origin_server_ts
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return create_local_event_from_event_dict(
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clock=self._clock,
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hostname=self._hostname,
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signing_key=self._signing_key,
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room_version=self.room_version,
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event_dict=event_dict,
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internal_metadata_dict=self.internal_metadata.get_dict(),
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)
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class EventBuilderFactory:
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def __init__(self, hs: "HomeServer"):
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self.clock = hs.get_clock()
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self.hostname = hs.hostname
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self.signing_key = hs.signing_key
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self.store = hs.get_datastores().main
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self.state = hs.get_state_handler()
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self._event_auth_handler = hs.get_event_auth_handler()
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def for_room_version(
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self, room_version: RoomVersion, key_values: dict
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) -> EventBuilder:
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"""Generate an event builder appropriate for the given room version
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Args:
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room_version:
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Version of the room that we're creating an event builder for
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key_values: Fields used as the basis of the new event
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Returns:
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EventBuilder
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"""
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return EventBuilder(
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store=self.store,
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state=self.state,
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event_auth_handler=self._event_auth_handler,
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clock=self.clock,
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hostname=self.hostname,
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signing_key=self.signing_key,
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room_version=room_version,
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type=key_values["type"],
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state_key=key_values.get("state_key"),
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room_id=key_values["room_id"],
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sender=key_values["sender"],
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content=key_values.get("content", {}),
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unsigned=key_values.get("unsigned", {}),
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redacts=key_values.get("redacts", None),
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origin_server_ts=key_values.get("origin_server_ts", None),
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)
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def create_local_event_from_event_dict(
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clock: Clock,
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hostname: str,
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signing_key: SigningKey,
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room_version: RoomVersion,
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event_dict: JsonDict,
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internal_metadata_dict: Optional[JsonDict] = None,
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) -> EventBase:
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"""Takes a fully formed event dict, ensuring that fields like `origin`
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and `origin_server_ts` have correct values for a locally produced event,
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then signs and hashes it.
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"""
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format_version = room_version.event_format
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if format_version not in KNOWN_EVENT_FORMAT_VERSIONS:
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raise Exception("No event format defined for version %r" % (format_version,))
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if internal_metadata_dict is None:
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internal_metadata_dict = {}
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time_now = int(clock.time_msec())
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if format_version == EventFormatVersions.ROOM_V1_V2:
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event_dict["event_id"] = _create_event_id(clock, hostname)
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event_dict["origin"] = hostname
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event_dict.setdefault("origin_server_ts", time_now)
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event_dict.setdefault("unsigned", {})
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age = event_dict["unsigned"].pop("age", 0)
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event_dict["unsigned"].setdefault("age_ts", time_now - age)
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event_dict.setdefault("signatures", {})
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add_hashes_and_signatures(room_version, event_dict, hostname, signing_key)
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return make_event_from_dict(
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event_dict, room_version, internal_metadata_dict=internal_metadata_dict
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)
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# A counter used when generating new event IDs
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_event_id_counter = 0
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def _create_event_id(clock: Clock, hostname: str) -> str:
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"""Create a new event ID
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Args:
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clock
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hostname: The server name for the event ID
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Returns:
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The new event ID
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"""
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global _event_id_counter
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i = str(_event_id_counter)
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_event_id_counter += 1
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local_part = str(int(clock.time())) + i + random_string(5)
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e_id = EventID(local_part, hostname)
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return e_id.to_string()
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