Make key fetches use regular federation client (#4426)

All this magic is redundant.

3 files changed, 8 insertions, 172 deletions

diff --git a/changelog.d/4426.misc b/changelog.d/4426.misc
new file mode 100644
index 0000000000..cda50438e0
--- /dev/null
+++ b/changelog.d/4426.misc
@@ -0,0 +1 @@
+Remove redundant SynapseKeyClientProtocol magic
\ No newline at end of file
diff --git a/synapse/crypto/keyclient.py b/synapse/crypto/keyclient.py
deleted file mode 100644
index d40e4b8591..0000000000
--- a/synapse/crypto/keyclient.py
+++ /dev/null
@@ -1,149 +0,0 @@
-# -*- 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 logging
-
-from six.moves import urllib
-
-from canonicaljson import json
-
-from twisted.internet import defer, reactor
-from twisted.internet.error import ConnectError
-from twisted.internet.protocol import Factory
-from twisted.names.error import DomainError
-from twisted.web.http import HTTPClient
-
-from synapse.http.endpoint import matrix_federation_endpoint
-from synapse.util import logcontext
-
-logger = logging.getLogger(__name__)
-
-KEY_API_V2 = "/_matrix/key/v2/server/%s"
-
-
-@defer.inlineCallbacks
-def fetch_server_key(server_name, tls_client_options_factory, key_id):
-    """Fetch the keys for a remote server."""
-
-    factory = SynapseKeyClientFactory()
-    factory.path = KEY_API_V2 % (urllib.parse.quote(key_id), )
-    factory.host = server_name
-    endpoint = matrix_federation_endpoint(
-        reactor, server_name, tls_client_options_factory, timeout=30
-    )
-
-    for i in range(5):
-        try:
-            with logcontext.PreserveLoggingContext():
-                protocol = yield endpoint.connect(factory)
-                server_response, server_certificate = yield protocol.remote_key
-                defer.returnValue((server_response, server_certificate))
-        except SynapseKeyClientError as e:
-            logger.warn("Error getting key for %r: %s", server_name, e)
-            if e.status.startswith(b"4"):
-                # Don't retry for 4xx responses.
-                raise IOError("Cannot get key for %r" % server_name)
-        except (ConnectError, DomainError) as e:
-            logger.warn("Error getting key for %r: %s", server_name, e)
-        except Exception:
-            logger.exception("Error getting key for %r", server_name)
-    raise IOError("Cannot get key for %r" % server_name)
-
-
-class SynapseKeyClientError(Exception):
-    """The key wasn't retrieved from the remote server."""
-    status = None
-    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()
-        self.host = None
-        self._peer = None
-
-    def connectionMade(self):
-        self._peer = self.transport.getPeer()
-        logger.debug("Connected to %s", self._peer)
-
-        if not isinstance(self.path, bytes):
-            self.path = self.path.encode('ascii')
-
-        if not isinstance(self.host, bytes):
-            self.host = self.host.encode('ascii')
-
-        self.sendCommand(b"GET", self.path)
-        if self.host:
-            self.sendHeader(b"Host", self.host)
-        self.endHeaders()
-        self.timer = reactor.callLater(
-            self.timeout,
-            self.on_timeout
-        )
-
-    def errback(self, error):
-        if not self.remote_key.called:
-            self.remote_key.errback(error)
-
-    def callback(self, result):
-        if not self.remote_key.called:
-            self.remote_key.callback(result)
-
-    def handleStatus(self, version, status, message):
-        if status != b"200":
-            # logger.info("Non-200 response from %s: %s %s",
-            #            self.transport.getHost(), status, message)
-            error = SynapseKeyClientError(
-                "Non-200 response %r from %r" % (status, self.host)
-            )
-            error.status = status
-            self.errback(error)
-            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.callback((json_response, certificate))
-        self.transport.abortConnection()
-        self.timer.cancel()
-
-    def on_timeout(self):
-        logger.debug(
-            "Timeout waiting for response from %s: %s",
-            self.host, self._peer,
-        )
-        self.errback(IOError("Timeout waiting for response"))
-        self.transport.abortConnection()
-
-
-class SynapseKeyClientFactory(Factory):
-    def protocol(self):
-        protocol = SynapseKeyClientProtocol()
-        protocol.path = self.path
-        protocol.host = self.host
-        return protocol
diff --git a/synapse/crypto/keyring.py b/synapse/crypto/keyring.py
index 515ebbc148..3a96980bed 100644
--- a/synapse/crypto/keyring.py
+++ b/synapse/crypto/keyring.py
@@ -14,10 +14,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import hashlib
 import logging
 from collections import namedtuple
 
+from six.moves import urllib
+
 from signedjson.key import (
     decode_verify_key_bytes,
     encode_verify_key_base64,
@@ -30,13 +31,11 @@ from signedjson.sign import (
     signature_ids,
     verify_signed_json,
 )
-from unpaddedbase64 import decode_base64, encode_base64
+from unpaddedbase64 import decode_base64
 
-from OpenSSL import crypto
 from twisted.internet import defer
 
 from synapse.api.errors import Codes, SynapseError
-from synapse.crypto.keyclient import fetch_server_key
 from synapse.util import logcontext, unwrapFirstError
 from synapse.util.logcontext import (
     LoggingContext,
@@ -503,31 +502,16 @@ class Keyring(object):
             if requested_key_id in keys:
                 continue
 
-            (response, tls_certificate) = yield fetch_server_key(
-                server_name, self.hs.tls_client_options_factory, requested_key_id
+            response = yield self.client.get_json(
+                destination=server_name,
+                path="/_matrix/key/v2/server/" + urllib.parse.quote(requested_key_id),
+                ignore_backoff=True,
             )
 
             if (u"signatures" not in response
                     or server_name not in response[u"signatures"]):
                 raise KeyLookupError("Key response not signed by remote server")
 
-            if "tls_fingerprints" not in response:
-                raise KeyLookupError("Key response missing TLS fingerprints")
-
-            certificate_bytes = crypto.dump_certificate(
-                crypto.FILETYPE_ASN1, tls_certificate
-            )
-            sha256_fingerprint = hashlib.sha256(certificate_bytes).digest()
-            sha256_fingerprint_b64 = encode_base64(sha256_fingerprint)
-
-            response_sha256_fingerprints = set()
-            for fingerprint in response[u"tls_fingerprints"]:
-                if u"sha256" in fingerprint:
-                    response_sha256_fingerprints.add(fingerprint[u"sha256"])
-
-            if sha256_fingerprint_b64 not in response_sha256_fingerprints:
-                raise KeyLookupError("TLS certificate not allowed by fingerprints")
-
             response_keys = yield self.process_v2_response(
                 from_server=server_name,
                 requested_ids=[requested_key_id],