pyssb/ssb/muxrpc.py

208 lines
5.9 KiB
Python

# SPDX-License-Identifier: MIT
#
# Copyright (c) 2017 PySSB contributors (see AUTHORS for more details)
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
"""MuxRPC"""
from async_generator import async_generator, yield_
from ssb.packet_stream import PSMessageType
class MuxRPCAPIException(Exception):
"""Exception to raise on MuxRPC API errors"""
class MuxRPCHandler: # pylint: disable=too-few-public-methods
"""Base MuxRPC handler class"""
def check_message(self, msg):
"""Check message validity"""
body = msg.body
if isinstance(body, dict) and "name" in body and body["name"] == "Error":
raise MuxRPCAPIException(body["message"])
class MuxRPCRequestHandler(MuxRPCHandler):
"""MuxRPC handler for incoming RPC requests"""
def __init__(self, ps_handler):
self.ps_handler = ps_handler
def __await__(self):
msg = yield from self.ps_handler.__await__()
self.check_message(msg)
return msg
class MuxRPCSourceHandler(MuxRPCHandler):
"""MuxRPC handler for source-type RPC requests"""
def __init__(self, ps_handler):
self.ps_handler = ps_handler
@async_generator
async def __aiter__(self):
async for msg in self.ps_handler:
self.check_message(msg)
await yield_(msg)
class MuxRPCSinkHandlerMixin: # pylint: disable=too-few-public-methods
"""Mixin for sink-type MuxRPC handlers"""
def send(self, msg, msg_type=PSMessageType.JSON, end=False):
"""Send a message through the stream"""
self.connection.send(msg, stream=True, msg_type=msg_type, req=self.req, end_err=end)
class MuxRPCDuplexHandler(MuxRPCSinkHandlerMixin, MuxRPCSourceHandler):
"""MuxRPC handler for duplex streams"""
def __init__(self, ps_handler, connection, req):
super().__init__(ps_handler)
self.connection = connection
self.req = req
class MuxRPCSinkHandler(MuxRPCHandler, MuxRPCSinkHandlerMixin):
"""MuxRPC handler for sinks"""
def __init__(self, connection, req):
self.connection = connection
self.req = req
def _get_appropriate_api_handler(type_, connection, ps_handler, req):
"""Find the appropriate MuxRPC handler"""
if type_ in {"sync", "async"}:
return MuxRPCRequestHandler(ps_handler)
if type_ == "source":
return MuxRPCSourceHandler(ps_handler)
if type_ == "sink":
return MuxRPCSinkHandler(connection, req)
if type_ == "duplex":
return MuxRPCDuplexHandler(ps_handler, connection, req)
return None
class MuxRPCRequest:
"""MuxRPC request"""
@classmethod
def from_message(cls, message):
"""Initialise a request from a raw packet stream message"""
body = message.body
return cls(".".join(body["name"]), body["args"])
def __init__(self, name, args):
self.name = name
self.args = args
def __repr__(self):
return f"<MuxRPCRequest {self.name} {self.args}>"
class MuxRPCMessage:
"""MuxRPC message"""
@classmethod
def from_message(cls, message):
"""Initialise a MuxRPC message from a raw packet stream message"""
return cls(message.body)
def __init__(self, body):
self.body = body
def __repr__(self):
return f"<MuxRPCMessage {self.body}>"
class MuxRPCAPI:
"""Generic MuxRPC API"""
def __init__(self):
self.handlers = {}
self.connection = None
async def process_messages(self):
"""Continuously process incoming messages"""
async for req_message in self.connection:
if req_message is None:
return
body = req_message.body
if isinstance(body, dict) and body.get("name"):
self.process(self.connection, MuxRPCRequest.from_message(req_message))
def add_connection(self, connection):
"""Set the packet stream connection of this RPC API"""
self.connection = connection
def define(self, name):
"""Decorator to define an RPC method handler"""
def _handle(f):
self.handlers[name] = f
return f
return _handle
def process(self, connection, request):
"""Process an incoming request"""
handler = self.handlers.get(request.name)
if not handler:
raise MuxRPCAPIException(f"Method {request.name} not found!")
handler(connection, request)
def call(self, name, args, type_="sync"):
"""Call an RPC method"""
if not self.connection.is_connected:
raise Exception("not connected") # pylint: disable=broad-exception-raised
old_counter = self.connection.req_counter
ps_handler = self.connection.send(
{"name": name.split("."), "args": args, "type": type_},
stream=type_ in {"sink", "source", "duplex"},
)
return _get_appropriate_api_handler(type_, self.connection, ps_handler, old_counter)