Allow attribute and key-based access. Make immutable.

stix2/__init__.py

@@ -1,3 +1,4 @@
+import collections
 from datetime import datetime
 import json
 import uuid
@@ -12,58 +13,76 @@ def format_datetime(dt):
     # 4. Add "Z"
     return dt.astimezone(pytz.utc).isoformat()[:-6] + "Z"
 
-# REQUIRED (all):
-# - type
-# - id
-# - created
-# - modified
 
-
-class Indicator(object):
-    # REQUIRED (Indicator):
-    # - type
-    # - labels
-    # - pattern
-    # - valid_from
-    required = ['']
+class Indicator(collections.Mapping):
 
     def __getitem__(self, key):
-        return getattr(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':
+            raise ValueError("Cannot modify properties after creation.")
+        super(Indicator, self).__setattr__(name, value)
 
     def __init__(self, type='indicator', id=None, created=None, modified=None,
                  labels=None, pattern=None, valid_from=None):
-        now = datetime.now(tz=pytz.UTC)
+        # TODO:
+        # - created_by_ref
+        # - revoked
+        # - external_references
+        # - object_marking_refs
+        # - granular_markings
+
+        # - name
+        # - description
+        # - valid_until
+        # - kill_chain_phases
+
+        if not created or not modified or not valid_from:
+            now = datetime.now(tz=pytz.UTC)
 
         if type != 'indicator':
             raise ValueError("Indicators must have type='indicator'.")
-        self.type = type
 
         if not id:
             id = 'indicator--' + str(uuid.uuid4())
         if not id.startswith('indicator--'):
             raise ValueError("Indicator id values must begin with 'indicator--'.")
-        self.id = id
-
-        self.created = created or now
-        self.modified = modified or now
 
         if not labels:
             raise ValueError("Missing required field for Indicator: 'labels'.")
-        self.labels = labels
 
         if not pattern:
             raise ValueError("Missing required field for Indicator: 'pattern'.")
-        self.pattern = pattern
-        self.valid_from = valid_from or now
+
+        self._inner = {
+            'type': type,
+            'id': id or now,
+            'created': created or now,
+            'modified': modified or now,
+            'labels': labels,
+            'pattern': pattern,
+            'valid_from': valid_from or now,
+        }
 
     def __str__(self):
         # TODO: put keys in specific order. Probably need custom JSON encoder.
         return json.dumps({
-            'type': self.type,
-            'id': self.id,
-            'created': format_datetime(self.created),
-            'modified': format_datetime(self.modified),
-            'labels': self.labels,
-            'pattern': self.pattern,
-            'valid_from': format_datetime(self.valid_from),
+            'type': self['type'],
+            'id': self['id'],
+            'created': format_datetime(self['created']),
+            'modified': format_datetime(self['modified']),
+            'labels': self['labels'],
+            'pattern': self['pattern'],
+            'valid_from': format_datetime(self['valid_from']),
         }, indent=4, sort_keys=True, separators=(",", ": "))  # Don't include spaces after commas.

stix2/test/test_stix2.py

@@ -102,3 +102,12 @@ def test_indicator_required_field_pattern():
         # Label is checked first, so make sure that is provided
         indicator = stix2.Indicator(labels=['malicious-activity'])
     assert "Missing required field for Indicator: 'pattern'." in str(excinfo)
+
+
+def test_cannot_assign_to_attributes():
+    indicator = stix2.Indicator(**KWARGS)
+
+    with pytest.raises(ValueError) as excinfo:
+        indicator.valid_from = datetime.datetime.now()
+
+    assert "Cannot modify properties after creation." in str(excinfo)