From c9fb4e8bc311a98c4fb9b7f08d44de55c6f8b2a3 Mon Sep 17 00:00:00 2001
From: Bob Halley <halley@dnspython.org>
Date: Sat, 23 May 2020 10:32:54 -0700
Subject: [PATCH] fix None pointers in LRU cache sentinel

---
 dns/resolver.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/dns/resolver.py b/dns/resolver.py
index 4339a06b..089021d3 100644
--- a/dns/resolver.py
+++ b/dns/resolver.py
@@ -407,6 +407,8 @@ class LRUCache(object):
         self.data = {}
         self.set_max_size(max_size)
         self.sentinel = LRUCacheNode(None, None)
+        self.sentinel.prev = self.sentinel
+        self.sentinel.next = self.sentinel
         self.lock = _threading.Lock()
 
     def set_max_size(self, max_size):
@@ -480,8 +482,7 @@ class LRUCache(object):
                 node = self.sentinel.next
                 while node != self.sentinel:
                     next = node.next
-                    node.prev = None
-                    node.next = None
+                    node.unlink()
                     node = next
                 self.data = {}
 
-- 
2.47.3