예제 #1
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    def __init__(self, metrics: Optional[Metrics] = None, address_index: Optional[AddressIndex] = None):
        """
        :param metrics: If not given, a new one is created.
        :type metrics: :py:class:`hathor.metrics.Metrics`
        """
        # Opened websocket connections so I can broadcast messages later
        # It contains only connections that have finished handshaking.
        self.connections: Set[HathorAdminWebsocketProtocol] = set()

        # Websocket connection for each address
        self.address_connections: DefaultDict[str, Set[HathorAdminWebsocketProtocol]] = defaultdict(set)
        super().__init__()

        # Limit the send message rate for specific type of data
        self.rate_limiter = RateLimiter(reactor=reactor)
        # Stores the buffer of messages that exceeded the rate limit and will be sent
        self.buffer_deques: Dict[str, Deque[Dict[str, Any]]] = {}

        self.metrics = metrics
        self.address_index = address_index

        self.is_running = False

        self.log = logger.new()

        # A timer to periodically broadcast dashboard metrics
        self._lc_send_metrics = LoopingCall(self._send_metrics)
        self._lc_send_metrics.clock = reactor
예제 #2
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    def __init__(self,
                 network: str,
                 my_peer: PeerId,
                 connections: Optional['ConnectionsManager'] = None,
                 *,
                 node: 'HathorManager',
                 use_ssl: bool) -> None:
        self.network = network
        self.my_peer = my_peer
        self.connections = connections
        self.node = node

        self._state_instances = {}

        self.app_version = 'Unknown'

        # The peer on the other side of the connection.
        self.peer = None

        # The last time a message has been received from this peer.
        self.last_message = 0
        self.metrics = self.Metrics()

        # The last time a request was send to this peer.
        self.last_request = 0

        # The time in which the connection was established.
        self.connection_time = 0.0

        # The current state of the connection.
        self.state: Optional[BaseState] = None

        # Default rate limit
        self.ratelimit = RateLimiter()
        # self.ratelimit.set_limit(self.RateLimitKeys.GLOBAL, 120, 60)

        # Connection string of the peer
        # Used to validate if entrypoints has this string
        self.connection_string: Optional[str] = None

        # Peer id sent in the connection url that is expected to connect (optional)
        self.expected_peer_id: Optional[str] = None

        # Set of warning flags that may be added during the connection process
        self.warning_flags: Set[str] = set()

        # If peer is connected
        self.connected = False

        self.use_ssl = use_ssl

        # Set to true if this node initiated the connection
        self.initiated_connection = False

        self.log = logger.new()
예제 #3
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    def __init__(self, metrics: Optional[Metrics] = None, wallet_index: Optional[WalletIndex] = None):
        """
        :param metrics: If not given, a new one is created.
        :type metrics: :py:class:`hathor.metrics.Metrics`
        """
        # Opened websocket connections so I can broadcast messages later
        self.connections: Set[HathorAdminWebsocketProtocol] = set()

        # Websocket connection for each address
        self.address_connections: DefaultDict[str, Set[HathorAdminWebsocketProtocol]] = defaultdict(set)
        super().__init__()

        # Limit the send message rate for specific type of data
        self.rate_limiter = RateLimiter(reactor=reactor)
        # Stores the buffer of messages that exceeded the rate limit and will be sent
        self.buffer_deques: Dict[str, Deque[Dict[str, Any]]] = {}

        self.metrics = metrics
        self.wallet_index = wallet_index

        self.is_running = False
예제 #4
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class HathorAdminWebsocketFactory(WebSocketServerFactory):
    """ Factory of the admin websocket protocol so we can subscribe to events and
        send messages in the Admin page to clients when the events are published
    """
    protocol = HathorAdminWebsocketProtocol

    def buildProtocol(self, addr):
        return self.protocol(self)

    def __init__(self,
                 metrics: Optional[Metrics] = None,
                 wallet_index: Optional[WalletIndex] = None):
        """
        :param metrics: If not given, a new one is created.
        :type metrics: :py:class:`hathor.metrics.Metrics`
        """
        # Opened websocket connections so I can broadcast messages later
        self.connections: Set[HathorAdminWebsocketProtocol] = set()

        # Websocket connection for each address
        self.address_connections: DefaultDict[
            str, Set[HathorAdminWebsocketProtocol]] = defaultdict(set)
        super().__init__()

        # Limit the send message rate for specific type of data
        self.rate_limiter = RateLimiter(reactor=reactor)
        # Stores the buffer of messages that exceeded the rate limit and will be sent
        self.buffer_deques: Dict[str, Deque[Dict[str, Any]]] = {}

        self.metrics = metrics
        self.wallet_index = wallet_index

        self.is_running = False

    def start(self):
        self.is_running = True

        # Start limiter
        self._setup_rate_limit()

        # Start metric sender
        self._schedule_and_send_metric()

    def stop(self):
        self.is_running = False

    def _setup_rate_limit(self):
        """ Set the limit of the RateLimiter and start the buffer deques with BUFFER_SIZE
        """
        for control_type, config in CONTROLLED_TYPES.items():
            self.rate_limiter.set_limit(control_type, config['max_hits'],
                                        config['hits_window_seconds'])
            self.buffer_deques[control_type] = deque(
                maxlen=config['buffer_size'])

    def _schedule_and_send_metric(self):
        """ Send dashboard metric to websocket and schedule next message
        """
        data = {
            'transactions': self.metrics.transactions,
            'blocks': self.metrics.blocks,
            'best_block_height': self.metrics.best_block_height,
            'hash_rate': self.metrics.hash_rate,
            'block_hash_rate': self.metrics.block_hash_rate,
            'tx_hash_rate': self.metrics.tx_hash_rate,
            'network_hash_rate':
            self.metrics.tx_hash_rate + self.metrics.block_hash_rate,
            'peers': self.metrics.peers,
            'type': 'dashboard:metrics',
            'time': reactor.seconds(),
        }
        self.broadcast_message(data)

        if self.is_running:
            # Schedule next message
            reactor.callLater(1, self._schedule_and_send_metric)

    def subscribe(self, pubsub):
        """ Subscribe to defined events for the pubsub received
        """
        events = [
            HathorEvents.NETWORK_NEW_TX_ACCEPTED,
            HathorEvents.WALLET_OUTPUT_RECEIVED,
            HathorEvents.WALLET_INPUT_SPENT,
            HathorEvents.WALLET_BALANCE_UPDATED,
            HathorEvents.WALLET_KEYS_GENERATED,
            HathorEvents.WALLET_GAP_LIMIT,
            HathorEvents.WALLET_HISTORY_UPDATED,
            HathorEvents.WALLET_ADDRESS_HISTORY,
            HathorEvents.WALLET_ELEMENT_WINNER,
            HathorEvents.WALLET_ELEMENT_VOIDED,
        ]

        for event in events:
            pubsub.subscribe(event, self.handle_publish)

    def handle_publish(self, key, args):
        """ This method is called when pubsub publishes an event that we subscribed
            Then we broadcast the data to all connected clients
        """
        data = self.serialize_message_data(key, args)
        data['type'] = key.value
        self.send_or_enqueue(data)

    def serialize_message_data(self, event, args):
        """ Receives the event and the args from the pubsub
            and serializes the data so it can be passed in the websocket
        """
        # Ready events don't need extra serialization
        ready_events = [
            HathorEvents.WALLET_KEYS_GENERATED,
            HathorEvents.WALLET_GAP_LIMIT,
            HathorEvents.WALLET_HISTORY_UPDATED,
            HathorEvents.WALLET_ADDRESS_HISTORY,
        ]
        data = args.__dict__
        if event in ready_events:
            return data
        elif event == HathorEvents.WALLET_OUTPUT_RECEIVED:
            data['output'] = data['output'].to_dict()
            return data
        elif event == HathorEvents.WALLET_INPUT_SPENT:
            data['output_spent'] = data['output_spent'].to_dict()
            return data
        elif event == HathorEvents.NETWORK_NEW_TX_ACCEPTED:
            tx = data['tx']
            data = tx.to_json_extended()
            data['is_block'] = tx.is_block
            return data
        elif event == HathorEvents.WALLET_BALANCE_UPDATED:
            data['balance'] = data['balance'][
                settings.HATHOR_TOKEN_UID]._asdict()
            return data
        else:
            raise ValueError(
                'Should never have entered here! We dont know this event')

    def execute_send(self, data: Dict[str, Any],
                     connections: Set[HathorAdminWebsocketProtocol]) -> None:
        """ Send data in ws message for the connections
        """
        payload = json.dumps(data).encode('utf-8')
        for c in connections:
            c.sendMessage(payload, False)

    def broadcast_message(self, data: Dict[str, Any]) -> None:
        """ Broadcast the update message to the connections
        """
        self.execute_send(data, self.connections)

    def send_message(self, data: Dict[str, Any]) -> None:
        """ Check if should broadcast the message to all connections or send directly to some connections only
        """
        if data['type'] in ADDRESS_EVENTS:
            # This ws message will only be sent if the address was subscribed
            if data['address'] in self.address_connections:
                self.execute_send(data,
                                  self.address_connections[data['address']])
        else:
            self.broadcast_message(data)

    def send_or_enqueue(self, data):
        """ Try to broadcast the message, or enqueue it when rate limit is exceeded and we've been throttled.
            Enqueued messages are automatically sent after a while if they are not discarded first.
            A message is discarded when new messages arrive and the queue buffer is full.
            Rate limits change according to the message type, which is obtained from data['type'].

            :param data: message to be sent
            :type data: Dict[string, X] -> X can be different types, depending on the type of message
        """
        if data['type'] in CONTROLLED_TYPES:
            # This type is controlled, so I need to check the deque
            if len(self.buffer_deques[data['type']]
                   ) or not self.rate_limiter.add_hit(data['type']):
                # If I am already with a buffer or if I hit the limit now, I enqueue for later
                self.enqueue_for_later(data)
            else:
                data['throttled'] = False
                self.send_message(data)
        else:
            self.send_message(data)

    def enqueue_for_later(self, data):
        """ Add this date to the correct deque to be processed later
            If this deque is not programed to be called later yet, we call it

            :param data: message to be sent
            :type data: Dict[string, X] -> X can be different types, depending on the type of message
        """
        # Add data to deque
        # We always add the new messages in the end
        # Adding parameter deque=True, so the admin can know this message was delayed
        data['throttled'] = True
        self.buffer_deques[data['type']].append(data)
        if len(self.buffer_deques[data['type']]) == 1:
            # If it's the first time we hit the limit (only one message in deque), we schedule process_deque
            reactor.callLater(CONTROLLED_TYPES[data['type']]['time_buffering'],
                              self.process_deque,
                              data_type=data['type'])

    def process_deque(self, data_type):
        """ Process the deque and check if I have limit to send the messages now

            :param data_type: Type of the message to be sent
            :type data_type: string
        """
        while len(self.buffer_deques[data_type]) > 0:
            if self.rate_limiter.add_hit(data_type):
                # We always process the older message first
                data = self.buffer_deques[data_type].popleft()
                if len(self.buffer_deques[data_type]) == 0:
                    data['throttled'] = False
                self.send_message(data)
            else:
                reactor.callLater(
                    CONTROLLED_TYPES[data_type]['time_buffering'],
                    self.process_deque,
                    data_type=data_type)
                break

    def handle_message(self, connection: HathorAdminWebsocketProtocol,
                       data: bytes) -> None:
        """ General message handler, detects type and deletages to specific handler."""
        message = json.loads(data)
        # we only handle ping messages for now
        if message['type'] == 'ping':
            self._handle_ping(connection, message)
        elif message['type'] == 'subscribe_address':
            self._handle_subscribe_address(connection, message)
        elif message['type'] == 'unsubscribe_address':
            self._handle_unsubscribe_address(connection, message)

    def _handle_ping(self, connection: HathorAdminWebsocketProtocol,
                     message: Dict[Any, Any]) -> None:
        """ Handler for ping message, should respond with a simple {"type": "pong"}"""
        payload = json.dumps({'type': 'pong'}).encode('utf-8')
        connection.sendMessage(payload, False)

    def _handle_subscribe_address(self,
                                  connection: HathorAdminWebsocketProtocol,
                                  message: Dict[Any, Any]) -> None:
        """ Handler for subscription to an address, consideirs subscription limits."""
        addr: str = message['address']
        subs: Set[str] = connection.subscribed_to
        if len(subs) >= settings.WS_MAX_SUBS_ADDRS_CONN:
            payload = json.dumps({
                'message':
                'Reached maximum number of subscribed '
                f'addresses ({settings.WS_MAX_SUBS_ADDRS_CONN}).',
                'type':
                'subscribe_address',
                'success':
                False
            }).encode('utf-8')
        elif self.wallet_index and _count_empty(
                subs, self.wallet_index) >= settings.WS_MAX_SUBS_ADDRS_EMPTY:
            payload = json.dumps({
                'message':
                'Reached maximum number of subscribed '
                f'addresses without output ({settings.WS_MAX_SUBS_ADDRS_EMPTY}).',
                'type':
                'subscribe_address',
                'success':
                False
            }).encode('utf-8')
        else:
            self.address_connections[addr].add(connection)
            connection.subscribed_to.add(addr)
            payload = json.dumps({
                'type': 'subscribe_address',
                'success': True
            }).encode('utf-8')
        connection.sendMessage(payload, False)

    def _handle_unsubscribe_address(self,
                                    connection: HathorAdminWebsocketProtocol,
                                    message: Dict[Any, Any]) -> None:
        """ Handler for unsubscribing from an address, also removes address connection set if it ends up empty."""
        addr = message['address']
        if addr in self.address_connections and connection in self.address_connections[
                addr]:
            connection.subscribed_to.remove(addr)
            self._remove_connection_from_address_dict(connection, addr)
            # Reply back to the client
            payload = json.dumps({
                'type': 'unsubscribe_address',
                'success': True
            }).encode('utf-8')
            connection.sendMessage(payload, False)

    def _remove_connection_from_address_dict(
            self, connection: HathorAdminWebsocketProtocol,
            address: str) -> None:
        """ Remove a connection from the address connections dict
            If this was the last connection for this address, we remove the key
        """
        self.address_connections[address].remove(connection)
        # If this was the last connection for this address, we delete it from the dict
        if len(self.address_connections[address]) == 0:
            del self.address_connections[address]

    def connection_closed(self,
                          connection: HathorAdminWebsocketProtocol) -> None:
        """ Called when a ws connection is closed
            We should remove it from self.connections and from self.address_connections set for each address
        """
        self.connections.remove(connection)
        for address in connection.subscribed_to:
            self._remove_connection_from_address_dict(connection, address)
예제 #5
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 def setUp(self):
     super().setUp()
     self.rate_limiter = RateLimiter(reactor=self.clock)
예제 #6
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class RateLimiterTestCase(unittest.TestCase):
    def setUp(self):
        super().setUp()
        self.rate_limiter = RateLimiter(reactor=self.clock)

    def test_limiter(self):
        key = 'test'
        self.rate_limiter.set_limit(key, 2, 2)

        # Hits limit
        self.assertTrue(self.rate_limiter.add_hit(key))
        self.assertTrue(self.rate_limiter.add_hit(key))
        self.assertFalse(self.rate_limiter.add_hit(key))

        # Advance 3 seconds to release limit
        self.clock.advance(3)

        # Add hits until limit again
        self.assertTrue(self.rate_limiter.add_hit(key))
        self.assertTrue(self.rate_limiter.add_hit(key))
        self.assertFalse(self.rate_limiter.add_hit(key))

        # Reset hits
        self.rate_limiter.reset(key)

        # Limit is free again
        self.assertTrue(self.rate_limiter.add_hit(key))

        # Get limit
        self.assertEqual(self.rate_limiter.get_limit(key).max_hits, 2)

        # Unset limit
        self.rate_limiter.unset_limit(key)
        self.assertIsNone(self.rate_limiter.get_limit(key))
예제 #7
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class HathorProtocol:
    """ Implements Hathor Peer-to-Peer Protocol. An instance of this class is
    created for each connection.

    When the connection is established, the protocol waits for a
    HELLO message, which will identify the application and give a
    nonce value.

    After receiving a HELLO message, the peer must reply with a PEER-ID
    message, which will identity the peer through its id, public key,
    and endpoints. There must be a signature of the nonce value which
    will be checked against the public key.

    After the PEER-ID message, the peer is ready to communicate.

    The available states are listed in PeerState class.
    The available commands are listed in the ProtocolMessages class.
    """
    log = Logger()

    class PeerState(Enum):
        HELLO = HelloState
        PEER_ID = PeerIdState
        READY = ReadyState

    class Metrics:
        def __init__(self) -> None:
            self.received_messages: int = 0
            self.sent_messages: int = 0
            self.received_bytes: int = 0
            self.sent_bytes: int = 0
            self.received_txs: int = 0
            self.discarded_txs: int = 0
            self.received_blocks: int = 0
            self.discarded_blocks: int = 0

        def format_bytes(self, value: int) -> str:
            """ Format bytes in MB and kB.
            """
            if value > 1024*1024:
                return '{:11.2f} MB'.format(value / 1024 / 1024)
            elif value > 1024:
                return '{:11.2f} kB'.format(value / 1024)
            else:
                return '{} B'.format(value)

        def print_stats(self, prefix: str = '') -> None:
            """ Print a status of the metrics in stdout.
            """
            print('----')
            print('{}Received:       {:8d} messages  {}'.format(
                prefix,
                self.received_messages,
                self.format_bytes(self.received_bytes))
            )
            print('{}Sent:           {:8d} messages  {}'.format(
                prefix,
                self.sent_messages,
                self.format_bytes(self.sent_bytes))
            )
            print('{}Blocks:         {:8d} received  {:8d} discarded ({:2.0f}%)'.format(
                prefix,
                self.received_blocks,
                self.discarded_blocks,
                100.0 * self.discarded_blocks / (self.received_blocks + self.discarded_blocks)
            ))
            print('{}Transactions:   {:8d} received  {:8d} discarded ({:2.0f}%)'.format(
                prefix,
                self.received_txs,
                self.discarded_txs,
                100.0 * self.discarded_txs / (self.received_txs + self.discarded_txs)
            ))
            print('----')

    class RateLimitKeys(str, Enum):
        GLOBAL = 'global'

    class WarningFlags(str, Enum):
        NO_PEER_ID_URL = 'no_peer_id_url'
        NO_ENTRYPOINTS = 'no_entrypoints'

    network: str
    my_peer: PeerId
    connections: Optional['ConnectionsManager']
    node: 'HathorManager'
    app_version: str
    last_message: float
    peer: Optional[PeerId]
    transport: ITransport
    state: Optional[BaseState]
    connection_time: float
    _state_instances: Dict[PeerState, BaseState]
    connection_string: Optional[str]
    expected_peer_id: Optional[str]
    warning_flags: Set[str]
    connected: bool
    initiated_connection: bool

    def __init__(self, network: str, my_peer: PeerId, connections: Optional['ConnectionsManager'] = None, *,
                 node: 'HathorManager', use_ssl: bool) -> None:
        self.network = network
        self.my_peer = my_peer
        self.connections = connections
        self.node = node

        self._state_instances = {}

        self.app_version = 'Unknown'

        # The peer on the other side of the connection.
        self.peer = None

        # The last time a message has been received from this peer.
        self.last_message = 0
        self.metrics = self.Metrics()

        # The last time a request was send to this peer.
        self.last_request = 0

        # The time in which the connection was established.
        self.connection_time = 0.0

        # The current state of the connection.
        self.state: Optional[BaseState] = None

        # Default rate limit
        self.ratelimit = RateLimiter()
        # self.ratelimit.set_limit(self.RateLimitKeys.GLOBAL, 120, 60)

        # Connection string of the peer
        # Used to validate if entrypoints has this string
        self.connection_string: Optional[str] = None

        # Peer id sent in the connection url that is expected to connect (optional)
        self.expected_peer_id: Optional[str] = None

        # Set of warning flags that may be added during the connection process
        self.warning_flags: Set[str] = set()

        # If peer is connected
        self.connected = False

        self.use_ssl = use_ssl

        # Set to true if this node initiated the connection
        self.initiated_connection = False

    def change_state(self, state_enum: PeerState) -> None:
        if state_enum not in self._state_instances:
            state_cls = state_enum.value
            instance = state_cls(self)
            instance.state_name = state_enum.name
            self._state_instances[state_enum] = instance
        new_state = self._state_instances[state_enum]
        if new_state != self.state:
            if self.state:
                self.state.on_exit()
            self.state = new_state
            if self.state:
                self.state.on_enter()

    def on_connect(self) -> None:
        """ Executed when the connection is established.
        """
        remote = self.transport.getPeer()
        self.log.info('HathorProtocol.connectionMade(): {remote}', remote=remote)

        self.connection_time = time.time()

        # The initial state is HELLO.
        self.change_state(self.PeerState.HELLO)

        self.connected = True

        if self.connections:
            self.connections.on_peer_connect(self)

    def on_disconnect(self, reason: str) -> None:
        """ Executed when the connection is lost.
        """
        remote = self.transport.getPeer()
        self.log.info('HathorProtocol.connectionLost(): {remote} {reason}', remote=remote, reason=reason)
        self.connected = False
        if self.state:
            self.state.on_exit()
        if self.connections:
            self.connections.on_peer_disconnect(self)

    def send_message(self, cmd: ProtocolMessages, payload: Optional[str] = None) -> None:
        """ A generic message which must be implemented to send a message
        to the peer. It depends on the underlying protocol in which
        HathorProtocol is running.
        """
        raise NotImplementedError

    def recv_message(self, cmd: ProtocolMessages, payload: str) -> Optional[Generator[Any, Any, None]]:
        """ Executed when a new message arrives.
        """
        assert self.state is not None

        self.last_message = self.node.reactor.seconds()

        if not self.ratelimit.add_hit(self.RateLimitKeys.GLOBAL):
            self.state.send_throttle(self.RateLimitKeys.GLOBAL)
            return None

        fn = self.state.cmd_map.get(cmd)
        if fn is not None:
            try:
                return fn(payload)
            except Exception as e:
                self.log.warn('Unhandled Exception: {e!r}', e=e)
                raise
        else:
            self.send_error('Invalid Command: {}'.format(cmd))

        return None

    def send_error(self, msg: str) -> None:
        """ Send an error message to the peer.
        """
        self.send_message(ProtocolMessages.ERROR, msg)

    def send_error_and_close_connection(self, msg: str) -> None:
        """ Send an ERROR message to the peer, and then closes the connection.
        """
        self.send_error(msg)
        # from twisted docs: "If a producer is being used with the transport, loseConnection will only close
        # the connection once the producer is unregistered." We call on_exit to make sure any producers (like
        # the one from node_sync) are unregistered
        if self.state:
            self.state.on_exit()
        self.transport.loseConnection()

    def handle_error(self, payload: str) -> None:
        """ Executed when an ERROR command is received.
        """
        self.log.warn('ERROR {payload}', payload=payload)
예제 #8
0
    def __init__(self,
                 network: str,
                 my_peer: PeerId,
                 connections: Optional['ConnectionsManager'] = None,
                 *,
                 node: 'HathorManager',
                 use_ssl: bool,
                 inbound: bool) -> None:
        self.network = network
        self.my_peer = my_peer
        self.connections = connections
        self.node = node

        if self.connections is not None:
            assert self.connections.reactor is not None
            self.reactor = self.connections.reactor
        else:
            from twisted.internet import reactor
            self.reactor = reactor

        # Indicate whether it is an inbound connection (true) or an outbound connection (false).
        self.inbound = inbound

        # Maximum period without receiving any messages.
        self.idle_timeout = settings.PEER_IDLE_TIMEOUT
        self._idle_timeout_call_later: Optional[IDelayedCall] = None

        self._state_instances = {}

        self.app_version = 'Unknown'
        self.diff_timestamp = None

        # The peer on the other side of the connection.
        self.peer = None

        # The last time a message has been received from this peer.
        self.last_message = 0
        self.metrics: 'ConnectionMetrics' = ConnectionMetrics()

        # The last time a request was send to this peer.
        self.last_request = 0

        # The time in which the connection was established.
        self.connection_time = 0.0

        # The current state of the connection.
        self.state: Optional[BaseState] = None

        # Default rate limit
        self.ratelimit: RateLimiter = RateLimiter()
        # self.ratelimit.set_limit(self.RateLimitKeys.GLOBAL, 120, 60)

        # Connection string of the peer
        # Used to validate if entrypoints has this string
        self.connection_string: Optional[str] = None

        # Peer id sent in the connection url that is expected to connect (optional)
        self.expected_peer_id: Optional[str] = None

        # Set of warning flags that may be added during the connection process
        self.warning_flags: Set[str] = set()

        # This property is used to indicate the connection is being dropped (either because of a prototcol error or
        # because the remote disconnected), and the following buffered lines are ignored.
        # See `HathorLineReceiver.lineReceived`
        self.aborting = False

        self.use_ssl: bool = use_ssl

        # Protocol version is initially unset
        self.sync_version = None

        self.log = logger.new()