Ausgabe der neuen DB Einträge

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

@@ -0,0 +1,125 @@
+# -*- test-case-name: twisted.names.test -*-
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+An in-memory caching resolver.
+"""
+
+from __future__ import division, absolute_import
+
+from twisted.names import dns, common
+from twisted.python import failure, log
+from twisted.internet import defer
+
+
+
+class CacheResolver(common.ResolverBase):
+    """
+    A resolver that serves records from a local, memory cache.
+
+    @ivar _reactor: A provider of L{interfaces.IReactorTime}.
+    """
+    cache = None
+
+    def __init__(self, cache=None, verbose=0, reactor=None):
+        common.ResolverBase.__init__(self)
+
+        self.cache = {}
+        self.verbose = verbose
+        self.cancel = {}
+        if reactor is None:
+            from twisted.internet import reactor
+        self._reactor = reactor
+
+        if cache:
+            for query, (seconds, payload) in cache.items():
+                self.cacheResult(query, payload, seconds)
+
+
+    def __setstate__(self, state):
+        self.__dict__ = state
+
+        now = self._reactor.seconds()
+        for (k, (when, (ans, add, ns))) in self.cache.items():
+            diff = now - when
+            for rec in ans + add + ns:
+                if rec.ttl < diff:
+                    del self.cache[k]
+                    break
+
+
+    def __getstate__(self):
+        for c in self.cancel.values():
+            c.cancel()
+        self.cancel.clear()
+        return self.__dict__
+
+
+    def _lookup(self, name, cls, type, timeout):
+        now = self._reactor.seconds()
+        q = dns.Query(name, type, cls)
+        try:
+            when, (ans, auth, add) = self.cache[q]
+        except KeyError:
+            if self.verbose > 1:
+                log.msg('Cache miss for ' + repr(name))
+            return defer.fail(failure.Failure(dns.DomainError(name)))
+        else:
+            if self.verbose:
+                log.msg('Cache hit for ' + repr(name))
+            diff = now - when
+
+            try:
+                result = (
+                    [dns.RRHeader(r.name.name, r.type, r.cls, r.ttl - diff,
+                                  r.payload) for r in ans],
+                    [dns.RRHeader(r.name.name, r.type, r.cls, r.ttl - diff,
+                                  r.payload) for r in auth],
+                    [dns.RRHeader(r.name.name, r.type, r.cls, r.ttl - diff,
+                                  r.payload) for r in add])
+            except ValueError:
+                return defer.fail(failure.Failure(dns.DomainError(name)))
+            else:
+                return defer.succeed(result)
+
+
+    def lookupAllRecords(self, name, timeout = None):
+        return defer.fail(failure.Failure(dns.DomainError(name)))
+
+
+    def cacheResult(self, query, payload, cacheTime=None):
+        """
+        Cache a DNS entry.
+
+        @param query: a L{dns.Query} instance.
+
+        @param payload: a 3-tuple of lists of L{dns.RRHeader} records, the
+            matching result of the query (answers, authority and additional).
+
+        @param cacheTime: The time (seconds since epoch) at which the entry is
+            considered to have been added to the cache. If L{None} is given,
+            the current time is used.
+        """
+        if self.verbose > 1:
+            log.msg('Adding %r to cache' % query)
+
+        self.cache[query] = (cacheTime or self._reactor.seconds(), payload)
+
+        if query in self.cancel:
+            self.cancel[query].cancel()
+
+        s = list(payload[0]) + list(payload[1]) + list(payload[2])
+        if s:
+            m = s[0].ttl
+            for r in s:
+                m = min(m, r.ttl)
+        else:
+            m = 0
+
+        self.cancel[query] = self._reactor.callLater(m, self.clearEntry, query)
+
+
+    def clearEntry(self, query):
+        del self.cache[query]
+        del self.cancel[query]