Remove ReplayedMetadataError

ReplayedMetadataError is a subset of
BadVersionNumberError and in a discussion with
Jussi we realized that ReplayedMetadataError can
be replaced by BadVersionNumberError with a
good message.

Signed-off-by: Martin Vrachev <mvrachev@vmware.com>

tests/test_trusted_metadata_set.py

@@ -245,7 +245,7 @@ def test_update_root_new_root_fail_threshold_verification(self) -> None:
             self.trusted_set.update_root(root.to_bytes())
 
     def test_update_root_new_root_ver_same_as_trusted_root_ver(self) -> None:
-        with self.assertRaises(exceptions.ReplayedMetadataError):
+        with self.assertRaises(exceptions.BadVersionNumberError):
             self.trusted_set.update_root(self.metadata[Root.type])
 
     def test_root_expired_final_root(self) -> None:
@@ -266,7 +266,7 @@ def version_modifier(timestamp: Timestamp) -> None:
 
         timestamp = self.modify_metadata(Timestamp.type, version_modifier)
         self.trusted_set.update_timestamp(timestamp)
-        with self.assertRaises(exceptions.ReplayedMetadataError):
+        with self.assertRaises(exceptions.BadVersionNumberError):
             self.trusted_set.update_timestamp(self.metadata[Timestamp.type])
 
     def test_update_timestamp_snapshot_ver_below_current(self) -> None:
@@ -278,7 +278,7 @@ def bump_snapshot_version(timestamp: Timestamp) -> None:
         self.trusted_set.update_timestamp(timestamp)
 
         # newtimestamp.meta.version < trusted_timestamp.meta.version
-        with self.assertRaises(exceptions.ReplayedMetadataError):
+        with self.assertRaises(exceptions.BadVersionNumberError):
             self.trusted_set.update_timestamp(self.metadata[Timestamp.type])
 
     def test_update_timestamp_expired(self) -> None:

tests/test_updater_top_level_update.py

@@ -19,7 +19,6 @@
 from tuf.api.exceptions import (
     BadVersionNumberError,
     ExpiredMetadataError,
-    ReplayedMetadataError,
     RepositoryError,
     UnsignedMetadataError,
 )
@@ -267,7 +266,7 @@ def test_new_root_same_version(self) -> None:
         # Check for a rollback_attack
         # Repository serves a root file with the same version as previous
         self.sim.publish_root()
-        with self.assertRaises(ReplayedMetadataError):
+        with self.assertRaises(BadVersionNumberError):
             self._run_refresh()
 
         # The update failed, latest root version is v1
@@ -278,7 +277,7 @@ def test_new_root_nonconsecutive_version(self) -> None:
         # Repository serves non-consecutive root version
         self.sim.root.version += 2
         self.sim.publish_root()
-        with self.assertRaises(ReplayedMetadataError):
+        with self.assertRaises(BadVersionNumberError):
             self._run_refresh()
 
         # The update failed, latest root version is v1
@@ -313,7 +312,7 @@ def test_new_timestamp_version_rollback(self) -> None:
         self._run_refresh()
 
         self.sim.timestamp.version = 1
-        with self.assertRaises(ReplayedMetadataError):
+        with self.assertRaises(BadVersionNumberError):
             self._run_refresh()
 
         self._assert_version_equals(Timestamp.type, 2)
@@ -328,7 +327,7 @@ def test_new_timestamp_snapshot_rollback(self) -> None:
         self.sim.timestamp.snapshot_meta.version = 1
         self.sim.timestamp.version += 1  # timestamp v3
 
-        with self.assertRaises(ReplayedMetadataError):
+        with self.assertRaises(BadVersionNumberError):
             self._run_refresh()
 
         self._assert_version_equals(Timestamp.type, 2)
@@ -423,7 +422,7 @@ def test_new_snapshot_version_rollback(self) -> None:
         self.sim.snapshot.version = 1
         self.sim.update_timestamp()
 
-        with self.assertRaises(ReplayedMetadataError):
+        with self.assertRaises(BadVersionNumberError):
             self._run_refresh()
 
         self._assert_version_equals(Snapshot.type, 2)

tuf/api/exceptions.py

@@ -39,32 +39,6 @@ class ExpiredMetadataError(RepositoryError):
     """Indicate that a TUF Metadata file has expired."""
 
 
-class ReplayedMetadataError(RepositoryError):
-    """Indicate that some metadata has been replayed to the client.
-
-    Args:
-        metadata_role: Name of the role that has been replayed
-        downloaded_version: The replayed downloaded version of the metadata
-        current_version: The current locally available version.
-    """
-
-    def __init__(
-        self, metadata_role: str, downloaded_version: int, current_version: int
-    ) -> None:
-        super().__init__()
-
-        self.metadata_role = metadata_role
-        self.downloaded_version = downloaded_version
-        self.current_version = current_version
-
-    def __str__(self) -> str:
-        return (
-            f"Downloaded {self.metadata_role} is older ("
-            f"{self.downloaded_version}) than the version currently installed"
-            f"({self.current_version})"
-        )
-
-
 #### Download Errors ####
 
 

tuf/ngclient/_internal/trusted_metadata_set.py

@@ -175,10 +175,9 @@ def update_root(self, data: bytes) -> Metadata[Root]:
         self.root.verify_delegate(Root.type, new_root)
 
         if new_root.signed.version != self.root.signed.version + 1:
-            raise exceptions.ReplayedMetadataError(
-                Root.type,
-                new_root.signed.version,
-                self.root.signed.version,
+            raise exceptions.BadVersionNumberError(
+                f"Expected root version {self.root.signed.version + 1}"
+                f" instead got version {new_root.signed.version}"
             )
 
         # Verify that new root is signed by itself
@@ -236,20 +235,17 @@ def update_timestamp(self, data: bytes) -> Metadata[Timestamp]:
         if self.timestamp is not None:
             # Prevent rolling back timestamp version
             if new_timestamp.signed.version < self.timestamp.signed.version:
-                raise exceptions.ReplayedMetadataError(
-                    Timestamp.type,
-                    new_timestamp.signed.version,
-                    self.timestamp.signed.version,
+                raise exceptions.BadVersionNumberError(
+                    f"New timestamp version {new_timestamp.signed.version} must"
+                    f" be >= {self.timestamp.signed.version}"
                 )
             # Prevent rolling back snapshot version
-            if (
-                new_timestamp.signed.snapshot_meta.version
-                < self.timestamp.signed.snapshot_meta.version
-            ):
-                raise exceptions.ReplayedMetadataError(
-                    Snapshot.type,
-                    new_timestamp.signed.snapshot_meta.version,
-                    self.timestamp.signed.snapshot_meta.version,
+            snapshot_meta = self.timestamp.signed.snapshot_meta
+            new_snapshot_meta = new_timestamp.signed.snapshot_meta
+            if new_snapshot_meta.version < snapshot_meta.version:
+                raise exceptions.BadVersionNumberError(
+                    f"New snapshot version must be >= {snapshot_meta.version}"
+                    f", got version {new_snapshot_meta.version}"
                 )
 
         # expiry not checked to allow old timestamp to be used for rollback