diff options
| -rw-r--r-- | synapse/http/federation/matrix_federation_agent.py | 16 | ||||
| -rw-r--r-- | synapse/http/federation/srv_resolver.py | 133 | ||||
| -rw-r--r-- | tests/http/federation/test_srv_resolver.py | 38 |
3 files changed, 104 insertions, 83 deletions
diff --git a/synapse/http/federation/matrix_federation_agent.py b/synapse/http/federation/matrix_federation_agent.py index 32bfd68ed1..64c780a341 100644 --- a/synapse/http/federation/matrix_federation_agent.py +++ b/synapse/http/federation/matrix_federation_agent.py @@ -22,7 +22,7 @@ from twisted.web.client import URI, Agent, HTTPConnectionPool from twisted.web.iweb import IAgent from synapse.http.endpoint import parse_server_name -from synapse.http.federation.srv_resolver import pick_server_from_list, resolve_service +from synapse.http.federation.srv_resolver import SrvResolver, pick_server_from_list from synapse.util.logcontext import make_deferred_yieldable logger = logging.getLogger(__name__) @@ -37,13 +37,23 @@ class MatrixFederationAgent(object): Args: reactor (IReactor): twisted reactor to use for underlying requests + tls_client_options_factory (ClientTLSOptionsFactory|None): factory to use for fetching client tls options, or none to disable TLS. + + srv_resolver (SrvResolver|None): + SRVResolver impl to use for looking up SRV records. None to use a default + implementation. """ - def __init__(self, reactor, tls_client_options_factory): + def __init__( + self, reactor, tls_client_options_factory, _srv_resolver=None, + ): self._reactor = reactor self._tls_client_options_factory = tls_client_options_factory + if _srv_resolver is None: + _srv_resolver = SrvResolver() + self._srv_resolver = _srv_resolver self._pool = HTTPConnectionPool(reactor) self._pool.retryAutomatically = False @@ -91,7 +101,7 @@ class MatrixFederationAgent(object): if port is not None: target = (host, port) else: - server_list = yield resolve_service(server_name_bytes) + server_list = yield self._srv_resolver.resolve_service(server_name_bytes) if not server_list: target = (host, 8448) logger.debug("No SRV record for %s, using %s", host, target) diff --git a/synapse/http/federation/srv_resolver.py b/synapse/http/federation/srv_resolver.py index e05f934d0b..71830c549d 100644 --- a/synapse/http/federation/srv_resolver.py +++ b/synapse/http/federation/srv_resolver.py @@ -84,73 +84,86 @@ def pick_server_from_list(server_list): ) -@defer.inlineCallbacks -def resolve_service(service_name, dns_client=client, cache=SERVER_CACHE, clock=time): - """Look up a SRV record, with caching +class SrvResolver(object): + """Interface to the dns client to do SRV lookups, with result caching. The default resolver in twisted.names doesn't do any caching (it has a CacheResolver, but the cache never gets populated), so we add our own caching layer here. Args: - service_name (bytes): record to look up dns_client (twisted.internet.interfaces.IResolver): twisted resolver impl cache (dict): cache object - clock (object): clock implementation. must provide a time() method. - - Returns: - Deferred[list[Server]]: a list of the SRV records, or an empty list if none found + get_time (callable): clock implementation. Should return seconds since the epoch """ - if not isinstance(service_name, bytes): - raise TypeError("%r is not a byte string" % (service_name,)) - - cache_entry = cache.get(service_name, None) - if cache_entry: - if all(s.expires > int(clock.time()) for s in cache_entry): - servers = list(cache_entry) - defer.returnValue(servers) - - try: - answers, _, _ = yield make_deferred_yieldable( - dns_client.lookupService(service_name), - ) - except DNSNameError: - # TODO: cache this. We can get the SOA out of the exception, and use - # the negative-TTL value. - defer.returnValue([]) - except DomainError as e: - # We failed to resolve the name (other than a NameError) - # Try something in the cache, else rereaise - cache_entry = cache.get(service_name, None) + def __init__(self, dns_client=client, cache=SERVER_CACHE, get_time=time.time): + self._dns_client = dns_client + self._cache = cache + self._get_time = get_time + + @defer.inlineCallbacks + def resolve_service(self, service_name): + """Look up a SRV record + + Args: + service_name (bytes): record to look up + + Returns: + Deferred[list[Server]]: + a list of the SRV records, or an empty list if none found + """ + now = int(self._get_time()) + + if not isinstance(service_name, bytes): + raise TypeError("%r is not a byte string" % (service_name,)) + + cache_entry = self._cache.get(service_name, None) if cache_entry: - logger.warn( - "Failed to resolve %r, falling back to cache. %r", - service_name, e + if all(s.expires > now for s in cache_entry): + servers = list(cache_entry) + defer.returnValue(servers) + + try: + answers, _, _ = yield make_deferred_yieldable( + self._dns_client.lookupService(service_name), ) - defer.returnValue(list(cache_entry)) - else: - raise e - - if (len(answers) == 1 - and answers[0].type == dns.SRV - and answers[0].payload - and answers[0].payload.target == dns.Name(b'.')): - raise ConnectError("Service %s unavailable" % service_name) - - servers = [] - - for answer in answers: - if answer.type != dns.SRV or not answer.payload: - continue - - payload = answer.payload - - servers.append(Server( - host=payload.target.name, - port=payload.port, - priority=payload.priority, - weight=payload.weight, - expires=int(clock.time()) + answer.ttl, - )) - - cache[service_name] = list(servers) - defer.returnValue(servers) + except DNSNameError: + # TODO: cache this. We can get the SOA out of the exception, and use + # the negative-TTL value. + defer.returnValue([]) + except DomainError as e: + # We failed to resolve the name (other than a NameError) + # Try something in the cache, else rereaise + cache_entry = self._cache.get(service_name, None) + if cache_entry: + logger.warn( + "Failed to resolve %r, falling back to cache. %r", + service_name, e + ) + defer.returnValue(list(cache_entry)) + else: + raise e + + if (len(answers) == 1 + and answers[0].type == dns.SRV + and answers[0].payload + and answers[0].payload.target == dns.Name(b'.')): + raise ConnectError("Service %s unavailable" % service_name) + + servers = [] + + for answer in answers: + if answer.type != dns.SRV or not answer.payload: + continue + + payload = answer.payload + + servers.append(Server( + host=payload.target.name, + port=payload.port, + priority=payload.priority, + weight=payload.weight, + expires=now + answer.ttl, + )) + + self._cache[service_name] = list(servers) + defer.returnValue(servers) diff --git a/tests/http/federation/test_srv_resolver.py b/tests/http/federation/test_srv_resolver.py index de4d0089c8..a872e2441e 100644 --- a/tests/http/federation/test_srv_resolver.py +++ b/tests/http/federation/test_srv_resolver.py @@ -21,7 +21,7 @@ from twisted.internet.defer import Deferred from twisted.internet.error import ConnectError from twisted.names import dns, error -from synapse.http.federation.srv_resolver import resolve_service +from synapse.http.federation.srv_resolver import SrvResolver from synapse.util.logcontext import LoggingContext from tests import unittest @@ -43,13 +43,13 @@ class SrvResolverTestCase(unittest.TestCase): dns_client_mock.lookupService.return_value = result_deferred cache = {} + resolver = SrvResolver(dns_client=dns_client_mock, cache=cache) @defer.inlineCallbacks def do_lookup(): + with LoggingContext("one") as ctx: - resolve_d = resolve_service( - service_name, dns_client=dns_client_mock, cache=cache - ) + resolve_d = resolver.resolve_service(service_name) self.assertNoResult(resolve_d) @@ -89,10 +89,9 @@ class SrvResolverTestCase(unittest.TestCase): entry.expires = 0 cache = {service_name: [entry]} + resolver = SrvResolver(dns_client=dns_client_mock, cache=cache) - servers = yield resolve_service( - service_name, dns_client=dns_client_mock, cache=cache - ) + servers = yield resolver.resolve_service(service_name) dns_client_mock.lookupService.assert_called_once_with(service_name) @@ -112,11 +111,12 @@ class SrvResolverTestCase(unittest.TestCase): entry.expires = 999999999 cache = {service_name: [entry]} - - servers = yield resolve_service( - service_name, dns_client=dns_client_mock, cache=cache, clock=clock + resolver = SrvResolver( + dns_client=dns_client_mock, cache=cache, get_time=clock.time, ) + servers = yield resolver.resolve_service(service_name) + self.assertFalse(dns_client_mock.lookupService.called) self.assertEquals(len(servers), 1) @@ -131,9 +131,10 @@ class SrvResolverTestCase(unittest.TestCase): service_name = b"test_service.example.com" cache = {} + resolver = SrvResolver(dns_client=dns_client_mock, cache=cache) with self.assertRaises(error.DNSServerError): - yield resolve_service(service_name, dns_client=dns_client_mock, cache=cache) + yield resolver.resolve_service(service_name) @defer.inlineCallbacks def test_name_error(self): @@ -144,10 +145,9 @@ class SrvResolverTestCase(unittest.TestCase): service_name = b"test_service.example.com" cache = {} + resolver = SrvResolver(dns_client=dns_client_mock, cache=cache) - servers = yield resolve_service( - service_name, dns_client=dns_client_mock, cache=cache - ) + servers = yield resolver.resolve_service(service_name) self.assertEquals(len(servers), 0) self.assertEquals(len(cache), 0) @@ -162,10 +162,9 @@ class SrvResolverTestCase(unittest.TestCase): dns_client_mock = Mock() dns_client_mock.lookupService.return_value = lookup_deferred cache = {} + resolver = SrvResolver(dns_client=dns_client_mock, cache=cache) - resolve_d = resolve_service( - service_name, dns_client=dns_client_mock, cache=cache - ) + resolve_d = resolver.resolve_service(service_name) self.assertNoResult(resolve_d) # returning a single "." should make the lookup fail with a ConenctError @@ -187,10 +186,9 @@ class SrvResolverTestCase(unittest.TestCase): dns_client_mock = Mock() dns_client_mock.lookupService.return_value = lookup_deferred cache = {} + resolver = SrvResolver(dns_client=dns_client_mock, cache=cache) - resolve_d = resolve_service( - service_name, dns_client=dns_client_mock, cache=cache - ) + resolve_d = resolver.resolve_service(service_name) self.assertNoResult(resolve_d) lookup_deferred.callback(( |