WIP: Mirrors redesign

tuf/client_rework/fetcher.py

@@ -0,0 +1,41 @@
+# Copyright 2021, New York University and the TUF contributors
+# SPDX-License-Identifier: MIT OR Apache-2.0
+
+"""Provides an interface for network IO abstraction.
+"""
+
+# Imports
+import abc
+
+
+# Classes
+class FetcherInterface:
+    """Defines an interface for abstract network download.
+
+    By providing a concrete implementation of the abstract interface,
+    users of the framework can plug-in their preferred/customized
+    network stack.
+    """
+
+    __metaclass__ = abc.ABCMeta
+
+    @abc.abstractmethod
+    def fetch(self, url, required_length):
+        """Fetches the contents of HTTP/HTTPS url from a remote server.
+
+        Ensures the length of the downloaded data is up to 'required_length'.
+
+        Arguments:
+            url: A URL string that represents a file location.
+            required_length: An integer value representing the file length in
+                bytes.
+
+        Raises:
+            tuf.exceptions.SlowRetrievalError: A timeout occurs while receiving
+                data.
+            tuf.exceptions.FetcherHTTPError: An HTTP error code is received.
+
+        Returns:
+            A bytes iterator
+        """
+        raise NotImplementedError  # pragma: no cover

tuf/client_rework/metadata_wrapper.py

@@ -9,7 +9,7 @@
 
 from securesystemslib.keys import format_metadata_to_key
 
-import tuf.exceptions
+from tuf import exceptions, formats
 from tuf.api import metadata
 
 
@@ -64,7 +64,7 @@ def verify(self, keys, threshold):
             verified += 1
 
         if verified < threshold:
-            raise tuf.exceptions.InsufficientKeysError
+            raise exceptions.InsufficientKeysError
 
     def persist(self, filename):
         """
@@ -77,13 +77,13 @@ def expires(self, reference_time=None):
         TODO
         """
         if reference_time is None:
-            expires_timestamp = tuf.formats.datetime_to_unix_timestamp(
+            expires_timestamp = formats.datetime_to_unix_timestamp(
                 self._meta.signed.expires
             )
             reference_time = int(time.time())
 
         if expires_timestamp < reference_time:
-            raise tuf.exceptions.ExpiredMetadataError
+            raise exceptions.ExpiredMetadataError
 
 
 class RootWrapper(MetadataWrapper):