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Significant headway on the rewrite.

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Handle crypto with the excellent crytography library, still a lot of TODOs to take care of but at least we can connect now
This commit is contained in:
Ammar Askar 2015-03-17 22:15:27 +05:00
parent f68206140b
commit 7e8df47352
8 changed files with 426 additions and 98 deletions
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3
.gitignore vendored
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@ -1,3 +1,6 @@
*.pyc
build/*
src/*
*.iml
.idea/

30
authentication/auth.py
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@ -12,13 +12,18 @@ class Response(object):
payload = None
class YggdrasilError(Exception):
def __init__(self, error='', human_readable_error=''):
self.error = error
self.human_readable_error = human_readable_error
def make_request(url, payload):
"""Makes http requests to the Yggdrasil authentication service
Returns a Response object with an error boolean, if there is an error
then it will also contain `error` and `human_error` fields
otherwise a `payload` field will be returned with the actual response
from Yggdrasil
Returns a Response object.
If there is an error then it will raise a YggdrasilError.
"""
response = Response()
@ -35,18 +40,21 @@ def make_request(url, payload):
error = e.read()
error = json.loads(error)
response.error = True
response.human_error = error['errorMessage']
response.error = error['error']
return response
raise YggdrasilError(error['error'], error['errorMessage'])
except urllib2.URLError, e:
response.error = True
response.human_error = e.reason
return response
raise YggdrasilError(e.reason, e.reason)
# ohey, everything didn't end up crashing and burning
if http_response == "":
http_response = "{}"
try:
json_response = json.loads(http_response)
except ValueError, e:
raise YggdrasilError(e.message, "JSON parsing exception on data: " + http_response)
response.payload = json_response
return response
@ -69,10 +77,6 @@ def login_to_minecraft(username, password):
response = make_request(BASE_URL + "authenticate", payload)
login_response = LoginResponse()
if response.error:
login_response.error = True
login_response.human_error = response.human_error
else:
payload = response.payload
login_response.error = False

215
network/connection.py
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@ -1,51 +1,89 @@
from collections import deque
from threading import Lock
from zlib import decompress
import threading
import socket
import time
import select
import authentication
from packets import *
from start import PROTOCOL_VERSION
from types import VarInt
PROTOCOL_VERSION = 47
class Connection:
class ConnectionOptions(object):
# TODO: allow these options to be overriden from a constructor below
address = None
port = None
use_encryption = True
compression_threshold = -1
compression_enabled = False
class Connection(object):
"""This class represents a connection to a minecraft
server, it handles everything from connecting, sending packets,
server, it handles everything from connecting, sending packets to
handling default network behaviour
"""
outgoing_packet_queue = deque()
write_lock = Lock()
_outgoing_packet_queue = deque()
_write_lock = Lock()
networking_thread = None
options = ConnectionOptions()
def __init__(self, address, port, login_response):
self.address = address
self.port = port
"""Sets up an instance of this object to be able to connect to a minecraft server
The connect method needs to be called in order to actually begin the connection
:param address: address of the server to connect to
:param port(int): port of the server to connect to
:param login_response: login_response object as obtained from the authentication package
"""
self.options.address = address
self.options.port = port
self.login_response = login_response
self.reactor = HandshakeReactor(self)
self.reactor = PacketReactor(self)
def _start_network_thread(self):
self.networking_thread = NetworkingThread(self)
self.networking_thread.start()
def write_packet(self, packet, force=False):
if force:
self.write_lock.acquire()
packet.write(self.socket)
self.write_lock.release()
else:
self.outgoing_packet_queue.append(packet)
"""Writes a packet to the server.
If force is set to true, the method attempts to acquire the write lock and write the packet
out immediately, and as such may block.
If force is false then the packet will be added to the end of the packet writing queue
to be sent 'as soon as possible'
# Mostly a convenience function, caller should make sure they have the
:param packet:
:param force(bool): Specifies if the packet write should be immediate
:return:
"""
if force:
self._write_lock.acquire()
if self.options.compression_enabled:
packet.write(self.socket, self.options.compression_threshold)
else:
packet.write(self.socket)
self._write_lock.release()
else:
self._outgoing_packet_queue.append(packet)
def _pop_packet(self):
# Pops the topmost packet off the outgoing queue and writes it out through the socket
#
# Mostly an internal convenience function, caller should make sure they have the
# write lock acquired to avoid issues caused by asynchronous access to the socket.
# This should be the only method that removes elements from the outbound queue
def _pop_packet(self):
if len(self.outgoing_packet_queue) == 0:
if len(self._outgoing_packet_queue) == 0:
return False
else:
packet = self.outgoing_packet_queue.popleft()
print "Writing out: " + hex(packet.id) + " / " + packet.name
packet = self._outgoing_packet_queue.popleft()
print "Writing out: " + hex(packet.id) + " / " + packet.packet_name
if self.options.compression_enabled:
packet.write(self.socket, self.options.compression_threshold)
else:
packet.write(self.socket)
return True
@ -59,23 +97,31 @@ class Connection:
self.write_packet(request_packet)
def connect(self):
"""Attempt to begin connecting to the server
"""
self._connect()
self._handshake()
self.reactor = LoginReactor(self)
self._start_network_thread()
login_start_packet = LoginStartPacket()
login_start_packet.name = self.login_response.username
self.write_packet(login_start_packet)
def _connect(self):
# Connect a socket to the server and create a file object from the socket
#The file object is used to read any and all data from the socket since it's "guaranteed"
#to read the number of bytes specified, the socket itself will mostly be
#used to write data upstream to the server
# The file object is used to read any and all data from the socket since it's "guaranteed"
# to read the number of bytes specified, the socket itself will mostly be
# used to write data upstream to the server
self.socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self.socket.connect((self.address, self.port))
self.socket.connect((self.options.address, self.options.port))
self.file_object = self.socket.makefile()
def _handshake(self, next_state=2):
handshake = HandShakePacket()
handshake.protocol_version = PROTOCOL_VERSION
handshake.server_address = self.address
handshake.server_port = self.port
handshake.server_address = self.options.address
handshake.server_port = self.options.port
handshake.next_state = next_state
self.write_packet(handshake)
@ -96,15 +142,12 @@ class NetworkingThread(threading.Thread):
break
# Attempt to write out as many as 300 packets as possible every 0.05 seconds (20 ticks per second)
num_packets = 0
self.connection.write_lock.acquire()
self.connection._write_lock.acquire()
while self.connection._pop_packet():
self.connection._pop_packet()
num_packets += 1
if num_packets >= 300:
break
self.connection.write_lock.release()
self.connection._write_lock.release()
# Read and react to as many as 50 packets
num_packets = 0
@ -121,7 +164,7 @@ class NetworkingThread(threading.Thread):
time.sleep(0.05)
class PacketReactor:
class PacketReactor(object):
state_name = None
clientbound_packets = None
@ -130,28 +173,122 @@ class PacketReactor:
def __init__(self, connection):
self.connection = connection
# Design objectives:
#
# Avoid buffering data as much as possible
# Wherever possible, read directly from the network stream
# Minimize any overheads, reading packets should be simple
def read_packet(self, stream):
ready = select.select([self.connection.socket], [], [], self.TIME_OUT)
if self.connection.socket in ready[0]:
length = VarInt.read_socket(self.connection.socket)
packet_id = VarInt.read(stream)
ready_to_read, _, __ = select.select([self.connection.socket], [], [], self.TIME_OUT)
real_stream = stream
if self.connection.socket in ready_to_read:
length = VarInt.read_socket(self.connection.socket)
if self.connection.options.compression_enabled:
compressed_size = VarInt.read(stream)
# If this is a compressed packet we'll need to decompress it into a buffer
# and then pretend that that is the actual network stream
if compressed_size > 0:
compressed_packet = stream.read(compressed_size)
stream = PacketBuffer()
stream.send(decompress(compressed_packet))
stream.reset_cursor()
packet_id = VarInt.read_socket(self.connection.socket)
print "Reading packet: " + str(packet_id) + " / " + hex(packet_id) + " (Size: " + str(length) + ")"
# If we know the structure of the packet, attempt to parse it
# otherwise just skip it
if packet_id in self.clientbound_packets:
packet = self.clientbound_packets[packet_id]()
packet.read(stream)
return packet
else:
print "Unkown packet: " + str(packet_id) + " / " + hex(packet_id)
# TODO: remove debug
print "Unknown packet: " + str(packet_id) + " / " + hex(packet_id) + " (Size: " + str(length) + ")"
# if this is a compressed packet then we've already read it from the stream
# otherwise we need to skip the rest of the bytes properly
if self.connection.options.compression_enabled and compressed_size > 0:
return Packet()
# if compression is enabled and the data isn't compressed then we need to
# subtract the size of the compressed_size and packet_id VarInts from the total data length
# to get the number of bytes to skip
if self.connection.options.compression_enabled and compressed_size == 0:
real_stream.read(length - (VarInt.size(compressed_size) + VarInt.size(packet_id)))
return Packet()
# If compression isn't enabled, just subtract the size of the packet_id VarInt we read
# from the total length of the packet
real_stream.read(length - VarInt.size(packet_id))
return Packet()
else:
return None
def react(self, packet):
pass
raise NotImplementedError("Call to base reactor")
class HandshakeReactor(PacketReactor):
clientbound_packets = state_handshake_clientbound
class LoginReactor(PacketReactor):
clientbound_packets = state_login_clientbound
def react(self, packet):
# TODO: Add some way to bypass encryption? (connection.options.use_encryption) Not sure if it's still possible.
if packet.packet_name == "encryption request":
import encryption
secret = encryption.generate_shared_secret()
encrypted_token, encrypted_secret = encryption.encrypt_token_and_secret(packet.public_key,
packet.verify_token, secret)
# A server id of '-' means the server is in offline mode
if packet.server_id != '-':
url = "https://sessionserver.mojang.com/session/minecraft/join"
server_id = encryption.generate_verification_hash(packet.server_id, secret, packet.public_key)
authentication.make_request(url, {'accessToken': self.connection.login_response.access_token,
'selectedProfile': self.connection.login_response.profile_id,
'serverId': server_id})
encryption_response = EncryptionResponsePacket()
encryption_response.shared_secret = encrypted_secret
encryption_response.verify_token = encrypted_token
# Forced because we don't want to send this encrypted which it will be
# if we put it in the queue as we'd have wrapped the socket and file object by then
self.connection.write_packet(encryption_response, force=True)
# Enable the encryption
cipher = encryption.create_AES_cipher(secret)
encryptor = cipher.encryptor()
decryptor = cipher.decryptor()
self.connection.socket = encryption.EncryptedSocketWrapper(self.connection.socket,
encryptor, decryptor)
self.connection.file_object = encryption.EncryptedFileObjectWrapper(self.connection.file_object,
decryptor)
if packet.packet_name == "disconnect":
print(packet.json_data) # TODO: handle propagating this back
if packet.packet_name == "login success":
self.connection.reactor = PlayingReactor(self.connection)
if packet.packet_name == "set compression":
self.connection.options.compression_threshold = packet.threshold
self.connection.options.compression_enabled = True
class PlayingReactor(PacketReactor):
clientbound_packets = state_playing_clientbound
def react(self, packet):
if packet.packet_name == "set compression":
self.connection.options.compression_threshold = packet.threshold
self.connection.options.compression_enabled = True
class StatusReactor(PacketReactor):

81
network/encryption.py Normal file
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@ -0,0 +1,81 @@
import os
from hashlib import sha1
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives.asymmetric import rsa
from cryptography.hazmat.primitives.asymmetric.padding import PKCS1v15
from cryptography.hazmat.primitives.serialization import load_der_public_key
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
def generate_shared_secret():
return os.urandom(16)
def create_AES_cipher(shared_secret):
cipher = Cipher(algorithms.AES(shared_secret), modes.CFB8(shared_secret), backend=default_backend())
return cipher
def encrypt_token_and_secret(pubkey, verification_token, shared_secret):
"""Encrypts the verification token and shared secret with the server's public key
:param pubkey: The RSA public key provided by the server
:param verification_token: The verification token provided by the server
:param shared_secret: The generated shared secret
:return: A tuple containing (encrypted token, encrypted secret)
"""
pubkey = load_der_public_key(pubkey, default_backend())
if not isinstance(pubkey, rsa.RSAPublicKey):
raise RuntimeError("Public key provided by server not an RSA key")
encrypted_token = pubkey.encrypt(verification_token, PKCS1v15())
encrypted_secret = pubkey.encrypt(shared_secret, PKCS1v15())
return encrypted_token, encrypted_secret
def generate_verification_hash(server_id, shared_secret, public_key):
verification_hash = sha1()
verification_hash.update(server_id)
verification_hash.update(shared_secret)
verification_hash.update(public_key)
# Minecraft first parses the sha1 bytes as a signed number and then spits outs
# its hex representation
number = _number_from_bytes(verification_hash.digest(), signed=True)
return format(number, 'x')
def _number_from_bytes(b, signed=False):
if len(b) == 0:
b = b'\x00'
num = int(str(b).encode('hex'), 16)
if signed and (ord(b[0]) & 0x80):
num -= 2 ** (len(b) * 8)
return num
class EncryptedFileObjectWrapper(object):
def __init__(self, file_object, decryptor):
self.actual_file_object = file_object
self.decryptor = decryptor
def read(self, length):
return self.decryptor.update(self.actual_file_object.read(length))
class EncryptedSocketWrapper(object):
def __init__(self, socket, encryptor, decryptor):
self.actual_socket = socket
self.encryptor = encryptor
self.decryptor = decryptor
def recv(self, length):
return self.decryptor.update(self.actual_socket.recv(length))
def send(self, data):
self.actual_socket.send(self.encryptor.update(data))
def fileno(self):
return self.actual_socket.fileno()

111
network/packets.py
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@ -1,4 +1,5 @@
from io import BytesIO
from zlib import compress
from types import *
@ -9,15 +10,26 @@ class PacketBuffer(object):
self.b = BytesIO()
def send(self, value):
"""
Writes the given bytes to the buffer, designed to emulate socket.send
:param value: The bytes to write
"""
self.b.write(value)
def read(self, length):
return self.b.read(length)
def reset_cursor(self):
self.b.seek(0)
def get_writable(self):
return self.b.getvalue()
class Packet(object):
name = "base"
packet_name = "base"
id = -0x01
definition = []
def __init__(self):
@ -26,12 +38,13 @@ class Packet(object):
def read(self, file_object):
for field in self.definition:
for var_name, data_type in field.iteritems():
setattr(self, var_name, data_type.read(file_object))
value = data_type.read(file_object)
setattr(self, var_name, value)
def write(self, socket):
def write(self, socket, compression_threshold=-1):
# buffer the data since we need to know the length of each packet's payload
packet_buffer = PacketBuffer()
# write off the id right off the bat
# write packet's id right off the bat in the header
VarInt.send(self.id, packet_buffer)
for field in self.definition:
@ -39,6 +52,8 @@ class Packet(object):
data = getattr(self, var_name)
data_type.send(data, packet_buffer)
# TODO: implement compression
VarInt.send(len(packet_buffer.get_writable()), socket) # Packet Size
socket.send(packet_buffer.get_writable()) # Packet Payload
@ -47,7 +62,7 @@ class Packet(object):
# ==============
class HandShakePacket(Packet):
id = 0x00
name = "handshake"
packet_name = "handshake"
definition = [
{'protocol_version': VarInt},
{'server_address': String},
@ -64,21 +79,20 @@ state_handshake_serverbound = {
# Status State
#==============
# ==============
class ResponsePacket(Packet):
id = 0x00
name = "response"
packet_name = "response"
definition = [
{'json_response': String}]
class PingPacket(Packet):
id = 0x01
name = "ping"
packet_name = "ping"
definition = [
{'time': Long}]
state_status_clientbound = {
0x00: ResponsePacket,
0x01: PingPacket
@ -87,71 +101,118 @@ state_status_clientbound = {
class RequestPacket(Packet):
id = 0x00
name = "request"
packet_name = "request"
definition = []
class PingPacket(Packet):
id = 0x01
name = "ping"
packet_name = "ping"
definition = [
{'time': Long}]
state_status_serverbound = {
0x00: RequestPacket,
0x01: PingPacket
}
# Login State
#==============
# ==============
class DisconnectPacket(Packet):
id = 0x00
name = "disconnect"
packet_name = "disconnect"
definition = [
{'json_data': String}]
class EncryptionRequestPacket(Packet):
id = 0x01
name = "encryption request"
packet_name = "encryption request"
definition = [
{'server_id': String},
{'public_key': ByteArray},
{'verify_token': ByteArray}]
{'public_key': VarIntPrefixedByteArray},
{'verify_token': VarIntPrefixedByteArray}]
class LoginSucessPacket(Packet):
class LoginSuccessPacket(Packet):
id = 0x02
name = "login success"
packet_name = "login success"
definition = [
{'UUID': String},
{'Username': String}]
class SetCompressionPacket(Packet):
id = 0x03
packet_name = "set compression"
definition = [
{'threshold': VarInt}]
state_login_clientbound = {
0x00: DisconnectPacket,
0x01: EncryptionRequestPacket,
0x02: LoginSucessPacket
0x02: LoginSuccessPacket,
0x03: SetCompressionPacket
}
class LoginStartPacket(Packet):
id = 0x00
name = "login start"
packet_name = "login start"
definition = [
{'name': String}]
class EncryptionResponsePacket(Packet):
id = 0x01
name = "encryption response"
packet_name = "encryption response"
definition = [
{'shared_secret': ByteArray},
{'verify_token': ByteArray}]
{'shared_secret': VarIntPrefixedByteArray},
{'verify_token': VarIntPrefixedByteArray}]
state_login_serverbound = {
0x00: LoginStartPacket,
0x01: EncryptionResponsePacket
}
# Playing State
# ==============
class KeepAlivePacket(Packet):
id = 0x00
packet_name = "keep alive"
definition = [
{'keep_alive_id': VarInt}]
class JoinGamePacket(Packet):
id = 0x01
packet_name = "join game"
definition = [
{'entity_id': Integer},
{'game_mode': UnsignedByte},
{'dimension': Byte},
{'difficulty': UnsignedByte},
{'max_players': UnsignedByte},
{'level_type': String},
{'reduced_debug_info': Boolean}]
class SetCompressionPacketPlayState(Packet):
id = 0x46
packet_name = "set compression"
definition = [
{'threshold': VarInt}]
state_playing_clientbound = {
0x00: KeepAlivePacket,
0x01: JoinGamePacket,
0x46: SetCompressionPacketPlayState
}
state_playing_serverbound = {
}

47
network/types.py
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@ -28,6 +28,16 @@ class Boolean(Type):
socket.send(struct.pack('?', value))
class UnsignedByte(Type):
@staticmethod
def read(file_object):
return struct.unpack('>B', file_object.read(1))[0]
@staticmethod
def send(value, socket):
socket.send(struct.pack('>B', value))
class Byte(Type):
@staticmethod
def read(file_object):
@ -103,6 +113,28 @@ class VarInt(Type):
break
socket.send(o)
@staticmethod
def size(value):
for max_value, size in VarInt_size_table.iteritems():
if value < max_value:
return size
# Maps (maximum integer value -> size of VarInt in bytes)
VarInt_size_table = {
2**7: 1,
2**14: 2,
2**21: 3,
2**28: 4,
2**35: 5,
2**42: 6,
2**49: 7,
2**56: 8,
2**63: 9,
2**70: 10,
2**77: 11,
2**84: 12
}
class Long(Type):
@staticmethod
@ -134,7 +166,7 @@ class Double(Type):
socket.send(struct.pack('>d', value))
class ByteArray(Type):
class ShortPrefixedByteArray(Type):
@staticmethod
def read(file_object, length=None):
if length is None:
@ -147,6 +179,19 @@ class ByteArray(Type):
socket.send(value)
class VarIntPrefixedByteArray(Type):
@staticmethod
def read(file_object, length=None):
if length is None:
length = VarInt.read(file_object)
return struct.unpack(str(length) + "s", file_object.read(length))[0]
@staticmethod
def send(value, socket):
VarInt.send(len(value), socket)
socket.send(struct.pack(str(len(value)) + "s", value))
class String(Type):
@staticmethod
def read(file_object):

2
requirements.txt
View File

@ -1 +1 @@
pycrypto>=2.5
cryptography

11
start.py
View File

@ -5,9 +5,6 @@ from optparse import OptionParser
import authentication
PROTOCOL_VERSION = 5
def main():
parser = OptionParser()
@ -28,13 +25,13 @@ def main():
if not options.password:
options.password = getpass.getpass("Enter your password: ")
try:
login_response = authentication.login_to_minecraft(options.username, options.password)
from pprint import pprint # TODO: remove debug
pprint(vars(login_response)) # TODO: remove debug
if login_response.error:
print login_response.human_error
except authentication.YggdrasilError as e:
print e.human_readable_error
return
print("Logged in as " + login_response.username)
@ -53,7 +50,7 @@ def main():
from network.connection import Connection
connection = Connection(address, port, login_response)
connection.status()
connection.connect()
while True:
try: