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# -*- coding: utf-8 -*-
# Copyright 2014 matrix.org
#
# 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.web.http import HTTPClient
from twisted.internet import defer, reactor
from twisted.internet.protocol import ClientFactory
from twisted.names.srvconnect import SRVConnector
import json
import logging
logger = logging.getLogger(__name__)
@defer.inlineCallbacks
def fetch_server_key(server_name, ssl_context_factory):
"""Fetch the keys for a remote server."""
factory = SynapseKeyClientFactory()
SRVConnector(
reactor, "matrix", server_name, factory,
protocol="tcp", connectFuncName="connectSSL", defaultPort=443,
connectFuncKwArgs=dict(contextFactory=ssl_context_factory)).connect()
server_key, server_certificate = yield factory.remote_key
defer.returnValue((server_key, server_certificate))
class SynapseKeyClientError(Exception):
"""The key wasn't retireved from the remote server."""
pass
class SynapseKeyClientProtocol(HTTPClient):
"""Low level HTTPS client which retrieves an application/json response from
the server and extracts the X.509 certificate for the remote peer from the
SSL connection."""
def connectionMade(self):
logger.debug("Connected to %s", self.transport.getHost())
self.sendCommand(b"GET", b"/key")
self.endHeaders()
self.timer = reactor.callLater(
self.factory.timeout_seconds,
self.on_timeout
)
def handleStatus(self, version, status, message):
if status != b"200":
logger.info("Non-200 response from %s: %s %s",
self.transport.getHost(), status, message)
self.transport.abortConnection()
def handleResponse(self, response_body_bytes):
try:
json_response = json.loads(response_body_bytes)
except ValueError:
logger.info("Invalid JSON response from %s",
self.transport.getHost())
self.transport.abortConnection()
return
certificate = self.transport.getPeerCertificate()
self.factory.on_remote_key((json_response, certificate))
self.transport.abortConnection()
self.timer.cancel()
def on_timeout(self):
logger.debug("Timeout waiting for response from %s",
self.transport.getHost())
self.transport.abortConnection()
class SynapseKeyClientFactory(ClientFactory):
protocol = SynapseKeyClientProtocol
max_retries = 5
timeout_seconds = 30
def __init__(self):
self.succeeded = False
self.retries = 0
self.remote_key = defer.Deferred()
def on_remote_key(self, key):
self.succeeded = True
self.remote_key.callback(key)
def retry_connection(self, connector):
self.retries += 1
if self.retries < self.max_retries:
connector.connector = None
connector.connect()
else:
self.remote_key.errback(
SynapseKeyClientError("Max retries exceeded"))
def clientConnectionFailed(self, connector, reason):
logger.info("Connection failed %s", reason)
self.retry_connection(connector)
def clientConnectionLost(self, connector, reason):
logger.info("Connection lost %s", reason)
if not self.succeeded:
self.retry_connection(connector)
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