Ejemplo n.º 1
0
async def test_one_notifier_on_two_nodes_with_listen():
    events_b = []
    messages = ["hello", "hello"]

    node_a_key_pair = create_new_key_pair()
    node_a_transport_opt = ["/ip4/127.0.0.1/tcp/0"]
    node_a = await new_node(node_a_key_pair,
                            transport_opt=node_a_transport_opt)
    await node_a.get_network().listen(
        multiaddr.Multiaddr(node_a_transport_opt[0]))

    # Set up node_b swarm to pass into host
    node_b_key_pair = create_new_key_pair()
    node_b_transport_opt = ["/ip4/127.0.0.1/tcp/0"]
    node_b_multiaddr = multiaddr.Multiaddr(node_b_transport_opt[0])
    node_b_swarm = initialize_default_swarm(node_b_key_pair,
                                            transport_opt=node_b_transport_opt)
    node_b = BasicHost(node_b_swarm)

    async def my_stream_handler(stream):
        # Ensure the listened, connected and opened_stream events were hit in Notifee obj
        # and that the stream passed into opened_stream matches the stream created on
        # node_b
        assert events_b == [
            ["listenedb", node_b_multiaddr],
            ["connectedb", stream.mplex_conn],
            ["opened_streamb", stream],
        ]
        for message in messages:
            read_string = (await stream.read(len(message))).decode()
            resp = ACK + read_string
            await stream.write(resp.encode())

    # Add notifee for node_a
    events_a = []
    assert node_a.get_network().notify(MyNotifee(events_a, "a"))

    # Add notifee for node_b
    assert node_b.get_network().notify(MyNotifee(events_b, "b"))

    # start listen on node_b_swarm
    await node_b.get_network().listen(node_b_multiaddr)

    node_b.set_stream_handler("/echo/1.0.0", my_stream_handler)
    # Associate the peer with local ip address (see default parameters of Libp2p())
    node_a.get_peerstore().add_addrs(node_b.get_id(), node_b.get_addrs(), 10)
    stream = await node_a.new_stream(node_b.get_id(), ["/echo/1.0.0"])

    # Ensure the connected and opened_stream events were hit in MyNotifee obj
    # and that stream passed into opened_stream matches the stream created on
    # node_a
    assert events_a == [["connecteda", stream.mplex_conn],
                        ["opened_streama", stream]]

    for message in messages:
        expected_resp = ACK + message
        await stream.write(message.encode())

        response = (await stream.read(len(expected_resp))).decode()

        assert response == expected_resp

    # Success, terminate pending tasks.
    await cleanup()
Ejemplo n.º 2
0
class Node(BaseService):

    _is_started: bool = False

    key_pair: KeyPair
    listen_ip: str
    listen_port: int
    host: BasicHost
    pubsub: Pubsub
    bootstrap_nodes: Optional[Tuple[Multiaddr, ...]]
    preferred_nodes: Optional[Tuple[Multiaddr, ...]]
    chain: BaseBeaconChain

    handshaked_peers: PeerPool = None

    def __init__(
            self,
            key_pair: KeyPair,
            listen_ip: str,
            listen_port: int,
            chain: BaseBeaconChain,
            security_protocol_ops: Dict[TProtocol, BaseSecureTransport] = None,
            muxer_protocol_ops: Dict[TProtocol, IMuxedConn] = None,
            gossipsub_params: Optional[GossipsubParams] = None,
            cancel_token: CancelToken = None,
            bootstrap_nodes: Tuple[Multiaddr, ...] = None,
            preferred_nodes: Tuple[Multiaddr, ...] = None) -> None:
        super().__init__(cancel_token)
        self.listen_ip = listen_ip
        self.listen_port = listen_port
        self.key_pair = key_pair
        self.bootstrap_nodes = bootstrap_nodes
        self.preferred_nodes = preferred_nodes
        # TODO: Add key and peer_id to the peerstore
        if security_protocol_ops is None:
            security_protocol_ops = {
                PLAINTEXT_PROTOCOL_ID: InsecureTransport(key_pair)
            }
        if muxer_protocol_ops is None:
            muxer_protocol_ops = {MPLEX_PROTOCOL_ID: Mplex}
        network: INetwork = initialize_default_swarm(
            key_pair=key_pair,
            transport_opt=[self.listen_maddr],
            muxer_opt=muxer_protocol_ops,
            sec_opt=security_protocol_ops,
            peerstore_opt=None,  # let the function initialize it
            disc_opt=None,  # no routing required here
        )
        self.host = BasicHost(network=network, router=None)

        if gossipsub_params is None:
            gossipsub_params = GossipsubParams()
        gossipsub_router = GossipSub(
            protocols=[GOSSIPSUB_PROTOCOL_ID],
            degree=gossipsub_params.DEGREE,
            degree_low=gossipsub_params.DEGREE_LOW,
            degree_high=gossipsub_params.DEGREE_HIGH,
            time_to_live=gossipsub_params.FANOUT_TTL,
            gossip_window=gossipsub_params.GOSSIP_WINDOW,
            gossip_history=gossipsub_params.GOSSIP_HISTORY,
            heartbeat_interval=gossipsub_params.HEARTBEAT_INTERVAL,
        )
        self.pubsub = Pubsub(
            host=self.host,
            router=gossipsub_router,
            my_id=self.peer_id,
        )

        self.chain = chain

        self.handshaked_peers = PeerPool()

        self.run_task(self.start())

    @property
    def is_started(self) -> bool:
        return self._is_started

    async def _run(self) -> None:
        self.logger.info("libp2p node %s is up", self.listen_maddr)
        await self.cancellation()

    async def start(self) -> None:
        # host
        self._register_rpc_handlers()
        # TODO: Register notifees
        await self.host.get_network().listen(self.listen_maddr)
        await self.connect_preferred_nodes()
        # TODO: Connect bootstrap nodes?

        # pubsub
        await self.pubsub.subscribe(PUBSUB_TOPIC_BEACON_BLOCK)
        await self.pubsub.subscribe(PUBSUB_TOPIC_BEACON_ATTESTATION)
        self._setup_topic_validators()

        self._is_started = True

    def _setup_topic_validators(self) -> None:
        self.pubsub.set_topic_validator(
            PUBSUB_TOPIC_BEACON_BLOCK,
            get_beacon_block_validator(self.chain),
            False,
        )
        self.pubsub.set_topic_validator(
            PUBSUB_TOPIC_BEACON_ATTESTATION,
            get_beacon_attestation_validator(self.chain),
            False,
        )

    async def dial_peer(self, ip: str, port: int, peer_id: ID) -> None:
        """
        Dial the peer ``peer_id`` through the IPv4 protocol
        """
        await self.host.connect(
            PeerInfo(
                peer_id=peer_id,
                addrs=[make_tcp_ip_maddr(ip, port)],
            )
        )

    async def dial_peer_maddr(self, maddr: Multiaddr) -> None:
        """
        Parse `maddr`, get the ip:port and PeerID, and call `dial_peer` with the parameters.
        """
        ip = maddr.value_for_protocol(protocols.P_IP4)
        port = maddr.value_for_protocol(protocols.P_TCP)
        peer_id = ID.from_base58(maddr.value_for_protocol(protocols.P_P2P))
        await self.dial_peer(ip=ip, port=port, peer_id=peer_id)

    async def connect_preferred_nodes(self) -> None:
        if self.preferred_nodes is None or len(self.preferred_nodes) == 0:
            return
        await asyncio.wait([
            self.dial_peer_maddr(node_maddr)
            for node_maddr in self.preferred_nodes
        ])

    async def disconnect_peer(self, peer_id: ID) -> None:
        if peer_id in self.handshaked_peers:
            self.logger.debug("Disconnect from %s", peer_id)
            self.handshaked_peers.remove(peer_id)
            await self.host.disconnect(peer_id)
        else:
            self.logger.debug("Already disconnected from %s", peer_id)

    async def broadcast_beacon_block(self, block: BaseBeaconBlock) -> None:
        await self._broadcast_data(PUBSUB_TOPIC_BEACON_BLOCK, ssz.encode(block))

    async def broadcast_attestation(self, attestation: Attestation) -> None:
        await self._broadcast_data(PUBSUB_TOPIC_BEACON_ATTESTATION, ssz.encode(attestation))

    async def _broadcast_data(self, topic: str, data: bytes) -> None:
        await self.pubsub.publish(topic, data)

    @property
    def peer_id(self) -> ID:
        return self.host.get_id()

    @property
    def listen_maddr(self) -> Multiaddr:
        return make_tcp_ip_maddr(self.listen_ip, self.listen_port)

    @property
    def listen_maddr_with_peer_id(self) -> Multiaddr:
        return self.listen_maddr.encapsulate(Multiaddr(f"/p2p/{self.peer_id.to_base58()}"))

    @property
    def peer_store(self) -> PeerStore:
        return self.host.get_network().peerstore

    async def close(self) -> None:
        # FIXME: Add `tear_down` to `Swarm` in the upstream
        network = self.host.get_network()
        for listener in network.listeners.values():
            listener.server.close()
            await listener.server.wait_closed()
        # TODO: Add `close` in `Pubsub`

    def _register_rpc_handlers(self) -> None:
        self.host.set_stream_handler(REQ_RESP_HELLO_SSZ, self._handle_hello)
        self.host.set_stream_handler(REQ_RESP_GOODBYE_SSZ, self._handle_goodbye)
        self.host.set_stream_handler(REQ_RESP_BEACON_BLOCKS_SSZ, self._handle_beacon_blocks)
        self.host.set_stream_handler(
            REQ_RESP_RECENT_BEACON_BLOCKS_SSZ,
            self._handle_recent_beacon_blocks,
        )

    #
    # RPC Handlers
    #

    # TODO: Add a wrapper or decorator to handle the exceptions in handlers,
    #   to close the streams safely. Probably starting from: if the function
    #   returns successfully, then close the stream. Otherwise, reset the stream.

    # TODO: Handle the reputation of peers. Deduct their scores and even disconnect when they
    #   behave.

    # TODO: Register notifee to the `Network` to
    #   - Record peers' joining time.
    #   - Disconnect peers when they fail to join in a certain amount of time.

    async def _validate_hello_req(self, hello_other_side: HelloRequest) -> None:
        state_machine = self.chain.get_state_machine()
        state = self.chain.get_head_state()
        config = state_machine.config
        if hello_other_side.fork_version != state.fork.current_version:
            raise ValidationError(
                "`fork_version` mismatches: "
                f"hello_other_side.fork_version={hello_other_side.fork_version}, "
                f"state.fork.current_version={state.fork.current_version}"
            )

        # Can not validate the checkpoint with `finalized_epoch` higher than ours
        if hello_other_side.finalized_epoch > state.finalized_checkpoint.epoch:
            return

        # Get the finalized root at `hello_other_side.finalized_epoch`
        # Edge case where nothing is finalized yet
        if (
            hello_other_side.finalized_epoch == 0 and
            hello_other_side.finalized_root == ZERO_SIGNING_ROOT
        ):
            return

        finalized_epoch_start_slot = compute_start_slot_of_epoch(
            hello_other_side.finalized_epoch,
            config.SLOTS_PER_EPOCH,
        )
        finalized_root = self.chain.get_canonical_block_root(
            finalized_epoch_start_slot)

        if hello_other_side.finalized_root != finalized_root:
            raise ValidationError(
                "`finalized_root` mismatches: "
                f"hello_other_side.finalized_root={hello_other_side.finalized_root}, "
                f"hello_other_side.finalized_epoch={hello_other_side.finalized_epoch}, "
                f"our `finalized_root` at the same `finalized_epoch`={finalized_root}"
            )

    def _make_hello_packet(self) -> HelloRequest:
        state = self.chain.get_head_state()
        head = self.chain.get_canonical_head()
        finalized_checkpoint = state.finalized_checkpoint
        return HelloRequest(
            fork_version=state.fork.current_version,
            finalized_root=finalized_checkpoint.root,
            finalized_epoch=finalized_checkpoint.epoch,
            head_root=head.hash_tree_root,
            head_slot=head.slot,
        )

    def _compare_chain_tip_and_finalized_epoch(self,
                                               peer_finalized_epoch: Epoch,
                                               peer_head_slot: Slot) -> None:
        checkpoint = self.chain.get_head_state().finalized_checkpoint
        head_block = self.chain.get_canonical_head()
        peer_has_higher_finalized_epoch = peer_finalized_epoch > checkpoint.epoch
        peer_has_equal_finalized_epoch = peer_finalized_epoch == checkpoint.epoch
        peer_has_higher_head_slot = peer_head_slot > head_block.slot
        if (
            peer_has_higher_finalized_epoch or
            (peer_has_equal_finalized_epoch and peer_has_higher_head_slot)
        ):
            # TODO: kickoff syncing process with this peer
            self.logger.debug("Peer's chain is ahead of us, start syncing with the peer.")
            pass

    async def _handle_hello(self, stream: INetStream) -> None:
        # TODO: Find out when we should respond the `ResponseCode`
        #   other than `ResponseCode.SUCCESS`.

        peer_id = stream.mplex_conn.peer_id

        self.logger.debug("Waiting for hello from the other side")
        try:
            hello_other_side = await read_req(stream, HelloRequest)
            has_error = False
        except (ReadMessageFailure, MplexStreamEOF, MplexStreamReset) as error:
            has_error = True
            if isinstance(error, ReadMessageFailure):
                await stream.reset()
            elif isinstance(error, MplexStreamEOF):
                await stream.close()
        finally:
            if has_error:
                await self.disconnect_peer(peer_id)
                return
        self.logger.debug("Received the hello message %s", hello_other_side)

        try:
            await self._validate_hello_req(hello_other_side)
        except ValidationError as error:
            self.logger.info(
                "Handshake failed: hello message %s is invalid: %s",
                hello_other_side,
                str(error)
            )
            await stream.reset()
            await self.say_goodbye(peer_id, GoodbyeReasonCode.IRRELEVANT_NETWORK)
            await self.disconnect_peer(peer_id)
            return

        hello_mine = self._make_hello_packet()

        self.logger.debug("Sending our hello message %s", hello_mine)
        try:
            await write_resp(stream, hello_mine, ResponseCode.SUCCESS)
            has_error = False
        except (WriteMessageFailure, MplexStreamEOF, MplexStreamReset) as error:
            has_error = True
            if isinstance(error, WriteMessageFailure):
                await stream.reset()
            elif isinstance(error, MplexStreamEOF):
                await stream.close()
        finally:
            if has_error:
                self.logger.info(
                    "Handshake failed: failed to write message %s",
                    hello_mine,
                )
                await self.disconnect_peer(peer_id)
                return

        if peer_id not in self.handshaked_peers:
            peer = Peer.from_hello_request(self, peer_id, hello_other_side)
            self.handshaked_peers.add(peer)
            self.logger.debug(
                "Handshake from %s is finished. Added to the `handshake_peers`",
                peer_id,
            )

        # Check if we are behind the peer
        self._compare_chain_tip_and_finalized_epoch(
            hello_other_side.finalized_epoch,
            hello_other_side.head_slot,
        )

        await stream.close()

    async def say_hello(self, peer_id: ID) -> None:
        hello_mine = self._make_hello_packet()

        self.logger.debug(
            "Opening new stream to peer=%s with protocols=%s",
            peer_id,
            [REQ_RESP_HELLO_SSZ],
        )
        stream = await self.host.new_stream(peer_id, [REQ_RESP_HELLO_SSZ])
        self.logger.debug("Sending our hello message %s", hello_mine)
        try:
            await write_req(stream, hello_mine)
            has_error = False
        except (WriteMessageFailure, MplexStreamEOF, MplexStreamReset) as error:
            has_error = True
            if isinstance(error, WriteMessageFailure):
                await stream.reset()
            elif isinstance(error, MplexStreamEOF):
                await stream.close()
        finally:
            if has_error:
                await self.disconnect_peer(peer_id)
                error_msg = f"fail to write request={hello_mine}"
                self.logger.info("Handshake failed: %s", error_msg)
                raise HandshakeFailure(error_msg)

        self.logger.debug("Waiting for hello from the other side")
        try:
            resp_code, hello_other_side = await read_resp(stream, HelloRequest)
            has_error = False
        except (ReadMessageFailure, MplexStreamEOF, MplexStreamReset) as error:
            has_error = True
            if isinstance(error, ReadMessageFailure):
                await stream.reset()
            elif isinstance(error, MplexStreamEOF):
                await stream.close()
        finally:
            if has_error:
                await self.disconnect_peer(peer_id)
                self.logger.info("Handshake failed: fail to read the response")
                raise HandshakeFailure("fail to read the response")

        self.logger.debug(
            "Received the hello message %s, resp_code=%s",
            hello_other_side,
            resp_code,
        )

        # TODO: Handle the case when `resp_code` is not success.
        if resp_code != ResponseCode.SUCCESS:
            # TODO: Do something according to the `ResponseCode`
            error_msg = (
                "resp_code != ResponseCode.SUCCESS, "
                f"resp_code={resp_code}, error_msg={hello_other_side}"
            )
            self.logger.info("Handshake failed: %s", error_msg)
            await stream.reset()
            await self.disconnect_peer(peer_id)
            raise HandshakeFailure(error_msg)

        hello_other_side = cast(HelloRequest, hello_other_side)
        try:
            await self._validate_hello_req(hello_other_side)
        except ValidationError as error:
            error_msg = f"hello message {hello_other_side} is invalid: {str(error)}"
            self.logger.info(
                "Handshake failed: %s. Disconnecting %s",
                error_msg,
                peer_id,
            )
            await stream.reset()
            await self.say_goodbye(peer_id, GoodbyeReasonCode.IRRELEVANT_NETWORK)
            await self.disconnect_peer(peer_id)
            raise HandshakeFailure(error_msg) from error

        if peer_id not in self.handshaked_peers:
            peer = Peer.from_hello_request(self, peer_id, hello_other_side)
            self.handshaked_peers.add(peer)
            self.logger.debug(
                "Handshake to peer=%s is finished. Added to the `handshake_peers`",
                peer_id,
            )

        # Check if we are behind the peer
        self._compare_chain_tip_and_finalized_epoch(
            hello_other_side.finalized_epoch,
            hello_other_side.head_slot,
        )

        await stream.close()

    async def _handle_goodbye(self, stream: INetStream) -> None:
        peer_id = stream.mplex_conn.peer_id
        self.logger.debug("Waiting for goodbye from %s", peer_id)
        try:
            goodbye = await read_req(stream, Goodbye)
            has_error = False
        except (ReadMessageFailure, MplexStreamEOF, MplexStreamReset) as error:
            has_error = True
            if isinstance(error, ReadMessageFailure):
                await stream.reset()
            elif isinstance(error, MplexStreamEOF):
                await stream.close()

        self.logger.debug("Received the goodbye message %s", goodbye)

        if not has_error:
            await stream.close()
        await self.disconnect_peer(peer_id)

    async def say_goodbye(self, peer_id: ID, reason: GoodbyeReasonCode) -> None:
        goodbye = Goodbye(reason)
        self.logger.debug(
            "Opening new stream to peer=%s with protocols=%s",
            peer_id,
            [REQ_RESP_GOODBYE_SSZ],
        )
        stream = await self.host.new_stream(peer_id, [REQ_RESP_GOODBYE_SSZ])
        self.logger.debug("Sending our goodbye message %s", goodbye)
        try:
            await write_req(stream, goodbye)
            has_error = False
        except (WriteMessageFailure, MplexStreamEOF, MplexStreamReset) as error:
            has_error = True
            if isinstance(error, WriteMessageFailure):
                await stream.reset()
            elif isinstance(error, MplexStreamEOF):
                await stream.close()

        if not has_error:
            await stream.close()
        await self.disconnect_peer(peer_id)

    @to_tuple
    def _get_blocks_from_canonical_chain_by_slot(
        self,
        slot_of_requested_blocks: Sequence[Slot],
    ) -> Iterable[BaseBeaconBlock]:
        # If peer's head block is on our canonical chain,
        # start getting the requested blocks by slots.
        for slot in slot_of_requested_blocks:
            try:
                block = self.chain.get_canonical_block_by_slot(slot)
            except BlockNotFound:
                pass
            else:
                yield block

    @to_tuple
    def _get_blocks_from_fork_chain_by_root(
        self,
        start_slot: Slot,
        peer_head_block: BaseBeaconBlock,
        slot_of_requested_blocks: Sequence[Slot],
    ) -> Iterable[BaseBeaconBlock]:
        # Peer's head block is on a fork chain,
        # start getting the requested blocks by
        # traversing the history from the head.

        # `slot_of_requested_blocks` starts with earliest slot
        # and end with most recent slot, so we start traversing
        # from the most recent slot.
        cur_index = len(slot_of_requested_blocks) - 1
        block = peer_head_block
        if block.slot == slot_of_requested_blocks[cur_index]:
            yield block
            cur_index -= 1
        while block.slot > start_slot and cur_index >= 0:
            try:
                block = self.chain.get_block_by_root(block.parent_root)
            except (BlockNotFound, ValidationError):
                # This should not happen as we only persist block if its
                # ancestors are also in the database.
                break
            else:
                while block.slot < slot_of_requested_blocks[cur_index]:
                    if cur_index > 0:
                        cur_index -= 1
                    else:
                        break
                if block.slot == slot_of_requested_blocks[cur_index]:
                    yield block

    def _validate_start_slot(self, start_slot: Slot) -> None:
        config = self.chain.get_state_machine().config
        state = self.chain.get_head_state()
        finalized_epoch_start_slot = compute_start_slot_of_epoch(
            epoch=state.finalized_checkpoint.epoch,
            slots_per_epoch=config.SLOTS_PER_EPOCH,
        )
        if start_slot < finalized_epoch_start_slot:
            raise ValidationError(
                f"`start_slot`({start_slot}) lower than our"
                f" latest finalized slot({finalized_epoch_start_slot})"
            )

    def _get_requested_beacon_blocks(
        self,
        beacon_blocks_request: BeaconBlocksRequest,
        requested_head_block: BaseBeaconBlock,
    ) -> Tuple[BaseBeaconBlock, ...]:
        slot_of_requested_blocks = tuple(
            beacon_blocks_request.start_slot + i * beacon_blocks_request.step
            for i in range(beacon_blocks_request.count)
        )
        self.logger.info("slot_of_requested_blocks: %s", slot_of_requested_blocks)
        slot_of_requested_blocks = tuple(
            filter(lambda slot: slot <= requested_head_block.slot, slot_of_requested_blocks)
        )

        if len(slot_of_requested_blocks) == 0:
            return tuple()

        # We have the peer's head block in our database,
        # next check if the head block is on our canonical chain.
        try:
            canonical_block_at_slot = self.chain.get_canonical_block_by_slot(
                requested_head_block.slot
            )
            block_match = canonical_block_at_slot == requested_head_block
        except BlockNotFound:
            self.logger.debug(
                (
                    "The requested head block is not on our canonical chain  "
                    "requested_head_block: %s  canonical_block_at_slot: %s"
                ),
                requested_head_block,
                canonical_block_at_slot,
            )
            block_match = False
        finally:
            if block_match:
                # Peer's head block is on our canonical chain
                return self._get_blocks_from_canonical_chain_by_slot(
                    slot_of_requested_blocks
                )
            else:
                # Peer's head block is not on our canonical chain
                # Validate `start_slot` is greater than our latest finalized slot
                self._validate_start_slot(beacon_blocks_request.start_slot)
                return self._get_blocks_from_fork_chain_by_root(
                    beacon_blocks_request.start_slot,
                    requested_head_block,
                    slot_of_requested_blocks,
                )

    async def _handle_beacon_blocks(self, stream: INetStream) -> None:
        peer_id = stream.mplex_conn.peer_id
        if peer_id not in self.handshaked_peers:
            self.logger.info(
                "Processing beacon blocks request failed: not handshaked with peer=%s yet",
                peer_id,
            )
            await stream.reset()
            return

        self.logger.debug("Waiting for beacon blocks request from the other side")
        try:
            beacon_blocks_request = await read_req(stream, BeaconBlocksRequest)
            has_error = False
        except (ReadMessageFailure, MplexStreamEOF, MplexStreamReset) as error:
            has_error = True
            if isinstance(error, ReadMessageFailure):
                await stream.reset()
            elif isinstance(error, MplexStreamEOF):
                await stream.close()
        finally:
            if has_error:
                return
        self.logger.debug("Received the beacon blocks request message %s", beacon_blocks_request)

        try:
            requested_head_block = self.chain.get_block_by_hash_tree_root(
                beacon_blocks_request.head_block_root
            )
        except (BlockNotFound, ValidationError) as error:
            self.logger.info("Sending empty blocks, reason: %s", error)
            # We don't have the chain data peer is requesting
            requested_beacon_blocks: Tuple[BaseBeaconBlock, ...] = tuple()
        else:
            # Check if slot of specified head block is greater than specified start slot
            if requested_head_block.slot < beacon_blocks_request.start_slot:
                reason = (
                    f"Invalid request: head block slot({requested_head_block.slot})"
                    f" lower than `start_slot`({beacon_blocks_request.start_slot})"
                )
                try:
                    await write_resp(stream, reason, ResponseCode.INVALID_REQUEST)
                    has_error = False
                except (WriteMessageFailure, MplexStreamEOF, MplexStreamReset) as error:
                    has_error = True
                    if isinstance(error, WriteMessageFailure):
                        await stream.reset()
                    elif isinstance(error, MplexStreamEOF):
                        await stream.close()
                finally:
                    if has_error:
                        self.logger.info(
                            "Processing beacon blocks request failed: failed to write message %s",
                            reason,
                        )
                        return
                await stream.close()
                return
            else:
                try:
                    requested_beacon_blocks = self._get_requested_beacon_blocks(
                        beacon_blocks_request, requested_head_block
                    )
                except ValidationError as val_error:
                    reason = "Invalid request: " + str(val_error)
                    try:
                        await write_resp(stream, reason, ResponseCode.INVALID_REQUEST)
                        has_error = False
                    except (WriteMessageFailure, MplexStreamEOF, MplexStreamReset) as error:
                        has_error = True
                        if isinstance(error, WriteMessageFailure):
                            await stream.reset()
                        elif isinstance(error, MplexStreamEOF):
                            await stream.close()
                    finally:
                        if has_error:
                            self.logger.info(
                                "Processing beacon blocks request failed: "
                                "failed to write message %s",
                                reason,
                            )
                            return
                    await stream.close()
                    return
        # TODO: Should it be a successful response if peer is requesting
        # blocks on a fork we don't have data for?
        beacon_blocks_response = BeaconBlocksResponse(blocks=requested_beacon_blocks)
        self.logger.debug("Sending beacon blocks response %s", beacon_blocks_response)
        try:
            await write_resp(stream, beacon_blocks_response, ResponseCode.SUCCESS)
            has_error = False
        except (WriteMessageFailure, MplexStreamEOF, MplexStreamReset) as error:
            has_error = True
            if isinstance(error, WriteMessageFailure):
                await stream.reset()
            elif isinstance(error, MplexStreamEOF):
                await stream.close()
        finally:
            if has_error:
                self.logger.info(
                    "Processing beacon blocks request failed: failed to write message %s",
                    beacon_blocks_response,
                )
                return

        self.logger.debug(
            "Processing beacon blocks request from %s is finished",
            peer_id,
        )
        await stream.close()

    async def request_beacon_blocks(self,
                                    peer_id: ID,
                                    head_block_root: HashTreeRoot,
                                    start_slot: Slot,
                                    count: int,
                                    step: int) -> Tuple[BaseBeaconBlock, ...]:
        if peer_id not in self.handshaked_peers:
            error_msg = f"not handshaked with peer={peer_id} yet"
            self.logger.info("Request beacon block failed: %s", error_msg)
            raise RequestFailure(error_msg)

        beacon_blocks_request = BeaconBlocksRequest(
            head_block_root=head_block_root,
            start_slot=start_slot,
            count=count,
            step=step,
        )

        self.logger.debug(
            "Opening new stream to peer=%s with protocols=%s",
            peer_id,
            [REQ_RESP_BEACON_BLOCKS_SSZ],
        )
        stream = await self.host.new_stream(peer_id, [REQ_RESP_BEACON_BLOCKS_SSZ])
        self.logger.debug("Sending beacon blocks request %s", beacon_blocks_request)
        try:
            await write_req(stream, beacon_blocks_request)
            has_error = False
        except (WriteMessageFailure, MplexStreamEOF, MplexStreamReset) as error:
            has_error = True
            if isinstance(error, WriteMessageFailure):
                await stream.reset()
            elif isinstance(error, MplexStreamEOF):
                await stream.close()
        finally:
            if has_error:
                error_msg = f"fail to write request={beacon_blocks_request}"
                self.logger.info("Request beacon blocks failed: %s", error_msg)
                raise RequestFailure(error_msg)

        self.logger.debug("Waiting for beacon blocks response")
        try:
            resp_code, beacon_blocks_response = await read_resp(stream, BeaconBlocksResponse)
            has_error = False
        except (ReadMessageFailure, MplexStreamEOF, MplexStreamReset) as error:
            has_error = True
            if isinstance(error, ReadMessageFailure):
                await stream.reset()
            elif isinstance(error, MplexStreamEOF):
                await stream.close()
        finally:
            if has_error:
                self.logger.info("Request beacon blocks failed: fail to read the response")
                raise RequestFailure("fail to read the response")

        self.logger.debug(
            "Received beacon blocks response %s, resp_code=%s",
            beacon_blocks_response,
            resp_code,
        )

        if resp_code != ResponseCode.SUCCESS:
            error_msg = (
                "resp_code != ResponseCode.SUCCESS, "
                f"resp_code={resp_code}, error_msg={beacon_blocks_response}"
            )
            self.logger.info("Request beacon blocks failed: %s", error_msg)
            await stream.reset()
            raise RequestFailure(error_msg)

        await stream.close()

        beacon_blocks_response = cast(BeaconBlocksResponse, beacon_blocks_response)
        return beacon_blocks_response.blocks

    async def _handle_recent_beacon_blocks(self, stream: INetStream) -> None:
        peer_id = stream.mplex_conn.peer_id
        if peer_id not in self.handshaked_peers:
            self.logger.info(
                "Processing recent beacon blocks request failed: not handshaked with peer=%s yet",
                peer_id,
            )
            await stream.reset()
            return

        self.logger.debug("Waiting for recent beacon blocks request from the other side")
        try:
            recent_beacon_blocks_request = await read_req(stream, RecentBeaconBlocksRequest)
            has_error = False
        except (ReadMessageFailure, MplexStreamEOF, MplexStreamReset) as error:
            has_error = True
            if isinstance(error, ReadMessageFailure):
                await stream.reset()
            elif isinstance(error, MplexStreamEOF):
                await stream.close()
        finally:
            if has_error:
                return
        self.logger.debug(
            "Received the recent beacon blocks request message %s",
            recent_beacon_blocks_request,
        )

        recent_beacon_blocks = []
        for block_root in recent_beacon_blocks_request.block_roots:
            try:
                block = self.chain.get_block_by_hash_tree_root(block_root)
            except (BlockNotFound, ValidationError):
                pass
            else:
                recent_beacon_blocks.append(block)

        recent_beacon_blocks_response = RecentBeaconBlocksResponse(blocks=recent_beacon_blocks)
        self.logger.debug("Sending recent beacon blocks response %s", recent_beacon_blocks_response)
        try:
            await write_resp(stream, recent_beacon_blocks_response, ResponseCode.SUCCESS)
            has_error = False
        except (WriteMessageFailure, MplexStreamEOF, MplexStreamReset) as error:
            has_error = True
            if isinstance(error, WriteMessageFailure):
                await stream.reset()
            elif isinstance(error, MplexStreamEOF):
                await stream.close()
        finally:
            if has_error:
                self.logger.info(
                    "Processing recent beacon blocks request failed: failed to write message %s",
                    recent_beacon_blocks_response,
                )
                return

        self.logger.debug(
            "Processing recent beacon blocks request from %s is finished",
            peer_id,
        )
        await stream.close()

    async def request_recent_beacon_blocks(
            self,
            peer_id: ID,
            block_roots: Sequence[HashTreeRoot]) -> Tuple[BaseBeaconBlock, ...]:
        if peer_id not in self.handshaked_peers:
            error_msg = f"not handshaked with peer={peer_id} yet"
            self.logger.info("Request recent beacon block failed: %s", error_msg)
            raise RequestFailure(error_msg)

        recent_beacon_blocks_request = RecentBeaconBlocksRequest(block_roots=block_roots)

        self.logger.debug(
            "Opening new stream to peer=%s with protocols=%s",
            peer_id,
            [REQ_RESP_RECENT_BEACON_BLOCKS_SSZ],
        )
        stream = await self.host.new_stream(peer_id, [REQ_RESP_RECENT_BEACON_BLOCKS_SSZ])
        self.logger.debug("Sending recent beacon blocks request %s", recent_beacon_blocks_request)
        try:
            await write_req(stream, recent_beacon_blocks_request)
            has_error = False
        except (WriteMessageFailure, MplexStreamEOF, MplexStreamReset) as error:
            has_error = True
            if isinstance(error, WriteMessageFailure):
                await stream.reset()
            elif isinstance(error, MplexStreamEOF):
                await stream.close()
        finally:
            if has_error:
                error_msg = f"fail to write request={recent_beacon_blocks_request}"
                self.logger.info("Request recent beacon blocks failed: %s", error_msg)
                raise RequestFailure(error_msg)

        self.logger.debug("Waiting for recent beacon blocks response")
        try:
            resp_code, recent_beacon_blocks_response = await read_resp(
                stream,
                RecentBeaconBlocksResponse,
            )
            has_error = False
        except (ReadMessageFailure, MplexStreamEOF, MplexStreamReset) as error:
            has_error = True
            if isinstance(error, ReadMessageFailure):
                await stream.reset()
            elif isinstance(error, MplexStreamEOF):
                await stream.close()
        finally:
            if has_error:
                self.logger.info("Request recent beacon blocks failed: fail to read the response")
                raise RequestFailure("fail to read the response")

        self.logger.debug(
            "Received recent beacon blocks response %s, resp_code=%s",
            recent_beacon_blocks_response,
            resp_code,
        )

        if resp_code != ResponseCode.SUCCESS:
            error_msg = (
                "resp_code != ResponseCode.SUCCESS, "
                f"resp_code={resp_code}, error_msg={recent_beacon_blocks_response}"
            )
            self.logger.info("Request recent beacon blocks failed: %s", error_msg)
            await stream.reset()
            raise RequestFailure(error_msg)

        await stream.close()

        recent_beacon_blocks_response = cast(
            RecentBeaconBlocksResponse,
            recent_beacon_blocks_response,
        )
        return recent_beacon_blocks_response.blocks
Ejemplo n.º 3
0
Archivo: node.py Proyecto: onyb/trinity
class Node(BaseService):

    _is_started: bool = False

    key_pair: KeyPair
    listen_ip: str
    listen_port: int
    host: BasicHost
    pubsub: Pubsub
    bootstrap_nodes: Tuple[Multiaddr, ...]
    preferred_nodes: Tuple[Multiaddr, ...]
    chain: BaseBeaconChain
    subnets: Set[SubnetId]
    _event_bus: EndpointAPI

    handshaked_peers: PeerPool = None

    def __init__(self,
                 key_pair: KeyPair,
                 listen_ip: str,
                 listen_port: int,
                 chain: BaseBeaconChain,
                 event_bus: EndpointAPI,
                 security_protocol_ops: Dict[TProtocol,
                                             BaseSecureTransport] = None,
                 muxer_protocol_ops: Dict[TProtocol, IMuxedConn] = None,
                 gossipsub_params: Optional[GossipsubParams] = None,
                 cancel_token: CancelToken = None,
                 bootstrap_nodes: Tuple[Multiaddr, ...] = (),
                 preferred_nodes: Tuple[Multiaddr, ...] = (),
                 subnets: Optional[Set[SubnetId]] = None) -> None:
        super().__init__(cancel_token)
        self.listen_ip = listen_ip
        self.listen_port = listen_port
        self.key_pair = key_pair
        self.bootstrap_nodes = bootstrap_nodes
        self.preferred_nodes = preferred_nodes
        self.subnets = subnets if subnets is not None else set()
        # TODO: Add key and peer_id to the peerstore
        if security_protocol_ops is None:
            security_protocol_ops = {SecIOID: SecIOTransport(key_pair)}
        if muxer_protocol_ops is None:
            muxer_protocol_ops = {MPLEX_PROTOCOL_ID: Mplex}
        network: INetwork = initialize_default_swarm(
            key_pair=key_pair,
            transport_opt=[self.listen_maddr],
            muxer_opt=muxer_protocol_ops,
            sec_opt=security_protocol_ops,
            peerstore_opt=None,  # let the function initialize it
        )
        self.host = BasicHost(network=network)

        if gossipsub_params is None:
            gossipsub_params = GossipsubParams()
        gossipsub_router = GossipSub(
            protocols=[GOSSIPSUB_PROTOCOL_ID],
            degree=gossipsub_params.DEGREE,
            degree_low=gossipsub_params.DEGREE_LOW,
            degree_high=gossipsub_params.DEGREE_HIGH,
            time_to_live=gossipsub_params.FANOUT_TTL,
            gossip_window=gossipsub_params.GOSSIP_WINDOW,
            gossip_history=gossipsub_params.GOSSIP_HISTORY,
            heartbeat_interval=gossipsub_params.HEARTBEAT_INTERVAL,
        )
        self.pubsub = Pubsub(
            host=self.host,
            router=gossipsub_router,
            my_id=self.peer_id,
        )

        self.chain = chain
        self._event_bus = event_bus

        self.handshaked_peers = PeerPool()

        self.run_task(self.start())

    @property
    def is_started(self) -> bool:
        return self._is_started

    async def _run(self) -> None:
        self.logger.info("libp2p node %s is up", self.listen_maddr)
        self.run_daemon_task(self.update_status())

        # Metrics and HTTP APIs
        self.run_daemon_task(self.handle_libp2p_peers_requests())
        self.run_daemon_task(self.handle_libp2p_peer_id_requests())

        await self.cancellation()

    async def start(self) -> None:
        # host
        self._register_rpc_handlers()
        # TODO: Register notifees
        is_listening = await self.host.get_network().listen(self.listen_maddr)
        if not is_listening:
            self.logger.error("Fail to listen on maddr: %s", self.listen_maddr)
            raise NodeStartError(
                f"Fail to listen on maddr: {self.listen_maddr}")
        self.logger.warning("Node listening: %s",
                            self.listen_maddr_with_peer_id)
        await self.connect_preferred_nodes()
        # TODO: Connect bootstrap nodes?

        # Pubsub
        # Global channel
        await self.pubsub.subscribe(PUBSUB_TOPIC_BEACON_BLOCK)
        await self.pubsub.subscribe(PUBSUB_TOPIC_BEACON_ATTESTATION)
        await self.pubsub.subscribe(PUBSUB_TOPIC_BEACON_AGGREGATE_AND_PROOF)
        # Attestation subnets
        for subnet_id in self.subnets:
            topic = PUBSUB_TOPIC_COMMITTEE_BEACON_ATTESTATION.substitute(
                subnet_id=str(subnet_id))
            await self.pubsub.subscribe(topic)

        self._setup_topic_validators()

        self._is_started = True

    def _setup_topic_validators(self) -> None:
        # Global channel
        self.pubsub.set_topic_validator(
            PUBSUB_TOPIC_BEACON_BLOCK,
            get_beacon_block_validator(self.chain),
            False,
        )
        self.pubsub.set_topic_validator(
            PUBSUB_TOPIC_BEACON_ATTESTATION,
            get_beacon_attestation_validator(self.chain),
            False,
        )
        # Attestation subnets
        for subnet_id in self.subnets:
            self.pubsub.set_topic_validator(
                PUBSUB_TOPIC_COMMITTEE_BEACON_ATTESTATION.substitute(
                    subnet_id=str(subnet_id)),
                get_committee_index_beacon_attestation_validator(
                    self.chain, subnet_id),
                False,
            )

        self.pubsub.set_topic_validator(
            PUBSUB_TOPIC_BEACON_AGGREGATE_AND_PROOF,
            get_beacon_aggregate_and_proof_validator(self.chain),
            False,
        )

    async def dial_peer_maddr(self, maddr: Multiaddr, peer_id: ID) -> None:
        """
        Dial the peer with given multi-address
        """
        self.logger.debug("Dialing peer_id: %s, maddr: %s", peer_id, maddr)
        try:
            await self.host.connect(PeerInfo(
                peer_id=peer_id,
                addrs=[maddr],
            ))
        except SwarmException as e:
            self.logger.debug("Fail to dial peer_id: %s, maddr: %s, error: %s",
                              peer_id, maddr, e)
            raise DialPeerError from e

        try:
            # TODO: set a time limit on completing handshake
            await self.request_status(peer_id)
        except HandshakeFailure as e:
            self.logger.debug("Fail to handshake with peer_id: %s, error: %s",
                              peer_id, e)
            raise DialPeerError from e
        self.logger.debug("Successfully connect to peer_id %s maddr %s",
                          peer_id, maddr)

    async def dial_peer_maddr_with_retries(self, maddr: Multiaddr) -> None:
        """
        Dial the peer with given multi-address repeatedly for `DIAL_RETRY_COUNT` times
        """
        try:
            p2p_id = maddr.value_for_protocol(protocols.P_P2P)
        except (BinaryParseError, ProtocolLookupError) as error:
            self.logger.debug("Invalid maddr: %s, error: %s", maddr, error)
            raise DialPeerError from error
        peer_id = ID.from_base58(p2p_id)

        for i in range(DIAL_RETRY_COUNT):
            try:
                # exponential backoff...
                await asyncio.sleep(2**i + random.random())
                await self.dial_peer_maddr(maddr, peer_id)
                return
            except DialPeerError:
                self.logger.debug(
                    "Could not dial peer: %s, maddr: %s retrying attempt %d of %d...",
                    peer_id,
                    maddr,
                    i,
                    DIAL_RETRY_COUNT,
                )
                continue
        raise DialPeerError

    async def connect_preferred_nodes(self) -> None:
        results = await asyncio.gather(
            *(self.dial_peer_maddr_with_retries(node_maddr)
              for node_maddr in self.preferred_nodes),
            return_exceptions=True,
        )
        for result, node_maddr in zip(results, self.preferred_nodes):
            if isinstance(result, Exception):
                logger.warning("Could not connect to preferred node at %s",
                               node_maddr)

    async def disconnect_peer(self, peer_id: ID) -> None:
        if peer_id in self.handshaked_peers:
            self.logger.debug("Disconnect from %s", peer_id)
            self.handshaked_peers.remove(peer_id)
            await self.host.disconnect(peer_id)
        else:
            self.logger.debug("Already disconnected from %s", peer_id)

    async def broadcast_beacon_block(self,
                                     block: BaseSignedBeaconBlock) -> None:
        await self._broadcast_data(PUBSUB_TOPIC_BEACON_BLOCK,
                                   ssz.encode(block))

    async def broadcast_attestation(self, attestation: Attestation) -> None:
        await self._broadcast_data(PUBSUB_TOPIC_BEACON_ATTESTATION,
                                   ssz.encode(attestation))

    async def broadcast_attestation_to_subnet(self, attestation: Attestation,
                                              subnet_id: SubnetId) -> None:
        await self._broadcast_data(
            PUBSUB_TOPIC_COMMITTEE_BEACON_ATTESTATION.substitute(
                subnet_id=str(subnet_id)), ssz.encode(attestation))

    async def broadcast_beacon_aggregate_and_proof(
            self, aggregate_and_proof: AggregateAndProof) -> None:
        await self._broadcast_data(
            PUBSUB_TOPIC_BEACON_AGGREGATE_AND_PROOF,
            ssz.encode(aggregate_and_proof),
        )

    async def _broadcast_data(self, topic: str, data: bytes) -> None:
        await self.pubsub.publish(topic, data)

    @property
    def peer_id(self) -> ID:
        return self.host.get_id()

    @property
    def listen_maddr(self) -> Multiaddr:
        return make_tcp_ip_maddr(self.listen_ip, self.listen_port)

    @property
    def listen_maddr_with_peer_id(self) -> Multiaddr:
        return self.listen_maddr.encapsulate(
            Multiaddr(f"/p2p/{self.peer_id.to_base58()}"))

    @property
    def peer_store(self) -> PeerStore:
        return self.host.get_network().peerstore

    async def close(self) -> None:
        # FIXME: Add `tear_down` to `Swarm` in the upstream
        network = self.host.get_network()
        for listener in network.listeners.values():
            listener.server.close()
            await listener.server.wait_closed()
        # TODO: Add `close` in `Pubsub`

    def _register_rpc_handlers(self) -> None:
        self.host.set_stream_handler(REQ_RESP_STATUS_SSZ, self._handle_status)
        self.host.set_stream_handler(REQ_RESP_GOODBYE_SSZ,
                                     self._handle_goodbye)
        self.host.set_stream_handler(
            REQ_RESP_BEACON_BLOCKS_BY_RANGE_SSZ,
            self._handle_beacon_blocks_by_range,
        )
        self.host.set_stream_handler(
            REQ_RESP_BEACON_BLOCKS_BY_ROOT_SSZ,
            self._handle_beacon_blocks_by_root,
        )

    #
    # RPC Handlers
    #

    async def new_stream(self, peer_id: ID, protocol: TProtocol) -> INetStream:
        return await self.host.new_stream(peer_id, [protocol])

    @asynccontextmanager
    async def new_handshake_interaction(
            self, stream: INetStream) -> AsyncIterator[Interaction]:
        try:
            async with Interaction(stream) as interaction:
                peer_id = interaction.peer_id
                yield interaction
        except MessageIOFailure as error:
            await self.disconnect_peer(peer_id)
            raise HandshakeFailure() from error
        except PeerRespondedAnError as error:
            await stream.reset()
            await self.disconnect_peer(peer_id)
            raise HandshakeFailure() from error
        except IrrelevantNetwork as error:
            await stream.reset()
            asyncio.ensure_future(
                self.say_goodbye(peer_id,
                                 GoodbyeReasonCode.IRRELEVANT_NETWORK))
            raise HandshakeFailure from error

    @asynccontextmanager
    async def post_handshake_handler_interaction(
            self, stream: INetStream) -> AsyncIterator[Interaction]:
        try:
            async with Interaction(stream) as interaction:
                yield interaction
        except WriteMessageFailure as error:
            self.logger.debug("WriteMessageFailure %s", error)
            return
        except ReadMessageFailure as error:
            self.logger.debug("ReadMessageFailure %s", error)
            return
        except UnhandshakedPeer:
            await stream.reset()
            return

    @asynccontextmanager
    async def my_request_interaction(
            self, stream: INetStream) -> AsyncIterator[Interaction]:
        try:
            async with Interaction(stream) as interaction:
                yield interaction
        except (MessageIOFailure, UnhandshakedPeer,
                PeerRespondedAnError) as error:
            raise RequestFailure(str(error)) from error

    # TODO: Handle the reputation of peers. Deduct their scores and even disconnect when they
    #   behave.

    # TODO: Register notifee to the `Network` to
    #   - Record peers' joining time.
    #   - Disconnect peers when they fail to join in a certain amount of time.

    def _add_peer_from_status(self, peer_id: ID, status: Status) -> None:
        peer = Peer.from_status(self, peer_id, status)
        self.handshaked_peers.add(peer)
        self.logger.debug(
            "Handshake from %s is finished. Added to the `handshake_peers`",
            peer_id,
        )

    async def _handle_status(self, stream: INetStream) -> None:
        # TODO: Find out when we should respond the `ResponseCode`
        #   other than `ResponseCode.SUCCESS`.

        async with self.new_handshake_interaction(stream) as interaction:
            peer_id = interaction.peer_id
            peer_status = await interaction.read_request(Status)
            self.logger.info("Received Status from %s  %s", str(peer_id),
                             peer_status)
            await validate_peer_status(self.chain, peer_status)

            my_status = get_my_status(self.chain)
            await interaction.write_response(my_status)

            self._add_peer_from_status(peer_id, peer_status)

            if peer_is_ahead(self.chain, peer_status):
                logger.debug(
                    "Peer's chain is ahead of us, start syncing with the peer(%s)",
                    str(peer_id),
                )
                await self._event_bus.broadcast(SyncRequest())

    async def request_status(self, peer_id: ID) -> None:
        self.logger.info("Initiate handshake with %s", str(peer_id))

        try:
            stream = await self.new_stream(peer_id, REQ_RESP_STATUS_SSZ)
        except StreamFailure as error:
            self.logger.debug("Fail to open stream to %s", str(peer_id))
            raise HandshakeFailure from error
        async with self.new_handshake_interaction(stream) as interaction:
            my_status = get_my_status(self.chain)
            await interaction.write_request(my_status)
            peer_status = await interaction.read_response(Status)

            await validate_peer_status(self.chain, peer_status)

            self._add_peer_from_status(peer_id, peer_status)

            if peer_is_ahead(self.chain, peer_status):
                logger.debug(
                    "Peer's chain is ahead of us, start syncing with the peer(%s)",
                    str(peer_id),
                )
                await self._event_bus.broadcast(SyncRequest())

    async def _handle_goodbye(self, stream: INetStream) -> None:
        async with Interaction(stream) as interaction:
            peer_id = interaction.peer_id
            try:
                await interaction.read_request(Goodbye)
            except ReadMessageFailure:
                pass
            await self.disconnect_peer(peer_id)

    async def say_goodbye(self, peer_id: ID,
                          reason: GoodbyeReasonCode) -> None:
        try:
            stream = await self.new_stream(peer_id, REQ_RESP_GOODBYE_SSZ)
        except StreamFailure:
            self.logger.debug("Fail to open stream to %s", str(peer_id))
        else:
            async with Interaction(stream) as interaction:
                goodbye = Goodbye.create(reason)
                try:
                    await interaction.write_request(goodbye)
                except WriteMessageFailure:
                    pass
        finally:
            await self.disconnect_peer(peer_id)

    def _check_peer_handshaked(self, peer_id: ID) -> None:
        if peer_id not in self.handshaked_peers:
            raise UnhandshakedPeer(peer_id)

    async def _handle_beacon_blocks_by_range(self, stream: INetStream) -> None:
        # TODO: Should it be a successful response if peer is requesting
        # blocks on a fork we don't have data for?

        async with self.post_handshake_handler_interaction(
                stream) as interaction:
            peer_id = interaction.peer_id
            self._check_peer_handshaked(peer_id)

            request = await interaction.read_request(BeaconBlocksByRangeRequest
                                                     )
            try:
                blocks = get_requested_beacon_blocks(self.chain, request)
            except InvalidRequest as error:
                error_message = str(error)[:128]
                await interaction.write_error_response(
                    error_message, ResponseCode.INVALID_REQUEST)
            else:
                await interaction.write_chunk_response(blocks)

    async def request_beacon_blocks_by_range(
        self,
        peer_id: ID,
        head_block_root: Root,
        start_slot: Slot,
        count: int,
        step: int,
    ) -> Tuple[BaseSignedBeaconBlock, ...]:
        try:
            stream = await self.new_stream(
                peer_id, REQ_RESP_BEACON_BLOCKS_BY_RANGE_SSZ)
        except StreamFailure as error:
            self.logger.debug("Fail to open stream to %s", str(peer_id))
            raise RequestFailure(str(error)) from error
        async with self.my_request_interaction(stream) as interaction:
            self._check_peer_handshaked(peer_id)
            request = BeaconBlocksByRangeRequest.create(
                head_block_root=head_block_root,
                start_slot=start_slot,
                count=count,
                step=step,
            )
            await interaction.write_request(request)
            blocks = tuple([
                block async for block in interaction.read_chunk_response(
                    SignedBeaconBlock, count)
            ])

            return blocks

    async def _handle_beacon_blocks_by_root(self, stream: INetStream) -> None:
        async with self.post_handshake_handler_interaction(
                stream) as interaction:
            peer_id = interaction.peer_id
            self._check_peer_handshaked(peer_id)
            request = await interaction.read_request(BeaconBlocksByRootRequest)
            blocks = get_beacon_blocks_by_root(self.chain, request)

            await interaction.write_chunk_response(blocks)

    async def request_beacon_blocks_by_root(
            self, peer_id: ID,
            block_roots: Sequence[Root]) -> Tuple[BaseSignedBeaconBlock, ...]:
        try:
            stream = await self.new_stream(peer_id,
                                           REQ_RESP_BEACON_BLOCKS_BY_ROOT_SSZ)
        except StreamFailure as error:
            self.logger.debug("Fail to open stream to %s", str(peer_id))
            raise RequestFailure(str(error)) from error
        async with self.my_request_interaction(stream) as interaction:
            self._check_peer_handshaked(peer_id)
            request = BeaconBlocksByRootRequest.create(block_roots=block_roots)
            await interaction.write_request(request)
            blocks = tuple([
                block async for block in interaction.read_chunk_response(
                    SignedBeaconBlock, len(block_roots))
            ])

            return blocks

    async def update_status(self) -> None:
        while True:
            for peer_id in self.handshaked_peers.peer_ids:
                asyncio.ensure_future(self.request_status(peer_id))
            await asyncio.sleep(NEXT_UPDATE_INTERVAL)

    #
    # Metrics and APIs
    #
    async def handle_libp2p_peers_requests(self) -> None:
        async for req in self.wait_iter(
                self._event_bus.stream(Libp2pPeersRequest)):
            peers = tuple(self.handshaked_peers.peer_ids)
            await self._event_bus.broadcast(
                Libp2pPeersResponse(peers),
                req.broadcast_config(),
            )

    async def handle_libp2p_peer_id_requests(self) -> None:
        async for req in self.wait_iter(
                self._event_bus.stream(Libp2pPeerIDRequest)):
            await self._event_bus.broadcast(
                Libp2pPeerIDResponse(self.peer_id),
                req.broadcast_config(),
            )
Ejemplo n.º 4
0
class Node(BaseService):

    _is_started: bool = False

    key_pair: KeyPair
    listen_ip: str
    listen_port: int
    host: BasicHost
    pubsub: Pubsub
    bootstrap_nodes: Tuple[Multiaddr, ...]
    preferred_nodes: Tuple[Multiaddr, ...]
    chain: BaseBeaconChain

    handshaked_peers: PeerPool = None

    def __init__(
            self,
            key_pair: KeyPair,
            listen_ip: str,
            listen_port: int,
            chain: BaseBeaconChain,
            security_protocol_ops: Dict[TProtocol, BaseSecureTransport] = None,
            muxer_protocol_ops: Dict[TProtocol, IMuxedConn] = None,
            gossipsub_params: Optional[GossipsubParams] = None,
            cancel_token: CancelToken = None,
            bootstrap_nodes: Tuple[Multiaddr, ...] = (),
            preferred_nodes: Tuple[Multiaddr, ...] = ()) -> None:
        super().__init__(cancel_token)
        self.listen_ip = listen_ip
        self.listen_port = listen_port
        self.key_pair = key_pair
        self.bootstrap_nodes = bootstrap_nodes
        self.preferred_nodes = preferred_nodes
        # TODO: Add key and peer_id to the peerstore
        if security_protocol_ops is None:
            security_protocol_ops = {
                SecIOID: SecIOTransport(key_pair)
            }
        if muxer_protocol_ops is None:
            muxer_protocol_ops = {MPLEX_PROTOCOL_ID: Mplex}
        network: INetwork = initialize_default_swarm(
            key_pair=key_pair,
            transport_opt=[self.listen_maddr],
            muxer_opt=muxer_protocol_ops,
            sec_opt=security_protocol_ops,
            peerstore_opt=None,  # let the function initialize it
            disc_opt=None,  # no routing required here
        )
        self.host = BasicHost(network=network, router=None)

        if gossipsub_params is None:
            gossipsub_params = GossipsubParams()
        gossipsub_router = GossipSub(
            protocols=[GOSSIPSUB_PROTOCOL_ID],
            degree=gossipsub_params.DEGREE,
            degree_low=gossipsub_params.DEGREE_LOW,
            degree_high=gossipsub_params.DEGREE_HIGH,
            time_to_live=gossipsub_params.FANOUT_TTL,
            gossip_window=gossipsub_params.GOSSIP_WINDOW,
            gossip_history=gossipsub_params.GOSSIP_HISTORY,
            heartbeat_interval=gossipsub_params.HEARTBEAT_INTERVAL,
        )
        self.pubsub = Pubsub(
            host=self.host,
            router=gossipsub_router,
            my_id=self.peer_id,
        )

        self.chain = chain

        self.handshaked_peers = PeerPool()

        self.run_task(self.start())

    @property
    def is_started(self) -> bool:
        return self._is_started

    async def _run(self) -> None:
        self.logger.info("libp2p node %s is up", self.listen_maddr)
        await self.cancellation()

    async def start(self) -> None:
        # host
        self._register_rpc_handlers()
        # TODO: Register notifees
        await self.host.get_network().listen(self.listen_maddr)
        await self.connect_preferred_nodes()
        # TODO: Connect bootstrap nodes?

        # pubsub
        await self.pubsub.subscribe(PUBSUB_TOPIC_BEACON_BLOCK)
        await self.pubsub.subscribe(PUBSUB_TOPIC_BEACON_ATTESTATION)
        self._setup_topic_validators()

        self._is_started = True

    def _setup_topic_validators(self) -> None:
        self.pubsub.set_topic_validator(
            PUBSUB_TOPIC_BEACON_BLOCK,
            get_beacon_block_validator(self.chain),
            False,
        )
        self.pubsub.set_topic_validator(
            PUBSUB_TOPIC_BEACON_ATTESTATION,
            get_beacon_attestation_validator(self.chain),
            False,
        )

    async def dial_peer(self, ip: str, port: int, peer_id: ID) -> None:
        """
        Dial the peer ``peer_id`` through the IPv4 protocol
        """
        await self.host.connect(
            PeerInfo(
                peer_id=peer_id,
                addrs=[make_tcp_ip_maddr(ip, port)],
            )
        )
        try:
            # TODO: set a time limit on completing handshake
            await self.request_status(peer_id)
        except HandshakeFailure as e:
            self.logger.info("HandshakeFailure: %s", str(e))
            # TODO: handle it

    async def dial_peer_with_retries(self, ip: str, port: int, peer_id: ID) -> None:
        """
        Dial the peer ``peer_id`` through the IPv4 protocol
        """
        for i in range(DIAL_RETRY_COUNT):
            try:
                # exponential backoff...
                await asyncio.sleep(2**i + random.random())
                await self.dial_peer(ip, port, peer_id)
                return
            except ConnectionRefusedError:
                logger.debug(
                    "could not connect to peer %s at %s:%d;"
                    " retrying attempt %d of %d...",
                    peer_id,
                    ip,
                    port,
                    i,
                    DIAL_RETRY_COUNT,
                )
                continue
        raise ConnectionRefusedError

    async def dial_peer_maddr(self, maddr: Multiaddr) -> None:
        """
        Parse `maddr`, get the ip:port and PeerID, and call `dial_peer` with the parameters.
        """
        try:
            ip = maddr.value_for_protocol(protocols.P_IP4)
            port = maddr.value_for_protocol(protocols.P_TCP)
            peer_id = ID.from_base58(maddr.value_for_protocol(protocols.P_P2P))
            await self.dial_peer_with_retries(ip=ip, port=port, peer_id=peer_id)
        except Exception:
            traceback.print_exc()
            raise

    async def connect_preferred_nodes(self) -> None:
        results = await asyncio.gather(
            *(self.dial_peer_maddr(node_maddr)
              for node_maddr in self.preferred_nodes),
            return_exceptions=True,
        )
        for result in results:
            if isinstance(result, Exception):
                logger.warning("could not connect to %s", result)

    async def disconnect_peer(self, peer_id: ID) -> None:
        if peer_id in self.handshaked_peers:
            self.logger.debug("Disconnect from %s", peer_id)
            self.handshaked_peers.remove(peer_id)
            await self.host.disconnect(peer_id)
        else:
            self.logger.debug("Already disconnected from %s", peer_id)

    async def broadcast_beacon_block(self, block: BaseBeaconBlock) -> None:
        await self._broadcast_data(PUBSUB_TOPIC_BEACON_BLOCK, ssz.encode(block))

    async def broadcast_attestation(self, attestation: Attestation) -> None:
        await self._broadcast_data(PUBSUB_TOPIC_BEACON_ATTESTATION, ssz.encode(attestation))

    async def _broadcast_data(self, topic: str, data: bytes) -> None:
        await self.pubsub.publish(topic, data)

    @property
    def peer_id(self) -> ID:
        return self.host.get_id()

    @property
    def listen_maddr(self) -> Multiaddr:
        return make_tcp_ip_maddr(self.listen_ip, self.listen_port)

    @property
    def listen_maddr_with_peer_id(self) -> Multiaddr:
        return self.listen_maddr.encapsulate(Multiaddr(f"/p2p/{self.peer_id.to_base58()}"))

    @property
    def peer_store(self) -> PeerStore:
        return self.host.get_network().peerstore

    async def close(self) -> None:
        # FIXME: Add `tear_down` to `Swarm` in the upstream
        network = self.host.get_network()
        for listener in network.listeners.values():
            listener.server.close()
            await listener.server.wait_closed()
        # TODO: Add `close` in `Pubsub`

    def _register_rpc_handlers(self) -> None:
        self.host.set_stream_handler(REQ_RESP_STATUS_SSZ, self._handle_status)
        self.host.set_stream_handler(REQ_RESP_GOODBYE_SSZ, self._handle_goodbye)
        self.host.set_stream_handler(
            REQ_RESP_BEACON_BLOCKS_BY_RANGE_SSZ,
            self._handle_beacon_blocks_by_range,
        )
        self.host.set_stream_handler(
            REQ_RESP_BEACON_BLOCKS_BY_ROOT_SSZ,
            self._handle_beacon_blocks_by_root,
        )

    #
    # RPC Handlers
    #

    async def new_stream(self, peer_id: ID, protocol: TProtocol) -> INetStream:
        return await self.host.new_stream(peer_id, [protocol])

    @asynccontextmanager
    async def new_handshake_interaction(self, stream: INetStream) -> AsyncIterator[Interaction]:
        try:
            async with Interaction(stream) as interaction:
                peer_id = interaction.peer_id
                yield interaction
        except MessageIOFailure as error:
            await self.disconnect_peer(peer_id)
            raise HandshakeFailure() from error
        except PeerRespondedAnError as error:
            await stream.reset()
            await self.disconnect_peer(peer_id)
            raise HandshakeFailure() from error
        except IrrelevantNetwork as error:
            await stream.reset()
            asyncio.ensure_future(
                self.say_goodbye(peer_id, GoodbyeReasonCode.IRRELEVANT_NETWORK)
            )
            raise HandshakeFailure from error

    @asynccontextmanager
    async def post_handshake_handler_interaction(
        self,
        stream: INetStream
    ) -> AsyncIterator[Interaction]:
        try:
            async with Interaction(stream) as interaction:
                yield interaction
        except WriteMessageFailure as error:
            self.logger.debug("WriteMessageFailure %s", error)
            return
        except ReadMessageFailure as error:
            self.logger.debug("ReadMessageFailure %s", error)
            return
        except UnhandshakedPeer:
            await stream.reset()
            return

    @asynccontextmanager
    async def my_request_interaction(self, stream: INetStream) -> AsyncIterator[Interaction]:
        try:
            async with Interaction(stream) as interaction:
                yield interaction
        except (MessageIOFailure, UnhandshakedPeer, PeerRespondedAnError) as error:
            raise RequestFailure(str(error)) from error

    # TODO: Handle the reputation of peers. Deduct their scores and even disconnect when they
    #   behave.

    # TODO: Register notifee to the `Network` to
    #   - Record peers' joining time.
    #   - Disconnect peers when they fail to join in a certain amount of time.

    def _add_peer_from_status(self, peer_id: ID, status: Status) -> None:
        peer = Peer.from_status(self, peer_id, status)
        self.handshaked_peers.add(peer)
        self.logger.debug(
            "Handshake from %s is finished. Added to the `handshake_peers`",
            peer_id,
        )

    async def _handle_status(self, stream: INetStream) -> None:
        # TODO: Find out when we should respond the `ResponseCode`
        #   other than `ResponseCode.SUCCESS`.

        async with self.new_handshake_interaction(stream) as interaction:
            peer_id = interaction.peer_id
            peer_status = await interaction.read_request(Status)
            self.logger.info("Received Status from %s  %s", str(peer_id), peer_status)
            await validate_peer_status(self.chain, peer_status)

            my_status = get_my_status(self.chain)
            await interaction.write_response(my_status)

            self._add_peer_from_status(peer_id, peer_status)

            # Check if we are behind the peer
            compare_chain_tip_and_finalized_epoch(self.chain, peer_status)

    async def request_status(self, peer_id: ID) -> None:
        self.logger.info("Initiate handshake with %s", str(peer_id))

        stream = await self.new_stream(peer_id, REQ_RESP_STATUS_SSZ)
        async with self.new_handshake_interaction(stream) as interaction:
            my_status = get_my_status(self.chain)
            await interaction.write_request(my_status)
            peer_status = await interaction.read_response(Status)

            await validate_peer_status(self.chain, peer_status)

            self._add_peer_from_status(peer_id, peer_status)

            # Check if we are behind the peer
            compare_chain_tip_and_finalized_epoch(self.chain, peer_status)

    async def _handle_goodbye(self, stream: INetStream) -> None:
        async with Interaction(stream) as interaction:
            peer_id = interaction.peer_id
            try:
                await interaction.read_request(Goodbye)
            except ReadMessageFailure:
                pass
            await self.disconnect_peer(peer_id)

    async def say_goodbye(self, peer_id: ID, reason: GoodbyeReasonCode) -> None:
        stream = await self.new_stream(peer_id, REQ_RESP_GOODBYE_SSZ)
        async with Interaction(stream) as interaction:
            goodbye = Goodbye(reason)
            try:
                await interaction.write_request(goodbye)
            except WriteMessageFailure:
                pass
            await self.disconnect_peer(peer_id)

    def _check_peer_handshaked(self, peer_id: ID) -> None:
        if peer_id not in self.handshaked_peers:
            raise UnhandshakedPeer(peer_id)

    async def _handle_beacon_blocks_by_range(self, stream: INetStream) -> None:
        # TODO: Should it be a successful response if peer is requesting
        # blocks on a fork we don't have data for?

        async with self.post_handshake_handler_interaction(stream) as interaction:
            peer_id = interaction.peer_id
            self._check_peer_handshaked(peer_id)

            request = await interaction.read_request(BeaconBlocksByRangeRequest)
            try:
                blocks = get_requested_beacon_blocks(self.chain, request)
            except InvalidRequest as error:
                error_message = str(error)[:128]
                await interaction.write_error_response(error_message, ResponseCode.INVALID_REQUEST)
            else:
                await interaction.write_chunk_response(blocks)

    async def request_beacon_blocks_by_range(
        self,
        peer_id: ID,
        head_block_root: SigningRoot,
        start_slot: Slot,
        count: int,
        step: int,
    ) -> Tuple[BaseBeaconBlock, ...]:
        stream = await self.new_stream(peer_id, REQ_RESP_BEACON_BLOCKS_BY_RANGE_SSZ)
        async with self.my_request_interaction(stream) as interaction:
            self._check_peer_handshaked(peer_id)
            request = BeaconBlocksByRangeRequest(
                head_block_root=head_block_root,
                start_slot=start_slot,
                count=count,
                step=step,
            )
            await interaction.write_request(request)
            blocks = tuple([
                block async for block in
                interaction.read_chunk_response(BeaconBlock, count)
            ])

            return blocks

    async def _handle_beacon_blocks_by_root(self, stream: INetStream) -> None:
        async with self.post_handshake_handler_interaction(stream) as interaction:
            peer_id = interaction.peer_id
            self._check_peer_handshaked(peer_id)
            request = await interaction.read_request(BeaconBlocksByRootRequest)
            blocks = get_beacon_blocks_by_root(self.chain, request)

            await interaction.write_chunk_response(blocks)

    async def request_beacon_blocks_by_root(
            self,
            peer_id: ID,
            block_roots: Sequence[SigningRoot]) -> Tuple[BaseBeaconBlock, ...]:
        stream = await self.new_stream(peer_id, REQ_RESP_BEACON_BLOCKS_BY_ROOT_SSZ)
        async with self.my_request_interaction(stream) as interaction:
            self._check_peer_handshaked(peer_id)
            request = BeaconBlocksByRootRequest(block_roots=block_roots)
            await interaction.write_request(request)
            blocks = tuple([
                block async for block in
                interaction.read_chunk_response(BeaconBlock, len(block_roots))
            ])

            return blocks
Ejemplo n.º 5
0
class Node(BaseService):

    key_pair: KeyPair
    listen_ip: str
    listen_port: int
    host: BasicHost
    pubsub: Pubsub
    bootstrap_nodes: Optional[Tuple[Multiaddr, ...]]
    preferred_nodes: Optional[Tuple[Multiaddr, ...]]
    chain: BaseBeaconChain

    handshaked_peers: Set[ID]

    def __init__(self,
                 key_pair: KeyPair,
                 listen_ip: str,
                 listen_port: int,
                 chain: BaseBeaconChain,
                 security_protocol_ops: Dict[TProtocol,
                                             BaseSecureTransport] = None,
                 muxer_protocol_ops: Dict[TProtocol, IMuxedConn] = None,
                 gossipsub_params: Optional[GossipsubParams] = None,
                 cancel_token: CancelToken = None,
                 bootstrap_nodes: Tuple[Multiaddr, ...] = None,
                 preferred_nodes: Tuple[Multiaddr, ...] = None) -> None:
        super().__init__(cancel_token)
        self.listen_ip = listen_ip
        self.listen_port = listen_port
        self.key_pair = key_pair
        self.bootstrap_nodes = bootstrap_nodes
        self.preferred_nodes = preferred_nodes
        # TODO: Add key and peer_id to the peerstore
        if security_protocol_ops is None:
            security_protocol_ops = {
                PLAINTEXT_PROTOCOL_ID: InsecureTransport(key_pair)
            }
        if muxer_protocol_ops is None:
            muxer_protocol_ops = {MPLEX_PROTOCOL_ID: Mplex}
        network: INetwork = initialize_default_swarm(
            key_pair=key_pair,
            transport_opt=[self.listen_maddr],
            muxer_opt=muxer_protocol_ops,
            sec_opt=security_protocol_ops,
            peerstore_opt=None,  # let the function initialize it
            disc_opt=None,  # no routing required here
        )
        self.host = BasicHost(network=network, router=None)

        if gossipsub_params is None:
            gossipsub_params = GossipsubParams()
        gossipsub_router = GossipSub(
            protocols=[GOSSIPSUB_PROTOCOL_ID],
            degree=gossipsub_params.DEGREE,
            degree_low=gossipsub_params.DEGREE_LOW,
            degree_high=gossipsub_params.DEGREE_HIGH,
            time_to_live=gossipsub_params.FANOUT_TTL,
            gossip_window=gossipsub_params.GOSSIP_WINDOW,
            gossip_history=gossipsub_params.GOSSIP_HISTORY,
            heartbeat_interval=gossipsub_params.HEARTBEAT_INTERVAL,
        )
        self.pubsub = Pubsub(
            host=self.host,
            router=gossipsub_router,
            my_id=self.peer_id,
        )

        self.chain = chain

        self.handshaked_peers = set()

    async def _run(self) -> None:
        self.run_daemon_task(self.start())
        self.logger.info("libp2p node %s is up", self.listen_maddr)
        await self.cancellation()

    async def start(self) -> None:
        # host
        self._register_rpc_handlers()
        # TODO: Register notifees
        await self.host.get_network().listen(self.listen_maddr)
        await self.connect_preferred_nodes()
        # TODO: Connect bootstrap nodes?

        # pubsub
        await self.pubsub.subscribe(PUBSUB_TOPIC_BEACON_BLOCK)
        await self.pubsub.subscribe(PUBSUB_TOPIC_BEACON_ATTESTATION)
        # TODO: Register topic validators

    async def dial_peer(self, ip: str, port: int, peer_id: ID) -> None:
        """
        Dial the peer ``peer_id`` through the IPv4 protocol
        """
        peer_data = PeerData()
        peer_data.addrs = [make_tcp_ip_maddr(ip, port)]
        await self.host.connect(
            PeerInfo(
                peer_id=peer_id,
                peer_data=peer_data,
            ))

    async def dial_peer_maddr(self, maddr: Multiaddr) -> None:
        """
        Parse `maddr`, get the ip:port and PeerID, and call `dial_peer` with the parameters.
        """
        ip = maddr.value_for_protocol(protocols.P_IP4)
        port = maddr.value_for_protocol(protocols.P_TCP)
        peer_id = ID.from_base58(maddr.value_for_protocol(protocols.P_P2P))
        await self.dial_peer(ip=ip, port=port, peer_id=peer_id)

    async def connect_preferred_nodes(self) -> None:
        if self.preferred_nodes is None:
            return
        await asyncio.wait([
            self.dial_peer_maddr(node_maddr)
            for node_maddr in self.preferred_nodes
        ])

    async def broadcast_beacon_block(self, block: BaseBeaconBlock) -> None:
        await self._broadcast_data(PUBSUB_TOPIC_BEACON_BLOCK,
                                   ssz.encode(block))

    async def broadcast_attestations(
            self, attestations: Sequence[Attestation]) -> None:
        await self._broadcast_data(PUBSUB_TOPIC_BEACON_ATTESTATION,
                                   ssz.encode(attestations))

    async def _broadcast_data(self, topic: str, data: bytes) -> None:
        await self.pubsub.publish(topic, data)

    @property
    def peer_id(self) -> ID:
        return self.host.get_id()

    @property
    def listen_maddr(self) -> Multiaddr:
        return make_tcp_ip_maddr(self.listen_ip, self.listen_port)

    @property
    def listen_maddr_with_peer_id(self) -> Multiaddr:
        return self.listen_maddr.encapsulate(Multiaddr(f"/p2p/{self.peer_id}"))

    @property
    def peer_store(self) -> PeerStore:
        return self.host.get_network().peerstore

    async def close(self) -> None:
        # FIXME: Add `tear_down` to `Swarm` in the upstream
        network = self.host.get_network()
        for listener in network.listeners.values():
            listener.server.close()
            await listener.server.wait_closed()
        # TODO: Add `close` in `Pubsub`

    def _register_rpc_handlers(self) -> None:
        self.host.set_stream_handler(REQ_RESP_HELLO_SSZ, self._handle_hello)

    #
    # RPC Handlers
    #

    # TODO: Add a wrapper or decorator to handle the exceptions in handlers,
    #   to close the streams safely. Probably starting from: if the function
    #   returns successfully, then close the stream. Otherwise, reset the stream.

    # TODO: Handle the reputation of peers. Deduct their scores and even disconnect when they
    #   behave.

    # TODO: Register notifee to the `Network` to
    #   - Record peers' joining time.
    #   - Disconnect peers when they fail to join in a certain amount of time.

    async def _validate_hello_req(self,
                                  hello_other_side: HelloRequest) -> None:
        state = self.chain.get_state_machine().state
        if hello_other_side.fork_version != state.fork.current_version:
            raise ValidationError(
                "`fork_version` mismatches: "
                f"hello_other_side.fork_version={hello_other_side.fork_version}, "
                f"state.fork.current_version={state.fork.current_version}")
        # TODO: Reject if the (finalized_root, finalized_epoch) shared by the peer
        #   is not in the client's chain at the expected epoch.

    async def _request_beacon_blocks(self) -> None:
        """
        TODO:
        Once the handshake completes, the client with the lower `finalized_epoch` or
        `head_slot` (if the clients have equal `finalized_epochs`) SHOULD request beacon blocks
        from its counterparty via the BeaconBlocks request.
        """

    def _make_hello_packet(self) -> HelloRequest:
        state = self.chain.get_state_machine().state
        finalized_checkpoint = state.finalized_checkpoint
        return HelloRequest(
            fork_version=state.fork.current_version,
            finalized_root=finalized_checkpoint.root,
            finalized_epoch=finalized_checkpoint.epoch,
            head_root=state.hash_tree_root,
            head_slot=state.slot,
        )

    async def _handle_hello(self, stream: INetStream) -> None:
        # TODO: Find out when we should respond the `ResponseCode`
        #   other than `ResponseCode.SUCCESS`.

        # TODO: Handle `stream.close` and `stream.reset`
        peer_id = stream.mplex_conn.peer_id
        if peer_id in self.handshaked_peers:
            self.logger.info(
                "Handshake failed: already handshaked with %s before",
                peer_id,
            )
            # FIXME: Use `Stream.reset()` when `NetStream` has this API.
            # await stream.reset()
            return

        self.logger.debug("Waiting for hello from the other side")
        try:
            hello_other_side = await read_req(stream, HelloRequest)
        except ReadMessageFailure as error:
            # FIXME: Use `Stream.reset()` when `NetStream` has this API.
            # await stream.reset()
            # TODO: Disconnect
            return
        self.logger.debug("Received the hello message %s", hello_other_side)

        try:
            await self._validate_hello_req(hello_other_side)
        except ValidationError:
            self.logger.info("Handshake failed: hello message %s is invalid",
                             hello_other_side)
            # FIXME: Use `Stream.reset()` when `NetStream` has this API.
            # await stream.reset()
            # TODO: Disconnect
            return

        hello_mine = self._make_hello_packet()

        self.logger.debug("Sending our hello message %s", hello_mine)
        try:
            await write_resp(stream, hello_mine, ResponseCode.SUCCESS)
        except WriteMessageFailure as error:
            self.logger.info(
                "Handshake failed: failed to write message %s",
                hello_mine,
            )
            # await stream.reset()
            # TODO: Disconnect
            return

        self.handshaked_peers.add(peer_id)

        self.logger.debug(
            "Handshake from %s is finished. Added to the `handshake_peers`",
            peer_id,
        )
        # TODO: If we have lower `finalized_epoch` or `head_slot`, request the later beacon blocks.

        await stream.close()

    async def say_hello(self, peer_id: ID) -> None:
        # TODO: Handle `stream.close` and `stream.reset`
        if peer_id in self.handshaked_peers:
            error_msg = f"already handshaked with {peer_id} before"
            self.logger.info("Handshake failed: %s", error_msg)
            raise HandshakeFailure(error_msg)

        hello_mine = self._make_hello_packet()

        self.logger.debug(
            "Opening new stream to peer=%s with protocols=%s",
            peer_id,
            [REQ_RESP_HELLO_SSZ],
        )
        stream = await self.host.new_stream(peer_id, [REQ_RESP_HELLO_SSZ])
        self.logger.debug("Sending our hello message %s", hello_mine)
        try:
            await write_req(stream, hello_mine)
        except WriteMessageFailure as error:
            # FIXME: Use `Stream.reset()` when `NetStream` has this API.
            # await stream.reset()
            # TODO: Disconnect
            error_msg = f"fail to write request={hello_mine}"
            self.logger.info("Handshake failed: %s", error_msg)
            raise HandshakeFailure(error_msg) from error

        self.logger.debug("Waiting for hello from the other side")
        try:
            resp_code, hello_other_side = await read_resp(stream, HelloRequest)
        except ReadMessageFailure as error:
            # FIXME: Use `Stream.reset()` when `NetStream` has this API.
            # await stream.reset()
            # TODO: Disconnect
            error_msg = "fail to read the response"
            self.logger.info("Handshake failed: %s", error_msg)
            raise HandshakeFailure(error_msg) from error

        self.logger.debug(
            "Received the hello message %s, resp_code=%s",
            hello_other_side,
            resp_code,
        )

        # TODO: Handle the case when `resp_code` is not success.
        if resp_code != ResponseCode.SUCCESS:
            # TODO: Do something according to the `ResponseCode`
            # TODO: Disconnect
            error_msg = (
                "resp_code != ResponseCode.SUCCESS, "
                f"resp_code={resp_code}, error_msg={hello_other_side}")
            self.logger.info("Handshake failed: %s", error_msg)
            # FIXME: Use `Stream.reset()` when `NetStream` has this API.
            # await stream.reset()
            # TODO: Disconnect
            raise HandshakeFailure(error_msg)

        try:
            await self._validate_hello_req(hello_other_side)
        except ValidationError as error:
            error_msg = f"hello message {hello_other_side} is invalid: {str(error)}"
            self.logger.info(
                "Handshake failed: %s. Disconnecting %s",
                error_msg,
                peer_id,
            )
            # FIXME: Use `Stream.reset()` when `NetStream` has this API.
            # await stream.reset()
            # TODO: Disconnect
            raise HandshakeFailure(error_msg) from error

        self.handshaked_peers.add(peer_id)

        self.logger.debug(
            "Handshake to peer=%s is finished. Added to the `handshake_peers`",
            peer_id,
        )
        # TODO: If we have lower `finalized_epoch` or `head_slot`, request the later beacon blocks.

        await stream.close()