bpo-17239: Disable external entities in SAX parser (GH-9217)

The SAX parser no longer processes general external entities by default
to increase security. Before, the parser created network connections
to fetch remote files or loaded local files from the file system for DTD
and entities.

Signed-off-by: Christian Heimes <christian@python.org>



https://bugs.python.org/issue17239

Lib/test/test_pulldom.py

@@ -3,6 +3,7 @@ import unittest
 import xml.sax
 
 from xml.sax.xmlreader import AttributesImpl
+from xml.sax.handler import feature_external_ges
 from xml.dom import pulldom
 
 from test.support import findfile
@@ -166,6 +167,12 @@ class PullDOMTestCase(unittest.TestCase):
             # This should have returned 'END_ELEMENT'.
             self.assertEqual(parser[-1][0], pulldom.START_DOCUMENT)
 
+    def test_external_ges_default(self):
+        parser = pulldom.parseString(SMALL_SAMPLE)
+        saxparser = parser.parser
+        ges = saxparser.getFeature(feature_external_ges)
+        self.assertEqual(ges, False)
+
 
 class ThoroughTestCase(unittest.TestCase):
     """Test the hard-to-reach parts of pulldom."""