diff options
Diffstat (limited to 'synapse/http/federation/matrix_federation_agent.py')
| -rw-r--r-- | synapse/http/federation/matrix_federation_agent.py | 90 |
1 files changed, 88 insertions, 2 deletions
diff --git a/synapse/http/federation/matrix_federation_agent.py b/synapse/http/federation/matrix_federation_agent.py index f81fcd4301..29804efe10 100644 --- a/synapse/http/federation/matrix_federation_agent.py +++ b/synapse/http/federation/matrix_federation_agent.py @@ -14,6 +14,8 @@ # limitations under the License. import json import logging +import random +import time import attr from netaddr import IPAddress @@ -22,13 +24,29 @@ from zope.interface import implementer from twisted.internet import defer from twisted.internet.endpoints import HostnameEndpoint, wrapClientTLS from twisted.web.client import URI, Agent, HTTPConnectionPool, readBody +from twisted.web.http import stringToDatetime 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.util.caches.ttlcache import TTLCache from synapse.util.logcontext import make_deferred_yieldable +# 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) @@ -57,6 +75,7 @@ class MatrixFederationAgent(object): self, reactor, tls_client_options_factory, _well_known_tls_policy=None, _srv_resolver=None, + _well_known_cache=well_known_cache, ): self._reactor = reactor self._tls_client_options_factory = tls_client_options_factory @@ -77,6 +96,8 @@ class MatrixFederationAgent(object): _well_known_agent = Agent(self._reactor, pool=self._pool, **agent_args) self._well_known_agent = _well_known_agent + self._well_known_cache = _well_known_cache + @defer.inlineCallbacks def request(self, method, uri, headers=None, bodyProducer=None): """ @@ -259,7 +280,14 @@ class MatrixFederationAgent(object): Deferred[bytes|None]: either the new server name, from the .well-known, or None if there was no .well-known file. """ - # FIXME: add a cache + try: + cached = self._well_known_cache[server_name] + defer.returnValue(cached) + except KeyError: + pass + + # TODO: should we linearise so that we don't end up doing two .well-known requests + # for the same server in parallel? uri = b"https://%s/.well-known/matrix/server" % (server_name, ) uri_str = uri.decode("ascii") @@ -270,12 +298,14 @@ class MatrixFederationAgent(object): ) except Exception as e: logger.info("Connection error fetching %s: %s", uri_str, e) + self._well_known_cache.set(server_name, None, WELL_KNOWN_INVALID_CACHE_PERIOD) defer.returnValue(None) body = yield make_deferred_yieldable(readBody(response)) if response.code != 200: logger.info("Error response %i from %s", response.code, uri_str) + self._well_known_cache.set(server_name, None, WELL_KNOWN_INVALID_CACHE_PERIOD) defer.returnValue(None) try: @@ -287,7 +317,63 @@ class MatrixFederationAgent(object): raise Exception("Missing key 'm.server'") except Exception as e: raise Exception("invalid .well-known response from %s: %s" % (uri_str, e,)) - defer.returnValue(parsed_body["m.server"].encode("ascii")) + + 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 hour after + # startup + cache_period += random.uniform(0, WELL_KNOWN_DEFAULT_CACHE_PERIOD_JITTER) + else: + cache_period = min(cache_period, WELL_KNOWN_MAX_CACHE_PERIOD) + + if cache_period > 0: + self._well_known_cache.set(server_name, result, cache_period) + + defer.returnValue(result) + + +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 |