WIP: Split/regroup client components

tuf/client_rework/fetcher.py

@@ -0,0 +1,39 @@
+# 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