Ausgabe der neuen DB Einträge

venv/lib/python3.9/site-packages/twisted/names/resolve.py

@@ -0,0 +1,99 @@
+# -*- test-case-name: twisted.names.test.test_resolve -*-
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+Lookup a name using multiple resolvers.
+
+Future Plans: This needs someway to specify which resolver answered
+the query, or someway to specify (authority|ttl|cache behavior|more?)
+"""
+
+from __future__ import division, absolute_import
+
+from zope.interface import implementer
+
+from twisted.internet import defer, interfaces
+from twisted.names import dns, common, error
+
+
+class FailureHandler:
+    def __init__(self, resolver, query, timeout):
+        self.resolver = resolver
+        self.query = query
+        self.timeout = timeout
+
+
+    def __call__(self, failure):
+        # AuthoritativeDomainErrors should halt resolution attempts
+        failure.trap(dns.DomainError, defer.TimeoutError, NotImplementedError)
+        return self.resolver(self.query, self.timeout)
+
+
+
+@implementer(interfaces.IResolver)
+class ResolverChain(common.ResolverBase):
+    """
+    Lookup an address using multiple L{IResolver}s
+    """
+    def __init__(self, resolvers):
+        """
+        @type resolvers: L{list}
+        @param resolvers: A L{list} of L{IResolver} providers.
+        """
+        common.ResolverBase.__init__(self)
+        self.resolvers = resolvers
+
+
+    def _lookup(self, name, cls, type, timeout):
+        """
+        Build a L{dns.Query} for the given parameters and dispatch it
+        to each L{IResolver} in C{self.resolvers} until an answer or
+        L{error.AuthoritativeDomainError} is returned.
+
+        @type name: C{str}
+        @param name: DNS name to resolve.
+
+        @type type: C{int}
+        @param type: DNS record type.
+
+        @type cls: C{int}
+        @param cls: DNS record class.
+
+        @type timeout: Sequence of C{int}
+        @param timeout: Number of seconds after which to reissue the query.
+            When the last timeout expires, the query is considered failed.
+
+        @rtype: L{Deferred}
+        @return: A L{Deferred} which fires with a three-tuple of lists of
+            L{twisted.names.dns.RRHeader} instances.  The first element of the
+            tuple gives answers.  The second element of the tuple gives
+            authorities.  The third element of the tuple gives additional
+            information.  The L{Deferred} may instead fail with one of the
+            exceptions defined in L{twisted.names.error} or with
+            C{NotImplementedError}.
+        """
+        if not self.resolvers:
+            return defer.fail(error.DomainError())
+        q = dns.Query(name, type, cls)
+        d = self.resolvers[0].query(q, timeout)
+        for r in self.resolvers[1:]:
+            d = d.addErrback(
+                FailureHandler(r.query, q, timeout)
+            )
+        return d
+
+
+    def lookupAllRecords(self, name, timeout=None):
+        # XXX: Why is this necessary? dns.ALL_RECORDS queries should
+        # be handled just the same as any other type by _lookup
+        # above. If I remove this method all names tests still
+        # pass. See #6604 -rwall
+        if not self.resolvers:
+            return defer.fail(error.DomainError())
+        d = self.resolvers[0].lookupAllRecords(name, timeout)
+        for r in self.resolvers[1:]:
+            d = d.addErrback(
+                FailureHandler(r.lookupAllRecords, name, timeout)
+            )
+        return d