Suggestions from review

Author: lyc8503

Lib/http/server.py

@@ -778,7 +778,7 @@ def send_head(self):
             if self._range:
                 start, end = self._range
                 if start is None:
-                    # parse_range() collapses (None, None) to None
+                    # parse_range() collapses (None, None) to None as it's invalid
                     assert end is not None
                     # `end` here means suffix length
                     start = max(0, fs.st_size - end)
@@ -974,6 +974,8 @@ def parse_range(self):
         if range_header is None:
             return None
         m = RANGE_REGEX_PATTERN.match(range_header)
+        # Ignore invalid Range header and return None
+        # https://datatracker.ietf.org/doc/html/rfc9110#name-range
         if m is None:
             return None
 

Lib/test/test_httpservers.py

@@ -607,6 +607,10 @@ def test_single_range_get_empty(self):
         self.assertEqual(response.getheader('content-range'), 'bytes */0')
         self.check_status_and_reason(response, HTTPStatus.REQUESTED_RANGE_NOT_SATISFIABLE)
 
+        # invalid Range header is always ignored
+        response = self.request(empty_path, headers={'Range': 'bytes=5-4'})
+        self.check_status_and_reason(response, HTTPStatus.OK)
+
     def test_multi_range_get(self):
         # multipart ranges (not supported currently)
         response = self.request(self.base_url + '/test', headers={'Range': 'bytes=1-2, 4-7'})