OpenSlides/openslides/utils/websocket.py

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from collections import defaultdict
from typing import Any, Dict, List, Optional
import jsonschema
from channels.generic.websocket import AsyncJsonWebsocketConsumer
from websockets.exceptions import ConnectionClosed
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from .autoupdate import AutoupdateFormat
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from .cache import element_cache
from .utils import split_element_id
# Custom Websocket error codes (not to be confused with the websocket *connection*
# status codes like 1000 or 1006. These are custom ones for OpenSlides to give a
# machine parseable response, so the client can react on errors.
WEBSOCKET_NOT_AUTHORIZED = 100
# E.g. if a user does not have the right permission(s) for a message.
WEBSOCKET_CHANGE_ID_TOO_HIGH = 101
# If data is requested and the given change id is higher than the highest change id
# from the element_cache.
WEBSOCKET_WRONG_FORMAT = 10
# If the recieved data has not the expected format.
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class ProtocollAsyncJsonWebsocketConsumer(AsyncJsonWebsocketConsumer):
"""
Mixin for JSONWebsocketConsumers, that speaks the a special protocol.
"""
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async def send_json(
self,
type: str,
content: Any,
id: Optional[str] = None,
in_response: Optional[str] = None,
silence_errors: Optional[bool] = True,
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) -> None:
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"""
Sends the data with the type.
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If silence_errors is True (default), all ConnectionClosed
and runtime errors during sending will be ignored.
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"""
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out = {"type": type, "content": content}
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if id:
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out["id"] = id
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if in_response:
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out["in_response"] = in_response
try:
await super().send_json(out)
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except (ConnectionClosed, RuntimeError) as e:
# The ConnectionClosed error is thrown by the websocket lib: websocket/protocol.py in ensure_open
# `websockets.exceptions.ConnectionClosed: WebSocket connection is closed: code = 1005
# (no status code [internal]), no reason` (Also with other codes)
# The RuntimeError is thrown by uvicorn: uvicorn/protocols/websockets/websockets_impl.py in asgi_send
# `RuntimeError: Unexpected ASGI message 'websocket.send', after sending 'websocket.close'`
if not silence_errors:
raise e
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async def send_error(
self,
code: int,
message: str,
in_response: Optional[str] = None,
silence_errors: Optional[bool] = True,
) -> None:
"""
Send generic error messages with a custom status code (see above) and a text message.
"""
await self.send_json(
"error",
{"code": code, "message": message},
None,
in_response=in_response,
silence_errors=silence_errors,
)
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async def receive_json(self, content: Any) -> None:
"""
Receives the json data, parses it and calls receive_content.
"""
try:
jsonschema.validate(content, schema)
except jsonschema.ValidationError as err:
try:
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in_response = content["id"]
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except (TypeError, KeyError):
# content is not a dict (TypeError) or has not the key id (KeyError)
in_response = None
await self.send_error(
code=WEBSOCKET_WRONG_FORMAT, message=str(err), in_response=in_response
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)
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return
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await websocket_client_messages[content["type"]].receive_content(
self, content["content"], id=content["id"]
)
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schema: Dict[str, Any] = {
"$schema": "http://json-schema.org/draft-07/schema#",
"title": "OpenSlidesWebsocketProtocol",
"description": "The packages that OpenSlides sends between the server and the client.",
"type": "object",
"properties": {
"type": {
"description": "Defines what kind of packages is packed.",
"type": "string",
},
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"content": {"description": "The content of the package."},
"id": {"description": "An identifier of the package.", "type": "string"},
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"in_response": {
"description": "The id of another package that the other part sent before.",
"type": "string",
},
},
"required": ["type", "content", "id"],
"anyOf": [], # This will be filled in register_client_message()
}
class BaseWebsocketClientMessage:
schema: Dict[str, object] = {}
"""
Optional schema.
If schema is not set, any value in content is accepted.
"""
identifier: str = ""
"""
A unique identifier for the websocket message.
This is used as value in the 'type' property in the websocket message.
"""
content_required = True
"""
Desiedes, if the content property is required.
"""
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async def receive_content(
self, consumer: "ProtocollAsyncJsonWebsocketConsumer", message: Any, id: str
) -> None:
raise NotImplementedError(
"WebsocketClientMessage needs the method receive_content()."
)
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websocket_client_messages: Dict[str, BaseWebsocketClientMessage] = {}
"""
Saves all websocket client message object ordered by there identifier.
"""
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def register_client_message(
websocket_client_message: BaseWebsocketClientMessage
) -> None:
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"""
Registers one websocket client message class.
"""
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if (
not websocket_client_message.identifier
or websocket_client_message.identifier in websocket_client_messages
):
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raise NotImplementedError("WebsocketClientMessage needs a unique identifier.")
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websocket_client_messages[
websocket_client_message.identifier
] = websocket_client_message
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# Add the message schema to the schema
message_schema: Dict[str, Any] = {
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"properties": {
"type": {"const": websocket_client_message.identifier},
"content": websocket_client_message.schema,
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}
}
if websocket_client_message.content_required:
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message_schema["required"] = ["content"]
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schema["anyOf"].append(message_schema)
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async def get_element_data(user_id: int, change_id: int = 0) -> AutoupdateFormat:
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"""
Returns all element data since a change_id.
"""
current_change_id = await element_cache.get_current_change_id()
if change_id > current_change_id:
raise ValueError(
f"Requested change_id {change_id} is higher this highest change_id {current_change_id}."
)
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try:
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changed_elements, deleted_element_ids = await element_cache.get_restricted_data(
user_id, change_id, current_change_id
)
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except RuntimeError:
# The change_id is lower the the lowerst change_id in redis. Return all data
changed_elements = await element_cache.get_all_restricted_data(user_id)
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all_data = True
deleted_elements: Dict[str, List[int]] = {}
else:
all_data = False
deleted_elements = defaultdict(list)
for element_id in deleted_element_ids:
collection_string, id = split_element_id(element_id)
deleted_elements[collection_string].append(id)
return AutoupdateFormat(
changed=changed_elements,
deleted=deleted_elements,
from_change_id=change_id,
to_change_id=current_change_id,
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all_data=all_data,
)