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# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
Tests for L{twisted.names.cache}.
"""
import time
from zope.interface.verify import verifyClass
from twisted.internet import interfaces, task
from twisted.names import cache, dns
from twisted.trial import unittest
class CachingTests(unittest.TestCase):
"""
Tests for L{cache.CacheResolver}.
"""
def test_interface(self):
"""
L{cache.CacheResolver} implements L{interfaces.IResolver}
"""
verifyClass(interfaces.IResolver, cache.CacheResolver)
def test_lookup(self):
c = cache.CacheResolver(
{
dns.Query(name=b"example.com", type=dns.MX, cls=dns.IN): (
time.time(),
([], [], []),
)
}
)
return c.lookupMailExchange(b"example.com").addCallback(
self.assertEqual, ([], [], [])
)
def test_constructorExpires(self):
"""
Cache entries passed into L{cache.CacheResolver.__init__} get
cancelled just like entries added with cacheResult
"""
r = (
[
dns.RRHeader(
b"example.com", dns.A, dns.IN, 60, dns.Record_A("127.0.0.1", 60)
)
],
[
dns.RRHeader(
b"example.com", dns.A, dns.IN, 50, dns.Record_A("127.0.0.1", 50)
)
],
[
dns.RRHeader(
b"example.com", dns.A, dns.IN, 40, dns.Record_A("127.0.0.1", 40)
)
],
)
clock = task.Clock()
query = dns.Query(name=b"example.com", type=dns.A, cls=dns.IN)
c = cache.CacheResolver({query: (clock.seconds(), r)}, reactor=clock)
# 40 seconds is enough to expire the entry because expiration is based
# on the minimum TTL.
clock.advance(40)
self.assertNotIn(query, c.cache)
return self.assertFailure(c.lookupAddress(b"example.com"), dns.DomainError)
def test_normalLookup(self):
"""
When a cache lookup finds a cached entry from 1 second ago, it is
returned with a TTL of original TTL minus the elapsed 1 second.
"""
r = (
[
dns.RRHeader(
b"example.com", dns.A, dns.IN, 60, dns.Record_A("127.0.0.1", 60)
)
],
[
dns.RRHeader(
b"example.com", dns.A, dns.IN, 50, dns.Record_A("127.0.0.1", 50)
)
],
[
dns.RRHeader(
b"example.com", dns.A, dns.IN, 40, dns.Record_A("127.0.0.1", 40)
)
],
)
clock = task.Clock()
c = cache.CacheResolver(reactor=clock)
c.cacheResult(dns.Query(name=b"example.com", type=dns.A, cls=dns.IN), r)
clock.advance(1)
def cbLookup(result):
self.assertEqual(result[0][0].ttl, 59)
self.assertEqual(result[1][0].ttl, 49)
self.assertEqual(result[2][0].ttl, 39)
self.assertEqual(result[0][0].name.name, b"example.com")
return c.lookupAddress(b"example.com").addCallback(cbLookup)
def test_cachedResultExpires(self):
"""
Once the TTL has been exceeded, the result is removed from the cache.
"""
r = (
[
dns.RRHeader(
b"example.com", dns.A, dns.IN, 60, dns.Record_A("127.0.0.1", 60)
)
],
[
dns.RRHeader(
b"example.com", dns.A, dns.IN, 50, dns.Record_A("127.0.0.1", 50)
)
],
[
dns.RRHeader(
b"example.com", dns.A, dns.IN, 40, dns.Record_A("127.0.0.1", 40)
)
],
)
clock = task.Clock()
c = cache.CacheResolver(reactor=clock)
query = dns.Query(name=b"example.com", type=dns.A, cls=dns.IN)
c.cacheResult(query, r)
clock.advance(40)
self.assertNotIn(query, c.cache)
return self.assertFailure(c.lookupAddress(b"example.com"), dns.DomainError)
def test_expiredTTLLookup(self):
"""
When the cache is queried exactly as the cached entry should expire but
before it has actually been cleared, the cache does not return the
expired entry.
"""
r = (
[
dns.RRHeader(
b"example.com", dns.A, dns.IN, 60, dns.Record_A("127.0.0.1", 60)
)
],
[
dns.RRHeader(
b"example.com", dns.A, dns.IN, 50, dns.Record_A("127.0.0.1", 50)
)
],
[
dns.RRHeader(
b"example.com", dns.A, dns.IN, 40, dns.Record_A("127.0.0.1", 40)
)
],
)
clock = task.Clock()
# Make sure timeouts never happen, so entries won't get cleared:
clock.callLater = lambda *args, **kwargs: None
c = cache.CacheResolver(
{
dns.Query(name=b"example.com", type=dns.A, cls=dns.IN): (
clock.seconds(),
r,
)
},
reactor=clock,
)
clock.advance(60.1)
return self.assertFailure(c.lookupAddress(b"example.com"), dns.DomainError)
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