From ab7ea069de5cecf1c26af50996a26e1a7f86def4 Mon Sep 17 00:00:00 2001
From: John Perkins <john.perkins@rackspace.com>
Date: Mon, 6 Oct 2014 16:24:57 -0500
Subject: [PATCH] Fix hostname regex pattern

Current hostname_pattern regex complexity grows exponentially
when given a string of just digits, which can be exploited to
cause neutron-server to freeze.

Change-Id: I886c6d883a9cb0acd9908495eec50bf0411d8ba8
Closes-bug: #1378450
---
 neutron/api/v2/attributes.py          | 4 ++--
 neutron/tests/unit/test_attributes.py | 1 +
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/neutron/api/v2/attributes.py b/neutron/api/v2/attributes.py
index 04875890b22..8eb2c3a587d 100644
--- a/neutron/api/v2/attributes.py
+++ b/neutron/api/v2/attributes.py
@@ -537,8 +537,8 @@ def convert_to_list(data):
         return [data]
 
 
-HOSTNAME_PATTERN = ("(?=^.{1,254}$)(^(?:(?!\d+\.|-)[a-zA-Z0-9_\-]"
-                    "{1,63}(?<!-)\.?)+(?:[a-zA-Z]{2,})$)")
+HOSTNAME_PATTERN = ("(?=^.{1,254}$)(^(?:(?!\d+.|-)[a-zA-Z0-9_\-]{1,62}"
+                    "[a-zA-Z0-9]\.?)+(?:[a-zA-Z]{2,})$)")
 
 HEX_ELEM = '[0-9A-Fa-f]'
 UUID_PATTERN = '-'.join([HEX_ELEM + '{8}', HEX_ELEM + '{4}',
diff --git a/neutron/tests/unit/test_attributes.py b/neutron/tests/unit/test_attributes.py
index 0282cdc0c22..61ff20d0009 100644
--- a/neutron/tests/unit/test_attributes.py
+++ b/neutron/tests/unit/test_attributes.py
@@ -283,6 +283,7 @@ class TestAttributes(base.BaseTestCase):
                     ['www.hostname.com', 'www.hostname.com'],
                     ['77.hostname.com'],
                     ['1000.0.0.1'],
+                    ['111111111111111111111111111111111111111111111111111111111111'],  # noqa
                     None]
 
         for ns in ns_pools: