MiNode/minode/structure.py

220 lines
6.9 KiB
Python

# -*- coding: utf-8 -*-
"""Protocol structures"""
import base64
import hashlib
import logging
import socket
import struct
import time
from abc import ABC, abstractmethod
from . import shared
class IStructure(ABC):
"""A base for typical structure"""
@abstractmethod
def to_bytes(self):
"""Serialize to bytes"""
@classmethod
@abstractmethod
def from_bytes(cls, b):
"""Parse from bytes"""
class VarInt(IStructure):
"""varint object"""
def __init__(self, n):
self.n = n
def to_bytes(self):
if self.n < 0xfd:
return struct.pack('>B', self.n)
if self.n <= 0xffff:
return b'\xfd' + struct.pack('>H', self.n)
if self.n <= 0xffffffff:
return b'\xfe' + struct.pack('>I', self.n)
return b'\xff' + struct.pack('>Q', self.n)
@staticmethod
def length(b):
if b == 0xfd:
return 3
if b == 0xfe:
return 5
if b == 0xff:
return 9
return 1
@classmethod
def from_bytes(cls, b):
if cls.length(b[0]) > 1:
b = b[1:]
n = int.from_bytes(b, 'big')
return cls(n)
class Object():
"""The 'object' message payload"""
def __init__(
self, nonce, expires_time, object_type, version,
stream_number, object_payload
):
self.nonce = nonce
self.expires_time = expires_time
self.object_type = object_type
self.version = version
self.stream_number = stream_number
self.object_payload = object_payload
self.vector = hashlib.sha512(hashlib.sha512(
self.to_bytes()).digest()).digest()[:32]
def __repr__(self):
return 'object, vector: {}'.format(
base64.b16encode(self.vector).decode())
@classmethod
def from_message(cls, m):
"""Decode message payload"""
payload = m.payload
nonce, expires_time, object_type = struct.unpack('>8sQL', payload[:20])
payload = payload[20:]
version_varint_length = VarInt.length(payload[0])
version = VarInt.from_bytes(payload[:version_varint_length]).n
payload = payload[version_varint_length:]
stream_number_varint_length = VarInt.length(payload[0])
stream_number = VarInt.from_bytes(
payload[:stream_number_varint_length]).n
payload = payload[stream_number_varint_length:]
return cls(
nonce, expires_time, object_type, version, stream_number, payload)
def to_bytes(self):
"""Serialize to bytes object payload"""
payload = b''
payload += self.nonce
payload += struct.pack('>QL', self.expires_time, self.object_type)
payload += (
VarInt(self.version).to_bytes()
+ VarInt(self.stream_number).to_bytes())
payload += self.object_payload
return payload
def is_expired(self):
"""Check if object's TTL is expired"""
return self.expires_time + 3 * 3600 < time.time()
def is_valid(self):
"""Checks the object validity"""
if self.is_expired():
logging.debug(
'Invalid object %s, reason: expired',
base64.b16encode(self.vector).decode())
return False
if self.expires_time > time.time() + 28 * 24 * 3600 + 3 * 3600:
logging.warning(
'Invalid object %s, reason: end of life too far in the future',
base64.b16encode(self.vector).decode())
return False
if len(self.object_payload) > 2**18:
logging.warning(
'Invalid object %s, reason: payload is too long',
base64.b16encode(self.vector).decode())
return False
if self.stream_number != 1:
logging.warning(
'Invalid object %s, reason: not in stream 1',
base64.b16encode(self.vector).decode())
return False
data = self.to_bytes()[8:]
# length = len(data) + 8 + shared.payload_length_extra_bytes
# dt = max(self.expires_time - time.time(), 0)
h = hashlib.sha512(data).digest()
pow_value = int.from_bytes(
hashlib.sha512(hashlib.sha512(
self.nonce + h).digest()).digest()[:8], 'big')
target = self.pow_target()
if target < pow_value:
logging.warning(
'Invalid object %s, reason: insufficient pow',
base64.b16encode(self.vector).decode())
return False
return True
def pow_target(self):
"""Compute PoW target"""
data = self.to_bytes()[8:]
length = len(data) + 8 + shared.payload_length_extra_bytes
dt = max(self.expires_time - time.time(), 0)
return int(
2 ** 64 / (
shared.nonce_trials_per_byte * (
length + (dt * length) / (2 ** 16))))
def pow_initial_hash(self):
"""Compute the initial hash for PoW"""
return hashlib.sha512(self.to_bytes()[8:]).digest()
class NetAddrNoPrefix(IStructure):
"""Network address"""
def __init__(self, services, host, port):
self.services = services
self.host = host
self.port = port
def __repr__(self):
return 'net_addr_no_prefix, services: {}, host: {}, port {}'.format(
self.services, self.host, self.port)
def to_bytes(self):
b = b''
b += struct.pack('>Q', self.services)
try:
host = socket.inet_pton(socket.AF_INET, self.host)
b += b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xFF\xFF' + host
except socket.error:
b += socket.inet_pton(socket.AF_INET6, self.host)
b += struct.pack('>H', int(self.port))
return b
@classmethod
def from_bytes(cls, b):
services, host, port = struct.unpack('>Q16sH', b)
if host.startswith(
b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xFF\xFF'):
host = socket.inet_ntop(socket.AF_INET, host[-4:])
else:
host = socket.inet_ntop(socket.AF_INET6, host)
return cls(services, host, port)
class NetAddr(IStructure):
"""Network address with time and stream"""
def __init__(self, services, host, port, stream=shared.stream):
self.stream = stream
self.services = services
self.host = host
self.port = port
def __repr__(self):
return 'net_addr, stream: {}, services: {}, host: {}, port {}'.format(
self.stream, self.services, self.host, self.port)
def to_bytes(self):
b = b''
b += struct.pack('>Q', int(time.time()))
b += struct.pack('>I', self.stream)
b += NetAddrNoPrefix(self.services, self.host, self.port).to_bytes()
return b
@classmethod
def from_bytes(cls, b):
stream, net_addr = struct.unpack('>QI26s', b)[1:]
n = NetAddrNoPrefix.from_bytes(net_addr)
return cls(n.services, n.host, n.port, stream)