mirror of
https://github.com/logos-blockchain/logos-blockchain-specs.git
synced 2026-01-10 09:03:08 +00:00
129 lines
4.0 KiB
Python
129 lines
4.0 KiB
Python
from __future__ import annotations
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import hashlib
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from dataclasses import dataclass
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from enum import Enum
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from typing import Awaitable, Callable, Self
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from mixnet.connection import DuplexConnection, MixSimplexConnection, SimplexConnection
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from mixnet.error import PeeringDegreeReached
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from mixnet.framework import Framework
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class Nomssip:
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"""
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A NomMix gossip channel that broadcasts messages to all connected peers.
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Peers are connected via DuplexConnection.
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"""
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@dataclass
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class Config:
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transmission_rate_per_sec: int
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peering_degree: int
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msg_size: int
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def __init__(
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self,
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framework: Framework,
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config: Config,
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handler: Callable[[bytes], Awaitable[None]],
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):
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self.framework = framework
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self.config = config
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self.conns: list[DuplexConnection] = []
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# A handler to process inbound messages.
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self.handler = handler
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self.packet_cache: set[bytes] = set()
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# A set just for gathering a reference of tasks to prevent them from being garbage collected.
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# https://docs.python.org/3/library/asyncio-task.html#asyncio.create_task
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self.tasks: set[Awaitable] = set()
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def can_accept_conn(self) -> bool:
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return len(self.conns) < self.config.peering_degree
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def add_conn(self, inbound: SimplexConnection, outbound: SimplexConnection):
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if not self.can_accept_conn():
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# For simplicity of the spec, reject the connection if the peering degree is reached.
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raise PeeringDegreeReached()
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noise_packet = FlaggedPacket(
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FlaggedPacket.Flag.NOISE, bytes(self.config.msg_size)
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).bytes()
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conn = DuplexConnection(
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inbound,
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MixSimplexConnection(
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self.framework,
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outbound,
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self.config.transmission_rate_per_sec,
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noise_packet,
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),
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)
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self.conns.append(conn)
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task = self.framework.spawn(self.__process_inbound_conn(conn))
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self.tasks.add(task)
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async def __process_inbound_conn(self, conn: DuplexConnection):
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while True:
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packet = await conn.recv()
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if self.__check_update_cache(packet):
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continue
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packet = FlaggedPacket.from_bytes(packet)
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match packet.flag:
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case FlaggedPacket.Flag.NOISE:
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# Drop noise packet
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continue
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case FlaggedPacket.Flag.REAL:
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await self.__gossip_flagged_packet(packet)
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await self.handler(packet.message)
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async def gossip(self, msg: bytes):
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"""
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Gossip a message to all connected peers with prepending a message flag
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"""
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# The message size must be fixed.
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assert len(msg) == self.config.msg_size
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packet = FlaggedPacket(FlaggedPacket.Flag.REAL, msg)
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await self.__gossip_flagged_packet(packet)
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async def __gossip_flagged_packet(self, packet: FlaggedPacket):
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"""
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An internal method to send a flagged packet to all connected peers
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"""
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for conn in self.conns:
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await conn.send(packet.bytes())
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def __check_update_cache(self, packet: bytes) -> bool:
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"""
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Add a message to the cache, and return True if the message was already in the cache.
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"""
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hash = hashlib.sha256(packet).digest()
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if hash in self.packet_cache:
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return True
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self.packet_cache.add(hash)
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return False
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class FlaggedPacket:
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class Flag(Enum):
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REAL = b"\x00"
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NOISE = b"\x01"
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def __init__(self, flag: Flag, message: bytes):
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self.flag = flag
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self.message = message
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def bytes(self) -> bytes:
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return self.flag.value + self.message
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@classmethod
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def from_bytes(cls, packet: bytes) -> Self:
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"""
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Parse a flagged packet from bytes
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"""
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if len(packet) < 1:
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raise ValueError("Invalid message format")
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return cls(cls.Flag(packet[:1]), packet[1:])
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