#!/usr/bin/env python3
from abc import ABC, abstractmethod
+import enum
import fnmatch
import logging
import re
-from typing import Any, Callable, List, Optional, Set
+from typing import Any, Callable, List, Optional, Set, Sequence
+from overrides import overrides
+
+# This module is commonly used by others in here and should avoid
+# taking any unnecessary dependencies back on them.
logger = logging.getLogger(__name__)
-ACL_ORDER_ALLOW_DENY = 1
-ACL_ORDER_DENY_ALLOW = 2
+class Order(enum.Enum):
+ """A helper to express the order of evaluation for allows/denies
+ in an Access Control List.
+ """
+
+ UNDEFINED = 0
+ ALLOW_DENY = 1
+ DENY_ALLOW = 2
class SimpleACL(ABC):
"""A simple Access Control List interface."""
- def __init__(
- self,
- *,
- order_to_check_allow_deny: int,
- default_answer: bool
- ):
+ def __init__(self, *, order_to_check_allow_deny: Order, default_answer: bool):
if order_to_check_allow_deny not in (
- ACL_ORDER_ALLOW_DENY, ACL_ORDER_DENY_ALLOW
+ Order.ALLOW_DENY,
+ Order.DENY_ALLOW,
):
raise Exception(
- 'order_to_check_allow_deny must be ACL_ORDER_ALLOW_DENY or ' +
- 'ACL_ORDER_DENY_ALLOW')
+ 'order_to_check_allow_deny must be Order.ALLOW_DENY or '
+ + 'Order.DENY_ALLOW'
+ )
self.order_to_check_allow_deny = order_to_check_allow_deny
self.default_answer = default_answer
def __call__(self, x: Any) -> bool:
"""Returns True if x is allowed, False otherwise."""
logger.debug(f'SimpleACL checking {x}')
- if self.order_to_check_allow_deny == ACL_ORDER_ALLOW_DENY:
+ if self.order_to_check_allow_deny == Order.ALLOW_DENY:
logger.debug('Checking allowed first...')
if self.check_allowed(x):
logger.debug(f'{x} was allowed explicitly.')
if self.check_denied(x):
logger.debug(f'{x} was denied explicitly.')
return False
- elif self.order_to_check_allow_deny == ACL_ORDER_DENY_ALLOW:
+ elif self.order_to_check_allow_deny == Order.DENY_ALLOW:
logger.debug('Checking denied first...')
if self.check_denied(x):
logger.debug(f'{x} was denied explicitly.')
return True
logger.debug(
- f'{x} was not explicitly allowed or denied; ' +
- f'using default answer ({self.default_answer})'
+ f'{x} was not explicitly allowed or denied; '
+ + f'using default answer ({self.default_answer})'
)
return self.default_answer
class SetBasedACL(SimpleACL):
"""An ACL that allows or denies based on membership in a set."""
- def __init__(self,
- *,
- allow_set: Optional[Set[Any]] = None,
- deny_set: Optional[Set[Any]] = None,
- order_to_check_allow_deny: int,
- default_answer: bool) -> None:
+
+ def __init__(
+ self,
+ *,
+ allow_set: Optional[Set[Any]] = None,
+ deny_set: Optional[Set[Any]] = None,
+ order_to_check_allow_deny: Order,
+ default_answer: bool,
+ ) -> None:
super().__init__(
order_to_check_allow_deny=order_to_check_allow_deny,
- default_answer=default_answer
+ default_answer=default_answer,
)
self.allow_set = allow_set
self.deny_set = deny_set
+ @overrides
def check_allowed(self, x: Any) -> bool:
if self.allow_set is None:
return False
return x in self.allow_set
+ @overrides
def check_denied(self, x: Any) -> bool:
if self.deny_set is None:
return False
return x in self.deny_set
+class AllowListACL(SetBasedACL):
+ """Convenience subclass for a list that only allows known items.
+ i.e. a 'allowlist'
+ """
+
+ def __init__(self, *, allow_set: Optional[Set[Any]]) -> None:
+ super().__init__(
+ allow_set=allow_set,
+ order_to_check_allow_deny=Order.ALLOW_DENY,
+ default_answer=False,
+ )
+
+
+class DenyListACL(SetBasedACL):
+ """Convenience subclass for a list that only disallows known items.
+ i.e. a 'blocklist'
+ """
+
+ def __init__(self, *, deny_set: Optional[Set[Any]]) -> None:
+ super().__init__(
+ deny_set=deny_set,
+ order_to_check_allow_deny=Order.ALLOW_DENY,
+ default_answer=True,
+ )
+
+
+class BlockListACL(SetBasedACL):
+ """Convenience subclass for a list that only disallows known items.
+ i.e. a 'blocklist'
+ """
+
+ def __init__(self, *, deny_set: Optional[Set[Any]]) -> None:
+ super().__init__(
+ deny_set=deny_set,
+ order_to_check_allow_deny=Order.ALLOW_DENY,
+ default_answer=True,
+ )
+
+
class PredicateListBasedACL(SimpleACL):
"""An ACL that allows or denies by applying predicates."""
- def __init__(self,
- *,
- allow_predicate_list: List[Callable[[Any], bool]] = None,
- deny_predicate_list: List[Callable[[Any], bool]] = None,
- order_to_check_allow_deny: int,
- default_answer: bool) -> None:
+
+ def __init__(
+ self,
+ *,
+ allow_predicate_list: Sequence[Callable[[Any], bool]] = None,
+ deny_predicate_list: Sequence[Callable[[Any], bool]] = None,
+ order_to_check_allow_deny: Order,
+ default_answer: bool,
+ ) -> None:
super().__init__(
order_to_check_allow_deny=order_to_check_allow_deny,
- default_answer=default_answer
+ default_answer=default_answer,
)
self.allow_predicate_list = allow_predicate_list
self.deny_predicate_list = deny_predicate_list
+ @overrides
def check_allowed(self, x: Any) -> bool:
if self.allow_predicate_list is None:
return False
return any(predicate(x) for predicate in self.allow_predicate_list)
+ @overrides
def check_denied(self, x: Any) -> bool:
if self.deny_predicate_list is None:
return False
class StringWildcardBasedACL(PredicateListBasedACL):
"""An ACL that allows or denies based on string glob (*, ?) patterns."""
- def __init__(self,
- *,
- allowed_patterns: Optional[List[str]] = None,
- denied_patterns: Optional[List[str]] = None,
- order_to_check_allow_deny: int,
- default_answer: bool) -> None:
+
+ def __init__(
+ self,
+ *,
+ allowed_patterns: Optional[List[str]] = None,
+ denied_patterns: Optional[List[str]] = None,
+ order_to_check_allow_deny: Order,
+ default_answer: bool,
+ ) -> None:
allow_predicates = []
if allowed_patterns is not None:
for pattern in allowed_patterns:
class StringREBasedACL(PredicateListBasedACL):
"""An ACL that allows or denies by applying regexps."""
- def __init__(self,
- *,
- allowed_regexs: Optional[List[re.Pattern]] = None,
- denied_regexs: Optional[List[re.Pattern]] = None,
- order_to_check_allow_deny: int,
- default_answer: bool) -> None:
+
+ def __init__(
+ self,
+ *,
+ allowed_regexs: Optional[List[re.Pattern]] = None,
+ denied_regexs: Optional[List[re.Pattern]] = None,
+ order_to_check_allow_deny: Order,
+ default_answer: bool,
+ ) -> None:
allow_predicates = None
if allowed_regexs is not None:
allow_predicates = []
)
-class AnyCompoundACL(object):
+class AnyCompoundACL(SimpleACL):
"""An ACL that allows if any of its subacls allow."""
- def __init__(self, subacls: List[SimpleACL]):
- assert subacls is not None
+
+ def __init__(
+ self,
+ *,
+ subacls: Optional[List[SimpleACL]] = None,
+ order_to_check_allow_deny: Order,
+ default_answer: bool,
+ ) -> None:
+ super().__init__(
+ order_to_check_allow_deny=order_to_check_allow_deny,
+ default_answer=default_answer,
+ )
self.subacls = subacls
- def __call__(self, x: Any):
+ @overrides
+ def check_allowed(self, x: Any) -> bool:
+ if self.subacls is None:
+ return False
return any(acl(x) for acl in self.subacls)
+ @overrides
+ def check_denied(self, x: Any) -> bool:
+ if self.subacls is None:
+ return False
+ return any(not acl(x) for acl in self.subacls)
-class AllCompoundACL(object):
+
+class AllCompoundACL(SimpleACL):
"""An ACL that allows if all of its subacls allow."""
- def __init__(self, subacls: List[SimpleACL]):
- assert subacls is not None
+
+ def __init__(
+ self,
+ *,
+ subacls: Optional[List[SimpleACL]] = None,
+ order_to_check_allow_deny: Order,
+ default_answer: bool,
+ ) -> None:
+ super().__init__(
+ order_to_check_allow_deny=order_to_check_allow_deny,
+ default_answer=default_answer,
+ )
self.subacls = subacls
- def __call__(self, x: Any):
+ @overrides
+ def check_allowed(self, x: Any) -> bool:
+ if self.subacls is None:
+ return False
return all(acl(x) for acl in self.subacls)
+
+ @overrides
+ def check_denied(self, x: Any) -> bool:
+ if self.subacls is None:
+ return False
+ return any(not acl(x) for acl in self.subacls)
projects / python_utils.git / blobdiff