forked-synapse/synapse/http/endpoint.py
Mark Haines 97ffc5690b Manually abort the underlying TLS connection.
The abort() method calls loseConnection() which tries to shutdown the
TLS connection cleanly. We now call abortConnection() directly which
should promptly close both the TLS connection and the underlying TCP
connection.

I also added some TODO markers to consider cancelling the old previous
timeout rather than checking time.time(). But given how urgently we want
to get this code released I'd rather leave the existing code with the
duplicate timeouts and the time.time() check.
2016-12-29 15:51:04 +00:00

318 lines
10 KiB
Python

# -*- coding: utf-8 -*-
# Copyright 2014-2016 OpenMarket Ltd
#
# 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.
from twisted.internet.endpoints import SSL4ClientEndpoint, TCP4ClientEndpoint
from twisted.internet import defer, reactor
from twisted.internet.error import ConnectError
from twisted.names import client, dns
from twisted.names.error import DNSNameError, DomainError
import collections
import logging
import random
import time
logger = logging.getLogger(__name__)
SERVER_CACHE = {}
_Server = collections.namedtuple(
"_Server", "priority weight host port expires"
)
def matrix_federation_endpoint(reactor, destination, ssl_context_factory=None,
timeout=None):
"""Construct an endpoint for the given matrix destination.
Args:
reactor: Twisted reactor.
destination (bytes): The name of the server to connect to.
ssl_context_factory (twisted.internet.ssl.ContextFactory): Factory
which generates SSL contexts to use for TLS.
timeout (int): connection timeout in seconds
"""
domain_port = destination.split(":")
domain = domain_port[0]
port = int(domain_port[1]) if domain_port[1:] else None
endpoint_kw_args = {}
if timeout is not None:
endpoint_kw_args.update(timeout=timeout)
if ssl_context_factory is None:
transport_endpoint = TCP4ClientEndpoint
default_port = 8008
else:
transport_endpoint = SSL4ClientEndpoint
endpoint_kw_args.update(sslContextFactory=ssl_context_factory)
default_port = 8448
if port is None:
return _WrappingEndpointFac(SRVClientEndpoint(
reactor, "matrix", domain, protocol="tcp",
default_port=default_port, endpoint=transport_endpoint,
endpoint_kw_args=endpoint_kw_args
))
else:
return _WrappingEndpointFac(transport_endpoint(
reactor, domain, port, **endpoint_kw_args
))
class _WrappingEndpointFac(object):
def __init__(self, endpoint_fac):
self.endpoint_fac = endpoint_fac
@defer.inlineCallbacks
def connect(self, protocolFactory):
conn = yield self.endpoint_fac.connect(protocolFactory)
conn = _WrappedConnection(conn)
defer.returnValue(conn)
class _WrappedConnection(object):
"""Wraps a connection and calls abort on it if it hasn't seen any action
for 2.5-3 minutes.
"""
__slots__ = ["conn", "last_request"]
def __init__(self, conn):
object.__setattr__(self, "conn", conn)
object.__setattr__(self, "last_request", time.time())
def __getattr__(self, name):
return getattr(self.conn, name)
def __setattr__(self, name, value):
setattr(self.conn, name, value)
def _time_things_out_maybe(self):
# We use a slightly shorter timeout here just in case the callLater is
# triggered early. Paranoia ftw.
# TODO: Cancel the previous callLater rather than comparing time.time()?
if time.time() - self.last_request >= 2.5 * 60:
self.abort()
# Abort the underlying TLS connection. The abort() method calls
# loseConnection() on the underlying TLS connection which tries to
# shutdown the connection cleanly. We call abortConnection()
# since that will promptly close the underlying TCP connection.
self.transport.abortConnection()
def request(self, request):
self.last_request = time.time()
# Time this connection out if we haven't send a request in the last
# N minutes
# TODO: Cancel the previous callLater?
reactor.callLater(3 * 60, self._time_things_out_maybe)
d = self.conn.request(request)
def update_request_time(res):
self.last_request = time.time()
# TODO: Cancel the previous callLater?
reactor.callLater(3 * 60, self._time_things_out_maybe)
return res
d.addCallback(update_request_time)
return d
class SpiderEndpoint(object):
"""An endpoint which refuses to connect to blacklisted IP addresses
Implements twisted.internet.interfaces.IStreamClientEndpoint.
"""
def __init__(self, reactor, host, port, blacklist, whitelist,
endpoint=TCP4ClientEndpoint, endpoint_kw_args={}):
self.reactor = reactor
self.host = host
self.port = port
self.blacklist = blacklist
self.whitelist = whitelist
self.endpoint = endpoint
self.endpoint_kw_args = endpoint_kw_args
@defer.inlineCallbacks
def connect(self, protocolFactory):
address = yield self.reactor.resolve(self.host)
from netaddr import IPAddress
ip_address = IPAddress(address)
if ip_address in self.blacklist:
if self.whitelist is None or ip_address not in self.whitelist:
raise ConnectError(
"Refusing to spider blacklisted IP address %s" % address
)
logger.info("Connecting to %s:%s", address, self.port)
endpoint = self.endpoint(
self.reactor, address, self.port, **self.endpoint_kw_args
)
connection = yield endpoint.connect(protocolFactory)
defer.returnValue(connection)
class SRVClientEndpoint(object):
"""An endpoint which looks up SRV records for a service.
Cycles through the list of servers starting with each call to connect
picking the next server.
Implements twisted.internet.interfaces.IStreamClientEndpoint.
"""
def __init__(self, reactor, service, domain, protocol="tcp",
default_port=None, endpoint=TCP4ClientEndpoint,
endpoint_kw_args={}):
self.reactor = reactor
self.service_name = "_%s._%s.%s" % (service, protocol, domain)
if default_port is not None:
self.default_server = _Server(
host=domain,
port=default_port,
priority=0,
weight=0,
expires=0,
)
else:
self.default_server = None
self.endpoint = endpoint
self.endpoint_kw_args = endpoint_kw_args
self.servers = None
self.used_servers = None
@defer.inlineCallbacks
def fetch_servers(self):
self.used_servers = []
self.servers = yield resolve_service(self.service_name)
def pick_server(self):
if not self.servers:
if self.used_servers:
self.servers = self.used_servers
self.used_servers = []
self.servers.sort()
elif self.default_server:
return self.default_server
else:
raise ConnectError(
"Not server available for %s" % self.service_name
)
min_priority = self.servers[0].priority
weight_indexes = list(
(index, server.weight + 1)
for index, server in enumerate(self.servers)
if server.priority == min_priority
)
total_weight = sum(weight for index, weight in weight_indexes)
target_weight = random.randint(0, total_weight)
for index, weight in weight_indexes:
target_weight -= weight
if target_weight <= 0:
server = self.servers[index]
del self.servers[index]
self.used_servers.append(server)
return server
@defer.inlineCallbacks
def connect(self, protocolFactory):
if self.servers is None:
yield self.fetch_servers()
server = self.pick_server()
logger.info("Connecting to %s:%s", server.host, server.port)
endpoint = self.endpoint(
self.reactor, server.host, server.port, **self.endpoint_kw_args
)
connection = yield endpoint.connect(protocolFactory)
defer.returnValue(connection)
@defer.inlineCallbacks
def resolve_service(service_name, dns_client=client, cache=SERVER_CACHE, clock=time):
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)
servers = []
try:
try:
answers, _, _ = yield dns_client.lookupService(service_name)
except DNSNameError:
defer.returnValue([])
if (len(answers) == 1
and answers[0].type == dns.SRV
and answers[0].payload
and answers[0].payload.target == dns.Name('.')):
raise ConnectError("Service %s unavailable" % service_name)
for answer in answers:
if answer.type != dns.SRV or not answer.payload:
continue
payload = answer.payload
host = str(payload.target)
srv_ttl = answer.ttl
try:
answers, _, _ = yield dns_client.lookupAddress(host)
except DNSNameError:
continue
for answer in answers:
if answer.type == dns.A and answer.payload:
ip = answer.payload.dottedQuad()
host_ttl = min(srv_ttl, answer.ttl)
servers.append(_Server(
host=ip,
port=int(payload.port),
priority=int(payload.priority),
weight=int(payload.weight),
expires=int(clock.time()) + host_ttl,
))
servers.sort()
cache[service_name] = list(servers)
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)
if cache_entry:
logger.warn(
"Failed to resolve %r, falling back to cache. %r",
service_name, e
)
servers = list(cache_entry)
else:
raise e
defer.returnValue(servers)