Merge pull request #1446 from MVrachev/snapshot-property

Metadata API: change meta type in Timestamp

Author: Jussi Kukkonen

tests/repository_simulator.py

@@ -100,8 +100,8 @@ def _initialize(self):
         snapshot = Snapshot(1, SPEC_VER, expiry, meta)
         self.md_snapshot = Metadata(snapshot, OrderedDict())
 
-        meta = {"snapshot.json": MetaFile(snapshot.version)}
-        timestamp = Timestamp(1, SPEC_VER, expiry, meta)
+        snapshot_meta = MetaFile(snapshot.version)
+        timestamp = Timestamp(1, SPEC_VER, expiry, snapshot_meta)
         self.md_timestamp = Metadata(timestamp, OrderedDict())
 
         root = Root(1, SPEC_VER, expiry, {}, {}, True)
@@ -175,7 +175,7 @@ def _fetch_metadata(self, role: str, version: Optional[int] = None) -> bytes:
             return md.to_bytes(JSONSerializer())
 
     def update_timestamp(self):
-        self.timestamp.meta["snapshot.json"].version = self.snapshot.version
+        self.timestamp.snapshot_meta.version = self.snapshot.version
 
         self.timestamp.version += 1
 

tests/test_api.py

@@ -350,11 +350,11 @@ def test_metadata_timestamp(self):
         fileinfo = MetaFile(2, 520, hashes)
 
         self.assertNotEqual(
-            timestamp.signed.meta['snapshot.json'].to_dict(), fileinfo.to_dict()
+            timestamp.signed.snapshot_meta.to_dict(), fileinfo.to_dict()
         )
         timestamp.signed.update(fileinfo)
         self.assertEqual(
-            timestamp.signed.meta['snapshot.json'].to_dict(), fileinfo.to_dict()
+            timestamp.signed.snapshot_meta.to_dict(), fileinfo.to_dict()
         )
 
 
@@ -563,7 +563,7 @@ def  test_length_and_hash_validation(self):
         timestamp_path = os.path.join(
             self.repo_dir, 'metadata', 'timestamp.json')
         timestamp = Metadata[Timestamp].from_file(timestamp_path)
-        snapshot_metafile = timestamp.signed.meta["snapshot.json"]
+        snapshot_metafile = timestamp.signed.snapshot_meta
 
         snapshot_path = os.path.join(
             self.repo_dir, 'metadata', 'snapshot.json')

tests/test_trusted_metadata_set.py

@@ -70,8 +70,8 @@ def setUpClass(cls):
             cls.keystore[role] = SSlibSigner(key_dict)
 
         def hashes_length_modifier(timestamp: Timestamp) -> None:
-            timestamp.meta["snapshot.json"].hashes = None
-            timestamp.meta["snapshot.json"].length = None
+            timestamp.snapshot_meta.hashes = None
+            timestamp.snapshot_meta.length = None
 
         cls.metadata["timestamp"] = cls.modify_metadata(
             cls, "timestamp", hashes_length_modifier
@@ -245,13 +245,13 @@ def version_modifier(timestamp: Timestamp) -> None:
 
     def test_update_timestamp_snapshot_ver_below_current(self):
         def bump_snapshot_version(timestamp: Timestamp) -> None:
-            timestamp.meta["snapshot.json"].version = 2
+            timestamp.snapshot_meta.version = 2
 
         # set current known snapshot.json version to 2
         timestamp = self.modify_metadata("timestamp", bump_snapshot_version)
         self.trusted_set.update_timestamp(timestamp)
 
-        # newtimestamp.meta["snapshot.json"].version < trusted_timestamp.meta["snapshot.json"].version
+        # newtimestamp.meta.version < trusted_timestamp.meta.version
         with self.assertRaises(exceptions.ReplayedMetadataError):
             self.trusted_set.update_timestamp(self.metadata["timestamp"])
 
@@ -271,7 +271,7 @@ def timestamp_expired_modifier(timestamp: Timestamp) -> None:
 
     def test_update_snapshot_length_or_hash_mismatch(self):
         def modify_snapshot_length(timestamp: Timestamp) -> None:
-            timestamp.meta["snapshot.json"].length = 1
+            timestamp.snapshot_meta.length = 1
 
         # set known snapshot.json length to 1
         timestamp = self.modify_metadata("timestamp", modify_snapshot_length)
@@ -289,7 +289,7 @@ def test_update_snapshot_cannot_verify_snapshot_with_threshold(self):
 
     def test_update_snapshot_version_different_timestamp_snapshot_version(self):
         def timestamp_version_modifier(timestamp: Timestamp) -> None:
-            timestamp.meta["snapshot.json"].version = 2
+            timestamp.snapshot_meta.version = 2
 
         timestamp = self.modify_metadata("timestamp", timestamp_version_modifier)
         self.trusted_set.update_timestamp(timestamp)
@@ -341,7 +341,7 @@ def snapshot_expired_modifier(snapshot: Snapshot) -> None:
 
     def test_update_snapshot_successful_rollback_checks(self):
         def meta_version_bump(timestamp: Timestamp) -> None:
-            timestamp.meta["snapshot.json"].version += 1
+            timestamp.snapshot_meta.version += 1
 
         def version_bump(snapshot: Snapshot) -> None:
             snapshot.version += 1

tuf/api/metadata.py

@@ -923,11 +923,11 @@ def verify_length_and_hashes(self, data: Union[bytes, IO[bytes]]) -> None:
 class Timestamp(Signed):
     """A container for the signed part of timestamp metadata.
 
-    Timestamp contains information about the snapshot Metadata file.
+    TUF file format uses a dictionary to contain the snapshot information:
+    this is not the case with Timestamp.snapshot_meta which is a MetaFile.
 
     Attributes:
-        meta: A dictionary of filenames to MetaFiles. The only valid key value
-            is the snapshot filename, as defined by the specification.
+        snapshot_meta: MetaFile instance with the snapshot meta information.
     """
 
     _signed_type = "timestamp"
@@ -937,33 +937,31 @@ def __init__(
         version: int,
         spec_version: str,
         expires: datetime,
-        meta: Dict[str, MetaFile],
+        snapshot_meta: MetaFile,
         unrecognized_fields: Optional[Mapping[str, Any]] = None,
     ) -> None:
         super().__init__(version, spec_version, expires, unrecognized_fields)
-        self.meta = meta
+        self.snapshot_meta = snapshot_meta
 
     @classmethod
     def from_dict(cls, signed_dict: Dict[str, Any]) -> "Timestamp":
         """Creates Timestamp object from its dict representation."""
         common_args = cls._common_fields_from_dict(signed_dict)
         meta_dict = signed_dict.pop("meta")
-        meta = {"snapshot.json": MetaFile.from_dict(meta_dict["snapshot.json"])}
+        snapshot_meta = MetaFile.from_dict(meta_dict["snapshot.json"])
         # All fields left in the timestamp_dict are unrecognized.
-        return cls(*common_args, meta, signed_dict)
+        return cls(*common_args, snapshot_meta, signed_dict)
 
     def to_dict(self) -> Dict[str, Any]:
         """Returns the dict representation of self."""
         res_dict = self._common_fields_to_dict()
-        res_dict["meta"] = {
-            "snapshot.json": self.meta["snapshot.json"].to_dict()
-        }
+        res_dict["meta"] = {"snapshot.json": self.snapshot_meta.to_dict()}
         return res_dict
 
     # Modification.
     def update(self, snapshot_meta: MetaFile) -> None:
-        """Assigns passed info about snapshot metadata to meta dict."""
-        self.meta["snapshot.json"] = snapshot_meta
+        """Assigns passed info about snapshot metadata."""
+        self.snapshot_meta = snapshot_meta
 
 
 class Snapshot(Signed):

tuf/ngclient/_internal/trusted_metadata_set.py

@@ -233,13 +233,13 @@ def update_timestamp(self, data: bytes) -> None:
                 )
             # Prevent rolling back snapshot version
             if (
-                new_timestamp.signed.meta["snapshot.json"].version
-                < self.timestamp.signed.meta["snapshot.json"].version
+                new_timestamp.signed.snapshot_meta.version
+                < self.timestamp.signed.snapshot_meta.version
             ):
                 raise exceptions.ReplayedMetadataError(
                     "snapshot",
-                    new_timestamp.signed.meta["snapshot.json"].version,
-                    self.timestamp.signed.meta["snapshot.json"].version,
+                    new_timestamp.signed.snapshot_meta.version,
+                    self.timestamp.signed.snapshot_meta.version,
                 )
 
         # expiry not checked to allow old timestamp to be used for rollback
@@ -286,11 +286,11 @@ def update_snapshot(self, data: bytes) -> None:
         # Snapshot cannot be loaded if final timestamp is expired
         self._check_final_timestamp()
 
-        meta = self.timestamp.signed.meta["snapshot.json"]
+        snapshot_meta = self.timestamp.signed.snapshot_meta
 
         # Verify against the hashes in timestamp, if any
         try:
-            meta.verify_length_and_hashes(data)
+            snapshot_meta.verify_length_and_hashes(data)
         except exceptions.LengthOrHashMismatchError as e:
             raise exceptions.RepositoryError(
                 "Snapshot length or hashes do not match"
@@ -345,14 +345,10 @@ def _check_final_snapshot(self) -> None:
         assert self.timestamp is not None  # nosec
         if self.snapshot.signed.is_expired(self.reference_time):
             raise exceptions.ExpiredMetadataError("snapshot.json is expired")
-
-        if (
-            self.snapshot.signed.version
-            != self.timestamp.signed.meta["snapshot.json"].version
-        ):
+        snapshot_meta = self.timestamp.signed.snapshot_meta
+        if self.snapshot.signed.version != snapshot_meta.version:
             raise exceptions.BadVersionNumberError(
-                f"Expected snapshot version "
-                f"{self.timestamp.signed.meta['snapshot.json'].version}, "
+                f"Expected snapshot version {snapshot_meta.version}, "
                 f"got {self.snapshot.signed.version}"
             )
 

tuf/ngclient/updater.py

@@ -352,11 +352,11 @@ def _load_snapshot(self) -> None:
             logger.debug("Local snapshot not valid as final: %s", e)
 
             assert self._trusted_set.timestamp is not None  # nosec
-            metainfo = self._trusted_set.timestamp.signed.meta["snapshot.json"]
-            length = metainfo.length or self.config.snapshot_max_length
+            snapshot_meta = self._trusted_set.timestamp.signed.snapshot_meta
+            length = snapshot_meta.length or self.config.snapshot_max_length
             version = None
             if self._trusted_set.root.signed.consistent_snapshot:
-                version = metainfo.version
+                version = snapshot_meta.version
 
             data = self._download_metadata("snapshot", length, version)
             self._trusted_set.update_snapshot(data)