MatrixSynapse/synapse/crypto/keyclient.py

# -*- coding: utf-8 -*-
# Copyright 2014, 2015 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.web.http import HTTPClient
from twisted.internet.protocol import Factory
from twisted.internet import defer, reactor
from synapse.http.endpoint import matrix_federation_endpoint
from synapse.util.logcontext import PreserveLoggingContext
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()
    endpoint = matrix_federation_endpoint(
        reactor, server_name, ssl_context_factory, timeout=30
    )

    for i in range(5):
        try:
            with PreserveLoggingContext():
                protocol = yield endpoint.connect(factory)
                server_response, server_certificate = yield protocol.remote_key
                defer.returnValue((server_response, server_certificate))
                return
        except Exception as e:
            logger.exception(e)
    raise IOError("Cannot get key for %s" % server_name)


class SynapseKeyClientError(Exception):
    """The key wasn't retrieved 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."""

    timeout = 30

    def __init__(self):
        self.remote_key = defer.Deferred()

    def connectionMade(self):
        logger.debug("Connected to %s", self.transport.getHost())
        self.sendCommand(b"GET", b"/_matrix/key/v1/")
        self.endHeaders()
        self.timer = reactor.callLater(
            self.timeout,
            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.remote_key.callback((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.remote_key.errback(IOError("Timeout waiting for response"))
        self.transport.abortConnection()


class SynapseKeyClientFactory(Factory):
    protocol = SynapseKeyClientProtocol