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pisa -> teos
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Sergi Delgado Segura
384
teos/inspector.py
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384
teos/inspector.py
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import re
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from binascii import unhexlify
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import common.cryptographer
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from common.constants import LOCATOR_LEN_HEX
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from common.cryptographer import Cryptographer, PublicKey
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from teos import errors, LOG_PREFIX
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from common.logger import Logger
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from common.appointment import Appointment
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from teos.block_processor import BlockProcessor
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logger = Logger(actor="Inspector", log_name_prefix=LOG_PREFIX)
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common.cryptographer.logger = Logger(actor="Cryptographer", log_name_prefix=LOG_PREFIX)
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# FIXME: The inspector logs the wrong messages sent form the users. A possible attack surface would be to send a really
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# long field that, even if not accepted by TEOS, would be stored in the logs. This is a possible DoS surface
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# since teos would store any kind of message (no matter the length). Solution: truncate the length of the fields
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# stored + blacklist if multiple wrong requests are received.
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BLOCKS_IN_A_MONTH = 4320 # 4320 = roughly a month in blocks
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ENCRYPTED_BLOB_MAX_SIZE_HEX = 2 * 2048
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class Inspector:
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"""
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The :class:`Inspector` class is in charge of verifying that the appointment data provided by the user is correct.
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"""
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def __init__(self, config):
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self.config = config
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def inspect(self, appointment_data, signature, public_key):
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"""
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Inspects whether the data provided by the user is correct.
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Args:
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appointment_data (:obj:`dict`): a dictionary containing the appointment data.
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signature (:obj:`str`): the appointment signature provided by the user (hex encoded).
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public_key (:obj:`str`): the user's public key (hex encoded).
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Returns:
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:obj:`Appointment <teos.appointment.Appointment>` or :obj:`tuple`: An appointment initialized with the
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provided data if it is correct.
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Returns a tuple ``(return code, message)`` describing the error otherwise.
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Errors are defined in :mod:`Errors <teos.errors>`.
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"""
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block_height = BlockProcessor.get_block_count()
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if block_height is not None:
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rcode, message = self.check_locator(appointment_data.get("locator"))
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if rcode == 0:
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rcode, message = self.check_start_time(appointment_data.get("start_time"), block_height)
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if rcode == 0:
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rcode, message = self.check_end_time(
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appointment_data.get("end_time"), appointment_data.get("start_time"), block_height
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)
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if rcode == 0:
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rcode, message = self.check_to_self_delay(appointment_data.get("to_self_delay"))
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if rcode == 0:
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rcode, message = self.check_blob(appointment_data.get("encrypted_blob"))
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# if rcode == 0:
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# rcode, message = self.check_appointment_signature(appointment_data, signature, public_key)
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if rcode == 0:
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r = Appointment.from_dict(appointment_data)
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else:
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r = (rcode, message)
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else:
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# In case of an unknown exception, assign a special rcode and reason.
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r = (errors.UNKNOWN_JSON_RPC_EXCEPTION, "Unexpected error occurred")
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return r
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@staticmethod
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def check_locator(locator):
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"""
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Checks if the provided ``locator`` is correct.
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Locators must be 16-byte hex encoded strings.
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Args:
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locator (:obj:`str`): the locator to be checked.
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Returns:
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:obj:`tuple`: A tuple (return code, message) as follows:
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- ``(0, None)`` if the ``locator`` is correct.
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- ``!= (0, None)`` otherwise.
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The possible return errors are: ``APPOINTMENT_EMPTY_FIELD``, ``APPOINTMENT_WRONG_FIELD_TYPE``,
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``APPOINTMENT_WRONG_FIELD_SIZE``, and ``APPOINTMENT_WRONG_FIELD_FORMAT``.
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"""
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message = None
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rcode = 0
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if locator is None:
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rcode = errors.APPOINTMENT_EMPTY_FIELD
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message = "empty locator received"
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elif type(locator) != str:
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rcode = errors.APPOINTMENT_WRONG_FIELD_TYPE
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message = "wrong locator data type ({})".format(type(locator))
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elif len(locator) != LOCATOR_LEN_HEX:
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rcode = errors.APPOINTMENT_WRONG_FIELD_SIZE
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message = "wrong locator size ({})".format(len(locator))
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# TODO: #12-check-txid-regexp
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elif re.search(r"^[0-9A-Fa-f]+$", locator) is None:
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rcode = errors.APPOINTMENT_WRONG_FIELD_FORMAT
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message = "wrong locator format ({})".format(locator)
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if message is not None:
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logger.error(message)
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return rcode, message
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@staticmethod
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def check_start_time(start_time, block_height):
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"""
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Checks if the provided ``start_time`` is correct.
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Start times must be ahead the current best chain tip.
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Args:
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start_time (:obj:`int`): the block height at which the tower is requested to start watching for breaches.
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block_height (:obj:`int`): the chain height.
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Returns:
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:obj:`tuple`: A tuple (return code, message) as follows:
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- ``(0, None)`` if the ``start_time`` is correct.
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- ``!= (0, None)`` otherwise.
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The possible return errors are: ``APPOINTMENT_EMPTY_FIELD``, ``APPOINTMENT_WRONG_FIELD_TYPE``, and
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``APPOINTMENT_FIELD_TOO_SMALL``.
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"""
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message = None
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rcode = 0
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# TODO: What's too close to the current height is not properly defined. Right now any appointment that is in the
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# future will be accepted (even if it's only one block away).
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t = type(start_time)
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if start_time is None:
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rcode = errors.APPOINTMENT_EMPTY_FIELD
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message = "empty start_time received"
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elif t != int:
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rcode = errors.APPOINTMENT_WRONG_FIELD_TYPE
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message = "wrong start_time data type ({})".format(t)
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elif start_time <= block_height:
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rcode = errors.APPOINTMENT_FIELD_TOO_SMALL
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if start_time < block_height:
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message = "start_time is in the past"
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else:
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message = (
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"start_time is too close to current height. "
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"Accepted times are: [current_height+1, current_height+6]"
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)
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elif start_time > block_height + 6:
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rcode = errors.APPOINTMENT_FIELD_TOO_BIG
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message = "start_time is too far in the future. Accepted start times are up to 6 blocks in the future"
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if message is not None:
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logger.error(message)
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return rcode, message
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@staticmethod
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def check_end_time(end_time, start_time, block_height):
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"""
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Checks if the provided ``end_time`` is correct.
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End times must be ahead both the ``start_time`` and the current best chain tip.
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Args:
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end_time (:obj:`int`): the block height at which the tower is requested to stop watching for breaches.
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start_time (:obj:`int`): the block height at which the tower is requested to start watching for breaches.
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block_height (:obj:`int`): the chain height.
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Returns:
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:obj:`tuple`: A tuple (return code, message) as follows:
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- ``(0, None)`` if the ``end_time`` is correct.
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- ``!= (0, None)`` otherwise.
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The possible return errors are: ``APPOINTMENT_EMPTY_FIELD``, ``APPOINTMENT_WRONG_FIELD_TYPE``, and
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``APPOINTMENT_FIELD_TOO_SMALL``.
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"""
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message = None
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rcode = 0
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# TODO: What's too close to the current height is not properly defined. Right now any appointment that ends in
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# the future will be accepted (even if it's only one block away).
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t = type(end_time)
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if end_time is None:
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rcode = errors.APPOINTMENT_EMPTY_FIELD
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message = "empty end_time received"
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elif t != int:
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rcode = errors.APPOINTMENT_WRONG_FIELD_TYPE
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message = "wrong end_time data type ({})".format(t)
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elif end_time > block_height + BLOCKS_IN_A_MONTH: # 4320 = roughly a month in blocks
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rcode = errors.APPOINTMENT_FIELD_TOO_BIG
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message = "end_time should be within the next month (<= current_height + 4320)"
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elif start_time >= end_time:
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rcode = errors.APPOINTMENT_FIELD_TOO_SMALL
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if start_time > end_time:
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message = "end_time is smaller than start_time"
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else:
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message = "end_time is equal to start_time"
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elif block_height >= end_time:
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rcode = errors.APPOINTMENT_FIELD_TOO_SMALL
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if block_height > end_time:
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message = "end_time is in the past"
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else:
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message = "end_time is too close to current height"
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if message is not None:
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logger.error(message)
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return rcode, message
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def check_to_self_delay(self, to_self_delay):
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"""
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Checks if the provided ``to_self_delay`` is correct.
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To self delays must be greater or equal to ``MIN_TO_SELF_DELAY``.
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Args:
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to_self_delay (:obj:`int`): The ``to_self_delay`` encoded in the ``csv`` of the ``htlc`` that this
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appointment is covering.
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Returns:
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:obj:`tuple`: A tuple (return code, message) as follows:
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- ``(0, None)`` if the ``to_self_delay`` is correct.
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- ``!= (0, None)`` otherwise.
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The possible return errors are: ``APPOINTMENT_EMPTY_FIELD``, ``APPOINTMENT_WRONG_FIELD_TYPE``, and
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``APPOINTMENT_FIELD_TOO_SMALL``.
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"""
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message = None
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rcode = 0
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t = type(to_self_delay)
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if to_self_delay is None:
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rcode = errors.APPOINTMENT_EMPTY_FIELD
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message = "empty to_self_delay received"
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elif t != int:
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rcode = errors.APPOINTMENT_WRONG_FIELD_TYPE
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message = "wrong to_self_delay data type ({})".format(t)
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elif to_self_delay > pow(2, 32):
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rcode = errors.APPOINTMENT_FIELD_TOO_BIG
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message = "to_self_delay must fit the transaction nLockTime field ({} > {})".format(
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to_self_delay, pow(2, 32)
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)
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elif to_self_delay < self.config.get("MIN_TO_SELF_DELAY"):
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rcode = errors.APPOINTMENT_FIELD_TOO_SMALL
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message = "to_self_delay too small. The to_self_delay should be at least {} (current: {})".format(
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self.config.get("MIN_TO_SELF_DELAY"), to_self_delay
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)
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if message is not None:
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logger.error(message)
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return rcode, message
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# ToDo: #6-define-checks-encrypted-blob
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@staticmethod
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def check_blob(encrypted_blob):
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"""
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Checks if the provided ``encrypted_blob`` may be correct.
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Args:
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encrypted_blob (:obj:`str`): the encrypted blob to be checked (hex encoded).
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Returns:
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:obj:`tuple`: A tuple (return code, message) as follows:
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- ``(0, None)`` if the ``encrypted_blob`` is correct.
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- ``!= (0, None)`` otherwise.
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The possible return errors are: ``APPOINTMENT_EMPTY_FIELD``, ``APPOINTMENT_WRONG_FIELD_TYPE``, and
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``APPOINTMENT_WRONG_FIELD_FORMAT``.
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"""
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message = None
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rcode = 0
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t = type(encrypted_blob)
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if encrypted_blob is None:
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rcode = errors.APPOINTMENT_EMPTY_FIELD
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message = "empty encrypted_blob received"
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elif t != str:
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rcode = errors.APPOINTMENT_WRONG_FIELD_TYPE
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message = "wrong encrypted_blob data type ({})".format(t)
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elif len(encrypted_blob) > ENCRYPTED_BLOB_MAX_SIZE_HEX:
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rcode = errors.APPOINTMENT_FIELD_TOO_BIG
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message = "encrypted_blob has to be 2Kib at most (current {})".format(len(encrypted_blob) // 2)
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elif re.search(r"^[0-9A-Fa-f]+$", encrypted_blob) is None:
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rcode = errors.APPOINTMENT_WRONG_FIELD_FORMAT
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message = "wrong encrypted_blob format ({})".format(encrypted_blob)
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if message is not None:
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logger.error(message)
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return rcode, message
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@staticmethod
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# Verifies that the appointment signature is a valid signature with public key
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def check_appointment_signature(appointment_data, signature, pk):
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"""
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Checks if the provided user signature is correct.
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Args:
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appointment_data (:obj:`dict`): the appointment that was signed by the user.
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signature (:obj:`str`): the user's signature (hex encoded).
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pk (:obj:`str`): the user's public key (hex encoded).
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Returns:
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:obj:`tuple`: A tuple (return code, message) as follows:
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- ``(0, None)`` if the ``signature`` is correct.
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- ``!= (0, None)`` otherwise.
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The possible return errors are: ``APPOINTMENT_EMPTY_FIELD``, ``APPOINTMENT_WRONG_FIELD_TYPE``, and
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``APPOINTMENT_WRONG_FIELD_FORMAT``.
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"""
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message = None
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rcode = 0
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if signature is None:
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rcode = errors.APPOINTMENT_EMPTY_FIELD
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message = "empty signature received"
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elif pk is None:
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rcode = errors.APPOINTMENT_EMPTY_FIELD
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message = "empty public key received"
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elif re.match(r"^[0-9A-Fa-f]{66}$", pk) is None:
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rcode = errors.APPOINTMENT_WRONG_FIELD
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message = "public key must be a hex encoded 33-byte long value"
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else:
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appointment = Appointment.from_dict(appointment_data)
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rpk = Cryptographer.recover_pk(appointment.serialize(), signature)
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pk = PublicKey(unhexlify(pk))
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valid_sig = Cryptographer.verify_rpk(pk, rpk)
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if not valid_sig:
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rcode = errors.APPOINTMENT_INVALID_SIGNATURE
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message = "invalid signature"
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return rcode, message
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