Files
python-teos/teos/inspector.py
Sergi Delgado Segura 83b3913cb5 Adds basic authentication logic.
+ Users need to be registered in order to send appointments (free registration for now)
+ The tower gives them a number of appointments to work with
+ Non-registered users and users with no enough appoitnemnts slots return the same error (to avoid proving)

- Authentication does not cover get_* requests yet
- No tests
- No docs
2020-03-25 17:13:35 +01:00

335 lines
12 KiB
Python

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