gh-103204: http.server - Enforce that HTTP version numbers must consist only of digits (#103205)

kenballus · arhadthedev · gpshead · web-flow · commit cf720acfcbd8 · 2023-05-12T13:25:58.000-07:00
Reject HTTP requests with invalid http/x.y version numbers: x or y being non-digits or too-long.

---------

Co-authored-by: Oleg Iarygin &lt;oleg@arhadthedev.net&gt;
Co-authored-by: Gregory P. Smith &lt;greg@krypto.org&gt;
diff --git a/Lib/http/server.py b/Lib/http/server.py
@@ -300,6 +300,10 @@ def parse_request(self):
                 #   - Leading zeros MUST be ignored by recipients.
                 if len(version_number) != 2:
                     raise ValueError
+                if any(not component.isdigit() for component in version_number):
+                    raise ValueError("non digit in http version")
+                if any(len(component) > 10 for component in version_number):
+                    raise ValueError("unreasonable length http version")
                 version_number = int(version_number[0]), int(version_number[1])
             except (ValueError, IndexError):
                 self.send_error(
diff --git a/Lib/test/test_httpservers.py b/Lib/test/test_httpservers.py
@@ -164,6 +164,27 @@ def test_version_digits(self):
         res = self.con.getresponse()
         self.assertEqual(res.status, HTTPStatus.BAD_REQUEST)
 
+    def test_version_signs_and_underscores(self):
+        self.con._http_vsn_str = 'HTTP/-9_9_9.+9_9_9'
+        self.con.putrequest('GET', '/')
+        self.con.endheaders()
+        res = self.con.getresponse()
+        self.assertEqual(res.status, HTTPStatus.BAD_REQUEST)
+
+    def test_major_version_number_too_long(self):
+        self.con._http_vsn_str = 'HTTP/909876543210.0'
+        self.con.putrequest('GET', '/')
+        self.con.endheaders()
+        res = self.con.getresponse()
+        self.assertEqual(res.status, HTTPStatus.BAD_REQUEST)
+
+    def test_minor_version_number_too_long(self):
+        self.con._http_vsn_str = 'HTTP/1.909876543210'
+        self.con.putrequest('GET', '/')
+        self.con.endheaders()
+        res = self.con.getresponse()
+        self.assertEqual(res.status, HTTPStatus.BAD_REQUEST)
+
     def test_version_none_get(self):
         self.con._http_vsn_str = ''
         self.con.putrequest('GET', '/')
diff --git a/Misc/NEWS.d/next/Library/2023-04-02-23-05-22.gh-issue-103204.bbDmu0.rst b/Misc/NEWS.d/next/Library/2023-04-02-23-05-22.gh-issue-103204.bbDmu0.rst
@@ -0,0 +1,3 @@
+Fixes :mod:`http.server` accepting HTTP requests with HTTP version numbers
+preceded by '+', or '-', or with digit-separating '_' characters.  The length
+of the version numbers is also constrained.
