Neil Booth
8 years ago
9 changed files with 515 additions and 279 deletions
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# Copyright (c) 2016, Neil Booth |
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# |
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# All rights reserved. |
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# |
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# See the file "LICENCE" for information about the copyright |
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# and warranty status of this software. |
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'''Class for handling JSON RPC 2.0 connections, server or client.''' |
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import asyncio |
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import json |
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import numbers |
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import time |
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from lib.util import LoggedClass |
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def json_result_payload(result, id_): |
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# We should not respond to notifications |
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assert id_ is not None |
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return {'jsonrpc': '2.0', 'error': None, 'result': result, 'id': id_} |
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def json_error_payload(message, code, id_=None): |
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error = {'message': message, 'code': code} |
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return {'jsonrpc': '2.0', 'error': error, 'result': None, 'id': id_} |
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def json_notification_payload(method, params): |
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return {'jsonrpc': '2.0', 'id': None, 'method': method, 'params': params} |
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class JSONRPC(asyncio.Protocol, LoggedClass): |
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'''Manages a JSONRPC connection. |
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Assumes JSON messages are newline-separated and that newlines |
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cannot appear in the JSON other than to separate lines. |
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Derived classes need to implement the synchronous functions |
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on_json_request() and method_handler(). They probably also want |
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to override connection_made() and connection_lost() but should be |
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sure to call the implementation in this base class first. |
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on_json_request() is passed a JSON request as a python object |
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after decoding. It should arrange to pass on to the asynchronous |
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handle_json_request() method. |
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method_handler() takes a method string and should return a function |
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that can be passed a parameters array, or None for an unknown method. |
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Handlers should raise an RPCError on error. |
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''' |
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# 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_PARAMS = -32602 |
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INTERAL_ERROR = -32603 |
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ID_TYPES = (type(None), str, numbers.Number) |
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class RPCError(Exception): |
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'''RPC handlers raise this error.''' |
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def __init__(self, msg, code=-1, **kw_args): |
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super().__init__(**kw_args) |
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self.msg = msg |
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self.code |
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def __init__(self): |
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super().__init__() |
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self.start = time.time() |
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self.transport = None |
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# Parts of an incomplete JSON line. We buffer them until |
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# getting a newline. |
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self.parts = [] |
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# recv_count is JSON messages not calls to data_received() |
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self.recv_count = 0 |
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self.recv_size = 0 |
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self.send_count = 0 |
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self.send_size = 0 |
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self.error_count = 0 |
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def connection_made(self, transport): |
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'''Handle an incoming client connection.''' |
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self.transport = transport |
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def peer_info(self): |
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'''Return peer info.''' |
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if self.transport: |
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return self.transport.get_extra_info('peername') |
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return None |
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def connection_lost(self, exc): |
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'''Handle client disconnection.''' |
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pass |
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def data_received(self, data): |
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'''Handle incoming data (synchronously). |
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Requests end in newline characters. Pass complete requests to |
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decode_message for handling. |
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''' |
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self.recv_size += len(data) |
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while True: |
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npos = data.find(ord('\n')) |
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if npos == -1: |
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self.parts.append(data) |
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break |
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self.recv_count += 1 |
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tail, data = data[:npos], data[npos + 1:] |
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parts, self.parts = self.parts, [] |
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parts.append(tail) |
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self.decode_message(b''.join(parts)) |
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def decode_message(self, message): |
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'''Decode a binary message and queue it for asynchronous handling. |
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Messages that cannot be decoded are logged and dropped. |
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''' |
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try: |
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message = message.decode() |
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except UnicodeDecodeError as e: |
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msg = 'cannot decode binary bytes: {}'.format(e) |
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self.logger.warning(msg) |
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self.send_json_error(msg, self.PARSE_ERROR) |
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return |
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try: |
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message = json.loads(message) |
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except json.JSONDecodeError as e: |
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msg = 'cannot decode JSON: {}'.format(e) |
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self.logger.warning(msg) |
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self.send_json_error(msg, self.PARSE_ERROR) |
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return |
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self.on_json_request(message) |
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def send_json_notification(self, method, params): |
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'''Create a json notification.''' |
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return self.send_json(json_notification_payload(method, params)) |
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def send_json_result(self, result, id_): |
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'''Send a JSON result.''' |
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return self.send_json(json_result_payload(result, id_)) |
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def send_json_error(self, message, code, id_=None): |
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'''Send a JSON error.''' |
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self.error_count += 1 |
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return self.send_json(json_error_payload(message, code, id_)) |
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def send_json(self, payload): |
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'''Send a JSON payload.''' |
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if self.transport.is_closing(): |
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self.logger.info('send_json: connection closing, not sending') |
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return False |
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try: |
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data = (json.dumps(payload) + '\n').encode() |
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except TypeError: |
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msg = 'JSON encoding failure: {}'.format(payload) |
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self.logger.error(msg) |
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return self.send_json_error(msg, self.INTERNAL_ERROR, |
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payload.get('id')) |
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self.send_count += 1 |
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self.send_size += len(data) |
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self.transport.write(data) |
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return True |
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async def handle_json_request(self, request): |
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'''Asynchronously handle a JSON request. |
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Handles batch requests. Returns True if the request response |
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was sent (or if nothing was sent because the request was a |
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notification). Returns False if the send was aborted because |
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the connection is closing. |
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''' |
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if isinstance(request, list): |
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payload = self.batch_request_payload(request) |
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else: |
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payload = await self.single_request_payload(request) |
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if not payload: |
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return True |
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return self.send_json(payload) |
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async def batch_request_payload(self, batch): |
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'''Return the JSON payload corresponding to a batch JSON request.''' |
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# Batches must have at least one request. |
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if not batch: |
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return json_error_payload('empty request list', |
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self.INVALID_REQUEST) |
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# PYTHON 3.6: use asynchronous comprehensions when supported |
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payload = [] |
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for item in request: |
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item_payload = await self.single_request_payload(item) |
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if item_payload: |
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payload.append(item_payload) |
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return payload |
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async def single_request_payload(self, request): |
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'''Return the JSON payload corresponding to a single JSON request. |
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Return None if the request is a notification. |
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''' |
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if not isinstance(request, dict): |
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return json_error_payload('request must be a dict', |
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self.INVALID_REQUEST) |
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id_ = request.get('id') |
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if not isinstance(id_, self.ID_TYPES): |
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return json_error_payload('invalid id: {}'.format(id_), |
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self.INVALID_REQUEST) |
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try: |
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result = await self.method_result(request.get('method'), |
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request.get('params', [])) |
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if id_ is None: |
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return None |
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return json_result_payload(result, id_) |
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except self.RPCError as e: |
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if id_ is None: |
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return None |
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return json_error_payload(e.msg, e.code, id_) |
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async def method_result(self, method, params): |
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if not isinstance(method, str): |
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raise self.RPCError('invalid method: {}'.format(method), |
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self.INVALID_REQUEST) |
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if not isinstance(params, list): |
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raise self.RPCError('params should be an array', |
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self.INVALID_REQUEST) |
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handler = self.method_handler(method) |
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if not handler: |
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raise self.RPCError('unknown method: {}'.format(method), |
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self.METHOD_NOT_FOUND) |
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return await handler(params) |
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def on_json_request(self, request): |
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raise NotImplementedError('on_json_request in class {}'. |
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format(self.__class__.__name__)) |
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def method_handler(self, method): |
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raise NotImplementedError('method_handler in class {}'. |
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format(self.__class__.__name__)) |
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