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be47cfa9c9
This is so that everything is done in one place, making it easier to change the event format based on room version
279 lines
8 KiB
Python
279 lines
8 KiB
Python
# -*- coding: utf-8 -*-
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# 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 attr
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from twisted.internet import defer
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from synapse.api.constants import (
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KNOWN_EVENT_FORMAT_VERSIONS,
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KNOWN_ROOM_VERSIONS,
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MAX_DEPTH,
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)
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from synapse.crypto.event_signing import add_hashes_and_signatures
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from synapse.types import EventID
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from synapse.util.stringutils import random_string
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from . import (
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_EventInternalMetadata,
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event_type_from_format_version,
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room_version_to_event_format,
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)
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@attr.s(slots=True, cmp=False, frozen=True)
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class EventBuilder(object):
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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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format_version (int): Event format version
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room_id (str)
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type (str)
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sender (str)
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content (dict)
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unsigned (dict)
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internal_metadata (_EventInternalMetadata)
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_state (StateHandler)
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_auth (synapse.api.Auth)
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_store (DataStore)
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_clock (Clock)
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_hostname (str): 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 = attr.ib()
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_auth = attr.ib()
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_store = attr.ib()
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_clock = attr.ib()
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_hostname = attr.ib()
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_signing_key = attr.ib()
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format_version = attr.ib()
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room_id = attr.ib()
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type = attr.ib()
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sender = attr.ib()
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content = attr.ib(default=attr.Factory(dict))
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unsigned = attr.ib(default=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 = attr.ib(default=None)
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_redacts = attr.ib(default=None)
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internal_metadata = attr.ib(default=attr.Factory(lambda: _EventInternalMetadata({})))
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@property
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def state_key(self):
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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):
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return self._state_key is not None
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@defer.inlineCallbacks
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def build(self, prev_event_ids):
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"""Transform into a fully signed and hashed event
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Args:
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prev_event_ids (list[str]): The event IDs to use as the prev events
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Returns:
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Deferred[FrozenEvent]
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"""
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state_ids = yield self._state.get_current_state_ids(
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self.room_id, prev_event_ids,
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)
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auth_ids = yield self._auth.compute_auth_events(
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self, state_ids,
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)
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auth_events = yield self._store.add_event_hashes(auth_ids)
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prev_events = yield self._store.add_event_hashes(prev_event_ids)
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old_depth = yield self._store.get_max_depth_of(
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prev_event_ids,
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)
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depth = old_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 = {
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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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"prev_state": [],
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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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defer.returnValue(
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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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format_version=self.format_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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)
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class EventBuilderFactory(object):
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def __init__(self, hs):
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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.config.signing_key[0]
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self.store = hs.get_datastore()
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self.state = hs.get_state_handler()
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self.auth = hs.get_auth()
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def new(self, room_version, key_values):
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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 (str): Version of the room that we're creating an
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event builder for
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key_values (dict): 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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# There's currently only the one event version defined
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if room_version not in KNOWN_ROOM_VERSIONS:
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raise Exception(
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"No event format defined for version %r" % (room_version,)
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)
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key_values["event_id"] = _create_event_id(self.clock, self.hostname)
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return EventBuilder(
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store=self.store,
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state=self.state,
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auth=self.auth,
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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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format_version=room_version_to_event_format(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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)
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def create_local_event_from_event_dict(clock, hostname, signing_key,
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format_version, event_dict,
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internal_metadata_dict=None):
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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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Args:
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clock (Clock)
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hostname (str)
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signing_key
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format_version (int)
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event_dict (dict)
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internal_metadata_dict (dict|None)
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Returns:
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FrozenEvent
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"""
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# There's currently only the one event version defined
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if format_version not in KNOWN_EVENT_FORMAT_VERSIONS:
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raise Exception(
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"No event format defined for version %r" % (format_version,)
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)
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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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event_dict["event_id"] = _create_event_id(clock, hostname)
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event_dict["origin"] = hostname
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event_dict["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(
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event_dict,
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hostname,
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signing_key,
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)
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return event_type_from_format_version(format_version)(
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event_dict, 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, hostname):
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"""Create a new event ID
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Args:
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clock (Clock)
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hostname (str): The server name for the event ID
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Returns:
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str
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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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