From ed514caed20995814712fd6c9e9c4120b4ac64be Mon Sep 17 00:00:00 2001
From: rroskam <rroskam@worthwhile.com>
Date: Tue, 16 Jun 2015 16:08:03 -0400
Subject: [PATCH] Fixed #24966 -- Added deployment system check for empty
 ALLOWED_HOSTS.

---
 django/core/checks/security/base.py    | 10 ++++++++++
 docs/ref/checks.txt                    |  1 +
 tests/check_framework/test_security.py | 15 +++++++++++++++
 3 files changed, 26 insertions(+)

diff --git a/django/core/checks/security/base.py b/django/core/checks/security/base.py
index f740b63c7b..eacbb90843 100644
--- a/django/core/checks/security/base.py
+++ b/django/core/checks/security/base.py
@@ -95,6 +95,11 @@ W019 = Warning(
     id='security.W019',
 )
 
+W020 = Warning(
+    "ALLOWED_HOSTS must not be empty in deployment.",
+    id='security.W020',
+)
+
 
 def _security_middleware():
     return "django.middleware.security.SecurityMiddleware" in settings.MIDDLEWARE_CLASSES
@@ -182,3 +187,8 @@ def check_xframe_deny(app_configs, **kwargs):
         settings.X_FRAME_OPTIONS == 'DENY'
     )
     return [] if passed_check else [W019]
+
+
+@register(Tags.security, deploy=True)
+def check_allowed_hosts(app_configs, **kwargs):
+    return [] if settings.ALLOWED_HOSTS else [W020]
diff --git a/docs/ref/checks.txt b/docs/ref/checks.txt
index 05a2e6e88f..3f81720c72 100644
--- a/docs/ref/checks.txt
+++ b/docs/ref/checks.txt
@@ -476,6 +476,7 @@ of the :djadmin:`check` command:
   ``'DENY'``. The default is ``'SAMEORIGIN'``, but unless there is a good reason
   for your site to serve other parts of itself in a frame, you should change
   it to ``'DENY'``.
+* **security.W020**: :setting:`ALLOWED_HOSTS` must not be empty in deployment.
 
 Sites
 -----
diff --git a/tests/check_framework/test_security.py b/tests/check_framework/test_security.py
index 42e186d639..adf1af952c 100644
--- a/tests/check_framework/test_security.py
+++ b/tests/check_framework/test_security.py
@@ -482,3 +482,18 @@ class CheckDebugTest(SimpleTestCase):
     @override_settings(DEBUG=False)
     def test_debug_false(self):
         self.assertEqual(self.func(None), [])
+
+
+class CheckAllowedHostsTest(SimpleTestCase):
+    @property
+    def func(self):
+        from django.core.checks.security.base import check_allowed_hosts
+        return check_allowed_hosts
+
+    @override_settings(ALLOWED_HOSTS=[])
+    def test_allowed_hosts_empty(self):
+        self.assertEqual(self.func(None), [base.W020])
+
+    @override_settings(ALLOWED_HOSTS=['.example.com', ])
+    def test_allowed_hosts_set(self):
+        self.assertEqual(self.func(None), [])