I have 3 dataclass objects say:
class Message1:
def __init__(a):
...
class Message2:
def __init__(d,e,f):
...
class Message3:
def __init__(g,i):
...
For these 3 messages I want to make a factory type method which can return one of the three objects if it succeeds and if not it should return either the one it identified as the correct message to be created but failed at creation or it should notify the user that it could not create any of the messages. Are there any OOP patterns for this?
My initial thought was to do a:
def factory_method(**parameters):
try:
Message1(**parameters)
except TypeError:
try:
Message2(**parameters)
except:
try:
Message3(**parameters)
except:
print("Could not deduce message type")
My issue with this idea is that:
It's not a dynamically scalable solution, with each new message class I introduce I need to add a new try catch block
If the whole nested block structure fails, I have no feedback as to why, was the parameters correct for one of the message but wrong value, or was it plain gibberish?
I realize this might be a bit opinion based on what the best outcome is. At the same time it might be the solution is not too elegant and the simplest way is to just tell the factory_method what kind of message to initialize. Any suggestions or ideas would be appreciated.
If you can't join them all in a single class and you can't point a call to a single class, i would match the arguments to the posible class. To make it work a type hint and a "proxy" class is required. This example asumes that any of the classes wont contain a __init__(*args, **kwargs), and to add a new class you just add it to Message.msg_cls, you can eval the global scope if you don't want to add manually each class.
class Message1:
def __init__(self, a: int, alt=None, num=10):
print('Message 1')
class Message2:
def __init__(self, d: str, e: str, f: int):
print('Message 2')
class Message3:
def __init__(self, g: int, i: any):
print('Message 3')
class Message:
msg_cls = (
Message1,
Message2,
Message3
)
#staticmethod
def eq_kwargs(cls, kwargs):
cls_kwargs = cls.__init__.__defaults__
if cls_kwargs is None:
if len(kwargs) > 0:
return False
else:
return True
cls_astr = cls.__init__.__code__
kw_types = [type(t) for t in cls_kwargs]
for k in kwargs:
if k in cls_astr.co_varnames:
if type(kwargs[k]) in kw_types:
kw_types.remove(type(kwargs[k]))
else:
if type(None) in kw_types:
kw_types.remove(type(None))
else:
return False
else:
return False
return True
#staticmethod
def eq_args(cls, args):
cls_args = cls.__init__.__annotations__
if len(cls_args) != len(args):
return False
for a, b in zip(args, cls_args):
if type(a) != cls_args[b] and cls_args[b] != any:
return False
return True
def __new__(cls, *args, **kwargs):
for mc in Message.msg_cls:
if Message.eq_args(mc, args):
if Message.eq_kwargs(mc, kwargs):
return mc(*args, **kwargs)
raise ValueError('Message.__new__, no match')
if __name__ == '__main__':
ms_1_a = Message(1, alt='a')
ms_1_b = Message(2, alt='a', num=5)
ms_2 = Message('X', 'Y', 5)
ms_3_a = Message(1, [1, 4])
ms_3_b = Message(2, Message(10))
As you can see, the connect function, is converting the _connect function into a lambda through convert and it's getting passed to run_api function. The exception thrown in _connect is not getting caught by the except in the run_api function. Is anything that needs to be done with respect to lambda?
The code looks good but still am not able to figure out why the exception is not getting caught incase of failure.
Here is my code.
def run_api(function, retry_count):
count = 0
while count < retry_count:
count += 1
try:
function()
return True
except (BleTestFail, BleTestError):
if count == retry_count:
return False
def convert(func):
return lambda: func
def _connect(self, target_id):
result = self.device.ble_central.connect(target_id)
self.logger.debug('Connect output %s', result)
if result['op'] != 'ok':
self.logger.error('Connect command execution failed')
raise ble_utils.BleTestFail('Failed to connect')
return True
def connect(self, target_ids, retry_count=1):
connected = []
unconnected = []
if not isinstance(target_ids, list):
target_ids = [target_ids]
for target_id in target_ids:
connect_function = ble_utils.convert(self._connect(target_id))
connect_status = ble_utils.run_api(connect_function, retry_count,
'connecting device %s' % target_id,
self.logger)
if connect_status:
connected.append(target_id)
else:
unconnected.append(target_id)
if connected:
self.logger.info('Connected to %s devices: %s', len(connected), connected)
if unconnected:
self.logger.error('Unable to connect %s devices: %s', len(unconnected),
unconnected)
return connected, unconnected
So, to clarify, we have the example "API" to which we want to provide a callback:
def run_api(function, retry_count):
count = 0
while count < retry_count:
count += 1
try:
function()
return True
except (BleTestFail, BleTestError):
if count == retry_count:
return False
And a method that we want to be called in that API, with a specific argument:
class Example:
# other stuff omitted...
def _connect(self, target_id):
result = self.device.ble_central.connect(target_id)
self.logger.debug('Connect output %s', result)
if result['op'] != 'ok':
self.logger.error('Connect command execution failed')
raise ble_utils.BleTestFail('Failed to connect')
return True
connection = Example()
So now we want to call run_api with connection._connect, but somehow provide the target_id information.
This is called binding, and the most elegant way to do it is with the standard library functools.partial:
from functools import partial
# This is how we can make the `convert` function from before:
def convert(func, param):
return partial(func, param)
# But there is no point to this, since we can just use `partial` directly.
# There was no hope for the original approach, because you were calling the
# function ahead of time and passing the returned result to `convert`.
# So, the process looks like this:
# target_id = 1, retry_count = 2
run_api(partial(connection._connect, 1), 2)
You can make it work with lambda, but I don't recommend it - functools.partial is more explicit, and elegantly handles more advanced use cases that have some unexpected gotchas (in particular, if you want to make multiple callbacks in a loop; you may find they all unexpectedly bind with the same value, or else you have to use a very ugly workaround). But for the sake of completion, that looks like so:
def convert(func, param):
return lambda: func(param)
Here is my client code.
import socket, pickle,time
from encryption import *
def Main():
host = '127.0.0.1'
port = 5006
s = socket.socket()
s.connect((host, port))
m= encryption()
pri_key,pub_key,n=m.generating_keys(1)
filename = input("Filename? -> ")
if filename != 'q':
data=[filename,pub_key,n]
msg=pickle.dumps(data)
s.send(msg)
data = s.recv(1024)
data=data.decode('utf-8')
if data == '1':
size = s.recv(1024)
size = int(size.decode('utf-8'))
filesize = size
message = input("File exists, " + str(filesize) +"Bytes, download? (Y/N)? -> ")
if message == 'Y':
s.send(b'1')
count=0
f = open('new_'+filename, 'wb')
data = s.recv(1024)
data=int.from_bytes(data,byteorder="little")
msg=m.decrypt(data,pri_key,n)
totalRecv = len(msg)
f.write(msg)
#count=0
while totalRecv<filesize:
#time.sleep(.300)
decipher = s.recv(1024)
decipher=int.from_bytes(decipher,byteorder="little")
print(decipher)
if(decipher==0):
break
msg=m.decrypt(decipher,pri_key,n)
totalRecv += len(msg)
f.write(msg)
print ("{0:.2f}".format((totalRecv/float(filesize))*100)+ "% Done")
print ("Download Complete!")
f.close()
else:
print ("File Does Not Exist!")
s.close()
if __name__ == '__main__':
Main()
Here is my server code.
import socket,threading,os,pickle
from encryption import *
def RetrFile(name, sock):
m=encryption()
filename = sock.recv(1024)
dat=pickle.loads(filename)
if os.path.isfile(dat[0]):
s='1'
s=s.encode('utf-8')
sock.send(s)
k=str(os.path.getsize(dat[0]))
k=k.encode('utf-8')
sock.send(k)
count=8
userResponse = sock.recv(1024)
if userResponse[:2] == (b'1'):
with open(dat[0],'rb') as f:
bytesToSend = f.read(1024)
#print(type(bytesToSend))
#print('1')
#print(bytesToSend)
msg= m.encrypt(bytesToSend,dat[1],dat[2])
#print(msg)
#print(1)
k=msg.bit_length()
if(k%8>=1):
k=k+1
msg=msg.to_bytes(k,byteorder="little")
#print (msg)
#msg=msg.encode('utf-8')
#print(msg)
sock.send(msg)
s=''
s=s.encode('utf-8')
while bytesToSend != s:
bytesToSend = f.read(1024)
msg= m.encrypt(bytesToSend,dat[1],dat[2])
k=msg.bit_length()
if(k%8>=1):
k=k//8+1
msg=msg.to_bytes(k,byteorder="little")
sock.send(msg)
#count=count.to_bytes(1,byteorder="little")
#sock.send(count)
else:
sock.send(b'ERR')
sock.close()
def Main():
host = '127.0.0.1'
port = 5006
s = socket.socket()
s.bind((host,port))
s.listen(5)
print ("Server Started.")
while True:
c, addr = s.accept()
print ("client connedted ip:<" + str(addr) + ">")
t = threading.Thread(target=RetrFile, args=("RetrThread", c))
t.start()
s.close()
if __name__ == '__main__':
Main()
Now my problem is that decipher.recv(1024) in client side is not receiving the message. what should i do.
On the server side, change the code to:
while bytesToSend != s:
bytesToSend = f.read(1024)
length = len(bytesTosend)
leng = length.to_bytes(4, 'little')
sock.sendall(leng)
msg = m.encrypt(bytesToSend, dat[1], dat[2])
k = msg.bit_length()
if k % 8 >= 1 :
k = k // 8 + 1
else:
k = k // 8
msg = msg.to_bytes(k, byteorder='little')
sock.sendall(msg)
And on the client side:
while True:
length = s.recv(4)
length = int.from_bytes(length, byteorder='little')
decipher = s.recv(leng)
decipher = int.from_bytes(decipher, byteorder='little')
if not decipher:
break
msg = m.decrypt(decipher, pri_key, n)
f.write(msg)
f.close()
It is rather difficult to check your code without seeing the encryption module referenced in your code. With such functionality absent, testing to find out where the problem is becomes impossible. As such, the following programs are provided along with the implementation of another encryption module.
The server should be run from the command line and requires a port number and password to be supplied upon execution. The only form of authentication or authorization used is proper understanding of the client. The client must use the same password to be understood by the server.
Server
#! /usr/bin/env python3
import argparse
import pathlib
import pickle
import pickletools
import random
import socket
import socketserver
import zlib
import encryption
BYTES_USED = bytes(range(1 << 8))
CHAIN_SIZE = 1 << 8
def main():
"""Start a file server and serve clients forever."""
parser = argparse.ArgumentParser(description='Execute a file server demo.')
parser.add_argument('port', type=int, help='location where server listens')
parser.add_argument('password', type=str, help='key to use on secure line')
arguments = parser.parse_args()
server_address = socket.gethostbyname(socket.gethostname()), arguments.port
server = CustomServer(server_address, CustomHandler, arguments.password)
server.serve_forever()
class CustomServer(socketserver.ThreadingTCPServer):
"""Provide server support for the management of encrypted data."""
def __init__(self, server_address, request_handler_class, password):
"""Initialize the server and keep a set of security credentials."""
super().__init__(server_address, request_handler_class, True)
self.key = encryption.Key.new_client_random(
BYTES_USED,
CHAIN_SIZE,
random.Random(password)
)
self.primer = encryption.Primer.new_client_random(
self.key,
random.Random(password)
)
class CustomHandler(socketserver.StreamRequestHandler):
"""Allow forwarding of data to all connected clients."""
def __init__(self, request, client_address, server):
"""Initialize the handler with security translators."""
self.decoder = encryption.Decrypter(server.key, server.primer)
self.encoder = encryption.Encrypter(server.key, server.primer)
super().__init__(request, client_address, server)
def handle(self):
"""Run the code to handle clients while dealing with errors."""
try:
self.process_file_request()
except (ConnectionResetError, EOFError):
pass
def process_file_request(self):
"""Deal with clients that wish to download a file."""
segment = self.load()
path = pathlib.Path(segment)
if path.is_file():
size = path.stat().st_size
self.dump(size)
accepted = self.load()
if accepted:
with path.open('rb') as file:
while True:
buffer = file.read(1 << 15)
self.dump(buffer)
if not buffer:
break
else:
error = 'The given path does not specify a file.'
self.dump(error)
def load(self):
"""Read the client's connection with blocking."""
data = self.decoder.load_16bit_frame(self.rfile)
bytes_object = zlib.decompress(data)
return pickle.loads(bytes_object)
def dump(self, obj):
"""Send an object securely over to the client if possible."""
pickle_string = pickle.dumps(obj, pickle.HIGHEST_PROTOCOL)
bytes_object = pickletools.optimize(pickle_string)
data = zlib.compress(bytes_object, zlib.Z_BEST_COMPRESSION)
self.encoder.dump_16bit_frame(data, self.wfile)
if __name__ == '__main__':
main()
The client should also be run from the command line and requires the host name, port number, and password for the server. Communications are encrypted with the password and cannot be decrypted properly if it is different. Please note that very little checking for errors is present in the two programs.
Client
#! /usr/bin/env python3
import argparse
import pathlib
import pickle
import pickletools
import random
import socket
import zlib
import encryption
BYTES_USED = bytes(range(1 << 8))
CHAIN_SIZE = 1 << 8
# These are possible answers accepted for yes/no style questions.
POSITIVE = tuple(map(str.casefold, ('yes', 'true', '1')))
NEGATIVE = tuple(map(str.casefold, ('no', 'false', '0')))
def main():
"""Connect a file client to a server and process incoming commands."""
parser = argparse.ArgumentParser(description='Execute a file client demo.')
parser.add_argument('host', type=str, help='name of server on the network')
parser.add_argument('port', type=int, help='location where server listens')
parser.add_argument('password', type=str, help='key to use on secure line')
arguments = parser.parse_args()
connection = socket.create_connection((arguments.host, arguments.port))
try:
talk_to_server(*make_dump_and_load(connection, arguments.password))
finally:
connection.shutdown(socket.SHUT_RDWR)
connection.close()
def make_dump_and_load(connection, password):
"""Create objects to help with the encrypted communications."""
reader = connection.makefile('rb', -1)
writer = connection.makefile('wb', 0)
chaos = random.Random(password)
key = encryption.Key.new_client_random(BYTES_USED, CHAIN_SIZE, chaos)
chaos = random.Random(password)
primer = encryption.Primer.new_client_random(key, chaos)
decoder = encryption.Decrypter(key, primer)
encoder = encryption.Encrypter(key, primer)
def dump(obj):
"""Write an object to the writer file in an encoded form."""
pickle_string = pickle.dumps(obj, pickle.HIGHEST_PROTOCOL)
bytes_object = pickletools.optimize(pickle_string)
data = zlib.compress(bytes_object, zlib.Z_BEST_COMPRESSION)
encoder.dump_16bit_frame(data, writer)
def load():
"""Read an object from the reader file and decode the results."""
data = decoder.load_16bit_frame(reader)
bytes_object = zlib.decompress(data)
return pickle.loads(bytes_object)
return dump, load
def talk_to_server(dump, load):
"""Converse with the serve while trying to get a file."""
segment = input('Filename: ')
dump(segment)
size = load()
if isinstance(size, int):
print('File exists and takes', size, 'bytes to download.')
response = get_response('Continue? ')
dump(response)
if response:
location = input('Where should the new file be created? ')
with pathlib.Path(location).open('wb') as file:
written = 0
while True:
buffer = load()
if not buffer:
break
written += file.write(buffer)
print('Progress: {:.1%}'.format(written / size))
print('Download complete!')
else:
print(size)
def get_response(query):
"""Ask the user yes/no style questions and return the results."""
while True:
answer = input(query).casefold()
if answer:
if any(option.startswith(answer) for option in POSITIVE):
return True
if any(option.startswith(answer) for option in NEGATIVE):
return False
print('Please provide a positive or negative answer.')
if __name__ == '__main__':
main()
Since access to the encryption module was not provided, an alternative implementation has been included below. No guarantee is made for its suitability in any capacity or for any purpose. It may be somewhat slow as the software is currently configured but works well if obfuscation is desired.
encryption
"""Provide an implementation of Markov Encryption for simplified use.
This module exposes primitives useful for executing Markov Encryption
processes. ME was inspired by a combination of Markov chains with the
puzzles of Sudoku. This implementation has undergone numerous changes
and optimizations since its original design. Please see documentation."""
###############################################################################
# Import several functions needed later in the code.
from collections import deque
from math import ceil
from random import Random, SystemRandom
from struct import calcsize, pack, unpack
from inspect import currentframe
__author__ = 'Stephen "Zero" Chappell <Noctis.Skytower#gmail.com>'
__date__ = '18 August 2016'
__version__ = 2, 0, 8
###############################################################################
# Create some tools to use in the classes down below.
_CHAOS = SystemRandom()
def slots(names=''):
"""Set the __slots__ variable in the calling context with private names.
This function allows a convenient syntax when specifying the slots
used in a class. Simply call it in a class definition context with
the needed names. Locals are modified with private slot names."""
currentframe().f_back.f_locals['__slots__'] = \
tuple('__' + name for name in names.replace(',', ' ').split())
###############################################################################
# Implement a Key primitive data type for Markov Encryption.
class Key:
"""Key(data) -> Key instance
This class represents a Markov Encryption Key primitive. It allows for
easy key creation, checks for proper data construction, and helps with
encoding and decoding indexes based on cached internal tables."""
slots('data dimensions base size encoder axes order decoder')
#classmethod
def new(cls, bytes_used, chain_size):
"""Return a Key instance created from bytes_used and chain_size.
Creating a new key is easy with this method. Call this class method
with the bytes you want the key to recognize along with the size of
the chains you want the encryption/decryption processes to use."""
selection, blocks = list(set(bytes_used)), []
for _ in range(chain_size):
_CHAOS.shuffle(selection)
blocks.append(bytes(selection))
return cls(tuple(blocks))
#classmethod
def new_deterministic(cls, bytes_used, chain_size):
"""Automatically create a key with the information provided."""
selection, blocks, chaos = list(set(bytes_used)), [], Random()
chaos.seed(chain_size.to_bytes(ceil(
chain_size.bit_length() / 8), 'big') + bytes(range(256)))
for _ in range(chain_size):
chaos.shuffle(selection)
blocks.append(bytes(selection))
return cls(tuple(blocks))
#classmethod
def new_client_random(cls, bytes_used, chain_size, chaos):
"""Create a key using chaos as the key's source of randomness."""
selection, blocks = list(set(bytes_used)), []
for _ in range(chain_size):
chaos.shuffle(selection)
blocks.append(bytes(selection))
return cls(tuple(blocks))
def __init__(self, data):
"""Initialize the Key instance's variables after testing the data.
Keys are created with tuples of carefully constructed bytes arrays.
This method tests the given data before going on to build internal
tables for efficient encoding and decoding methods later on."""
self.__test_data(data)
self.__make_vars(data)
#staticmethod
def __test_data(data):
"""Test the data for correctness in its construction.
The data must be a tuple of at least two byte arrays. Each byte
array must have at least two bytes, all of which must be unique.
Furthermore, all arrays should share the exact same byte set."""
if not isinstance(data, tuple):
raise TypeError('Data must be a tuple object!')
if len(data) < 2:
raise ValueError('Data must contain at least two items!')
item = data[0]
if not isinstance(item, bytes):
raise TypeError('Data items must be bytes objects!')
length = len(item)
if length < 2:
raise ValueError('Data items must contain at least two bytes!')
unique = set(item)
if len(unique) != length:
raise ValueError('Data items must contain unique byte sets!')
for item in data[1:]:
if not isinstance(item, bytes):
raise TypeError('Data items must be bytes objects!')
next_length = len(item)
if next_length != length:
raise ValueError('All data items must have the same size!')
next_unique = set(item)
if len(next_unique) != next_length:
raise ValueError('Data items must contain unique byte sets!')
if next_unique ^ unique:
raise ValueError('All data items must use the same byte set!')
def __make_vars(self, data):
"""Build various internal tables for optimized calculations.
Encoding and decoding rely on complex relationships with the given
data. This method caches several of these key relationships for use
when the encryption and decryption processes are being executed."""
self.__data = data
self.__dimensions = len(data)
base, *mutations = data
self.__base = base = tuple(base)
self.__size = size = len(base)
offset = -sum(base.index(block[0]) for block in mutations[:-1]) % size
self.__encoder = base[offset:] + base[:offset]
self.__axes = tuple(reversed([tuple(base.index(byte) for byte in block)
for block in mutations]))
self.__order = key = tuple(sorted(base))
grid = []
for rotation in range(size):
block, row = base[rotation:] + base[:rotation], [None] * size
for byte, value in zip(block, key):
row[key.index(byte)] = value
grid.append(tuple(row))
self.__decoder = tuple(grid[offset:] + grid[:offset])
def test_primer(self, primer):
"""Raise an error if the primer is not compatible with this key.
Key and primers have a certain relationship that must be maintained
in order for them to work together. Since the primer understands
the requirements, it is asked to check this key for compatibility."""
primer.test_key(self)
def encode(self, index):
"""Encode index based on internal tables and return byte code.
An index probes into the various axes of the multidimensional,
virtual grid that a key represents. The index is evaluated, and
the value at its coordinates is returned by running this method."""
assert len(index) == self.__dimensions, \
'Index size is not compatible with key dimensions!'
*probes, current = index
return self.__encoder[(sum(
table[probe] for table, probe in zip(self.__axes, probes)
) + current) % self.__size]
def decode(self, index):
"""Decode index based on internal tables and return byte code.
Decoding does the exact same thing as encoding, but it indexes
into a virtual grid that represents the inverse of the encoding
grid. Tables are used to make the process fast and efficient."""
assert len(index) == self.__dimensions, \
'Index size is not compatible with key dimensions!'
*probes, current = index
return self.__decoder[sum(
table[probe] for table, probe in zip(self.__axes, probes)
) % self.__size][current]
#property
def data(self):
"""Data that the instance was initialized with.
This is the tuple of byte arrays used to create this key and can
be used to create an exact copy of this key at some later time."""
return self.__data
#property
def dimensions(self):
"""Dimensions that the internal, virtual grid contains.
The virtual grid has a number of axes that can be referenced when
indexing into it, and this number is the count of its dimensions."""
return self.__dimensions
#property
def base(self):
"""Base value that the internal grid is built from.
The Sudoku nature of the grid comes from rotating this value by
offsets, keeping values unique along any axis while traveling."""
return self.__base
#property
def order(self):
"""Order of base after its values have been sorted.
A sorted base is important when constructing inverse rows and when
encoding raw bytes for use in updating an encode/decode index."""
return self.__order
###############################################################################
# Implement a Primer primitive data type for Markov Encryption.
class Primer:
"""Primer(data) -> Primer instance
This class represents a Markov Encryption Primer primitive. It is very
important for starting both the encryption and decryption processes. A
method is provided for their easy creation with a related key."""
slots('data')
#classmethod
def new(cls, key):
"""Return a Primer instance from a parent Key.
Primers must be compatible with the keys they are used with. This
method takes a key and constructs a cryptographically sound primer
that is ready to use in the beginning stages of encryption."""
base = key.base
return cls(bytes(_CHAOS.choice(base)
for _ in range(key.dimensions - 1)))
#classmethod
def new_deterministic(cls, key):
"""Automatically create a primer with the information provided."""
base, chain_size, chaos = key.base, key.dimensions, Random()
chaos.seed(chain_size.to_bytes(ceil(
chain_size.bit_length() / 8), 'big') + bytes(range(256)))
return cls(bytes(chaos.choice(base) for _ in range(chain_size - 1)))
#classmethod
def new_client_random(cls, key, chaos):
"""Create a primer using chaos as the primer's source of randomness."""
base = key.base
return cls(
bytes(chaos.choice(base) for _ in range(key.dimensions - 1))
)
def __init__(self, data):
"""Initialize the Primer instance after testing validity of data.
Though not as complicated in its requirements as keys, primers do
need some simple structure in the data they are given. A checking
method is run before saving the data to the instance's attribute."""
self.__test_data(data)
self.__data = data
#staticmethod
def __test_data(data):
"""Test the data for correctness and test the data.
In order for the primer to be compatible with the nature of the
Markov Encryption processes, the data must be an array of bytes;
and to act as a primer, it must contain at least some information."""
if not isinstance(data, bytes):
raise TypeError('Data must be a bytes object!')
if not data:
raise ValueError('Data must contain at least one byte!')
def test_key(self, key):
"""Raise an error if the key is not compatible with this primer.
Primers provide needed data to start encryption and decryption. For
it be compatible with a key, it must contain one byte less than the
key's dimensions and must be a subset of the base in the key."""
if len(self.__data) != key.dimensions - 1:
raise ValueError('Key size must be one more than the primer size!')
if not set(self.__data).issubset(key.base):
raise ValueError('Key data must be a superset of primer data!')
#property
def data(self):
"""Data that the instance was initialized with.
This is the byte array used to create this primer and can be used
if desired to create an copy of this primer at some later time."""
return self.__data
###############################################################################
# Create an abstract processing class for use in encryption and decryption.
class _Processor:
"""_Processor(key, primer) -> NotImplementedError exception
This class acts as a base for the encryption and decryption processes.
The given key is saved, and several tables are created along with an
index. Since it is abstract, calling the class will raise an exception."""
slots('key into index from')
def __init__(self, key, primer):
"""Initialize the _Processor instance if it is from a child class.
After passing several tests for creating a valid processing object,
the key is saved, and the primer is used to start an index. Tables
are also formed for converting byte values between systems."""
if type(self) is _Processor:
raise NotImplementedError('This is an abstract class!')
key.test_primer(primer)
self.__key = key
self.__into = table = dict(map(reversed, enumerate(key.order)))
self.__index = deque(map(table.__getitem__, primer.data),
key.dimensions)
self.__from = dict(map(reversed, table.items()))
def process(self, data):
"""Process the data and return its transformed state.
A cache for the data transformation is created and an internal
method is run to quickly encode or decode the given bytes. The
cache is finally converted to immutable bytes when returned."""
cache = bytearray()
self._run(data, cache.append, self.__key, self.__into, self.__index)
return bytes(cache)
#staticmethod
def _run(data, cache_append, key, table, index):
"""Run the processing algorithm in an overloaded method.
Since this is only an abstract base class for encoding/decoding,
this method will raise an exception when run. Inheriting classes
should implement whatever is appropriate for the intended function."""
raise NotImplementedError('This is an abstract method!')
#property
def primer(self):
"""Primer representing the state of the internal index.
The index can be retrieved as a primer, useful for initializing
another processor in the same starting state as the current one."""
index = self.__index
index.append(None)
index.pop()
return Primer(bytes(map(self.__from.__getitem__, index)))
###############################################################################
# Inherit from _Processor and implement the ME encoding algorithm.
class Encrypter(_Processor):
"""Encrypter(key, primer) -> Encrypter instance
This class represents a state-aware encryption engine that can be fed
data and will return a stream of coherent cipher-text. An index is
maintained, and a state-continuation primer can be retrieved at will."""
slots()
#staticmethod
def _run(data, cache_append, key, table, index):
"""Encrypt the data with the given arguments.
To run the encryption process as fast as possible, methods are
cached as names. As the algorithm operates, only recognized bytes
are encoded while running through the selective processing loop."""
encode, index_append = key.encode, index.append
for byte in data:
if byte in table:
index_append(table[byte])
cache_append(encode(index))
else:
cache_append(byte)
def dump_16bit_frame(self, data, file):
"""Write the data to the file using a guaranteed frame size."""
size = len(data)
if not 1 <= size <= 1 << 16:
raise ValueError('data has an unsupported length')
packed = self.process(pack('<H{}s'.format(size), size - 1, data))
if file.write(packed) != len(packed):
raise IOError('frame was not properly written to file')
###############################################################################
# Inherit from _Processor and implement the ME decoding algorithm.
class Decrypter(_Processor):
"""Decrypter(key, primer) -> Decrypter instance
This class represents a state-aware decryption engine that can be fed
data and will return a stream of coherent plain-text. An index is
maintained, and a state-continuation primer can be retrieved at will."""
slots()
SIZE = '<H'
DATA = '{}s'
#staticmethod
def _run(data, cache_append, key, table, index):
"""Decrypt the data with the given arguments.
To run the decryption process as fast as possible, methods are
cached as names. As the algorithm operates, only recognized bytes
are decoded while running through the selective processing loop."""
decode, index_append = key.decode, index.append
for byte in data:
if byte in table:
index_append(table[byte])
value = decode(index)
cache_append(value)
index[-1] = table[value]
else:
cache_append(byte)
def load_16bit_frame(self, file):
"""Read some data from the file using a guaranteed frame size."""
size = unpack(self.SIZE, self.process(self.read_all(
file,
calcsize(self.SIZE)
)))[0] + 1
return unpack(self.DATA.format(size), self.process(self.read_all(
file,
size
)))[0]
#staticmethod
def read_all(file, size):
"""Get all the data that has been requested from the file."""
if not 1 <= size <= 1 << 16:
raise ValueError('size has an unsupported value')
buffer = bytearray()
while size > 0:
data = file.read(size)
if not data:
raise EOFError('file has unexpectedly reached the end')
buffer.extend(data)
size -= len(data)
if size < 0:
raise IOError('more data was read than was required')
return bytes(buffer)
When I create an object in some method, I can't use it in any other method. So the use of the object is limited just to that method. But I would like to create the object somehow, that could use it in my whole module.
Here is the code of the module in which I want to create the object so I could use it in every method. (It's not so important what it should do, but for those who cares, it'll be network configurator which using netlink socket to communicate with the kernel).
In the method configureBridge() (the 4th method from the beginning) I tried to create an object and use it (ip = IPRoute() ... ip.release()) and it worked, but I couldn't use the object variable ip in any other function apart from configureBridge(). Could someone help me with that?
class PyrouteTwo(Configurator):
def __init__(self, inRollback=False):
super(PyrouteTwo, self).__init__(ConfigApplier(), inRollback)
self.runningConfig = RunningConfig()
logging.debug("testmark.PyR2.init")
def begin(self):
if self.configApplier is None:
self.configApplier = ConfigApplier()
if self.runningConfig is None:
self.runningConfig = RunningConfig()
logging.debug("testmark.PyR2.begin")
def commit(self):
self.configApplier = None
self.runningConfig.save()
self.runningConfig = None
logging.debug("testmark.PyR2.commit")
def configureBridge(self, bridge, **opts):
self.configApplier.addBridge(bridge)
if bridge.port:
bridge.port.configure(**opts)
self.configApplier.addBridgePort(bridge)
self.configApplier.setIfaceConfigAndUp(bridge)
logging.debug("testmark.PyR2.confBridge..")
# I am using the object here:
ip = IPRoute(fork=True)
dev = ip.link_lookup(ifname='em1')[0]
logging.debug("pyroute2 link_lookup output: %d", dev)
ip.release()
# there are some similar functions like configureVAN etc. in which I want
# to use the object
class ConfigApplier(object):
def _setIpConfig(self, iface):
ipConfig = iface.ipConfig
logging.debug("testmark.PyR2.ConfApplier.setIpConf.")
if ipConfig.ipaddr:
self.removeIpConfig(iface)
ipwrapper.addrAdd(iface.name, ipConfig.ipaddr,
ipConfig.netmask)
if ipConfig.gateway and ipConfig.defaultRoute:
ipwrapper.routeAdd(['default', 'via', ipConfig.gateway])
def removeIpConfig(self, iface):
ipwrapper.addrFlush(iface.name)
def setIfaceMtu(self, iface, mtu):
ipwrapper.linkSet(iface, ['mtu', str(mtu)])
def ifup(self, iface):
ipwrapper.linkSet(iface.name, ['up'])
if iface.ipConfig.bootproto == 'dhcp':
dhclient = DhcpClient(iface.name)
dhclient.start(iface.ipConfig.async)
def ifdown(self, iface):
ipwrapper.linkSet(iface.name, ['down'])
dhclient = DhcpClient(iface.name)
dhclient.shutdown()
def setIfaceConfigAndUp(self, iface):
if iface.ip:
self._setIpConfig(iface)
if iface.mtu:
self.setIfaceMtu(iface.name, iface.mtu)
self.ifup(iface)
def addBridge(self, bridge):
rc, _, err = execCmd([EXT_BRCTL, 'addbr', bridge.name])
if rc != 0:
raise ConfigNetworkError(ERR_FAILED_IFUP, err)
def addBridgePort(self, bridge):
rc, _, err = execCmd([EXT_BRCTL, 'addif', bridge.name,
bridge.port.name])
if rc != 0:
raise ConfigNetworkError(ERR_FAILED_IFUP, err)
def removeBridge(self, bridge):
rc, _, err = execCmd([EXT_BRCTL, 'delbr', bridge.name])
if rc != 0:
raise ConfigNetworkError(ERR_FAILED_IFDOWN, err)
logging.debug("testmarkPyR2.ConfApplier.remBridge")
# ...
def createLibvirtNetwork(self, network, bridged, iface, qosInbound=None,
qosOutbound=None):
netXml = libvirtCfg.createNetworkDef(network, bridged, iface,
qosInbound, qosOutbound)
libvirtCfg.createNetwork(netXml)
logging.debug("testmarkPyR2.ConfApplier.createLibvirtNetwork")
def removeLibvirtNetwork(self, network):
libvirtCfg.removeNetwork(network)
logging.debug("testmarkPyR2.ConfApplier.remLibvirtNetwork")
You can either declare it as object specific attibute by doing -
self.ip = value # Now its a object specific variable
or make it a class veriable before assign it a value.
class PyrouteTwo(Configurator):
ip = None # Now its a class variable