diff options
| -rw-r--r-- | changelog.d/5836.misc | 1 | ||||
| -rw-r--r-- | synapse/http/federation/matrix_federation_agent.py | 162 | ||||
| -rw-r--r-- | synapse/http/federation/well_known_resolver.py | 187 | ||||
| -rw-r--r-- | tests/http/federation/test_matrix_federation_agent.py | 43 |
4 files changed, 222 insertions, 171 deletions
diff --git a/changelog.d/5836.misc b/changelog.d/5836.misc new file mode 100644 index 0000000000..18f2488201 --- /dev/null +++ b/changelog.d/5836.misc @@ -0,0 +1 @@ +Add a lower bound to well-known lookup cache time to avoid repeated lookups. diff --git a/synapse/http/federation/matrix_federation_agent.py b/synapse/http/federation/matrix_federation_agent.py index a0d5139839..71a15f434d 100644 --- a/synapse/http/federation/matrix_federation_agent.py +++ b/synapse/http/federation/matrix_federation_agent.py @@ -12,10 +12,8 @@ # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. -import json + import logging -import random -import time import attr from netaddr import IPAddress @@ -24,31 +22,16 @@ from zope.interface import implementer from twisted.internet import defer from twisted.internet.endpoints import HostnameEndpoint, wrapClientTLS from twisted.internet.interfaces import IStreamClientEndpoint -from twisted.web.client import URI, Agent, HTTPConnectionPool, RedirectAgent, readBody -from twisted.web.http import stringToDatetime +from twisted.web.client import URI, Agent, HTTPConnectionPool from twisted.web.http_headers import Headers from twisted.web.iweb import IAgent from synapse.http.federation.srv_resolver import SrvResolver, pick_server_from_list +from synapse.http.federation.well_known_resolver import WellKnownResolver from synapse.logging.context import make_deferred_yieldable from synapse.util import Clock -from synapse.util.caches.ttlcache import TTLCache -from synapse.util.metrics import Measure - -# period to cache .well-known results for by default -WELL_KNOWN_DEFAULT_CACHE_PERIOD = 24 * 3600 - -# jitter to add to the .well-known default cache ttl -WELL_KNOWN_DEFAULT_CACHE_PERIOD_JITTER = 10 * 60 - -# period to cache failure to fetch .well-known for -WELL_KNOWN_INVALID_CACHE_PERIOD = 1 * 3600 - -# cap for .well-known cache period -WELL_KNOWN_MAX_CACHE_PERIOD = 48 * 3600 logger = logging.getLogger(__name__) -well_known_cache = TTLCache("well-known") @implementer(IAgent) @@ -78,7 +61,7 @@ class MatrixFederationAgent(object): reactor, tls_client_options_factory, _srv_resolver=None, - _well_known_cache=well_known_cache, + _well_known_cache=None, ): self._reactor = reactor self._clock = Clock(reactor) @@ -93,20 +76,15 @@ class MatrixFederationAgent(object): self._pool.maxPersistentPerHost = 5 self._pool.cachedConnectionTimeout = 2 * 60 - _well_known_agent = RedirectAgent( - Agent( + self._well_known_resolver = WellKnownResolver( + self._reactor, + agent=Agent( self._reactor, pool=self._pool, contextFactory=tls_client_options_factory, - ) + ), + well_known_cache=_well_known_cache, ) - self._well_known_agent = _well_known_agent - - # our cache of .well-known lookup results, mapping from server name - # to delegated name. The values can be: - # `bytes`: a valid server-name - # `None`: there is no (valid) .well-known here - self._well_known_cache = _well_known_cache @defer.inlineCallbacks def request(self, method, uri, headers=None, bodyProducer=None): @@ -217,7 +195,10 @@ class MatrixFederationAgent(object): if lookup_well_known: # try a .well-known lookup - well_known_server = yield self._get_well_known(parsed_uri.host) + well_known_result = yield self._well_known_resolver.get_well_known( + parsed_uri.host + ) + well_known_server = well_known_result.delegated_server if well_known_server: # if we found a .well-known, start again, but don't do another @@ -280,85 +261,6 @@ class MatrixFederationAgent(object): target_port=port, ) - @defer.inlineCallbacks - def _get_well_known(self, server_name): - """Attempt to fetch and parse a .well-known file for the given server - - Args: - server_name (bytes): name of the server, from the requested url - - Returns: - Deferred[bytes|None]: either the new server name, from the .well-known, or - None if there was no .well-known file. - """ - try: - result = self._well_known_cache[server_name] - except KeyError: - # TODO: should we linearise so that we don't end up doing two .well-known - # requests for the same server in parallel? - with Measure(self._clock, "get_well_known"): - result, cache_period = yield self._do_get_well_known(server_name) - - if cache_period > 0: - self._well_known_cache.set(server_name, result, cache_period) - - return result - - @defer.inlineCallbacks - def _do_get_well_known(self, server_name): - """Actually fetch and parse a .well-known, without checking the cache - - Args: - server_name (bytes): name of the server, from the requested url - - Returns: - Deferred[Tuple[bytes|None|object],int]: - result, cache period, where result is one of: - - the new server name from the .well-known (as a `bytes`) - - None if there was no .well-known file. - - INVALID_WELL_KNOWN if the .well-known was invalid - """ - uri = b"https://%s/.well-known/matrix/server" % (server_name,) - uri_str = uri.decode("ascii") - logger.info("Fetching %s", uri_str) - try: - response = yield make_deferred_yieldable( - self._well_known_agent.request(b"GET", uri) - ) - body = yield make_deferred_yieldable(readBody(response)) - if response.code != 200: - raise Exception("Non-200 response %s" % (response.code,)) - - parsed_body = json.loads(body.decode("utf-8")) - logger.info("Response from .well-known: %s", parsed_body) - if not isinstance(parsed_body, dict): - raise Exception("not a dict") - if "m.server" not in parsed_body: - raise Exception("Missing key 'm.server'") - except Exception as e: - logger.info("Error fetching %s: %s", uri_str, e) - - # add some randomness to the TTL to avoid a stampeding herd every hour - # after startup - cache_period = WELL_KNOWN_INVALID_CACHE_PERIOD - cache_period += random.uniform(0, WELL_KNOWN_DEFAULT_CACHE_PERIOD_JITTER) - return (None, cache_period) - - result = parsed_body["m.server"].encode("ascii") - - cache_period = _cache_period_from_headers( - response.headers, time_now=self._reactor.seconds - ) - if cache_period is None: - cache_period = WELL_KNOWN_DEFAULT_CACHE_PERIOD - # add some randomness to the TTL to avoid a stampeding herd every 24 hours - # after startup - cache_period += random.uniform(0, WELL_KNOWN_DEFAULT_CACHE_PERIOD_JITTER) - else: - cache_period = min(cache_period, WELL_KNOWN_MAX_CACHE_PERIOD) - - return (result, cache_period) - @implementer(IStreamClientEndpoint) class LoggingHostnameEndpoint(object): @@ -374,44 +276,6 @@ class LoggingHostnameEndpoint(object): return self.ep.connect(protocol_factory) -def _cache_period_from_headers(headers, time_now=time.time): - cache_controls = _parse_cache_control(headers) - - if b"no-store" in cache_controls: - return 0 - - if b"max-age" in cache_controls: - try: - max_age = int(cache_controls[b"max-age"]) - return max_age - except ValueError: - pass - - expires = headers.getRawHeaders(b"expires") - if expires is not None: - try: - expires_date = stringToDatetime(expires[-1]) - return expires_date - time_now() - except ValueError: - # RFC7234 says 'A cache recipient MUST interpret invalid date formats, - # especially the value "0", as representing a time in the past (i.e., - # "already expired"). - return 0 - - return None - - -def _parse_cache_control(headers): - cache_controls = {} - for hdr in headers.getRawHeaders(b"cache-control", []): - for directive in hdr.split(b","): - splits = [x.strip() for x in directive.split(b"=", 1)] - k = splits[0].lower() - v = splits[1] if len(splits) > 1 else None - cache_controls[k] = v - return cache_controls - - @attr.s class _RoutingResult(object): """The result returned by `_route_matrix_uri`. diff --git a/synapse/http/federation/well_known_resolver.py b/synapse/http/federation/well_known_resolver.py new file mode 100644 index 0000000000..d2866ff67d --- /dev/null +++ b/synapse/http/federation/well_known_resolver.py @@ -0,0 +1,187 @@ +# -*- coding: utf-8 -*- +# Copyright 2019 The Matrix.org Foundation C.I.C. +# +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. + +import json +import logging +import random +import time + +import attr + +from twisted.internet import defer +from twisted.web.client import RedirectAgent, readBody +from twisted.web.http import stringToDatetime + +from synapse.logging.context import make_deferred_yieldable +from synapse.util import Clock +from synapse.util.caches.ttlcache import TTLCache +from synapse.util.metrics import Measure + +# period to cache .well-known results for by default +WELL_KNOWN_DEFAULT_CACHE_PERIOD = 24 * 3600 + +# jitter to add to the .well-known default cache ttl +WELL_KNOWN_DEFAULT_CACHE_PERIOD_JITTER = 10 * 60 + +# period to cache failure to fetch .well-known for +WELL_KNOWN_INVALID_CACHE_PERIOD = 1 * 3600 + +# cap for .well-known cache period +WELL_KNOWN_MAX_CACHE_PERIOD = 48 * 3600 + +# lower bound for .well-known cache period +WELL_KNOWN_MIN_CACHE_PERIOD = 5 * 60 + +logger = logging.getLogger(__name__) + + +_well_known_cache = TTLCache("well-known") + + +@attr.s(slots=True, frozen=True) +class WellKnownLookupResult(object): + delegated_server = attr.ib() + + +class WellKnownResolver(object): + """Handles well-known lookups for matrix servers. + """ + + def __init__(self, reactor, agent, well_known_cache=None): + self._reactor = reactor + self._clock = Clock(reactor) + + if well_known_cache is None: + well_known_cache = _well_known_cache + + self._well_known_cache = well_known_cache + self._well_known_agent = RedirectAgent(agent) + + @defer.inlineCallbacks + def get_well_known(self, server_name): + """Attempt to fetch and parse a .well-known file for the given server + + Args: + server_name (bytes): name of the server, from the requested url + + Returns: + Deferred[WellKnownLookupResult]: The result of the lookup + """ + try: + result = self._well_known_cache[server_name] + except KeyError: + # TODO: should we linearise so that we don't end up doing two .well-known + # requests for the same server in parallel? + with Measure(self._clock, "get_well_known"): + result, cache_period = yield self._do_get_well_known(server_name) + + if cache_period > 0: + self._well_known_cache.set(server_name, result, cache_period) + + return WellKnownLookupResult(delegated_server=result) + + @defer.inlineCallbacks + def _do_get_well_known(self, server_name): + """Actually fetch and parse a .well-known, without checking the cache + + Args: + server_name (bytes): name of the server, from the requested url + + Returns: + Deferred[Tuple[bytes|None|object],int]: + result, cache period, where result is one of: + - the new server name from the .well-known (as a `bytes`) + - None if there was no .well-known file. + - INVALID_WELL_KNOWN if the .well-known was invalid + """ + uri = b"https://%s/.well-known/matrix/server" % (server_name,) + uri_str = uri.decode("ascii") + logger.info("Fetching %s", uri_str) + try: + response = yield make_deferred_yieldable( + self._well_known_agent.request(b"GET", uri) + ) + body = yield make_deferred_yieldable(readBody(response)) + if response.code != 200: + raise Exception("Non-200 response %s" % (response.code,)) + + parsed_body = json.loads(body.decode("utf-8")) + logger.info("Response from .well-known: %s", parsed_body) + if not isinstance(parsed_body, dict): + raise Exception("not a dict") + if "m.server" not in parsed_body: + raise Exception("Missing key 'm.server'") + except Exception as e: + logger.info("Error fetching %s: %s", uri_str, e) + + # add some randomness to the TTL to avoid a stampeding herd every hour + # after startup + cache_period = WELL_KNOWN_INVALID_CACHE_PERIOD + cache_period += random.uniform(0, WELL_KNOWN_DEFAULT_CACHE_PERIOD_JITTER) + return (None, cache_period) + + result = parsed_body["m.server"].encode("ascii") + + cache_period = _cache_period_from_headers( + response.headers, time_now=self._reactor.seconds + ) + if cache_period is None: + cache_period = WELL_KNOWN_DEFAULT_CACHE_PERIOD + # add some randomness to the TTL to avoid a stampeding herd every 24 hours + # after startup + cache_period += random.uniform(0, WELL_KNOWN_DEFAULT_CACHE_PERIOD_JITTER) + else: + cache_period = min(cache_period, WELL_KNOWN_MAX_CACHE_PERIOD) + cache_period = max(cache_period, WELL_KNOWN_MIN_CACHE_PERIOD) + + return (result, cache_period) + + +def _cache_period_from_headers(headers, time_now=time.time): + cache_controls = _parse_cache_control(headers) + + if b"no-store" in cache_controls: + return 0 + + if b"max-age" in cache_controls: + try: + max_age = int(cache_controls[b"max-age"]) + return max_age + except ValueError: + pass + + expires = headers.getRawHeaders(b"expires") + if expires is not None: + try: + expires_date = stringToDatetime(expires[-1]) + return expires_date - time_now() + except ValueError: + # RFC7234 says 'A cache recipient MUST interpret invalid date formats, + # especially the value "0", as representing a time in the past (i.e., + # "already expired"). + return 0 + + return None + + +def _parse_cache_control(headers): + cache_controls = {} + for hdr in headers.getRawHeaders(b"cache-control", []): + for directive in hdr.split(b","): + splits = [x.strip() for x in directive.split(b"=", 1)] + k = splits[0].lower() + v = splits[1] if len(splits) > 1 else None + cache_controls[k] = v + return cache_controls diff --git a/tests/http/federation/test_matrix_federation_agent.py b/tests/http/federation/test_matrix_federation_agent.py index 4255add097..1435baede2 100644 --- a/tests/http/federation/test_matrix_federation_agent.py +++ b/tests/http/federation/test_matrix_federation_agent.py @@ -25,17 +25,19 @@ from twisted.internet._sslverify import ClientTLSOptions, OpenSSLCertificateOpti from twisted.internet.protocol import Factory from twisted.protocols.tls import TLSMemoryBIOFactory from twisted.web._newclient import ResponseNeverReceived +from twisted.web.client import Agent from twisted.web.http import HTTPChannel from twisted.web.http_headers import Headers from twisted.web.iweb import IPolicyForHTTPS from synapse.config.homeserver import HomeServerConfig from synapse.crypto.context_factory import ClientTLSOptionsFactory -from synapse.http.federation.matrix_federation_agent import ( - MatrixFederationAgent, +from synapse.http.federation.matrix_federation_agent import MatrixFederationAgent +from synapse.http.federation.srv_resolver import Server +from synapse.http.federation.well_known_resolver import ( + WellKnownResolver, _cache_period_from_headers, ) -from synapse.http.federation.srv_resolver import Server from synapse.logging.context import LoggingContext from synapse.util.caches.ttlcache import TTLCache @@ -79,9 +81,10 @@ class MatrixFederationAgentTests(TestCase): self._config = config = HomeServerConfig() config.parse_config_dict(config_dict, "", "") + self.tls_factory = ClientTLSOptionsFactory(config) self.agent = MatrixFederationAgent( reactor=self.reactor, - tls_client_options_factory=ClientTLSOptionsFactory(config), + tls_client_options_factory=self.tls_factory, _srv_resolver=self.mock_resolver, _well_known_cache=self.well_known_cache, ) @@ -928,20 +931,16 @@ class MatrixFederationAgentTests(TestCase): self.reactor.pump((0.1,)) self.successResultOf(test_d) - @defer.inlineCallbacks - def do_get_well_known(self, serv): - try: - result = yield self.agent._get_well_known(serv) - logger.info("Result from well-known fetch: %s", result) - except Exception as e: - logger.warning("Error fetching well-known: %s", e) - raise - return result - def test_well_known_cache(self): + well_known_resolver = WellKnownResolver( + self.reactor, + Agent(self.reactor, contextFactory=self.tls_factory), + well_known_cache=self.well_known_cache, + ) + self.reactor.lookups["testserv"] = "1.2.3.4" - fetch_d = self.do_get_well_known(b"testserv") + fetch_d = well_known_resolver.get_well_known(b"testserv") # there should be an attempt to connect on port 443 for the .well-known clients = self.reactor.tcpClients @@ -953,26 +952,26 @@ class MatrixFederationAgentTests(TestCase): well_known_server = self._handle_well_known_connection( client_factory, expected_sni=b"testserv", - response_headers={b"Cache-Control": b"max-age=10"}, + response_headers={b"Cache-Control": b"max-age=1000"}, content=b'{ "m.server": "target-server" }', ) r = self.successResultOf(fetch_d) - self.assertEqual(r, b"target-server") + self.assertEqual(r.delegated_server, b"target-server") # close the tcp connection well_known_server.loseConnection() # repeat the request: it should hit the cache - fetch_d = self.do_get_well_known(b"testserv") + fetch_d = well_known_resolver.get_well_known(b"testserv") r = self.successResultOf(fetch_d) - self.assertEqual(r, b"target-server") + self.assertEqual(r.delegated_server, b"target-server") # expire the cache - self.reactor.pump((10.0,)) + self.reactor.pump((1000.0,)) # now it should connect again - fetch_d = self.do_get_well_known(b"testserv") + fetch_d = well_known_resolver.get_well_known(b"testserv") self.assertEqual(len(clients), 1) (host, port, client_factory, _timeout, _bindAddress) = clients.pop(0) @@ -986,7 +985,7 @@ class MatrixFederationAgentTests(TestCase): ) r = self.successResultOf(fetch_d) - self.assertEqual(r, b"other-server") + self.assertEqual(r.delegated_server, b"other-server") class TestCachePeriodFromHeaders(TestCase): |