321 lines
9.4 KiB
Python
321 lines
9.4 KiB
Python
# -*- coding: utf-8 -*-
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"""Protocol message objects"""
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import base64
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import hashlib
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import struct
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import time
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from abc import ABC, abstractmethod
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from . import shared, structure
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class IMessage(ABC):
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"""A base for typical message"""
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@abstractmethod
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def __repr__(self):
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"""Make a printable form"""
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@abstractmethod
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def to_bytes(self):
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"""Serialize to bytes the full message"""
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@classmethod
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@abstractmethod
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def from_message(cls, m):
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"""Parse from message"""
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class Header(structure.IStructure):
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"""Message header structure"""
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def __init__(self, command, payload_length, payload_checksum):
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self.command = command
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self.payload_length = payload_length
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self.payload_checksum = payload_checksum
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def __repr__(self):
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return (
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'type: header, command: "{}", payload_length: {},'
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' payload_checksum: {}'
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).format(
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self.command.decode(), self.payload_length,
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base64.b16encode(self.payload_checksum).decode())
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def to_bytes(self):
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b = b''
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b += shared.magic_bytes
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b += self.command.ljust(12, b'\x00')
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b += struct.pack('>L', self.payload_length)
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b += self.payload_checksum
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return b
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@classmethod
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def from_bytes(cls, b):
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magic_bytes, command, payload_length, payload_checksum = struct.unpack(
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'>4s12sL4s', b)
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if magic_bytes != shared.magic_bytes:
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raise ValueError('magic_bytes do not match')
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command = command.rstrip(b'\x00')
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return cls(command, payload_length, payload_checksum)
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class Message(structure.IStructure):
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"""Common message structure"""
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def __init__(self, command, payload):
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self.command = command
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self.payload = payload
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self.payload_length = len(payload)
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self.payload_checksum = hashlib.sha512(payload).digest()[:4]
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def __repr__(self):
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return '{}, payload_length: {}, payload_checksum: {}'.format(
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self.command.decode(), self.payload_length,
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base64.b16encode(self.payload_checksum).decode())
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def to_bytes(self):
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b = Header(
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self.command, self.payload_length, self.payload_checksum
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).to_bytes()
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b += self.payload
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return b
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@classmethod
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def from_bytes(cls, b):
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h = Header.from_bytes(b[:24])
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payload = b[24:]
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payload_length = len(payload)
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if payload_length != h.payload_length:
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raise ValueError(
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'wrong payload length, expected {}, got {}'.format(
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h.payload_length, payload_length))
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payload_checksum = hashlib.sha512(payload).digest()[:4]
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if payload_checksum != h.payload_checksum:
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raise ValueError(
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'wrong payload checksum, expected {}, got {}'.format(
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h.payload_checksum, payload_checksum))
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return cls(h.command, payload)
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def _payload_read_int(data):
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varint_length = structure.VarInt.length(data[0])
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return (
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structure.VarInt.from_bytes(data[:varint_length]).n,
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data[varint_length:])
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class Version(IMessage):
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"""The version message payload"""
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def __init__(
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self, host, port, protocol_version=shared.protocol_version,
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services=shared.services, nonce=shared.nonce,
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user_agent=shared.user_agent, streams=None
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):
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self.host = host
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self.port = port
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self.protocol_version = protocol_version
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self.services = services
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self.nonce = nonce
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self.user_agent = user_agent
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self.streams = streams or [shared.stream]
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if len(self.streams) > 160000:
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self.streams = self.streams[:160000]
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def __repr__(self):
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return (
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'version, protocol_version: {}, services: {}, host: {}, port: {},'
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' nonce: {}, user_agent: {}').format(
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self.protocol_version, self.services, self.host, self.port,
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base64.b16encode(self.nonce).decode(), self.user_agent)
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def to_bytes(self):
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payload = b''
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payload += struct.pack('>I', self.protocol_version)
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payload += struct.pack('>Q', self.services)
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payload += struct.pack('>Q', int(time.time()))
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payload += structure.NetAddrNoPrefix(
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1, self.host, self.port).to_bytes()
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payload += structure.NetAddrNoPrefix(
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self.services, '127.0.0.1', 8444).to_bytes()
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payload += self.nonce
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payload += structure.VarInt(len(self.user_agent)).to_bytes()
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payload += self.user_agent
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payload += structure.VarInt(len(self.streams)).to_bytes()
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for stream in self.streams:
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payload += structure.VarInt(stream).to_bytes()
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return Message(b'version', payload).to_bytes()
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@classmethod
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def from_message(cls, m):
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payload = m.payload
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( # unused: net_addr_local
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protocol_version, services, timestamp, net_addr_remote, _, nonce
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) = struct.unpack('>IQQ26s26s8s', payload[:80])
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if abs(time.time() - timestamp) > 3600:
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raise ValueError('remote time offset is too large')
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net_addr_remote = structure.NetAddrNoPrefix.from_bytes(net_addr_remote)
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host = net_addr_remote.host
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port = net_addr_remote.port
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payload = payload[80:]
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user_agent_length, payload = _payload_read_int(payload)
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user_agent = payload[:user_agent_length]
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payload = payload[user_agent_length:]
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streams_count, payload = _payload_read_int(payload)
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if streams_count > 160000:
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raise ValueError('malformed Version message, to many streams')
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streams = []
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while payload:
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stream, payload = _payload_read_int(payload)
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streams.append(stream)
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if streams_count != len(streams):
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raise ValueError('malformed Version message, wrong streams_count')
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return cls(
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host, port, protocol_version, services, nonce, user_agent, streams)
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class Inv(IMessage):
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"""The inv message payload"""
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def __init__(self, vectors):
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self.vectors = set(vectors)
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def __repr__(self):
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return 'inv, count: {}'.format(len(self.vectors))
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def to_bytes(self):
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return Message(
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b'inv', structure.VarInt(len(self.vectors)).to_bytes()
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+ b''.join(self.vectors)
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).to_bytes()
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@classmethod
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def from_message(cls, m):
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payload = m.payload
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vector_count, payload = _payload_read_int(payload)
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vectors = set()
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while payload:
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vectors.add(payload[:32])
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payload = payload[32:]
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if vector_count != len(vectors):
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raise ValueError('malformed Inv message, wrong vector_count')
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return cls(vectors)
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class GetData(IMessage):
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"""The getdata message payload"""
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def __init__(self, vectors):
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self.vectors = set(vectors)
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def __repr__(self):
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return 'getdata, count: {}'.format(len(self.vectors))
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def to_bytes(self):
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return Message(
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b'getdata', structure.VarInt(len(self.vectors)).to_bytes()
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+ b''.join(self.vectors)
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).to_bytes()
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@classmethod
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def from_message(cls, m):
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payload = m.payload
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vector_count, payload = _payload_read_int(payload)
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vectors = set()
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while payload:
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vectors.add(payload[:32])
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payload = payload[32:]
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if vector_count != len(vectors):
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raise ValueError('malformed GetData message, wrong vector_count')
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return cls(vectors)
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class Addr(IMessage):
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"""The addr message payload"""
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def __init__(self, addresses):
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self.addresses = addresses
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def __repr__(self):
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return 'addr, count: {}'.format(len(self.addresses))
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def to_bytes(self):
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return Message(
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b'addr', structure.VarInt(len(self.addresses)).to_bytes()
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+ b''.join({addr.to_bytes() for addr in self.addresses})
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).to_bytes()
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@classmethod
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def from_message(cls, m):
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payload = m.payload
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# not validating addr_count
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_, payload = _payload_read_int(payload)
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addresses = set()
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while payload:
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addresses.add(structure.NetAddr.from_bytes(payload[:38]))
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payload = payload[38:]
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return cls(addresses)
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class Error(IMessage):
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"""The error message payload"""
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def __init__(self, error_text=b'', fatal=0, ban_time=0, vector=b''):
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self.error_text = error_text
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self.fatal = fatal
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self.ban_time = ban_time
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self.vector = vector
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def __repr__(self):
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return 'error, text: {}'.format(self.error_text)
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def to_bytes(self):
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return Message(
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b'error', structure.VarInt(self.fatal).to_bytes()
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+ structure.VarInt(self.ban_time).to_bytes()
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+ structure.VarInt(len(self.vector)).to_bytes() + self.vector
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+ structure.VarInt(len(self.error_text)).to_bytes()
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+ self.error_text
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).to_bytes()
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@classmethod
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def from_message(cls, m):
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payload = m.payload
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fatal, payload = _payload_read_int(payload)
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ban_time, payload = _payload_read_int(payload)
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vector_length, payload = _payload_read_int(payload)
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vector = payload[:vector_length]
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payload = payload[vector_length:]
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error_text_length, payload = _payload_read_int(payload)
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error_text = payload[:error_text_length]
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return cls(error_text, fatal, ban_time, vector)
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