Started working on django-cms#1019, it should prevent the issue in mo…

…st cases,

however it's really insanely hard to cover edge-cases (especially for
home-pages) since it's not trivial to check if a page will be the
homepage or not.

cms/admin/forms.py

@@ -170,6 +170,35 @@ def clean(self):
                     raise forms.ValidationError(_('A page with this reverse URL id exists already.'))
         return cleaned_data
 
+    def clean_redirect(self):
+        """
+        Prevent infinite redirects
+        """
+        redirect = self.cleaned_data.get('redirect', None)
+        if not redirect:
+            return redirect
+        slug = self.cleaned_data.get('slug', None)
+        if not slug:
+            return redirect
+        parent_id = self.cleaned_data.get('parent', None)
+        old_slug = self.instance.get_slug()
+        if old_slug == slug and self.instance.parent_id == parent_id:
+            url = self.instance.get_absolute_url()
+        else:
+            if parent_id:
+                url = Page.objects.get(pk=parent_id).get_absolute_url()
+            else:
+                url = '/'
+            if parent_id:
+                url += slug
+            elif not self.instance.is_home():
+                url += slug
+            if not url.endswith('/'):
+                url += '/'
+        if url == redirect:
+            raise forms.ValidationError("Inifinite redirect, please chose a different redirect")
+        return redirect
+
     def clean_overwrite_url(self):
         if 'overwrite_url' in self.fields:
             url = self.cleaned_data['overwrite_url']

cms/api.py

@@ -30,6 +30,12 @@
 from cms.utils.permissions import _thread_locals
 
 
+#==============================================================================
+# Exceptions
+#==============================================================================
+
+class InfiniteRedirectLoop(Exception): pass
+
 #===============================================================================
 # Constants 
 #===============================================================================
@@ -193,7 +199,7 @@ def create_page(title, template, language, menu_title=None, slug=None,
     if settings.CMS_MODERATOR and _thread_locals.user:
         page.pagemoderator_set.create(user=_thread_locals.user)
 
-    create_title(
+    title = create_title(
         language=language,
         title=title,
         menu_title=menu_title,
@@ -207,8 +213,15 @@ def create_page(title, template, language, menu_title=None, slug=None,
     )
 
     del _thread_locals.user
-    return page
 
+    redirect = page.get_redirect(language)
+    if redirect and redirect == page.get_absolute_url(language):
+        title.delete()
+        page.delete()
+        raise InfiniteRedirectLoop()
+
+    return page
+
 def create_title(language, title, page, menu_title=None, slug=None,
                  apphook=None, redirect=None, meta_description=None,
                  meta_keywords=None, parent=None, overwrite_url=None):

cms/tests/admin.py

@@ -967,3 +967,24 @@ def test_clean_overwrite_url(self):
             Title.objects.set_or_create(request, instance, form, 'en')
             form = PageForm(data, instance=instance)
             self.assertTrue(form.is_valid(), form.errors.as_text())
+
+    def test_infinite_redirect(self):
+        user = AnonymousUser()
+        user.is_superuser = True
+        user.pk = 1
+        site = Site.objects.get_current()
+        template = settings.CMS_TEMPLATES[0][0]
+        instance = create_page('Test Page', template, 'en', site=site, published=True)
+        with SettingsOverride(CMS_MODERATOR=False):
+            data = {
+                'title': 'TestPage',
+                'slug': 'test-page',
+                'language': 'en',
+                'redirect': '/',
+                'site': site.pk,
+                'template': template,
+                'published': True
+            }
+
+            form = PageForm(data, instance=instance)
+            self.assertFalse(form.is_valid(), form.errors.as_text())

cms/tests/api.py

@@ -1,6 +1,6 @@
 from __future__ import with_statement
 from cms.api import (_generate_valid_slug, create_page, _verify_plugin_type, 
-    assign_user_to_page, publish_page)
+    assign_user_to_page, InfiniteRedirectLoop)
 from cms.apphook_pool import apphook_pool
 from cms.models.pagemodel import Page
 from cms.plugin_base import CMSPluginBase
@@ -186,3 +186,8 @@ def test_create_page_can_overwrite_url(self):
         page = create_page(**page_attrs)
         self.assertTrue(page.get_title_obj_attribute('has_url_overwrite'))
         self.assertEqual(page.get_title_obj_attribute('path'), 'test/home')
+
+    def test_create_page_infinite_redirect(self):
+        self.assertRaises(InfiniteRedirectLoop, create_page, "one",
+                          "nav_playground.html", "en", published=True,
+                          redirect='/')