451 lines
17 KiB
Python
451 lines
17 KiB
Python
# pylint: disable=too-many-boolean-expressions,too-many-return-statements,too-many-locals,too-many-statements
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"""
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protocol.py
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===========
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Low-level protocol-related functions.
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"""
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from __future__ import absolute_import
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import base64
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import hashlib
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import random
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import socket
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import sys
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import time
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import traceback
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from binascii import hexlify
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from struct import pack, unpack, Struct
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import defaults
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import highlevelcrypto
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import state
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from addresses import (
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encodeVarint, decodeVarint, decodeAddress, varintDecodeError)
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from bmconfigparser import BMConfigParser
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from debug import logger
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from fallback import RIPEMD160Hash
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from helper_sql import sqlExecute
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from version import softwareVersion
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# Service flags
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NODE_NETWORK = 1
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NODE_SSL = 2
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NODE_DANDELION = 8
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# Bitfield flags
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BITFIELD_DOESACK = 1
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# Error types
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STATUS_WARNING = 0
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STATUS_ERROR = 1
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STATUS_FATAL = 2
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# Object types
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OBJECT_GETPUBKEY = 0
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OBJECT_PUBKEY = 1
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OBJECT_MSG = 2
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OBJECT_BROADCAST = 3
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OBJECT_ONIONPEER = 0x746f72
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OBJECT_I2P = 0x493250
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OBJECT_ADDR = 0x61646472
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eightBytesOfRandomDataUsedToDetectConnectionsToSelf = pack(
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'>Q', random.randrange(1, 18446744073709551615))
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# Compiled struct for packing/unpacking headers
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# New code should use CreatePacket instead of Header.pack
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Header = Struct('!L12sL4s')
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VersionPacket = Struct('>LqQ20s4s36sH')
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# Bitfield
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def getBitfield(address):
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"""Get a bitfield from an address"""
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# bitfield of features supported by me (see the wiki).
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bitfield = 0
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# send ack
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if not BMConfigParser().safeGetBoolean(address, 'dontsendack'):
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bitfield |= BITFIELD_DOESACK
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return pack('>I', bitfield)
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def checkBitfield(bitfieldBinary, flags):
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"""Check if a bitfield matches the given flags"""
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bitfield, = unpack('>I', bitfieldBinary)
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return (bitfield & flags) == flags
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def isBitSetWithinBitfield(fourByteString, n):
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"""Check if a particular bit is set in a bitfeld"""
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# Uses MSB 0 bit numbering across 4 bytes of data
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n = 31 - n
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x, = unpack('>L', fourByteString)
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return x & 2**n != 0
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# ip addresses
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def encodeHost(host):
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"""Encode a given host to be used in low-level socket operations"""
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if host.find('.onion') > -1:
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return '\xfd\x87\xd8\x7e\xeb\x43' + base64.b32decode(host.split(".")[0], True)
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elif host.find(':') == -1:
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return '\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xFF\xFF' + \
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socket.inet_aton(host)
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return socket.inet_pton(socket.AF_INET6, host)
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def networkType(host):
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"""Determine if a host is IPv4, IPv6 or an onion address"""
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if host.find('.onion') > -1:
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return 'onion'
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elif host.find(':') == -1:
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return 'IPv4'
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return 'IPv6'
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def checkIPAddress(host, private=False):
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"""Returns hostStandardFormat if it is a valid IP address, otherwise returns False"""
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if host[0:12] == '\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xFF\xFF':
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hostStandardFormat = socket.inet_ntop(socket.AF_INET, host[12:])
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return checkIPv4Address(host[12:], hostStandardFormat, private)
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elif host[0:6] == '\xfd\x87\xd8\x7e\xeb\x43':
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# Onion, based on BMD/bitcoind
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hostStandardFormat = base64.b32encode(host[6:]).lower() + ".onion"
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if private:
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return False
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return hostStandardFormat
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else:
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try:
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hostStandardFormat = socket.inet_ntop(socket.AF_INET6, host)
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except ValueError:
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return False
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if hostStandardFormat == "":
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# This can happen on Windows systems which are not 64-bit compatible
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# so let us drop the IPv6 address.
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return False
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return checkIPv6Address(host, hostStandardFormat, private)
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def checkIPv4Address(host, hostStandardFormat, private=False):
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"""Returns hostStandardFormat if it is an IPv4 address, otherwise returns False"""
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if host[0] == '\x7F': # 127/8
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if not private:
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logger.debug('Ignoring IP address in loopback range: %s', hostStandardFormat)
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return hostStandardFormat if private else False
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if host[0] == '\x0A': # 10/8
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if not private:
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logger.debug('Ignoring IP address in private range: %s', hostStandardFormat)
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return hostStandardFormat if private else False
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if host[0:2] == '\xC0\xA8': # 192.168/16
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if not private:
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logger.debug('Ignoring IP address in private range: %s', hostStandardFormat)
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return hostStandardFormat if private else False
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if host[0:2] >= '\xAC\x10' and host[0:2] < '\xAC\x20': # 172.16/12
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if not private:
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logger.debug('Ignoring IP address in private range: %s', hostStandardFormat)
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return hostStandardFormat if private else False
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return False if private else hostStandardFormat
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def checkIPv6Address(host, hostStandardFormat, private=False):
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"""Returns hostStandardFormat if it is an IPv6 address, otherwise returns False"""
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if host == ('\x00' * 15) + '\x01':
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if not private:
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logger.debug('Ignoring loopback address: %s', hostStandardFormat)
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return False
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if host[0] == '\xFE' and (ord(host[1]) & 0xc0) == 0x80:
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if not private:
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logger.debug('Ignoring local address: %s', hostStandardFormat)
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return hostStandardFormat if private else False
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if (ord(host[0]) & 0xfe) == 0xfc:
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if not private:
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logger.debug('Ignoring unique local address: %s', hostStandardFormat)
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return hostStandardFormat if private else False
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return False if private else hostStandardFormat
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def haveSSL(server=False):
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"""
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Predicate to check if ECDSA server support is required and available
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python < 2.7.9's ssl library does not support ECDSA server due to
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missing initialisation of available curves, but client works ok
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"""
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if not server:
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return True
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elif sys.version_info >= (2, 7, 9):
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return True
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return False
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def checkSocksIP(host):
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"""Predicate to check if we're using a SOCKS proxy"""
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try:
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if state.socksIP is None or not state.socksIP:
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state.socksIP = socket.gethostbyname(BMConfigParser().get("bitmessagesettings", "sockshostname"))
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# uninitialised
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except NameError:
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state.socksIP = socket.gethostbyname(BMConfigParser().get("bitmessagesettings", "sockshostname"))
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# resolving failure
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except socket.gaierror:
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state.socksIP = BMConfigParser().get("bitmessagesettings", "sockshostname")
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return state.socksIP == host
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def isProofOfWorkSufficient(data,
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nonceTrialsPerByte=0,
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payloadLengthExtraBytes=0,
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recvTime=0):
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"""
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Validate an object's Proof of Work using method described in:
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https://bitmessage.org/wiki/Proof_of_work
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Arguments:
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int nonceTrialsPerByte (default: from default.py)
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int payloadLengthExtraBytes (default: from default.py)
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float recvTime (optional) UNIX epoch time when object was
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received from the network (default: current system time)
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Returns:
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True if PoW valid and sufficient, False in all other cases
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"""
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if nonceTrialsPerByte < defaults.networkDefaultProofOfWorkNonceTrialsPerByte:
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nonceTrialsPerByte = defaults.networkDefaultProofOfWorkNonceTrialsPerByte
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if payloadLengthExtraBytes < defaults.networkDefaultPayloadLengthExtraBytes:
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payloadLengthExtraBytes = defaults.networkDefaultPayloadLengthExtraBytes
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endOfLifeTime, = unpack('>Q', data[8:16])
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TTL = endOfLifeTime - (int(recvTime) if recvTime else int(time.time()))
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if TTL < 300:
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TTL = 300
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POW, = unpack('>Q', hashlib.sha512(hashlib.sha512(data[
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:8] + hashlib.sha512(data[8:]).digest()).digest()).digest()[0:8])
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return POW <= 2 ** 64 / (nonceTrialsPerByte *
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(len(data) + payloadLengthExtraBytes +
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((TTL * (len(data) + payloadLengthExtraBytes)) / (2 ** 16))))
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# Packet creation
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def CreatePacket(command, payload=''):
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"""Construct and return a number of bytes from a payload"""
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payload_length = len(payload)
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checksum = hashlib.sha512(payload).digest()[0:4]
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b = bytearray(Header.size + payload_length)
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Header.pack_into(b, 0, 0xE9BEB4D9, command, payload_length, checksum)
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b[Header.size:] = payload
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return bytes(b)
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def assembleVersionMessage(remoteHost, remotePort, participatingStreams, server=False, nodeid=None):
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"""Construct the payload of a version message, return the resultng bytes of running CreatePacket() on it"""
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payload = ''
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payload += pack('>L', 3) # protocol version.
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# bitflags of the services I offer.
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payload += pack(
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'>q',
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NODE_NETWORK |
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(NODE_SSL if haveSSL(server) else 0) |
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(NODE_DANDELION if state.dandelion else 0)
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)
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payload += pack('>q', int(time.time()))
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payload += pack(
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'>q', 1) # boolservices of remote connection; ignored by the remote host.
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if checkSocksIP(remoteHost) and server: # prevent leaking of tor outbound IP
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payload += encodeHost('127.0.0.1')
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payload += pack('>H', 8444)
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else:
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payload += encodeHost(remoteHost)
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payload += pack('>H', remotePort) # remote IPv6 and port
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# bitflags of the services I offer.
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payload += pack(
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'>q',
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NODE_NETWORK |
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(NODE_SSL if haveSSL(server) else 0) |
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(NODE_DANDELION if state.dandelion else 0)
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)
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# = 127.0.0.1. This will be ignored by the remote host. The actual remote connected IP will be used.
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payload += '\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xFF\xFF' + pack('>L', 2130706433)
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# we have a separate extPort and incoming over clearnet or outgoing through clearnet
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if BMConfigParser().safeGetBoolean('bitmessagesettings', 'upnp') and state.extPort \
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and ((server and not checkSocksIP(remoteHost)) or
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(BMConfigParser().get("bitmessagesettings", "socksproxytype") == "none" and not server)):
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payload += pack('>H', state.extPort)
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elif checkSocksIP(remoteHost) and server: # incoming connection over Tor
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payload += pack('>H', BMConfigParser().getint('bitmessagesettings', 'onionport'))
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else: # no extPort and not incoming over Tor
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payload += pack('>H', BMConfigParser().getint('bitmessagesettings', 'port'))
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random.seed()
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if nodeid is not None:
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payload += nodeid[0:8]
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else:
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payload += eightBytesOfRandomDataUsedToDetectConnectionsToSelf
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userAgent = '/PyBitmessage:' + softwareVersion + '/'
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payload += encodeVarint(len(userAgent))
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payload += userAgent
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# Streams
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payload += encodeVarint(len(participatingStreams))
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count = 0
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for stream in sorted(participatingStreams):
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payload += encodeVarint(stream)
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count += 1
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# protocol limit, see specification
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if count >= 160000:
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break
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return CreatePacket('version', payload)
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def assembleErrorMessage(fatal=0, banTime=0, inventoryVector='', errorText=''):
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"""Construct the payload of an error message, return the resultng bytes of running CreatePacket() on it"""
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payload = encodeVarint(fatal)
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payload += encodeVarint(banTime)
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payload += encodeVarint(len(inventoryVector))
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payload += inventoryVector
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payload += encodeVarint(len(errorText))
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payload += errorText
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return CreatePacket('error', payload)
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# Packet decoding
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def decryptAndCheckPubkeyPayload(data, address):
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"""
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Version 4 pubkeys are encrypted. This function is run when we
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already have the address to which we want to try to send a message.
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The 'data' may come either off of the wire or we might have had it
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already in our inventory when we tried to send a msg to this
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particular address.
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"""
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try:
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addressVersion, streamNumber, ripe = decodeAddress(address)[1:]
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readPosition = 20 # bypass the nonce, time, and object type
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embeddedAddressVersion, varintLength = decodeVarint(
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data[readPosition:readPosition + 10])
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readPosition += varintLength
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embeddedStreamNumber, varintLength = decodeVarint(
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data[readPosition:readPosition + 10])
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readPosition += varintLength
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# We'll store the address version and stream number
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# (and some more) in the pubkeys table.
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storedData = data[20:readPosition]
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if addressVersion != embeddedAddressVersion:
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logger.info(
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'Pubkey decryption was UNsuccessful'
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' due to address version mismatch.')
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return 'failed'
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if streamNumber != embeddedStreamNumber:
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logger.info(
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'Pubkey decryption was UNsuccessful'
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' due to stream number mismatch.')
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return 'failed'
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tag = data[readPosition:readPosition + 32]
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readPosition += 32
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# the time through the tag. More data is appended onto
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# signedData below after the decryption.
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signedData = data[8:readPosition]
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encryptedData = data[readPosition:]
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# Let us try to decrypt the pubkey
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toAddress, cryptorObject = state.neededPubkeys[tag]
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if toAddress != address:
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logger.critical(
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'decryptAndCheckPubkeyPayload failed due to toAddress'
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' mismatch. This is very peculiar.'
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' toAddress: %s, address %s',
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toAddress, address
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)
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# the only way I can think that this could happen
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# is if someone encodes their address data two different ways.
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# That sort of address-malleability should have been caught
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# by the UI or API and an error given to the user.
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return 'failed'
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try:
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decryptedData = cryptorObject.decrypt(encryptedData)
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except:
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# Someone must have encrypted some data with a different key
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# but tagged it with a tag for which we are watching.
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logger.info('Pubkey decryption was unsuccessful.')
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return 'failed'
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readPosition = 0
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# bitfieldBehaviors = decryptedData[readPosition:readPosition + 4]
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readPosition += 4
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publicSigningKey = '\x04' + decryptedData[readPosition:readPosition + 64]
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readPosition += 64
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publicEncryptionKey = '\x04' + decryptedData[readPosition:readPosition + 64]
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readPosition += 64
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specifiedNonceTrialsPerByteLength = decodeVarint(
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decryptedData[readPosition:readPosition + 10])[1]
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readPosition += specifiedNonceTrialsPerByteLength
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specifiedPayloadLengthExtraBytesLength = decodeVarint(
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decryptedData[readPosition:readPosition + 10])[1]
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readPosition += specifiedPayloadLengthExtraBytesLength
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storedData += decryptedData[:readPosition]
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signedData += decryptedData[:readPosition]
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signatureLength, signatureLengthLength = decodeVarint(
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decryptedData[readPosition:readPosition + 10])
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readPosition += signatureLengthLength
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signature = decryptedData[readPosition:readPosition + signatureLength]
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if not highlevelcrypto.verify(
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signedData, signature, hexlify(publicSigningKey)):
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logger.info(
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'ECDSA verify failed (within decryptAndCheckPubkeyPayload)')
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return 'failed'
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logger.info(
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'ECDSA verify passed (within decryptAndCheckPubkeyPayload)')
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sha = hashlib.new('sha512')
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sha.update(publicSigningKey + publicEncryptionKey)
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embeddedRipe = RIPEMD160Hash(sha.digest()).digest()
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if embeddedRipe != ripe:
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# Although this pubkey object had the tag were were looking for
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# and was encrypted with the correct encryption key,
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# it doesn't contain the correct pubkeys. Someone is
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# either being malicious or using buggy software.
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logger.info(
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'Pubkey decryption was UNsuccessful due to RIPE mismatch.')
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return 'failed'
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# Everything checked out. Insert it into the pubkeys table.
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logger.info(
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'within decryptAndCheckPubkeyPayload, '
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'addressVersion: %s, streamNumber: %s\nripe %s\n'
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'publicSigningKey in hex: %s\npublicEncryptionKey in hex: %s',
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addressVersion, streamNumber, hexlify(ripe),
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hexlify(publicSigningKey), hexlify(publicEncryptionKey)
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)
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t = (address, addressVersion, storedData, int(time.time()), 'yes')
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sqlExecute('''INSERT INTO pubkeys VALUES (?,?,?,?,?)''', *t)
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return 'successful'
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except varintDecodeError:
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logger.info(
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'Pubkey decryption was UNsuccessful due to a malformed varint.')
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return 'failed'
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except Exception:
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logger.critical(
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'Pubkey decryption was UNsuccessful because of'
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' an unhandled exception! This is definitely a bug! \n%s',
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traceback.format_exc()
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)
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return 'failed'
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