452 lines
16 KiB
Python
452 lines
16 KiB
Python
import asyncio
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import logging
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import time
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from typing import (
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TYPE_CHECKING,
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Awaitable,
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Callable,
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Dict,
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List,
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NamedTuple,
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Tuple,
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Union,
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cast,
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)
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from lru import LRU
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from libp2p.exceptions import ValidationError
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from libp2p.host.host_interface import IHost
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from libp2p.network.stream.net_stream_interface import INetStream
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from libp2p.peer.id import ID
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from libp2p.typing import TProtocol
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from libp2p.utils import encode_varint_prefixed, read_varint_prefixed_bytes
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from .pb import rpc_pb2
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from .pubsub_notifee import PubsubNotifee
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from .validators import signature_validator
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if TYPE_CHECKING:
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from .pubsub_router_interface import IPubsubRouter # noqa: F401
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log = logging.getLogger(__name__)
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def get_msg_id(msg: rpc_pb2.Message) -> Tuple[bytes, bytes]:
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# NOTE: `string(from, seqno)` in Go
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return (msg.seqno, msg.from_id)
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SyncValidatorFn = Callable[[ID, rpc_pb2.Message], bool]
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AsyncValidatorFn = Callable[[ID, rpc_pb2.Message], Awaitable[bool]]
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ValidatorFn = Union[SyncValidatorFn, AsyncValidatorFn]
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class TopicValidator(NamedTuple):
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validator: ValidatorFn
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is_async: bool
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class Pubsub:
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host: IHost
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my_id: ID
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router: "IPubsubRouter"
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peer_queue: "asyncio.Queue[ID]"
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protocols: List[TProtocol]
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incoming_msgs_from_peers: "asyncio.Queue[rpc_pb2.Message]"
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outgoing_messages: "asyncio.Queue[rpc_pb2.Message]"
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seen_messages: LRU
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my_topics: Dict[str, "asyncio.Queue[rpc_pb2.Message]"]
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peer_topics: Dict[str, List[ID]]
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peers: Dict[ID, INetStream]
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topic_validators: Dict[str, TopicValidator]
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# TODO: Be sure it is increased atomically everytime.
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counter: int # uint64
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def __init__(
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self, host: IHost, router: "IPubsubRouter", my_id: ID, cache_size: int = None
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) -> None:
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"""
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Construct a new Pubsub object, which is responsible for handling all
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Pubsub-related messages and relaying messages as appropriate to the
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Pubsub router (which is responsible for choosing who to send messages to).
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Since the logic for choosing peers to send pubsub messages to is
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in the router, the same Pubsub impl can back floodsub, gossipsub, etc.
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"""
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self.host = host
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self.router = router
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self.my_id = my_id
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# Attach this new Pubsub object to the router
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self.router.attach(self)
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# Register a notifee
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self.peer_queue = asyncio.Queue()
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self.host.get_network().notify(PubsubNotifee(self.peer_queue))
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# Register stream handlers for each pubsub router protocol to handle
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# the pubsub streams opened on those protocols
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self.protocols = self.router.get_protocols()
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for protocol in self.protocols:
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self.host.set_stream_handler(protocol, self.stream_handler)
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# Use asyncio queues for proper context switching
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self.incoming_msgs_from_peers = asyncio.Queue()
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self.outgoing_messages = asyncio.Queue()
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# keeps track of seen messages as LRU cache
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if cache_size is None:
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self.cache_size = 128
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else:
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self.cache_size = cache_size
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self.seen_messages = LRU(self.cache_size)
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# Map of topics we are subscribed to blocking queues
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# for when the given topic receives a message
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self.my_topics = {}
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# Map of topic to peers to keep track of what peers are subscribed to
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self.peer_topics = {}
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# Create peers map, which maps peer_id (as string) to stream (to a given peer)
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self.peers = {}
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# Map of topic to topic validator
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self.topic_validators = {}
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self.counter = time.time_ns()
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# Call handle peer to keep waiting for updates to peer queue
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asyncio.ensure_future(self.handle_peer_queue())
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def get_hello_packet(self) -> rpc_pb2.RPC:
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"""
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Generate subscription message with all topics we are subscribed to
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only send hello packet if we have subscribed topics
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"""
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packet = rpc_pb2.RPC()
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for topic_id in self.my_topics:
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packet.subscriptions.extend(
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[rpc_pb2.RPC.SubOpts(subscribe=True, topicid=topic_id)]
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)
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return packet
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async def continuously_read_stream(self, stream: INetStream) -> None:
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"""
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Read from input stream in an infinite loop. Process
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messages from other nodes
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:param stream: stream to continously read from
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"""
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peer_id = stream.mplex_conn.peer_id
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while True:
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incoming: bytes = await read_varint_prefixed_bytes(stream)
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rpc_incoming: rpc_pb2.RPC = rpc_pb2.RPC()
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rpc_incoming.ParseFromString(incoming)
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if rpc_incoming.publish:
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# deal with RPC.publish
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for msg in rpc_incoming.publish:
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if not self._is_subscribed_to_msg(msg):
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continue
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asyncio.ensure_future(self.push_msg(msg_forwarder=peer_id, msg=msg))
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if rpc_incoming.subscriptions:
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# deal with RPC.subscriptions
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# We don't need to relay the subscription to our
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# peers because a given node only needs its peers
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# to know that it is subscribed to the topic (doesn't
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# need everyone to know)
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for message in rpc_incoming.subscriptions:
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self.handle_subscription(peer_id, message)
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# NOTE: Check if `rpc_incoming.control` is set through `HasField`.
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# This is necessary because `control` is an optional field in pb2.
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# Ref: https://developers.google.com/protocol-buffers/docs/reference/python-generated#singular-fields-proto2 # noqa: E501
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if rpc_incoming.HasField("control"):
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# Pass rpc to router so router could perform custom logic
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await self.router.handle_rpc(rpc_incoming, peer_id)
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# Force context switch
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await asyncio.sleep(0)
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def set_topic_validator(
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self, topic: str, validator: ValidatorFn, is_async_validator: bool
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) -> None:
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"""
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Register a validator under the given topic. One topic can only have one validtor.
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:param topic: the topic to register validator under
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:param validator: the validator used to validate messages published to the topic
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:param is_async_validator: indicate if the validator is an asynchronous validator
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"""
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self.topic_validators[topic] = TopicValidator(validator, is_async_validator)
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def remove_topic_validator(self, topic: str) -> None:
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"""
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Remove the validator from the given topic.
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:param topic: the topic to remove validator from
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"""
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if topic in self.topic_validators:
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del self.topic_validators[topic]
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def get_msg_validators(self, msg: rpc_pb2.Message) -> Tuple[TopicValidator, ...]:
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"""
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Get all validators corresponding to the topics in the message.
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:param msg: the message published to the topic
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"""
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return tuple(
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self.topic_validators[topic]
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for topic in msg.topicIDs
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if topic in self.topic_validators
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)
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async def stream_handler(self, stream: INetStream) -> None:
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"""
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Stream handler for pubsub. Gets invoked whenever a new stream is created
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on one of the supported pubsub protocols.
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:param stream: newly created stream
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"""
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await self.continuously_read_stream(stream)
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async def _handle_new_peer(self, peer_id: ID) -> None:
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stream: INetStream = await self.host.new_stream(peer_id, self.protocols)
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self.peers[peer_id] = stream
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# Send hello packet
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hello = self.get_hello_packet()
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await stream.write(encode_varint_prefixed(hello.SerializeToString()))
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# TODO: Check EOF of this stream.
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# TODO: Check if the peer in black list.
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self.router.add_peer(peer_id, stream.get_protocol())
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async def handle_peer_queue(self) -> None:
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"""
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Continuously read from peer queue and each time a new peer is found,
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open a stream to the peer using a supported pubsub protocol
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TODO: Handle failure for when the peer does not support any of the
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pubsub protocols we support
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"""
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while True:
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peer_id: ID = await self.peer_queue.get()
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# Add Peer
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asyncio.ensure_future(self._handle_new_peer(peer_id))
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# Force context switch
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await asyncio.sleep(0)
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def handle_subscription(
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self, origin_id: ID, sub_message: rpc_pb2.RPC.SubOpts
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) -> None:
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"""
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Handle an incoming subscription message from a peer. Update internal
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mapping to mark the peer as subscribed or unsubscribed to topics as
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defined in the subscription message
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:param origin_id: id of the peer who subscribe to the message
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:param sub_message: RPC.SubOpts
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"""
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if sub_message.subscribe:
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if sub_message.topicid not in self.peer_topics:
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self.peer_topics[sub_message.topicid] = [origin_id]
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elif origin_id not in self.peer_topics[sub_message.topicid]:
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# Add peer to topic
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self.peer_topics[sub_message.topicid].append(origin_id)
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else:
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if sub_message.topicid in self.peer_topics:
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if origin_id in self.peer_topics[sub_message.topicid]:
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self.peer_topics[sub_message.topicid].remove(origin_id)
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# FIXME(mhchia): Change the function name?
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async def handle_talk(self, publish_message: rpc_pb2.Message) -> None:
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"""
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Put incoming message from a peer onto my blocking queue
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:param publish_message: RPC.Message format
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"""
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# Check if this message has any topics that we are subscribed to
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for topic in publish_message.topicIDs:
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if topic in self.my_topics:
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# we are subscribed to a topic this message was sent for,
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# so add message to the subscription output queue
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# for each topic
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await self.my_topics[topic].put(publish_message)
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async def subscribe(self, topic_id: str) -> "asyncio.Queue[rpc_pb2.Message]":
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"""
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Subscribe ourself to a topic
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:param topic_id: topic_id to subscribe to
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"""
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# Already subscribed
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if topic_id in self.my_topics:
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return self.my_topics[topic_id]
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# Map topic_id to blocking queue
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self.my_topics[topic_id] = asyncio.Queue()
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# Create subscribe message
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packet: rpc_pb2.RPC = rpc_pb2.RPC()
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packet.subscriptions.extend(
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[rpc_pb2.RPC.SubOpts(subscribe=True, topicid=topic_id)]
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)
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# Send out subscribe message to all peers
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await self.message_all_peers(packet.SerializeToString())
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# Tell router we are joining this topic
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await self.router.join(topic_id)
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# Return the asyncio queue for messages on this topic
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return self.my_topics[topic_id]
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async def unsubscribe(self, topic_id: str) -> None:
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"""
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Unsubscribe ourself from a topic
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:param topic_id: topic_id to unsubscribe from
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"""
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# Return if we already unsubscribed from the topic
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if topic_id not in self.my_topics:
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return
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# Remove topic_id from map if present
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del self.my_topics[topic_id]
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# Create unsubscribe message
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packet: rpc_pb2.RPC = rpc_pb2.RPC()
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packet.subscriptions.extend(
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[rpc_pb2.RPC.SubOpts(subscribe=False, topicid=topic_id)]
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)
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# Send out unsubscribe message to all peers
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await self.message_all_peers(packet.SerializeToString())
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# Tell router we are leaving this topic
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await self.router.leave(topic_id)
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async def message_all_peers(self, raw_msg: bytes) -> None:
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"""
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Broadcast a message to peers
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:param raw_msg: raw contents of the message to broadcast
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"""
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# Broadcast message
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for stream in self.peers.values():
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# Write message to stream
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await stream.write(encode_varint_prefixed(raw_msg))
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async def publish(self, topic_id: str, data: bytes) -> None:
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"""
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Publish data to a topic
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:param topic_id: topic which we are going to publish the data to
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:param data: data which we are publishing
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"""
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msg = rpc_pb2.Message(
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data=data,
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topicIDs=[topic_id],
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# Origin is ourself.
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from_id=self.host.get_id().to_bytes(),
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seqno=self._next_seqno(),
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)
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# TODO: Sign with our signing key
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await self.push_msg(self.host.get_id(), msg)
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async def validate_msg(self, msg_forwarder: ID, msg: rpc_pb2.Message) -> None:
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"""
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Validate the received message
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:param msg_forwarder: the peer who forward us the message.
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:param msg: the message.
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"""
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sync_topic_validators = []
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async_topic_validator_futures: List[Awaitable[bool]] = []
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for topic_validator in self.get_msg_validators(msg):
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if topic_validator.is_async:
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async_topic_validator_futures.append(
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cast(Awaitable[bool], topic_validator.validator(msg_forwarder, msg))
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)
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else:
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sync_topic_validators.append(
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cast(SyncValidatorFn, topic_validator.validator)
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)
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for validator in sync_topic_validators:
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if not validator(msg_forwarder, msg):
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raise ValidationError(f"Validation failed for msg={msg}")
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# TODO: Implement throttle on async validators
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if len(async_topic_validator_futures) > 0:
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results = await asyncio.gather(*async_topic_validator_futures)
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if not all(results):
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raise ValidationError(f"Validation failed for msg={msg}")
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async def push_msg(self, msg_forwarder: ID, msg: rpc_pb2.Message) -> None:
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"""
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Push a pubsub message to others.
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:param msg_forwarder: the peer who forward us the message.
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:param msg: the message we are going to push out.
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"""
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# TODO: Check if the `source` is in the blacklist. If yes, reject.
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# TODO: Check if the `from` is in the blacklist. If yes, reject.
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# TODO: Check if signing is required and if so signature should be attached.
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# If the message is processed before, return(i.e., don't further process the message).
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if self._is_msg_seen(msg):
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return
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# TODO: - Validate the message. If failed, reject it.
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# Validate the signature of the message
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# FIXME: `signature_validator` is currently a stub.
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if not signature_validator(msg.key, msg.SerializeToString()):
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log.debug(f"Signature validation failed for msg={msg}")
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return
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# Validate the message with registered topic validators.
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# If the validation failed, return(i.e., don't further process the message).
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try:
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await self.validate_msg(msg_forwarder, msg)
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except ValidationError:
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log.debug(f"Topic validation failed for msg={msg}")
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return
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self._mark_msg_seen(msg)
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await self.handle_talk(msg)
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await self.router.publish(msg_forwarder, msg)
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def _next_seqno(self) -> bytes:
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"""
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Make the next message sequence id.
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"""
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self.counter += 1
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return self.counter.to_bytes(8, "big")
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def _is_msg_seen(self, msg: rpc_pb2.Message) -> bool:
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msg_id = get_msg_id(msg)
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return msg_id in self.seen_messages
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def _mark_msg_seen(self, msg: rpc_pb2.Message) -> None:
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msg_id = get_msg_id(msg)
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# FIXME: Mapping `msg_id` to `1` is quite awkward. Should investigate if there is a
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# more appropriate way.
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self.seen_messages[msg_id] = 1
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def _is_subscribed_to_msg(self, msg: rpc_pb2.Message) -> bool:
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if not self.my_topics:
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return False
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return any(topic in self.my_topics for topic in msg.topicIDs)
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