802 lines
28 KiB
Python
802 lines
28 KiB
Python
# Copyright (c) 2018, Neil Booth
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#
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# All rights reserved.
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#
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# The MIT License (MIT)
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#
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# Permission is hereby granted, free of charge, to any person obtaining
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# a copy of this software and associated documentation files (the
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# "Software"), to deal in the Software without restriction, including
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# without limitation the rights to use, copy, modify, merge, publish,
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# distribute, sublicense, and/or sell copies of the Software, and to
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# permit persons to whom the Software is furnished to do so, subject to
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# the following conditions:
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#
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# The above copyright notice and this permission notice shall be
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# included in all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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"""Classes for JSONRPC versions 1.0 and 2.0, and a loose interpretation."""
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__all__ = ('JSONRPC', 'JSONRPCv1', 'JSONRPCv2', 'JSONRPCLoose',
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'JSONRPCAutoDetect', 'Request', 'Notification', 'Batch',
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'RPCError', 'ProtocolError',
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'JSONRPCConnection', 'handler_invocation')
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import itertools
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import json
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from functools import partial
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from numbers import Number
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import attr
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from asyncio import Queue, Event, CancelledError
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from .util import signature_info
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class SingleRequest(object):
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__slots__ = ('method', 'args')
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def __init__(self, method, args):
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if not isinstance(method, str):
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raise ProtocolError(JSONRPC.METHOD_NOT_FOUND,
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'method must be a string')
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if not isinstance(args, (list, tuple, dict)):
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raise ProtocolError.invalid_args('request arguments must be a '
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'list or a dictionary')
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self.args = args
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self.method = method
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def __repr__(self):
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return f'{self.__class__.__name__}({self.method!r}, {self.args!r})'
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def __eq__(self, other):
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return (isinstance(other, self.__class__) and
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self.method == other.method and self.args == other.args)
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class Request(SingleRequest):
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def send_result(self, response):
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return None
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class Notification(SingleRequest):
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pass
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class Batch:
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__slots__ = ('items', )
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def __init__(self, items):
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if not isinstance(items, (list, tuple)):
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raise ProtocolError.invalid_request('items must be a list')
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if not items:
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raise ProtocolError.empty_batch()
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if not (all(isinstance(item, SingleRequest) for item in items) or
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all(isinstance(item, Response) for item in items)):
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raise ProtocolError.invalid_request('batch must be homogeneous')
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self.items = items
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def __len__(self):
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return len(self.items)
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def __getitem__(self, item):
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return self.items[item]
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def __iter__(self):
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return iter(self.items)
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def __repr__(self):
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return f'Batch({len(self.items)} items)'
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class Response(object):
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__slots__ = ('result', )
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def __init__(self, result):
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# Type checking happens when converting to a message
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self.result = result
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class CodeMessageError(Exception):
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def __init__(self, code, message):
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super().__init__(code, message)
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@property
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def code(self):
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return self.args[0]
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@property
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def message(self):
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return self.args[1]
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def __eq__(self, other):
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return (isinstance(other, self.__class__) and
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self.code == other.code and self.message == other.message)
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def __hash__(self):
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# overridden to make the exception hashable
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# see https://bugs.python.org/issue28603
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return hash((self.code, self.message))
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@classmethod
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def invalid_args(cls, message):
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return cls(JSONRPC.INVALID_ARGS, message)
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@classmethod
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def invalid_request(cls, message):
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return cls(JSONRPC.INVALID_REQUEST, message)
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@classmethod
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def empty_batch(cls):
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return cls.invalid_request('batch is empty')
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class RPCError(CodeMessageError):
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pass
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class ProtocolError(CodeMessageError):
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def __init__(self, code, message):
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super().__init__(code, message)
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# If not None send this unframed message over the network
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self.error_message = None
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# If the error was in a JSON response message; its message ID.
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# Since None can be a response message ID, "id" means the
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# error was not sent in a JSON response
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self.response_msg_id = id
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class JSONRPC(object):
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"""Abstract base class that interprets and constructs JSON RPC messages."""
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# Error codes. See http://www.jsonrpc.org/specification
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PARSE_ERROR = -32700
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INVALID_REQUEST = -32600
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METHOD_NOT_FOUND = -32601
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INVALID_ARGS = -32602
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INTERNAL_ERROR = -32603
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# Codes specific to this library
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ERROR_CODE_UNAVAILABLE = -100
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# Can be overridden by derived classes
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allow_batches = True
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@classmethod
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def _message_id(cls, message, require_id):
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"""Validate the message is a dictionary and return its ID.
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Raise an error if the message is invalid or the ID is of an
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invalid type. If it has no ID, raise an error if require_id
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is True, otherwise return None.
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"""
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raise NotImplementedError
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@classmethod
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def _validate_message(cls, message):
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"""Validate other parts of the message other than those
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done in _message_id."""
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pass
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@classmethod
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def _request_args(cls, request):
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"""Validate the existence and type of the arguments passed
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in the request dictionary."""
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raise NotImplementedError
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@classmethod
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def _process_request(cls, payload):
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request_id = None
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try:
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request_id = cls._message_id(payload, False)
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cls._validate_message(payload)
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method = payload.get('method')
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if request_id is None:
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item = Notification(method, cls._request_args(payload))
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else:
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item = Request(method, cls._request_args(payload))
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return item, request_id
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except ProtocolError as error:
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code, message = error.code, error.message
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raise cls._error(code, message, True, request_id)
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@classmethod
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def _process_response(cls, payload):
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request_id = None
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try:
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request_id = cls._message_id(payload, True)
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cls._validate_message(payload)
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return Response(cls.response_value(payload)), request_id
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except ProtocolError as error:
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code, message = error.code, error.message
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raise cls._error(code, message, False, request_id)
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@classmethod
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def _message_to_payload(cls, message):
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"""Returns a Python object or a ProtocolError."""
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try:
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return json.loads(message.decode())
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except UnicodeDecodeError:
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message = 'messages must be encoded in UTF-8'
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except json.JSONDecodeError:
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message = 'invalid JSON'
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raise cls._error(cls.PARSE_ERROR, message, True, None)
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@classmethod
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def _error(cls, code, message, send, msg_id):
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error = ProtocolError(code, message)
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if send:
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error.error_message = cls.response_message(error, msg_id)
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else:
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error.response_msg_id = msg_id
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return error
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#
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# External API
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#
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@classmethod
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def message_to_item(cls, message):
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"""Translate an unframed received message and return an
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(item, request_id) pair.
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The item can be a Request, Notification, Response or a list.
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A JSON RPC error response is returned as an RPCError inside a
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Response object.
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If a Batch is returned, request_id is an iterable of request
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ids, one per batch member.
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If the message violates the protocol in some way a
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ProtocolError is returned, except if the message was
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determined to be a response, in which case the ProtocolError
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is placed inside a Response object. This is so that client
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code can mark a request as having been responded to even if
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the response was bad.
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raises: ProtocolError
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"""
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payload = cls._message_to_payload(message)
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if isinstance(payload, dict):
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if 'method' in payload:
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return cls._process_request(payload)
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else:
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return cls._process_response(payload)
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elif isinstance(payload, list) and cls.allow_batches:
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if not payload:
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raise cls._error(JSONRPC.INVALID_REQUEST, 'batch is empty',
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True, None)
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return payload, None
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raise cls._error(cls.INVALID_REQUEST,
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'request object must be a dictionary', True, None)
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# Message formation
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@classmethod
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def request_message(cls, item, request_id):
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"""Convert an RPCRequest item to a message."""
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assert isinstance(item, Request)
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return cls.encode_payload(cls.request_payload(item, request_id))
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@classmethod
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def notification_message(cls, item):
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"""Convert an RPCRequest item to a message."""
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assert isinstance(item, Notification)
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return cls.encode_payload(cls.request_payload(item, None))
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@classmethod
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def response_message(cls, result, request_id):
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"""Convert a response result (or RPCError) to a message."""
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if isinstance(result, CodeMessageError):
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payload = cls.error_payload(result, request_id)
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else:
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payload = cls.response_payload(result, request_id)
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return cls.encode_payload(payload)
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@classmethod
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def batch_message(cls, batch, request_ids):
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"""Convert a request Batch to a message."""
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assert isinstance(batch, Batch)
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if not cls.allow_batches:
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raise ProtocolError.invalid_request(
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'protocol does not permit batches')
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id_iter = iter(request_ids)
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rm = cls.request_message
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nm = cls.notification_message
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parts = (rm(request, next(id_iter)) if isinstance(request, Request)
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else nm(request) for request in batch)
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return cls.batch_message_from_parts(parts)
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@classmethod
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def batch_message_from_parts(cls, messages):
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"""Convert messages, one per batch item, into a batch message. At
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least one message must be passed.
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"""
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# Comma-separate the messages and wrap the lot in square brackets
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middle = b', '.join(messages)
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if not middle:
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raise ProtocolError.empty_batch()
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return b''.join([b'[', middle, b']'])
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@classmethod
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def encode_payload(cls, payload):
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"""Encode a Python object as JSON and convert it to bytes."""
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try:
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return json.dumps(payload).encode()
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except TypeError:
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msg = f'JSON payload encoding error: {payload}'
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raise ProtocolError(cls.INTERNAL_ERROR, msg) from None
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class JSONRPCv1(JSONRPC):
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"""JSON RPC version 1.0."""
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allow_batches = False
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@classmethod
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def _message_id(cls, message, require_id):
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# JSONv1 requires an ID always, but without constraint on its type
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# No need to test for a dictionary here as we don't handle batches.
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if 'id' not in message:
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raise ProtocolError.invalid_request('request has no "id"')
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return message['id']
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@classmethod
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def _request_args(cls, request):
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args = request.get('params')
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if not isinstance(args, list):
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raise ProtocolError.invalid_args(
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f'invalid request arguments: {args}')
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return args
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@classmethod
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def _best_effort_error(cls, error):
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# Do our best to interpret the error
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code = cls.ERROR_CODE_UNAVAILABLE
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message = 'no error message provided'
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if isinstance(error, str):
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message = error
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elif isinstance(error, int):
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code = error
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elif isinstance(error, dict):
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if isinstance(error.get('message'), str):
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message = error['message']
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if isinstance(error.get('code'), int):
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code = error['code']
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return RPCError(code, message)
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@classmethod
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def response_value(cls, payload):
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if 'result' not in payload or 'error' not in payload:
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raise ProtocolError.invalid_request(
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'response must contain both "result" and "error"')
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result = payload['result']
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error = payload['error']
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if error is None:
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return result # It seems None can be a valid result
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if result is not None:
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raise ProtocolError.invalid_request(
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'response has a "result" and an "error"')
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return cls._best_effort_error(error)
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@classmethod
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def request_payload(cls, request, request_id):
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"""JSON v1 request (or notification) payload."""
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if isinstance(request.args, dict):
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raise ProtocolError.invalid_args(
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'JSONRPCv1 does not support named arguments')
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return {
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'method': request.method,
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'params': request.args,
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'id': request_id
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}
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@classmethod
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def response_payload(cls, result, request_id):
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"""JSON v1 response payload."""
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return {
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'result': result,
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'error': None,
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'id': request_id
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}
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@classmethod
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def error_payload(cls, error, request_id):
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return {
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'result': None,
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'error': {'code': error.code, 'message': error.message},
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'id': request_id
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}
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class JSONRPCv2(JSONRPC):
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"""JSON RPC version 2.0."""
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@classmethod
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def _message_id(cls, message, require_id):
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if not isinstance(message, dict):
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raise ProtocolError.invalid_request(
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'request object must be a dictionary')
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if 'id' in message:
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request_id = message['id']
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if not isinstance(request_id, (Number, str, type(None))):
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raise ProtocolError.invalid_request(
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f'invalid "id": {request_id}')
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return request_id
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else:
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if require_id:
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raise ProtocolError.invalid_request('request has no "id"')
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return None
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@classmethod
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def _validate_message(cls, message):
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if message.get('jsonrpc') != '2.0':
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raise ProtocolError.invalid_request('"jsonrpc" is not "2.0"')
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@classmethod
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def _request_args(cls, request):
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args = request.get('params', [])
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if not isinstance(args, (dict, list)):
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raise ProtocolError.invalid_args(
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f'invalid request arguments: {args}')
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return args
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@classmethod
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def response_value(cls, payload):
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if 'result' in payload:
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if 'error' in payload:
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raise ProtocolError.invalid_request(
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'response contains both "result" and "error"')
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return payload['result']
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if 'error' not in payload:
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raise ProtocolError.invalid_request(
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'response contains neither "result" nor "error"')
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# Return an RPCError object
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error = payload['error']
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if isinstance(error, dict):
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code = error.get('code')
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message = error.get('message')
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if isinstance(code, int) and isinstance(message, str):
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return RPCError(code, message)
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raise ProtocolError.invalid_request(
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f'ill-formed response error object: {error}')
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@classmethod
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def request_payload(cls, request, request_id):
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"""JSON v2 request (or notification) payload."""
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payload = {
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'jsonrpc': '2.0',
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'method': request.method,
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}
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# A notification?
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if request_id is not None:
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payload['id'] = request_id
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# Preserve empty dicts as missing params is read as an array
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if request.args or request.args == {}:
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payload['params'] = request.args
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return payload
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@classmethod
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def response_payload(cls, result, request_id):
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"""JSON v2 response payload."""
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return {
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'jsonrpc': '2.0',
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'result': result,
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'id': request_id
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}
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@classmethod
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def error_payload(cls, error, request_id):
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return {
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'jsonrpc': '2.0',
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'error': {'code': error.code, 'message': error.message},
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'id': request_id
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}
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class JSONRPCLoose(JSONRPC):
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"""A relaxed versin of JSON RPC."""
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# Don't be so loose we accept any old message ID
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_message_id = JSONRPCv2._message_id
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_validate_message = JSONRPC._validate_message
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_request_args = JSONRPCv2._request_args
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# Outoing messages are JSONRPCv2 so we give the other side the
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# best chance to assume / detect JSONRPCv2 as default protocol.
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error_payload = JSONRPCv2.error_payload
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request_payload = JSONRPCv2.request_payload
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response_payload = JSONRPCv2.response_payload
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@classmethod
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def response_value(cls, payload):
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# Return result, unless it is None and there is an error
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if payload.get('error') is not None:
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if payload.get('result') is not None:
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raise ProtocolError.invalid_request(
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'response contains both "result" and "error"')
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return JSONRPCv1._best_effort_error(payload['error'])
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if 'result' not in payload:
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raise ProtocolError.invalid_request(
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'response contains neither "result" nor "error"')
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# Can be None
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return payload['result']
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class JSONRPCAutoDetect(JSONRPCv2):
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@classmethod
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def message_to_item(cls, message):
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return cls.detect_protocol(message), None
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@classmethod
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def detect_protocol(cls, message):
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"""Attempt to detect the protocol from the message."""
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main = cls._message_to_payload(message)
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def protocol_for_payload(payload):
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if not isinstance(payload, dict):
|
|
return JSONRPCLoose # Will error
|
|
# Obey an explicit "jsonrpc"
|
|
version = payload.get('jsonrpc')
|
|
if version == '2.0':
|
|
return JSONRPCv2
|
|
if version == '1.0':
|
|
return JSONRPCv1
|
|
|
|
# Now to decide between JSONRPCLoose and JSONRPCv1 if possible
|
|
if 'result' in payload and 'error' in payload:
|
|
return JSONRPCv1
|
|
return JSONRPCLoose
|
|
|
|
if isinstance(main, list):
|
|
parts = set(protocol_for_payload(payload) for payload in main)
|
|
# If all same protocol, return it
|
|
if len(parts) == 1:
|
|
return parts.pop()
|
|
# If strict protocol detected, return it, preferring JSONRPCv2.
|
|
# This means a batch of JSONRPCv1 will fail
|
|
for protocol in (JSONRPCv2, JSONRPCv1):
|
|
if protocol in parts:
|
|
return protocol
|
|
# Will error if no parts
|
|
return JSONRPCLoose
|
|
|
|
return protocol_for_payload(main)
|
|
|
|
|
|
class JSONRPCConnection(object):
|
|
"""Maintains state of a JSON RPC connection, in particular
|
|
encapsulating the handling of request IDs.
|
|
|
|
protocol - the JSON RPC protocol to follow
|
|
max_response_size - responses over this size send an error response
|
|
instead.
|
|
"""
|
|
|
|
_id_counter = itertools.count()
|
|
|
|
def __init__(self, protocol):
|
|
self._protocol = protocol
|
|
# Sent Requests and Batches that have not received a response.
|
|
# The key is its request ID; for a batch it is sorted tuple
|
|
# of request IDs
|
|
self._requests = {}
|
|
# A public attribute intended to be settable dynamically
|
|
self.max_response_size = 0
|
|
|
|
def _oversized_response_message(self, request_id):
|
|
text = f'response too large (over {self.max_response_size:,d} bytes'
|
|
error = RPCError.invalid_request(text)
|
|
return self._protocol.response_message(error, request_id)
|
|
|
|
def _receive_response(self, result, request_id):
|
|
if request_id not in self._requests:
|
|
if request_id is None and isinstance(result, RPCError):
|
|
message = f'diagnostic error received: {result}'
|
|
else:
|
|
message = f'response to unsent request (ID: {request_id})'
|
|
raise ProtocolError.invalid_request(message) from None
|
|
request, event = self._requests.pop(request_id)
|
|
event.result = result
|
|
event.set()
|
|
return []
|
|
|
|
def _receive_request_batch(self, payloads):
|
|
def item_send_result(request_id, result):
|
|
nonlocal size
|
|
part = protocol.response_message(result, request_id)
|
|
size += len(part) + 2
|
|
if size > self.max_response_size > 0:
|
|
part = self._oversized_response_message(request_id)
|
|
parts.append(part)
|
|
if len(parts) == count:
|
|
return protocol.batch_message_from_parts(parts)
|
|
return None
|
|
|
|
parts = []
|
|
items = []
|
|
size = 0
|
|
count = 0
|
|
protocol = self._protocol
|
|
for payload in payloads:
|
|
try:
|
|
item, request_id = protocol._process_request(payload)
|
|
items.append(item)
|
|
if isinstance(item, Request):
|
|
count += 1
|
|
item.send_result = partial(item_send_result, request_id)
|
|
except ProtocolError as error:
|
|
count += 1
|
|
parts.append(error.error_message)
|
|
|
|
if not items and parts:
|
|
protocol_error = ProtocolError(0, "")
|
|
protocol_error.error_message = protocol.batch_message_from_parts(parts)
|
|
raise protocol_error
|
|
return items
|
|
|
|
def _receive_response_batch(self, payloads):
|
|
request_ids = []
|
|
results = []
|
|
for payload in payloads:
|
|
# Let ProtocolError exceptions through
|
|
item, request_id = self._protocol._process_response(payload)
|
|
request_ids.append(request_id)
|
|
results.append(item.result)
|
|
|
|
ordered = sorted(zip(request_ids, results), key=lambda t: t[0])
|
|
ordered_ids, ordered_results = zip(*ordered)
|
|
if ordered_ids not in self._requests:
|
|
raise ProtocolError.invalid_request('response to unsent batch')
|
|
request_batch, event = self._requests.pop(ordered_ids)
|
|
event.result = ordered_results
|
|
event.set()
|
|
return []
|
|
|
|
def _send_result(self, request_id, result):
|
|
message = self._protocol.response_message(result, request_id)
|
|
if len(message) > self.max_response_size > 0:
|
|
message = self._oversized_response_message(request_id)
|
|
return message
|
|
|
|
def _event(self, request, request_id):
|
|
event = Event()
|
|
self._requests[request_id] = (request, event)
|
|
return event
|
|
|
|
#
|
|
# External API
|
|
#
|
|
def send_request(self, request):
|
|
"""Send a Request. Return a (message, event) pair.
|
|
|
|
The message is an unframed message to send over the network.
|
|
Wait on the event for the response; which will be in the
|
|
"result" attribute.
|
|
|
|
Raises: ProtocolError if the request violates the protocol
|
|
in some way..
|
|
"""
|
|
request_id = next(self._id_counter)
|
|
message = self._protocol.request_message(request, request_id)
|
|
return message, self._event(request, request_id)
|
|
|
|
def send_notification(self, notification):
|
|
return self._protocol.notification_message(notification)
|
|
|
|
def send_batch(self, batch):
|
|
ids = tuple(next(self._id_counter)
|
|
for request in batch if isinstance(request, Request))
|
|
message = self._protocol.batch_message(batch, ids)
|
|
event = self._event(batch, ids) if ids else None
|
|
return message, event
|
|
|
|
def receive_message(self, message):
|
|
"""Call with an unframed message received from the network.
|
|
|
|
Raises: ProtocolError if the message violates the protocol in
|
|
some way. However, if it happened in a response that can be
|
|
paired with a request, the ProtocolError is instead set in the
|
|
result attribute of the send_request() that caused the error.
|
|
"""
|
|
try:
|
|
item, request_id = self._protocol.message_to_item(message)
|
|
except ProtocolError as e:
|
|
if e.response_msg_id is not id:
|
|
return self._receive_response(e, e.response_msg_id)
|
|
raise
|
|
|
|
if isinstance(item, Request):
|
|
item.send_result = partial(self._send_result, request_id)
|
|
return [item]
|
|
if isinstance(item, Notification):
|
|
return [item]
|
|
if isinstance(item, Response):
|
|
return self._receive_response(item.result, request_id)
|
|
if isinstance(item, list):
|
|
if all(isinstance(payload, dict)
|
|
and ('result' in payload or 'error' in payload)
|
|
for payload in item):
|
|
return self._receive_response_batch(item)
|
|
else:
|
|
return self._receive_request_batch(item)
|
|
else:
|
|
# Protocol auto-detection hack
|
|
assert issubclass(item, JSONRPC)
|
|
self._protocol = item
|
|
return self.receive_message(message)
|
|
|
|
def cancel_pending_requests(self):
|
|
"""Cancel all pending requests."""
|
|
exception = CancelledError()
|
|
for request, event in self._requests.values():
|
|
event.result = exception
|
|
event.set()
|
|
self._requests.clear()
|
|
|
|
def pending_requests(self):
|
|
"""All sent requests that have not received a response."""
|
|
return [request for request, event in self._requests.values()]
|
|
|
|
|
|
def handler_invocation(handler, request):
|
|
method, args = request.method, request.args
|
|
if handler is None:
|
|
raise RPCError(JSONRPC.METHOD_NOT_FOUND,
|
|
f'unknown method "{method}"')
|
|
|
|
# We must test for too few and too many arguments. How
|
|
# depends on whether the arguments were passed as a list or as
|
|
# a dictionary.
|
|
info = signature_info(handler)
|
|
if isinstance(args, (tuple, list)):
|
|
if len(args) < info.min_args:
|
|
s = '' if len(args) == 1 else 's'
|
|
raise RPCError.invalid_args(
|
|
f'{len(args)} argument{s} passed to method '
|
|
f'"{method}" but it requires {info.min_args}')
|
|
if info.max_args is not None and len(args) > info.max_args:
|
|
s = '' if len(args) == 1 else 's'
|
|
raise RPCError.invalid_args(
|
|
f'{len(args)} argument{s} passed to method '
|
|
f'{method} taking at most {info.max_args}')
|
|
return partial(handler, *args)
|
|
|
|
# Arguments passed by name
|
|
if info.other_names is None:
|
|
raise RPCError.invalid_args(f'method "{method}" cannot '
|
|
f'be called with named arguments')
|
|
|
|
missing = set(info.required_names).difference(args)
|
|
if missing:
|
|
s = '' if len(missing) == 1 else 's'
|
|
missing = ', '.join(sorted(f'"{name}"' for name in missing))
|
|
raise RPCError.invalid_args(f'method "{method}" requires '
|
|
f'parameter{s} {missing}')
|
|
|
|
if info.other_names is not any:
|
|
excess = set(args).difference(info.required_names)
|
|
excess = excess.difference(info.other_names)
|
|
if excess:
|
|
s = '' if len(excess) == 1 else 's'
|
|
excess = ', '.join(sorted(f'"{name}"' for name in excess))
|
|
raise RPCError.invalid_args(f'method "{method}" does not '
|
|
f'take parameter{s} {excess}')
|
|
return partial(handler, **args)
|