#-----------------------------------------------------------------------------
# Copyright (c) 2012 - 2022, Anaconda, Inc., and Bokeh Contributors.
# All rights reserved.
#
# The full license is in the file LICENSE.txt, distributed with this software.
#-----------------------------------------------------------------------------
''' Provide a web socket handler for the Bokeh Server application.
'''
#-----------------------------------------------------------------------------
# Boilerplate
#-----------------------------------------------------------------------------
from __future__ import annotations
import logging # isort:skip
log = logging.getLogger(__name__)
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------
# Standard library imports
import calendar
import datetime as dt
from typing import (
Any,
Dict,
List,
Union,
cast,
)
from urllib.parse import urlparse
# External imports
from tornado import locks, web
from tornado.websocket import WebSocketClosedError, WebSocketHandler
# Bokeh imports
from bokeh.settings import settings
from bokeh.util.token import check_token_signature, get_session_id, get_token_payload
# Bokeh imports
from ...protocol import Protocol
from ...protocol.exceptions import MessageError, ProtocolError, ValidationError
from ...protocol.message import Message
from ...protocol.receiver import Receiver
from ...util.dataclasses import dataclass
from ..protocol_handler import ProtocolHandler
from .auth_mixin import AuthMixin
#-----------------------------------------------------------------------------
# Globals and constants
#-----------------------------------------------------------------------------
__all__ = (
'WSHandler',
)
#-----------------------------------------------------------------------------
# General API
#-----------------------------------------------------------------------------
#-----------------------------------------------------------------------------
# Dev API
#-----------------------------------------------------------------------------
[docs]class WSHandler(AuthMixin, WebSocketHandler):
''' Implements a custom Tornado WebSocketHandler for the Bokeh Server.
'''
def __init__(self, tornado_app, *args, **kw) -> None:
self.receiver = None
self.handler = None
self.connection = None
self.application_context = kw['application_context']
self.latest_pong = -1
# write_lock allows us to lock the connection to send multiple
# messages atomically.
self.write_lock = locks.Lock()
self._token = None
self._compression_level = kw.pop('compression_level', None)
self._mem_level = kw.pop('mem_level', None)
# Note: tornado_app is stored as self.application
super().__init__(tornado_app, *args, **kw)
[docs] def initialize(self, application_context, bokeh_websocket_path):
pass
[docs] def check_origin(self, origin: str) -> bool:
''' Implement a check_origin policy for Tornado to call.
The supplied origin will be compared to the Bokeh server allowlist. If the
origin is not allow, an error will be logged and ``False`` will be returned.
Args:
origin (str) :
The URL of the connection origin
Returns:
bool, True if the connection is allowed, False otherwise
'''
from ..util import check_allowlist
parsed_origin = urlparse(origin)
origin_host = parsed_origin.netloc.lower()
allowed_hosts = self.application.websocket_origins
if settings.allowed_ws_origin():
allowed_hosts = set(settings.allowed_ws_origin())
allowed = check_allowlist(origin_host, allowed_hosts)
if allowed:
return True
else:
log.error("Refusing websocket connection from Origin '%s'; \
use --allow-websocket-origin=%s or set BOKEH_ALLOW_WS_ORIGIN=%s to permit this; currently we allow origins %r",
origin, origin_host, origin_host, allowed_hosts)
return False
[docs] @web.authenticated
def open(self) -> None:
''' Initialize a connection to a client.
Returns:
None
'''
log.info('WebSocket connection opened')
token = self._token
if self.selected_subprotocol != 'bokeh':
self.close()
raise ProtocolError("Subprotocol header is not 'bokeh'")
elif token is None:
self.close()
raise ProtocolError("No token received in subprotocol header")
now = calendar.timegm(dt.datetime.utcnow().utctimetuple())
payload = get_token_payload(token)
if 'session_expiry' not in payload:
self.close()
raise ProtocolError("Session expiry has not been provided")
elif now >= payload['session_expiry']:
self.close()
raise ProtocolError("Token is expired.")
elif not check_token_signature(token,
signed=self.application.sign_sessions,
secret_key=self.application.secret_key):
session_id = get_session_id(token)
log.error("Token for session %r had invalid signature", session_id)
raise ProtocolError("Invalid token signature")
try:
self.application.io_loop.add_callback(self._async_open, self._token)
except Exception as e:
# this isn't really an error (unless we have a
# bug), it just means a client disconnected
# immediately, most likely.
log.debug("Failed to fully open connection %r", e)
[docs] def select_subprotocol(self, subprotocols: List[str]) -> str | None:
log.debug('Subprotocol header received')
log.trace('Supplied subprotocol headers: %r', subprotocols)
if not len(subprotocols) == 2:
return None
self._token = subprotocols[1]
return subprotocols[0]
[docs] def get_compression_options(self) -> Dict[str, Any] | None:
if self._compression_level is None:
return None
options = {'compression_level': self._compression_level}
if self._mem_level is not None:
options['mem_level'] = self._mem_level
return options
async def _async_open(self, token: str) -> None:
''' Perform the specific steps needed to open a connection to a Bokeh session
Specifically, this method coordinates:
* Getting a session for a session ID (creating a new one if needed)
* Creating a protocol receiver and handler
* Opening a new ServerConnection and sending it an ACK
Args:
session_id (str) :
A session ID to for a session to connect to
If no session exists with the given ID, a new session is made
Returns:
None
'''
try:
session_id = get_session_id(token)
await self.application_context.create_session_if_needed(session_id, self.request, token)
session = self.application_context.get_session(session_id)
protocol = Protocol()
self.receiver = Receiver(protocol)
log.debug("Receiver created for %r", protocol)
self.handler = ProtocolHandler()
log.debug("ProtocolHandler created for %r", protocol)
self.connection = self.application.new_connection(protocol, self, self.application_context, session)
log.info("ServerConnection created")
except ProtocolError as e:
log.error("Could not create new server session, reason: %s", e)
self.close()
raise e
msg = self.connection.protocol.create('ACK')
await self.send_message(msg)
return None
[docs] async def on_message(self, fragment: str | bytes) -> None:
''' Process an individual wire protocol fragment.
The websocket RFC specifies opcodes for distinguishing text frames
from binary frames. Tornado passes us either a text or binary string
depending on that opcode, we have to look at the type of the fragment
to see what we got.
Args:
fragment (unicode or bytes) : wire fragment to process
'''
# We shouldn't throw exceptions from on_message because the caller is
# just Tornado and it doesn't know what to do with them other than
# report them as an unhandled Future
try:
message = await self._receive(fragment)
except Exception as e:
# If you go look at self._receive, it's catching the
# expected error types... here we have something weird.
log.error("Unhandled exception receiving a message: %r: %r", e, fragment, exc_info=True)
self._internal_error("server failed to parse a message")
message = None
try:
if message:
if _message_test_port is not None:
_message_test_port.received.append(message)
work = await self._handle(message)
if work:
await self._schedule(work)
except Exception as e:
log.error("Handler or its work threw an exception: %r: %r", e, message, exc_info=True)
self._internal_error("server failed to handle a message")
return None
[docs] def on_pong(self, data: bytes) -> None:
# if we get an invalid integer or utf-8 back, either we
# sent a buggy ping or the client is evil/broken.
try:
self.latest_pong = int(data.decode("utf-8"))
except UnicodeDecodeError:
log.trace("received invalid unicode in pong %r", data, exc_info=True)
except ValueError:
log.trace("received invalid integer in pong %r", data, exc_info=True)
[docs] async def send_message(self, message: Message[Any]) -> None:
''' Send a Bokeh Server protocol message to the connected client.
Args:
message (Message) : a message to send
'''
try:
if _message_test_port is not None:
_message_test_port.sent.append(message)
await message.send(self)
except WebSocketClosedError:
# on_close() is / will be called anyway
log.warning("Failed sending message as connection was closed")
return None
[docs] async def write_message(self, message: Union[bytes, str, Dict[str, Any]],
binary: bool = False, locked: bool = True) -> None:
''' Override parent write_message with a version that acquires a
write lock before writing.
'''
if locked:
with await self.write_lock.acquire():
await super().write_message(message, binary)
else:
await super().write_message(message, binary)
[docs] def on_close(self) -> None:
''' Clean up when the connection is closed.
'''
log.info('WebSocket connection closed: code=%s, reason=%r', self.close_code, self.close_reason)
if self.connection is not None:
self.application.client_lost(self.connection)
async def _receive(self, fragment: str | bytes) -> Message[Any] | None:
# Receive fragments until a complete message is assembled
try:
message = await self.receiver.consume(fragment)
return message
except (MessageError, ProtocolError, ValidationError) as e:
self._protocol_error(str(e))
return None
async def _handle(self, message: Message[Any]) -> Any | None:
# Handle the message, possibly resulting in work to do
try:
work = await self.handler.handle(message, self.connection)
return work
except (MessageError, ProtocolError, ValidationError) as e: # TODO (other exceptions?)
self._internal_error(str(e))
return None
async def _schedule(self, work: Any) -> None:
if isinstance(work, Message):
await self.send_message(cast(Message[Any], work))
else:
self._internal_error(f"expected a Message not {work!r}")
return None
def _internal_error(self, message: str) -> None:
log.error("Bokeh Server internal error: %s, closing connection", message)
self.close(10000, message)
def _protocol_error(self, message: str) -> None:
log.error("Bokeh Server protocol error: %s, closing connection", message)
self.close(10001, message)
#-----------------------------------------------------------------------------
# Private API
#-----------------------------------------------------------------------------
# This is an undocumented API purely for harvesting low level messages
# for testing. When needed it will be set by the testing machinery, and
# should not be used for any other purpose.
@dataclass
class MessageTestPort:
sent: List[Message[Any]]
received: List[Message[Any]]
_message_test_port: MessageTestPort | None = None
#-----------------------------------------------------------------------------
# Code
#-----------------------------------------------------------------------------