ExceptionCachingResolver: Avoid NoMetaqueries

jayvdb · jayvdb · commit 5f571ef53af6 · 2020-09-01T18:45:08.000+07:00
NoMetaqueries do not use sockets, and caching them could
replace other cache entries which are more important.
diff --git a/dns_cache/resolver.py b/dns_cache/resolver.py
@@ -4,7 +4,7 @@
 from dns.name import from_text
 from dns.rdataclass import IN
 from dns.rdatatype import A
-from dns.resolver import NXDOMAIN, Answer, Resolver
+from dns.resolver import NXDOMAIN, Answer, NoMetaqueries, Resolver
 from dns.version import MAJOR as _MAJOR, MINOR as _MINOR
 
 import dns_cache.expiration
@@ -102,6 +102,8 @@ def resolve(self, qname, rdtype=A, rdclass=IN,
                 qname, rdtype, rdclass, tcp, source,
                 raise_on_no_answer, source_port, lifetime,
             )
+        except NoMetaqueries:
+            raise
         except DNSException as e:
             self._cache_exception(e, qname, rdtype, rdclass)
             raise
@@ -131,6 +133,8 @@ def query(self, qname, rdtype=A, rdclass=IN, **kwargs):
             return super(ExceptionCachingResolver, self).query(
                 qname, rdtype, rdclass, **kwargs
             )
+        except NoMetaqueries:
+            raise
         except DNSException as e:
             self._cache_exception(e, qname, rdtype, rdclass)
             raise
