Refs #32800 -- Added _add_new_csrf_cookie() helper function.

cjerdonek · carltongibson · commit 231de683d863 · 2021-08-17T12:23:54.000+02:00
This centralizes the logic to use when setting a new cookie. It also
eliminates the need for the _get_new_csrf_token() function, which is now
removed.
diff --git a/django/middleware/csrf.py b/django/middleware/csrf.py
@@ -79,8 +79,14 @@ def _unmask_cipher_token(token):
     return ''.join(chars[x - y] for x, y in pairs)  # Note negative values are ok
 
 
-def _get_new_csrf_token():
-    return _mask_cipher_secret(_get_new_csrf_string())
+def _add_new_csrf_cookie(request):
+    """Generate a new random CSRF_COOKIE value, and add it to request.META."""
+    csrf_secret = _get_new_csrf_string()
+    request.META.update({
+        'CSRF_COOKIE': _mask_cipher_secret(csrf_secret),
+        'CSRF_COOKIE_NEEDS_UPDATE': True,
+    })
+    return csrf_secret
 
 
 def get_token(request):
@@ -93,15 +99,14 @@ def get_token(request):
     header to the outgoing response.  For this reason, you may need to use this
     function lazily, as is done by the csrf context processor.
     """
-    if "CSRF_COOKIE" not in request.META:
-        csrf_secret = _get_new_csrf_string()
-        request.META["CSRF_COOKIE"] = _mask_cipher_secret(csrf_secret)
-    else:
+    if 'CSRF_COOKIE' in request.META:
         csrf_secret = _unmask_cipher_token(request.META["CSRF_COOKIE"])
-    # Since the cookie is being used, flag to send the cookie in
-    # process_response() (even if the client already has it) in order to renew
-    # the expiry timer.
-    request.META['CSRF_COOKIE_NEEDS_UPDATE'] = True
+        # Since the cookie is being used, flag to send the cookie in
+        # process_response() (even if the client already has it) in order to
+        # renew the expiry timer.
+        request.META['CSRF_COOKIE_NEEDS_UPDATE'] = True
+    else:
+        csrf_secret = _add_new_csrf_cookie(request)
     return _mask_cipher_secret(csrf_secret)
 
 
@@ -110,10 +115,7 @@ def rotate_token(request):
     Change the CSRF token in use for a request - should be done on login
     for security purposes.
     """
-    request.META.update({
-        'CSRF_COOKIE': _get_new_csrf_token(),
-        'CSRF_COOKIE_NEEDS_UPDATE': True,
-    })
+    _add_new_csrf_cookie(request)
 
 
 class InvalidTokenFormat(Exception):
@@ -377,12 +379,11 @@ def process_request(self, request):
         try:
             csrf_token = self._get_token(request)
         except InvalidTokenFormat:
-            csrf_token = _get_new_csrf_token()
-            request.META["CSRF_COOKIE_NEEDS_UPDATE"] = True
-
-        if csrf_token is not None:
-            # Use same token next time.
-            request.META['CSRF_COOKIE'] = csrf_token
+            _add_new_csrf_cookie(request)
+        else:
+            if csrf_token is not None:
+                # Use same token next time.
+                request.META['CSRF_COOKIE'] = csrf_token
 
     def process_view(self, request, callback, callback_args, callback_kwargs):
         if getattr(request, 'csrf_processing_done', False):
