Check that hash exists before getting its value. Fixes #211

Author: gtback

cybox/common/hashes.py

@@ -133,47 +133,47 @@ def _fix_value(self, value):
 
     @property
     def md5(self):
-        return self._hash_lookup(Hash.TYPE_MD5).value
+        return self._get_hash_value(Hash.TYPE_MD5)
 
     @md5.setter
     def md5(self, value):
         self._set_hash(Hash.TYPE_MD5, value)
 
     @property
     def sha1(self):
-        return self._hash_lookup(Hash.TYPE_SHA1).value
+        return self._get_hash_value(Hash.TYPE_SHA1)
 
     @sha1.setter
     def sha1(self, value):
         self._set_hash(Hash.TYPE_SHA1, value)
 
     @property
     def sha224(self):
-        return self._hash_lookup(Hash.TYPE_SHA224).value
+        return self._get_hash_value(Hash.TYPE_SHA224)
 
     @sha224.setter
     def sha224(self, value):
         self._set_hash(Hash.TYPE_SHA224, value)
 
     @property
     def sha256(self):
-        return self._hash_lookup(Hash.TYPE_SHA256).value
+        return self._get_hash_value(Hash.TYPE_SHA256)
 
     @sha256.setter
     def sha256(self, value):
         self._set_hash(Hash.TYPE_SHA256, value)
 
     @property
     def sha384(self):
-        return self._hash_lookup(Hash.TYPE_SHA384).value
+        return self._get_hash_value(Hash.TYPE_SHA384)
 
     @sha384.setter
     def sha384(self, value):
         self._set_hash(Hash.TYPE_SHA384, value)
 
     @property
     def sha512(self):
-        return self._hash_lookup(Hash.TYPE_SHA512).value
+        return self._get_hash_value(Hash.TYPE_SHA512)
 
     @sha512.setter
     def sha512(self, value):
@@ -191,3 +191,10 @@ def _set_hash(self, type_, value):
             h.simple_hash_value = value
         else:
             self.append(Hash(value, type_))
+
+    def _get_hash_value(self, type_):
+        """Return the hash with a given type_, or None"""
+        h = self._hash_lookup(type_)
+        if h:
+            return h.value
+        return None

cybox/test/common/hash_test.py

@@ -154,6 +154,15 @@ def test_round_trip(self):
         hashlist_list2 = HashList.list_from_object(hashlist_obj)
         self.assertEqual(hashlist_list, hashlist_list2)
 
+    def test_hash_lookup(self):
+        h = HashList()
+        self.assertEqual(None, h.md5)
+        self.assertEqual(None, h.sha1)
+        self.assertEqual(None, h.sha224)
+        self.assertEqual(None, h.sha256)
+        self.assertEqual(None, h.sha384)
+        self.assertEqual(None, h.sha512)
+
     def test_namespace_count(self):
         h = HashList()
         h.append(EMPTY_MD5)