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# Copyright 2021-2022 Google LLC
#
# 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
#
# https://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.
# -----------------------------------------------------------------------------
# Imports
# -----------------------------------------------------------------------------
import logging
import websockets
from .common import Transport, ParserSource, PumpedPacketSink
# -----------------------------------------------------------------------------
# Logging
# -----------------------------------------------------------------------------
logger = logging.getLogger(__name__)
# -----------------------------------------------------------------------------
async def open_ws_server_transport(spec: str) -> Transport:
'''
Open a WebSocket server transport.
The parameter string has this syntax:
<local-host>:<local-port>
Where <local-host> may be the address of a local network interface, or '_'
to accept connections on all local network interfaces.
Example: _:9001
'''
class WsServerTransport(Transport):
def __init__(self):
source = ParserSource()
sink = PumpedPacketSink(self.send_packet)
self.connection = None
self.server = None
super().__init__(source, sink)
async def serve(self, local_host, local_port):
self.sink.start()
# pylint: disable-next=no-member
self.server = await websockets.serve(
ws_handler=self.on_connection,
host=local_host if local_host != '_' else None,
port=int(local_port),
)
logger.debug(f'websocket server ready on port {local_port}')
async def on_connection(self, connection):
logger.debug(
f'new connection on {connection.local_address} '
f'from {connection.remote_address}'
)
self.connection = connection
# pylint: disable=no-member
try:
async for packet in connection:
if isinstance(packet, bytes):
self.source.parser.feed_data(packet)
else:
logger.warning('discarding packet: not a BINARY frame')
except websockets.WebSocketException as error:
logger.debug(f'exception while receiving packet: {error}')
# We're now disconnected
self.connection = None
async def send_packet(self, packet):
if self.connection is None:
logger.debug('no connection, dropping packet')
return
return await self.connection.send(packet)
local_host, local_port = spec.split(':')
transport = WsServerTransport()
await transport.serve(local_host, local_port)
return transport
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