409 lines
14 KiB
Python
409 lines
14 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.
|
|
import socket
|
|
|
|
from twisted.internet.endpoints import HostnameEndpoint, wrapClientTLS
|
|
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 = {}
|
|
|
|
# our record of an individual server which can be tried to reach a destination.
|
|
#
|
|
# "host" is actually a dotted-quad or ipv6 address string. Except when there's
|
|
# no SRV record, in which case it is the original hostname.
|
|
_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 = HostnameEndpoint
|
|
default_port = 8008
|
|
else:
|
|
def transport_endpoint(reactor, host, port, timeout):
|
|
return wrapClientTLS(
|
|
ssl_context_factory,
|
|
HostnameEndpoint(reactor, host, port, timeout=timeout))
|
|
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=HostnameEndpoint, 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=HostnameEndpoint,
|
|
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(
|
|
"No server available for %s" % self.service_name
|
|
)
|
|
|
|
# look for all servers with the same priority
|
|
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]
|
|
# XXX: this looks totally dubious:
|
|
#
|
|
# (a) we never reuse a server until we have been through
|
|
# all of the servers at the same priority, so if the
|
|
# weights are A: 100, B:1, we always do ABABAB instead of
|
|
# AAAA...AAAB (approximately).
|
|
#
|
|
# (b) After using all the servers at the lowest priority,
|
|
# we move onto the next priority. We should only use the
|
|
# second priority if servers at the top priority are
|
|
# unreachable.
|
|
#
|
|
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
|
|
|
|
hosts = yield _get_hosts_for_srv_record(
|
|
dns_client, str(payload.target)
|
|
)
|
|
|
|
for (ip, ttl) in hosts:
|
|
host_ttl = min(answer.ttl, 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)
|
|
|
|
|
|
@defer.inlineCallbacks
|
|
def _get_hosts_for_srv_record(dns_client, host):
|
|
"""Look up each of the hosts in a SRV record
|
|
|
|
Args:
|
|
dns_client (twisted.names.dns.IResolver):
|
|
host (basestring): host to look up
|
|
|
|
Returns:
|
|
Deferred[list[(str, int)]]: a list of (host, ttl) pairs
|
|
|
|
"""
|
|
ip4_servers = []
|
|
ip6_servers = []
|
|
|
|
def cb(res):
|
|
# lookupAddress and lookupIP6Address return a three-tuple
|
|
# giving the answer, authority, and additional sections of the
|
|
# response.
|
|
#
|
|
# we only care about the answers.
|
|
|
|
return res[0]
|
|
|
|
def eb(res, record_type):
|
|
if res.check(DNSNameError):
|
|
return []
|
|
logger.warn("Error looking up %s for %s: %s", record_type, host, res)
|
|
return res
|
|
|
|
# no logcontexts here, so we can safely fire these off and gatherResults
|
|
d1 = dns_client.lookupAddress(host).addCallbacks(
|
|
cb, eb, errbackArgs=("A", ))
|
|
d2 = dns_client.lookupIPV6Address(host).addCallbacks(
|
|
cb, eb, errbackArgs=("AAAA", ))
|
|
results = yield defer.DeferredList(
|
|
[d1, d2], consumeErrors=True)
|
|
|
|
# if all of the lookups failed, raise an exception rather than blowing out
|
|
# the cache with an empty result.
|
|
if results and all(s == defer.FAILURE for (s, _) in results):
|
|
defer.returnValue(results[0][1])
|
|
|
|
for (success, result) in results:
|
|
if success == defer.FAILURE:
|
|
continue
|
|
|
|
for answer in result:
|
|
if not answer.payload:
|
|
continue
|
|
|
|
try:
|
|
if answer.type == dns.A:
|
|
ip = answer.payload.dottedQuad()
|
|
ip4_servers.append((ip, answer.ttl))
|
|
elif answer.type == dns.AAAA:
|
|
ip = socket.inet_ntop(
|
|
socket.AF_INET6, answer.payload.address,
|
|
)
|
|
ip6_servers.append((ip, answer.ttl))
|
|
else:
|
|
# the most likely candidate here is a CNAME record.
|
|
# rfc2782 says srvs may not point to aliases.
|
|
logger.warn(
|
|
"Ignoring unexpected DNS record type %s for %s",
|
|
answer.type, host,
|
|
)
|
|
continue
|
|
except Exception as e:
|
|
logger.warn("Ignoring invalid DNS response for %s: %s",
|
|
host, e)
|
|
continue
|
|
|
|
# keep the ipv4 results before the ipv6 results, mostly to match historical
|
|
# behaviour.
|
|
defer.returnValue(ip4_servers + ip6_servers)
|