232 lines
9.0 KiB
Python
232 lines
9.0 KiB
Python
"""Base class for type definitions in the stix2 library."""
|
|
|
|
import collections
|
|
import copy
|
|
import datetime as dt
|
|
import json
|
|
|
|
from .exceptions import (AtLeastOnePropertyError, DependentPropertiesError, ExtraPropertiesError, ImmutableError,
|
|
InvalidObjRefError, InvalidValueError, MissingPropertiesError, MutuallyExclusivePropertiesError,
|
|
RevokeError, UnmodifiablePropertyError)
|
|
from .utils import NOW, format_datetime, get_timestamp, parse_into_datetime
|
|
|
|
__all__ = ['STIXJSONEncoder', '_STIXBase']
|
|
|
|
DEFAULT_ERROR = "{type} must have {property}='{expected}'."
|
|
|
|
|
|
class STIXJSONEncoder(json.JSONEncoder):
|
|
|
|
def default(self, obj):
|
|
if isinstance(obj, (dt.date, dt.datetime)):
|
|
return format_datetime(obj)
|
|
elif isinstance(obj, _STIXBase):
|
|
return dict(obj)
|
|
else:
|
|
return super(STIXJSONEncoder, self).default(obj)
|
|
|
|
|
|
def get_required_properties(properties):
|
|
return (k for k, v in properties.items() if v.required)
|
|
|
|
|
|
class _STIXBase(collections.Mapping):
|
|
"""Base class for STIX object types"""
|
|
|
|
def _check_property(self, prop_name, prop, kwargs):
|
|
if prop_name not in kwargs:
|
|
if hasattr(prop, 'default'):
|
|
value = prop.default()
|
|
if value == NOW:
|
|
value = self.__now
|
|
kwargs[prop_name] = value
|
|
|
|
if prop_name in kwargs:
|
|
try:
|
|
kwargs[prop_name] = prop.clean(kwargs[prop_name])
|
|
except ValueError as exc:
|
|
raise InvalidValueError(self.__class__, prop_name, reason=str(exc))
|
|
|
|
# interproperty constraint methods
|
|
|
|
def _check_mutually_exclusive_properties(self, list_of_properties, at_least_one=True):
|
|
current_properties = self.properties_populated()
|
|
count = len(set(list_of_properties).intersection(current_properties))
|
|
# at_least_one allows for xor to be checked
|
|
if count > 1 or (at_least_one and count == 0):
|
|
raise MutuallyExclusivePropertiesError(self.__class__, list_of_properties)
|
|
|
|
def _check_at_least_one_property(self, list_of_properties=None):
|
|
if not list_of_properties:
|
|
list_of_properties = sorted(list(self.__class__._properties.keys()))
|
|
if "type" in list_of_properties:
|
|
list_of_properties.remove("type")
|
|
current_properties = self.properties_populated()
|
|
list_of_properties_populated = set(list_of_properties).intersection(current_properties)
|
|
if list_of_properties and (not list_of_properties_populated or list_of_properties_populated == set(["extensions"])):
|
|
raise AtLeastOnePropertyError(self.__class__, list_of_properties)
|
|
|
|
def _check_properties_dependency(self, list_of_properties, list_of_dependent_properties, values=[]):
|
|
failed_dependency_pairs = []
|
|
current_properties = self.properties_populated()
|
|
for p in list_of_properties:
|
|
v = values.pop() if values else None
|
|
for dp in list_of_dependent_properties:
|
|
if dp in current_properties and (p not in current_properties or (v and not current_properties(p) == v)):
|
|
failed_dependency_pairs.append((p, dp))
|
|
if failed_dependency_pairs:
|
|
raise DependentPropertiesError(self.__class__, failed_dependency_pairs)
|
|
|
|
def _check_object_constraints(self):
|
|
if self.granular_markings:
|
|
for m in self.granular_markings:
|
|
# TODO: check selectors
|
|
pass
|
|
|
|
def __init__(self, **kwargs):
|
|
cls = self.__class__
|
|
|
|
# Use the same timestamp for any auto-generated datetimes
|
|
self.__now = get_timestamp()
|
|
|
|
# Detect any keyword arguments not allowed for a specific type
|
|
extra_kwargs = list(set(kwargs) - set(cls._properties))
|
|
if extra_kwargs:
|
|
raise ExtraPropertiesError(cls, extra_kwargs)
|
|
|
|
# Remove any keyword arguments whose value is None
|
|
setting_kwargs = {}
|
|
for prop_name, prop_value in kwargs.items():
|
|
if prop_value:
|
|
setting_kwargs[prop_name] = prop_value
|
|
|
|
# Detect any missing required properties
|
|
required_properties = get_required_properties(cls._properties)
|
|
missing_kwargs = set(required_properties) - set(setting_kwargs)
|
|
if missing_kwargs:
|
|
raise MissingPropertiesError(cls, missing_kwargs)
|
|
|
|
for prop_name, prop_metadata in cls._properties.items():
|
|
self._check_property(prop_name, prop_metadata, setting_kwargs)
|
|
|
|
self._inner = setting_kwargs
|
|
|
|
self._check_object_constraints()
|
|
|
|
def __getitem__(self, key):
|
|
return self._inner[key]
|
|
|
|
def __iter__(self):
|
|
return iter(self._inner)
|
|
|
|
def __len__(self):
|
|
return len(self._inner)
|
|
|
|
# Handle attribute access just like key access
|
|
def __getattr__(self, name):
|
|
return self.get(name)
|
|
|
|
def __setattr__(self, name, value):
|
|
if name != '_inner' and not name.startswith("_STIXBase__"):
|
|
raise ImmutableError
|
|
super(_STIXBase, self).__setattr__(name, value)
|
|
|
|
def __str__(self):
|
|
# TODO: put keys in specific order. Probably need custom JSON encoder.
|
|
return json.dumps(self, indent=4, sort_keys=True, cls=STIXJSONEncoder,
|
|
separators=(",", ": ")) # Don't include spaces after commas.
|
|
|
|
def __repr__(self):
|
|
props = [(k, self[k]) for k in sorted(self._properties) if self.get(k)]
|
|
return "{0}({1})".format(self.__class__.__name__,
|
|
", ".join(["{0!s}={1!r}".format(k, v) for k, v in props]))
|
|
|
|
def __deepcopy__(self, memo):
|
|
# Assumption: we can ignore the memo argument, because no object will ever contain the same sub-object multiple times.
|
|
new_inner = copy.deepcopy(self._inner, memo)
|
|
cls = type(self)
|
|
return cls(**new_inner)
|
|
|
|
def properties_populated(self):
|
|
return list(self._inner.keys())
|
|
|
|
# Versioning API
|
|
|
|
def new_version(self, **kwargs):
|
|
unchangable_properties = []
|
|
if self.revoked:
|
|
raise RevokeError("new_version")
|
|
new_obj_inner = copy.deepcopy(self._inner)
|
|
properties_to_change = kwargs.keys()
|
|
for prop in ["created", "created_by_ref", "id", "type"]:
|
|
if prop in properties_to_change:
|
|
unchangable_properties.append(prop)
|
|
if unchangable_properties:
|
|
raise UnmodifiablePropertyError(unchangable_properties)
|
|
cls = type(self)
|
|
if 'modified' not in kwargs:
|
|
kwargs['modified'] = get_timestamp()
|
|
else:
|
|
new_modified_property = parse_into_datetime(kwargs['modified'])
|
|
if new_modified_property < self.modified:
|
|
raise InvalidValueError(cls, 'modified', "The new modified datetime cannot be before the current modified datatime.")
|
|
new_obj_inner.update(kwargs)
|
|
return cls(**new_obj_inner)
|
|
|
|
def revoke(self):
|
|
if self.revoked:
|
|
raise RevokeError("revoke")
|
|
return self.new_version(revoked=True)
|
|
|
|
|
|
class _Observable(_STIXBase):
|
|
|
|
def __init__(self, **kwargs):
|
|
# the constructor might be called independently of an observed data object
|
|
if '_valid_refs' in kwargs:
|
|
self._STIXBase__valid_refs = kwargs.pop('_valid_refs')
|
|
else:
|
|
self._STIXBase__valid_refs = []
|
|
super(_Observable, self).__init__(**kwargs)
|
|
|
|
def _check_ref(self, ref, prop, prop_name):
|
|
if ref not in self._STIXBase__valid_refs:
|
|
raise InvalidObjRefError(self.__class__, prop_name, "'%s' is not a valid object in local scope" % ref)
|
|
|
|
try:
|
|
allowed_types = prop.contained.valid_types
|
|
except AttributeError:
|
|
try:
|
|
allowed_types = prop.valid_types
|
|
except AttributeError:
|
|
raise ValueError("'%s' is named like an object reference property but "
|
|
"is not an ObjectReferenceProperty or a ListProperty "
|
|
"containing ObjectReferenceProperty." % prop_name)
|
|
|
|
if allowed_types:
|
|
try:
|
|
ref_type = self._STIXBase__valid_refs[ref]
|
|
except TypeError:
|
|
raise ValueError("'%s' must be created with _valid_refs as a dict, not a list." % self.__class__.__name__)
|
|
if ref_type not in allowed_types:
|
|
raise InvalidObjRefError(self.__class__, prop_name, "object reference '%s' is of an invalid type '%s'" % (ref, ref_type))
|
|
|
|
def _check_property(self, prop_name, prop, kwargs):
|
|
super(_Observable, self)._check_property(prop_name, prop, kwargs)
|
|
if prop_name not in kwargs:
|
|
return
|
|
|
|
if prop_name.endswith('_ref'):
|
|
ref = kwargs[prop_name]
|
|
self._check_ref(ref, prop, prop_name)
|
|
elif prop_name.endswith('_refs'):
|
|
for ref in kwargs[prop_name]:
|
|
self._check_ref(ref, prop, prop_name)
|
|
|
|
|
|
class _Extension(_STIXBase):
|
|
|
|
def _check_object_constraints(self):
|
|
super(_Extension, self)._check_object_constraints()
|
|
self._check_at_least_one_property()
|