New metadata API: add support for ADR 0008

tests/test_api.py

@@ -330,6 +330,37 @@ def test_metadata_targets(self):
         # Verify that data is updated
         self.assertEqual(targets.signed.targets[filename], fileinfo)
 
+    def setup_dict_with_unrecognized_field(self, file_path, field, value):
+        json_dict = {}
+        with open(file_path) as f:
+            json_dict = json.loads(f.read())
+        # We are changing the json dict without changing the signature.
+        # This could be a problem if we want to do verification on this dict.
+        json_dict["signed"][field] = value
+        return json_dict
+
+    def test_support_for_unrecognized_fields(self):
+        for metadata in ["root", "timestamp", "snapshot", "targets"]:
+            path = os.path.join(self.repo_dir, "metadata", metadata + ".json")
+            dict1 = self.setup_dict_with_unrecognized_field(path, "f", "b")
+            # Test that the metadata classes store unrecognized fields when
+            # initializing and passes them when casting the instance to a dict.
+
+            temp_copy = copy.deepcopy(dict1)
+            metadata_obj = Metadata.from_dict(temp_copy)
+
+            self.assertEqual(dict1["signed"], metadata_obj.signed.to_dict())
+
+            # Test that two instances of the same class could have different
+            # unrecognized fields.
+            dict2 = self.setup_dict_with_unrecognized_field(path, "f2", "b2")
+            temp_copy2 = copy.deepcopy(dict2)
+            metadata_obj2 = Metadata.from_dict(temp_copy2)
+            self.assertNotEqual(
+                metadata_obj.signed.to_dict(), metadata_obj2.signed.to_dict()
+            )
+
+
 # Run unit test.
 if __name__ == '__main__':
     utils.configure_test_logging(sys.argv)

tuf/api/metadata.py

@@ -300,14 +300,20 @@ class Signed:
         spec_version: The TUF specification version number (semver) the
             metadata format adheres to.
         expires: The metadata expiration datetime object.
+        unrecognized_fields: Dictionary of all unrecognized fields.
 
     """
 
     # NOTE: Signed is a stupid name, because this might not be signed yet, but
     # we keep it to match spec terminology (I often refer to this as "payload",
     # or "inner metadata")
     def __init__(
-        self, _type: str, version: int, spec_version: str, expires: datetime
+        self,
+        _type: str,
+        version: int,
+        spec_version: str,
+        expires: datetime,
+        unrecognized_fields: Optional[Mapping[str, Any]] = None,
     ) -> None:
 
         self._type = _type
@@ -318,6 +324,7 @@ def __init__(
         if version < 0:
             raise ValueError(f"version must be >= 0, got {version}")
         self.version = version
+        self.unrecognized_fields = unrecognized_fields or {}
 
     @staticmethod
     def _common_fields_from_dict(signed_dict: Mapping[str, Any]) -> list:
@@ -349,6 +356,7 @@ def _common_fields_to_dict(self) -> Dict[str, Any]:
             "version": self.version,
             "spec_version": self.spec_version,
             "expires": self.expires.isoformat() + "Z",
+            **self.unrecognized_fields,
         }
 
     # Modification.
@@ -409,8 +417,11 @@ def __init__(
         consistent_snapshot: bool,
         keys: Mapping[str, Any],
         roles: Mapping[str, Any],
+        unrecognized_fields: Optional[Mapping[str, Any]] = None,
     ) -> None:
-        super().__init__(_type, version, spec_version, expires)
+        super().__init__(
+            _type, version, spec_version, expires, unrecognized_fields
+        )
         # TODO: Add classes for keys and roles
         self.consistent_snapshot = consistent_snapshot
         self.keys = keys
@@ -423,7 +434,8 @@ def from_dict(cls, root_dict: Mapping[str, Any]) -> "Root":
         consistent_snapshot = root_dict.pop("consistent_snapshot")
         keys = root_dict.pop("keys")
         roles = root_dict.pop("roles")
-        return cls(*common_args, consistent_snapshot, keys, roles)
+        # All fields left in the root_dict are unrecognized.
+        return cls(*common_args, consistent_snapshot, keys, roles, root_dict)
 
     def to_dict(self) -> Dict[str, Any]:
         """Returns the dict representation of self. """
@@ -485,8 +497,11 @@ def __init__(
         spec_version: str,
         expires: datetime,
         meta: Mapping[str, Any],
+        unrecognized_fields: Optional[Mapping[str, Any]] = None,
     ) -> None:
-        super().__init__(_type, version, spec_version, expires)
+        super().__init__(
+            _type, version, spec_version, expires, unrecognized_fields
+        )
         # TODO: Add class for meta
         self.meta = meta
 
@@ -495,7 +510,8 @@ def from_dict(cls, timestamp_dict: Mapping[str, Any]) -> "Timestamp":
         """Creates Timestamp object from its dict representation. """
         common_args = cls._common_fields_from_dict(timestamp_dict)
         meta = timestamp_dict.pop("meta")
-        return cls(*common_args, meta)
+        # All fields left in the timestamp_dict are unrecognized.
+        return cls(*common_args, meta, timestamp_dict)
 
     def to_dict(self) -> Dict[str, Any]:
         """Returns the dict representation of self. """
@@ -549,8 +565,11 @@ def __init__(
         spec_version: str,
         expires: datetime,
         meta: Mapping[str, Any],
+        unrecognized_fields: Optional[Mapping[str, Any]] = None,
     ) -> None:
-        super().__init__(_type, version, spec_version, expires)
+        super().__init__(
+            _type, version, spec_version, expires, unrecognized_fields
+        )
         # TODO: Add class for meta
         self.meta = meta
 
@@ -559,7 +578,8 @@ def from_dict(cls, snapshot_dict: Mapping[str, Any]) -> "Snapshot":
         """Creates Snapshot object from its dict representation. """
         common_args = cls._common_fields_from_dict(snapshot_dict)
         meta = snapshot_dict.pop("meta")
-        return cls(*common_args, meta)
+        # All fields left in the snapshot_dict are unrecognized.
+        return cls(*common_args, meta, snapshot_dict)
 
     def to_dict(self) -> Dict[str, Any]:
         """Returns the dict representation of self. """
@@ -652,8 +672,11 @@ def __init__(
         expires: datetime,
         targets: Mapping[str, Any],
         delegations: Mapping[str, Any],
+        unrecognized_fields: Optional[Mapping[str, Any]] = None,
     ) -> None:
-        super().__init__(_type, version, spec_version, expires)
+        super().__init__(
+            _type, version, spec_version, expires, unrecognized_fields
+        )
         # TODO: Add class for meta
         self.targets = targets
         self.delegations = delegations
@@ -664,7 +687,8 @@ def from_dict(cls, targets_dict: Mapping[str, Any]) -> "Targets":
         common_args = cls._common_fields_from_dict(targets_dict)
         targets = targets_dict.pop("targets")
         delegations = targets_dict.pop("delegations")
-        return cls(*common_args, targets, delegations)
+        # All fields left in the targets_dict are unrecognized.
+        return cls(*common_args, targets, delegations, targets_dict)
 
     def to_dict(self) -> Dict[str, Any]:
         """Returns the dict representation of self. """