From 7e8df473520d57ca22fb57888681f51705128cdc Mon Sep 17 00:00:00 2001 From: Ammar Askar Date: Tue, 17 Mar 2015 22:15:27 +0500 Subject: [PATCH] Significant headway on the rewrite. Handle crypto with the excellent crytography library, still a lot of TODOs to take care of but at least we can connect now --- .gitignore | 5 +- authentication/auth.py | 42 ++++---- network/connection.py | 219 +++++++++++++++++++++++++++++++++-------- network/encryption.py | 81 +++++++++++++++ network/packets.py | 111 ++++++++++++++++----- network/types.py | 47 ++++++++- requirements.txt | 2 +- start.py | 17 ++-- 8 files changed, 426 insertions(+), 98 deletions(-) create mode 100644 network/encryption.py diff --git a/.gitignore b/.gitignore index ae1c951..9389b83 100644 --- a/.gitignore +++ b/.gitignore @@ -1,3 +1,6 @@ *.pyc build/* -src/* \ No newline at end of file +src/* + +*.iml +.idea/ \ No newline at end of file diff --git a/authentication/auth.py b/authentication/auth.py index df2855c..be21558 100644 --- a/authentication/auth.py +++ b/authentication/auth.py @@ -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 - json_response = json.loads(http_response) + 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 @@ -69,15 +77,11 @@ 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 + payload = response.payload - login_response.error = False - login_response.access_token = payload["accessToken"] - login_response.profile_id = payload["selectedProfile"]["id"] - login_response.username = payload["selectedProfile"]["name"] + login_response.error = False + login_response.access_token = payload["accessToken"] + login_response.profile_id = payload["selectedProfile"]["id"] + login_response.username = payload["selectedProfile"]["name"] return login_response diff --git a/network/connection.py b/network/connection.py index 64dd91b..860d4b6 100644 --- a/network/connection.py +++ b/network/connection.py @@ -1,52 +1,90 @@ 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' + + :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) - # Mostly a 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: + # 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 + 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.write(self.socket) + 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 def status(self): @@ -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): diff --git a/network/encryption.py b/network/encryption.py new file mode 100644 index 0000000..01871c6 --- /dev/null +++ b/network/encryption.py @@ -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() \ No newline at end of file diff --git a/network/packets.py b/network/packets.py index b33c56f..992a8a2 100644 --- a/network/packets.py +++ b/network/packets.py @@ -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 = { + } \ No newline at end of file diff --git a/network/types.py b/network/types.py index 9b92c06..9c878c3 100644 --- a/network/types.py +++ b/network/types.py @@ -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): diff --git a/requirements.txt b/requirements.txt index c9cd909..0d38bc5 100755 --- a/requirements.txt +++ b/requirements.txt @@ -1 +1 @@ -pycrypto>=2.5 \ No newline at end of file +cryptography diff --git a/start.py b/start.py index d7630e6..d1ae6bf 100644 --- a/start.py +++ b/start.py @@ -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: ") - login_response = authentication.login_to_minecraft(options.username, options.password) - from pprint import pprint # TODO: remove debug + 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 + pprint(vars(login_response)) # TODO: remove debug + 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: