bpo-36226: Fix email parsing more than headers

grische · grische · commit bb9dd1b765d3 · 2019-09-05T12:15:23.000+02:00
Currently parse_headers only gives headers to the parser. For the parser
to correctly handle this case, it also needs to set headersonly=True

This fixes false StartBoundaryNotFoundDefects
diff --git a/Lib/http/client.py b/Lib/http/client.py
@@ -211,7 +211,7 @@ def parse_headers(fp, _class=HTTPMessage):
         if line in (b'\r\n', b'\n', b''):
             break
     hstring = b''.join(headers).decode('iso-8859-1')
-    return email.parser.Parser(_class=_class).parsestr(hstring)
+    return email.parser.Parser(_class=_class).parsestr(hstring, headersonly=True)
 
 
 class HTTPResponse(io.BufferedIOBase):
diff --git a/Lib/test/test_httplib.py b/Lib/test/test_httplib.py
@@ -359,6 +359,11 @@ def test_headers_debuglevel(self):
         self.assertEqual(lines[1], "header: First: val")
         self.assertEqual(lines[2], "header: Second: val")
 
+    def test_parse_valid_multipart_header(self):
+        header = b'Content-Type: multipart/related; boundary="==="\r\n\r\n'
+        fp = io.BytesIO(header)
+        message = client.parse_headers(fp)
+        self.assertListEqual(message.defects, [])
 
 class TransferEncodingTest(TestCase):
     expected_body = b"It's just a flesh wound"
diff --git a/Misc/NEWS.d/next/Library/2019-09-05-12-14-30.bpo-36226.KJV4rP.rst b/Misc/NEWS.d/next/Library/2019-09-05-12-14-30.bpo-36226.KJV4rP.rst
@@ -0,0 +1,2 @@
+Fixes false StartBoundaryNotFoundDefects which were triggered by
+parse_headers not forwarding the headersonly to the email parser.

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	`+Fixes false StartBoundaryNotFoundDefects which were triggered by`
	`2`	`+parse_headers not forwarding the headersonly to the email parser.`