Mini Shell
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
Test cases for Twisted.names' root resolver.
"""
from zope.interface import implementer
from zope.interface.verify import verifyClass
from twisted.internet.defer import Deferred, TimeoutError, gatherResults, succeed
from twisted.internet.interfaces import IResolverSimple
from twisted.names import client, root
from twisted.names.dns import (
CNAME,
ENAME,
HS,
IN,
NS,
OK,
A,
Message,
Name,
Query,
Record_A,
Record_CNAME,
Record_NS,
RRHeader,
)
from twisted.names.error import DNSNameError, ResolverError
from twisted.names.root import Resolver
from twisted.names.test.test_util import MemoryReactor
from twisted.python.log import msg
from twisted.trial import util
from twisted.trial.unittest import SynchronousTestCase, TestCase
def getOnePayload(results):
"""
From the result of a L{Deferred} returned by L{IResolver.lookupAddress},
return the payload of the first record in the answer section.
"""
ans, auth, add = results
return ans[0].payload
def getOneAddress(results):
"""
From the result of a L{Deferred} returned by L{IResolver.lookupAddress},
return the first IPv4 address from the answer section.
"""
return getOnePayload(results).dottedQuad()
class RootResolverTests(TestCase):
"""
Tests for L{twisted.names.root.Resolver}.
"""
def _queryTest(self, filter):
"""
Invoke L{Resolver._query} and verify that it sends the correct DNS
query. Deliver a canned response to the query and return whatever the
L{Deferred} returned by L{Resolver._query} fires with.
@param filter: The value to pass for the C{filter} parameter to
L{Resolver._query}.
"""
reactor = MemoryReactor()
resolver = Resolver([], reactor=reactor)
d = resolver._query(
Query(b"foo.example.com", A, IN), [("1.1.2.3", 1053)], (30,), filter
)
# A UDP port should have been started.
portNumber, transport = reactor.udpPorts.popitem()
# And a DNS packet sent.
[(packet, address)] = transport._sentPackets
message = Message()
message.fromStr(packet)
# It should be a query with the parameters used above.
self.assertEqual(message.queries, [Query(b"foo.example.com", A, IN)])
self.assertEqual(message.answers, [])
self.assertEqual(message.authority, [])
self.assertEqual(message.additional, [])
response = []
d.addCallback(response.append)
self.assertEqual(response, [])
# Once a reply is received, the Deferred should fire.
del message.queries[:]
message.answer = 1
message.answers.append(
RRHeader(b"foo.example.com", payload=Record_A("5.8.13.21"))
)
transport._protocol.datagramReceived(message.toStr(), ("1.1.2.3", 1053))
return response[0]
def test_filteredQuery(self):
"""
L{Resolver._query} accepts a L{Query} instance and an address, issues
the query, and returns a L{Deferred} which fires with the response to
the query. If a true value is passed for the C{filter} parameter, the
result is a three-tuple of lists of records.
"""
answer, authority, additional = self._queryTest(True)
self.assertEqual(
answer, [RRHeader(b"foo.example.com", payload=Record_A("5.8.13.21", ttl=0))]
)
self.assertEqual(authority, [])
self.assertEqual(additional, [])
def test_unfilteredQuery(self):
"""
Similar to L{test_filteredQuery}, but for the case where a false value
is passed for the C{filter} parameter. In this case, the result is a
L{Message} instance.
"""
message = self._queryTest(False)
self.assertIsInstance(message, Message)
self.assertEqual(message.queries, [])
self.assertEqual(
message.answers,
[RRHeader(b"foo.example.com", payload=Record_A("5.8.13.21", ttl=0))],
)
self.assertEqual(message.authority, [])
self.assertEqual(message.additional, [])
def _respond(self, answers=[], authority=[], additional=[], rCode=OK):
"""
Create a L{Message} suitable for use as a response to a query.
@param answers: A C{list} of two-tuples giving data for the answers
section of the message. The first element of each tuple is a name
for the L{RRHeader}. The second element is the payload.
@param authority: A C{list} like C{answers}, but for the authority
section of the response.
@param additional: A C{list} like C{answers}, but for the
additional section of the response.
@param rCode: The response code the message will be created with.
@return: A new L{Message} initialized with the given values.
"""
response = Message(rCode=rCode)
for (section, data) in [
(response.answers, answers),
(response.authority, authority),
(response.additional, additional),
]:
section.extend(
[
RRHeader(
name, record.TYPE, getattr(record, "CLASS", IN), payload=record
)
for (name, record) in data
]
)
return response
def _getResolver(self, serverResponses, maximumQueries=10):
"""
Create and return a new L{root.Resolver} modified to resolve queries
against the record data represented by C{servers}.
@param serverResponses: A mapping from dns server addresses to
mappings. The inner mappings are from query two-tuples (name,
type) to dictionaries suitable for use as **arguments to
L{_respond}. See that method for details.
"""
roots = ["1.1.2.3"]
resolver = Resolver(roots, maximumQueries)
def query(query, serverAddresses, timeout, filter):
msg(f"Query for QNAME {query.name} at {serverAddresses!r}")
for addr in serverAddresses:
try:
server = serverResponses[addr]
except KeyError:
continue
records = server[query.name.name, query.type]
return succeed(self._respond(**records))
resolver._query = query
return resolver
def test_lookupAddress(self):
"""
L{root.Resolver.lookupAddress} looks up the I{A} records for the
specified hostname by first querying one of the root servers the
resolver was created with and then following the authority delegations
until a result is received.
"""
servers = {
("1.1.2.3", 53): {
(b"foo.example.com", A): {
"authority": [(b"foo.example.com", Record_NS(b"ns1.example.com"))],
"additional": [(b"ns1.example.com", Record_A("34.55.89.144"))],
},
},
("34.55.89.144", 53): {
(b"foo.example.com", A): {
"answers": [(b"foo.example.com", Record_A("10.0.0.1"))],
}
},
}
resolver = self._getResolver(servers)
d = resolver.lookupAddress(b"foo.example.com")
d.addCallback(getOneAddress)
d.addCallback(self.assertEqual, "10.0.0.1")
return d
def test_lookupChecksClass(self):
"""
If a response includes a record with a class different from the one
in the query, it is ignored and lookup continues until a record with
the right class is found.
"""
badClass = Record_A("10.0.0.1")
badClass.CLASS = HS
servers = {
("1.1.2.3", 53): {
(b"foo.example.com", A): {
"answers": [(b"foo.example.com", badClass)],
"authority": [(b"foo.example.com", Record_NS(b"ns1.example.com"))],
"additional": [(b"ns1.example.com", Record_A("10.0.0.2"))],
},
},
("10.0.0.2", 53): {
(b"foo.example.com", A): {
"answers": [(b"foo.example.com", Record_A("10.0.0.3"))],
},
},
}
resolver = self._getResolver(servers)
d = resolver.lookupAddress(b"foo.example.com")
d.addCallback(getOnePayload)
d.addCallback(self.assertEqual, Record_A("10.0.0.3"))
return d
def test_missingGlue(self):
"""
If an intermediate response includes no glue records for the
authorities, separate queries are made to find those addresses.
"""
servers = {
("1.1.2.3", 53): {
(b"foo.example.com", A): {
"authority": [(b"foo.example.com", Record_NS(b"ns1.example.org"))],
# Conspicuous lack of an additional section naming ns1.example.com
},
(b"ns1.example.org", A): {
"answers": [(b"ns1.example.org", Record_A("10.0.0.1"))],
},
},
("10.0.0.1", 53): {
(b"foo.example.com", A): {
"answers": [(b"foo.example.com", Record_A("10.0.0.2"))],
},
},
}
resolver = self._getResolver(servers)
d = resolver.lookupAddress(b"foo.example.com")
d.addCallback(getOneAddress)
d.addCallback(self.assertEqual, "10.0.0.2")
return d
def test_missingName(self):
"""
If a name is missing, L{Resolver.lookupAddress} returns a L{Deferred}
which fails with L{DNSNameError}.
"""
servers = {
("1.1.2.3", 53): {
(b"foo.example.com", A): {
"rCode": ENAME,
},
},
}
resolver = self._getResolver(servers)
d = resolver.lookupAddress(b"foo.example.com")
return self.assertFailure(d, DNSNameError)
def test_answerless(self):
"""
If a query is responded to with no answers or nameserver records, the
L{Deferred} returned by L{Resolver.lookupAddress} fires with
L{ResolverError}.
"""
servers = {
("1.1.2.3", 53): {
(b"example.com", A): {},
},
}
resolver = self._getResolver(servers)
d = resolver.lookupAddress(b"example.com")
return self.assertFailure(d, ResolverError)
def test_delegationLookupError(self):
"""
If there is an error resolving the nameserver in a delegation response,
the L{Deferred} returned by L{Resolver.lookupAddress} fires with that
error.
"""
servers = {
("1.1.2.3", 53): {
(b"example.com", A): {
"authority": [(b"example.com", Record_NS(b"ns1.example.com"))],
},
(b"ns1.example.com", A): {
"rCode": ENAME,
},
},
}
resolver = self._getResolver(servers)
d = resolver.lookupAddress(b"example.com")
return self.assertFailure(d, DNSNameError)
def test_delegationLookupEmpty(self):
"""
If there are no records in the response to a lookup of a delegation
nameserver, the L{Deferred} returned by L{Resolver.lookupAddress} fires
with L{ResolverError}.
"""
servers = {
("1.1.2.3", 53): {
(b"example.com", A): {
"authority": [(b"example.com", Record_NS(b"ns1.example.com"))],
},
(b"ns1.example.com", A): {},
},
}
resolver = self._getResolver(servers)
d = resolver.lookupAddress(b"example.com")
return self.assertFailure(d, ResolverError)
def test_lookupNameservers(self):
"""
L{Resolver.lookupNameservers} is like L{Resolver.lookupAddress}, except
it queries for I{NS} records instead of I{A} records.
"""
servers = {
("1.1.2.3", 53): {
(b"example.com", A): {
"rCode": ENAME,
},
(b"example.com", NS): {
"answers": [(b"example.com", Record_NS(b"ns1.example.com"))],
},
},
}
resolver = self._getResolver(servers)
d = resolver.lookupNameservers(b"example.com")
def getOneName(results):
ans, auth, add = results
return ans[0].payload.name
d.addCallback(getOneName)
d.addCallback(self.assertEqual, Name(b"ns1.example.com"))
return d
def test_returnCanonicalName(self):
"""
If a I{CNAME} record is encountered as the answer to a query for
another record type, that record is returned as the answer.
"""
servers = {
("1.1.2.3", 53): {
(b"example.com", A): {
"answers": [
(b"example.com", Record_CNAME(b"example.net")),
(b"example.net", Record_A("10.0.0.7")),
],
},
},
}
resolver = self._getResolver(servers)
d = resolver.lookupAddress(b"example.com")
d.addCallback(lambda results: results[0]) # Get the answer section
d.addCallback(
self.assertEqual,
[
RRHeader(b"example.com", CNAME, payload=Record_CNAME(b"example.net")),
RRHeader(b"example.net", A, payload=Record_A("10.0.0.7")),
],
)
return d
def test_followCanonicalName(self):
"""
If no record of the requested type is included in a response, but a
I{CNAME} record for the query name is included, queries are made to
resolve the value of the I{CNAME}.
"""
servers = {
("1.1.2.3", 53): {
(b"example.com", A): {
"answers": [(b"example.com", Record_CNAME(b"example.net"))],
},
(b"example.net", A): {
"answers": [(b"example.net", Record_A("10.0.0.5"))],
},
},
}
resolver = self._getResolver(servers)
d = resolver.lookupAddress(b"example.com")
d.addCallback(lambda results: results[0]) # Get the answer section
d.addCallback(
self.assertEqual,
[
RRHeader(b"example.com", CNAME, payload=Record_CNAME(b"example.net")),
RRHeader(b"example.net", A, payload=Record_A("10.0.0.5")),
],
)
return d
def test_detectCanonicalNameLoop(self):
"""
If there is a cycle between I{CNAME} records in a response, this is
detected and the L{Deferred} returned by the lookup method fails
with L{ResolverError}.
"""
servers = {
("1.1.2.3", 53): {
(b"example.com", A): {
"answers": [
(b"example.com", Record_CNAME(b"example.net")),
(b"example.net", Record_CNAME(b"example.com")),
],
},
},
}
resolver = self._getResolver(servers)
d = resolver.lookupAddress(b"example.com")
return self.assertFailure(d, ResolverError)
def test_boundedQueries(self):
"""
L{Resolver.lookupAddress} won't issue more queries following
delegations than the limit passed to its initializer.
"""
servers = {
("1.1.2.3", 53): {
# First query - force it to start over with a name lookup of
# ns1.example.com
(b"example.com", A): {
"authority": [(b"example.com", Record_NS(b"ns1.example.com"))],
},
# Second query - let it resume the original lookup with the
# address of the nameserver handling the delegation.
(b"ns1.example.com", A): {
"answers": [(b"ns1.example.com", Record_A("10.0.0.2"))],
},
},
("10.0.0.2", 53): {
# Third query - let it jump straight to asking the
# delegation server by including its address here (different
# case from the first query).
(b"example.com", A): {
"authority": [(b"example.com", Record_NS(b"ns2.example.com"))],
"additional": [(b"ns2.example.com", Record_A("10.0.0.3"))],
},
},
("10.0.0.3", 53): {
# Fourth query - give it the answer, we're done.
(b"example.com", A): {
"answers": [(b"example.com", Record_A("10.0.0.4"))],
},
},
}
# Make two resolvers. One which is allowed to make 3 queries
# maximum, and so will fail, and on which may make 4, and so should
# succeed.
failer = self._getResolver(servers, 3)
failD = self.assertFailure(failer.lookupAddress(b"example.com"), ResolverError)
succeeder = self._getResolver(servers, 4)
succeedD = succeeder.lookupAddress(b"example.com")
succeedD.addCallback(getOnePayload)
succeedD.addCallback(self.assertEqual, Record_A("10.0.0.4"))
return gatherResults([failD, succeedD])
class ResolverFactoryArguments(Exception):
"""
Raised by L{raisingResolverFactory} with the *args and **kwargs passed to
that function.
"""
def __init__(self, args, kwargs):
"""
Store the supplied args and kwargs as attributes.
@param args: Positional arguments.
@param kwargs: Keyword arguments.
"""
self.args = args
self.kwargs = kwargs
def raisingResolverFactory(*args, **kwargs):
"""
Raise a L{ResolverFactoryArguments} exception containing the
positional and keyword arguments passed to resolverFactory.
@param args: A L{list} of all the positional arguments supplied by
the caller.
@param kwargs: A L{list} of all the keyword arguments supplied by
the caller.
"""
raise ResolverFactoryArguments(args, kwargs)
class RootResolverResolverFactoryTests(TestCase):
"""
Tests for L{root.Resolver._resolverFactory}.
"""
def test_resolverFactoryArgumentPresent(self):
"""
L{root.Resolver.__init__} accepts a C{resolverFactory}
argument and assigns it to C{self._resolverFactory}.
"""
r = Resolver(hints=[None], resolverFactory=raisingResolverFactory)
self.assertIs(r._resolverFactory, raisingResolverFactory)
def test_resolverFactoryArgumentAbsent(self):
"""
L{root.Resolver.__init__} sets L{client.Resolver} as the
C{_resolverFactory} if a C{resolverFactory} argument is not
supplied.
"""
r = Resolver(hints=[None])
self.assertIs(r._resolverFactory, client.Resolver)
def test_resolverFactoryOnlyExpectedArguments(self):
"""
L{root.Resolver._resolverFactory} is supplied with C{reactor} and
C{servers} keyword arguments.
"""
dummyReactor = object()
r = Resolver(
hints=["192.0.2.101"],
resolverFactory=raisingResolverFactory,
reactor=dummyReactor,
)
e = self.assertRaises(ResolverFactoryArguments, r.lookupAddress, "example.com")
self.assertEqual(
((), {"reactor": dummyReactor, "servers": [("192.0.2.101", 53)]}),
(e.args, e.kwargs),
)
ROOT_SERVERS = [
"a.root-servers.net",
"b.root-servers.net",
"c.root-servers.net",
"d.root-servers.net",
"e.root-servers.net",
"f.root-servers.net",
"g.root-servers.net",
"h.root-servers.net",
"i.root-servers.net",
"j.root-servers.net",
"k.root-servers.net",
"l.root-servers.net",
"m.root-servers.net",
]
@implementer(IResolverSimple)
class StubResolver:
"""
An L{IResolverSimple} implementer which traces all getHostByName
calls and their deferred results. The deferred results can be
accessed and fired synchronously.
"""
def __init__(self):
"""
@type calls: L{list} of L{tuple} containing C{args} and
C{kwargs} supplied to C{getHostByName} calls.
@type pendingResults: L{list} of L{Deferred} returned by
C{getHostByName}.
"""
self.calls = []
self.pendingResults = []
def getHostByName(self, *args, **kwargs):
"""
A fake implementation of L{IResolverSimple.getHostByName}
@param args: A L{list} of all the positional arguments supplied by
the caller.
@param kwargs: A L{list} of all the keyword arguments supplied by
the caller.
@return: A L{Deferred} which may be fired later from the test
fixture.
"""
self.calls.append((args, kwargs))
d = Deferred()
self.pendingResults.append(d)
return d
verifyClass(IResolverSimple, StubResolver)
class BootstrapTests(SynchronousTestCase):
"""
Tests for L{root.bootstrap}
"""
def test_returnsDeferredResolver(self):
"""
L{root.bootstrap} returns an object which is initially a
L{root.DeferredResolver}.
"""
deferredResolver = root.bootstrap(StubResolver())
self.assertIsInstance(deferredResolver, root.DeferredResolver)
def test_resolves13RootServers(self):
"""
The L{IResolverSimple} supplied to L{root.bootstrap} is used to lookup
the IP addresses of the 13 root name servers.
"""
stubResolver = StubResolver()
root.bootstrap(stubResolver)
self.assertEqual(stubResolver.calls, [((s,), {}) for s in ROOT_SERVERS])
def test_becomesResolver(self):
"""
The L{root.DeferredResolver} initially returned by L{root.bootstrap}
becomes a L{root.Resolver} when the supplied resolver has successfully
looked up all root hints.
"""
stubResolver = StubResolver()
deferredResolver = root.bootstrap(stubResolver)
for d in stubResolver.pendingResults:
d.callback("192.0.2.101")
self.assertIsInstance(deferredResolver, Resolver)
def test_resolverReceivesRootHints(self):
"""
The L{root.Resolver} which eventually replaces L{root.DeferredResolver}
is supplied with the IP addresses of the 13 root servers.
"""
stubResolver = StubResolver()
deferredResolver = root.bootstrap(stubResolver)
for d in stubResolver.pendingResults:
d.callback("192.0.2.101")
self.assertEqual(deferredResolver.hints, ["192.0.2.101"] * 13)
def test_continuesWhenSomeRootHintsFail(self):
"""
The L{root.Resolver} is eventually created, even if some of the root
hint lookups fail. Only the working root hint IP addresses are supplied
to the L{root.Resolver}.
"""
stubResolver = StubResolver()
deferredResolver = root.bootstrap(stubResolver)
results = iter(stubResolver.pendingResults)
d1 = next(results)
for d in results:
d.callback("192.0.2.101")
d1.errback(TimeoutError())
def checkHints(res):
self.assertEqual(deferredResolver.hints, ["192.0.2.101"] * 12)
d1.addBoth(checkHints)
def test_continuesWhenAllRootHintsFail(self):
"""
The L{root.Resolver} is eventually created, even if all of the root hint
lookups fail. Pending and new lookups will then fail with
AttributeError.
"""
stubResolver = StubResolver()
deferredResolver = root.bootstrap(stubResolver)
results = iter(stubResolver.pendingResults)
d1 = next(results)
for d in results:
d.errback(TimeoutError())
d1.errback(TimeoutError())
def checkHints(res):
self.assertEqual(deferredResolver.hints, [])
d1.addBoth(checkHints)
self.addCleanup(self.flushLoggedErrors, TimeoutError)
def test_passesResolverFactory(self):
"""
L{root.bootstrap} accepts a C{resolverFactory} argument which is passed
as an argument to L{root.Resolver} when it has successfully looked up
root hints.
"""
stubResolver = StubResolver()
deferredResolver = root.bootstrap(
stubResolver, resolverFactory=raisingResolverFactory
)
for d in stubResolver.pendingResults:
d.callback("192.0.2.101")
self.assertIs(deferredResolver._resolverFactory, raisingResolverFactory)
class StubDNSDatagramProtocol:
"""
A do-nothing stand-in for L{DNSDatagramProtocol} which can be used to avoid
network traffic in tests where that kind of thing doesn't matter.
"""
def query(self, *a, **kw):
return Deferred()
_retrySuppression = util.suppress(
category=DeprecationWarning,
message=(
"twisted.names.root.retry is deprecated since Twisted 10.0. Use a "
"Resolver object for retry logic."
),
)
Zerion Mini Shell 1.0