synapse-old/synapse/http/endpoint.py

256 lines
8.3 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
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 SRVClientEndpoint(
reactor, "matrix", domain, protocol="tcp",
default_port=default_port, endpoint=transport_endpoint,
endpoint_kw_args=endpoint_kw_args
)
else:
return transport_endpoint(reactor, domain, port, **endpoint_kw_args)
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)