cti-python-stix2/stix2/base.py

106 lines
3.3 KiB
Python

"""Base class for type definitions in the stix2 library."""
import collections
import datetime as dt
import json
from .exceptions import ExtraFieldsError, ImmutableError, InvalidValueError, \
MissingFieldsError
from .utils import format_datetime, get_timestamp, NOW
__all__ = ['STIXJSONEncoder', '_STIXBase']
DEFAULT_ERROR = "{type} must have {field}='{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))
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 ExtraFieldsError(cls, extra_kwargs)
# Detect any missing required fields
required_fields = get_required_properties(cls._properties)
missing_kwargs = set(required_fields) - set(kwargs)
if missing_kwargs:
raise MissingFieldsError(cls, missing_kwargs)
for prop_name, prop_metadata in cls._properties.items():
self._check_property(prop_name, prop_metadata, kwargs)
self._inner = kwargs
if self.granular_markings:
for m in self.granular_markings:
# TODO: check selectors
pass
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]))
class Observable(_STIXBase):
pass