105 lines
3.4 KiB
Python
Executable File
105 lines
3.4 KiB
Python
Executable File
#!/usr/bin/env python3.6
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# -*- coding: utf-8 -*-
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"""
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TFC - Onion-routed, endpoint secure messaging system
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Copyright (C) 2013-2019 Markus Ottela
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This file is part of TFC.
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TFC is free software: you can redistribute it and/or modify it under the terms
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of the GNU General Public License as published by the Free Software Foundation,
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either version 3 of the License, or (at your option) any later version.
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TFC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
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without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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PURPOSE. See the GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with TFC. If not, see <https://www.gnu.org/licenses/>.
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"""
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import random
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import threading
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import time
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import typing
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from typing import Any, Dict, Optional, Tuple, Union
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from src.common.misc import ignored
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from src.common.statics import *
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if typing.TYPE_CHECKING:
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from multiprocessing import Queue
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from src.common.db_contacts import ContactList
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from src.common.db_settings import Settings
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QueueDict = Dict[bytes, Queue]
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class HideRunTime(object):
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"""Runtime hiding time context manager.
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By joining a thread that sleeps for a longer time than it takes for
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the function to run, this context manager hides the actual running
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time of the function.
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Note that random.SystemRandom() uses the Kernel CSPRNG (/dev/urandom),
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not Python's weak PRNG based on Mersenne Twister:
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https://docs.python.org/2/library/random.html#random.SystemRandom
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"""
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def __init__(self,
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settings: 'Settings',
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delay_type: str = STATIC,
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duration: float = 0.0
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) -> None:
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if delay_type == TRAFFIC_MASKING:
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self.length = settings.tm_static_delay
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self.length += random.SystemRandom().uniform(0, settings.tm_random_delay)
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elif delay_type == STATIC:
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self.length = duration
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def __enter__(self) -> None:
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self.timer = threading.Thread(target=time.sleep, args=(self.length,))
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self.timer.start()
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def __exit__(self, exc_type: Any, exc_value: Any, traceback: Any) -> None:
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self.timer.join()
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def noise_loop(queues: 'QueueDict',
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contact_list: Optional['ContactList'] = None,
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unittest: bool = False
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) -> None:
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"""Generate noise packets for traffic masking.
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This process ensures noise packet / noise command queue always has
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noise assembly packets available.
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"""
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log_messages = True # This setting is ignored: settings.log_file_masking controls logging of noise packets.
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log_as_ph = True
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header = C_N_HEADER if contact_list is None else P_N_HEADER
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noise_assembly_packet = header + bytes(PADDING_LENGTH)
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if contact_list is None:
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# Noise command
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queue = queues[TM_NOISE_COMMAND_QUEUE]
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content = noise_assembly_packet # type: Union[bytes, Tuple[bytes, bool, bool]]
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else:
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# Noise packet
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queue = queues[TM_NOISE_PACKET_QUEUE]
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content = (noise_assembly_packet, log_messages, log_as_ph)
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while True:
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with ignored(EOFError, KeyboardInterrupt):
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while queue.qsize() < NOISE_PACKET_BUFFER:
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queue.put(content)
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time.sleep(0.1)
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if unittest:
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break
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