Remove fetching keys via the deprecated v1 kex method (#4120)

changelog.d/4120.removal

@@ -0,0 +1 @@
+Synapse will no longer fetch keys using the fallback deprecated v1 key exchange method and will now always use v2.

synapse/crypto/keyclient.py

@@ -15,6 +15,8 @@
 
 import logging
 
+from six.moves import urllib
+
 from canonicaljson import json
 
 from twisted.internet import defer, reactor
@@ -28,15 +30,15 @@ from synapse.util import logcontext
 
 logger = logging.getLogger(__name__)
 
-KEY_API_V1 = b"/_matrix/key/v1/"
+KEY_API_V2 = "/_matrix/key/v2/server/%s"
 
 
 @defer.inlineCallbacks
-def fetch_server_key(server_name, tls_client_options_factory, path=KEY_API_V1):
+def fetch_server_key(server_name, tls_client_options_factory, key_id):
     """Fetch the keys for a remote server."""
 
     factory = SynapseKeyClientFactory()
-    factory.path = path
+    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

synapse/crypto/keyring.py

@@ -1,6 +1,6 @@
 # -*- coding: utf-8 -*-
 # Copyright 2014-2016 OpenMarket Ltd
-# Copyright 2017 New Vector Ltd.
+# Copyright 2017, 2018 New Vector Ltd.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -18,8 +18,6 @@ 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,
@@ -395,32 +393,13 @@ class Keyring(object):
 
     @defer.inlineCallbacks
     def get_keys_from_server(self, server_name_and_key_ids):
-        @defer.inlineCallbacks
-        def get_key(server_name, key_ids):
-            keys = None
-            try:
-                keys = yield self.get_server_verify_key_v2_direct(
-                    server_name, key_ids
-                )
-            except Exception as e:
-                logger.info(
-                    "Unable to get key %r for %r directly: %s %s",
-                    key_ids, server_name,
-                    type(e).__name__, str(e),
-                )
-
-            if not keys:
-                keys = yield self.get_server_verify_key_v1_direct(
-                    server_name, key_ids
-                )
-
-                keys = {server_name: keys}
-
-            defer.returnValue(keys)
-
         results = yield logcontext.make_deferred_yieldable(defer.gatherResults(
             [
-                run_in_background(get_key, server_name, key_ids)
+                run_in_background(
+                    self.get_server_verify_key_v2_direct,
+                    server_name,
+                    key_ids,
+                )
                 for server_name, key_ids in server_name_and_key_ids
             ],
             consumeErrors=True,
@@ -525,10 +504,7 @@ class Keyring(object):
                 continue
 
             (response, tls_certificate) = yield fetch_server_key(
-                server_name, self.hs.tls_client_options_factory,
+                server_name, self.hs.tls_client_options_factory, requested_key_id
-                path=("/_matrix/key/v2/server/%s" % (
-                    urllib.parse.quote(requested_key_id),
-                )).encode("ascii"),
             )
 
             if (u"signatures" not in response
@@ -657,78 +633,6 @@ class Keyring(object):
 
         defer.returnValue(results)
 
-    @defer.inlineCallbacks
-    def get_server_verify_key_v1_direct(self, server_name, key_ids):
-        """Finds a verification key for the server with one of the key ids.
-        Args:
-            server_name (str): The name of the server to fetch a key for.
-            keys_ids (list of str): The key_ids to check for.
-        """
-
-        # Try to fetch the key from the remote server.
-
-        (response, tls_certificate) = yield fetch_server_key(
-            server_name, self.hs.tls_client_options_factory
-        )
-
-        # Check the response.
-
-        x509_certificate_bytes = crypto.dump_certificate(
-            crypto.FILETYPE_ASN1, tls_certificate
-        )
-
-        if ("signatures" not in response
-                or server_name not in response["signatures"]):
-            raise KeyLookupError("Key response not signed by remote server")
-
-        if "tls_certificate" not in response:
-            raise KeyLookupError("Key response missing TLS certificate")
-
-        tls_certificate_b64 = response["tls_certificate"]
-
-        if encode_base64(x509_certificate_bytes) != tls_certificate_b64:
-            raise KeyLookupError("TLS certificate doesn't match")
-
-        # Cache the result in the datastore.
-
-        time_now_ms = self.clock.time_msec()
-
-        verify_keys = {}
-        for key_id, key_base64 in response["verify_keys"].items():
-            if is_signing_algorithm_supported(key_id):
-                key_bytes = decode_base64(key_base64)
-                verify_key = decode_verify_key_bytes(key_id, key_bytes)
-                verify_key.time_added = time_now_ms
-                verify_keys[key_id] = verify_key
-
-        for key_id in response["signatures"][server_name]:
-            if key_id not in response["verify_keys"]:
-                raise KeyLookupError(
-                    "Key response must include verification keys for all"
-                    " signatures"
-                )
-            if key_id in verify_keys:
-                verify_signed_json(
-                    response,
-                    server_name,
-                    verify_keys[key_id]
-                )
-
-        yield self.store.store_server_certificate(
-            server_name,
-            server_name,
-            time_now_ms,
-            tls_certificate,
-        )
-
-        yield self.store_keys(
-            server_name=server_name,
-            from_server=server_name,
-            verify_keys=verify_keys,
-        )
-
-        defer.returnValue(verify_keys)
-
     def store_keys(self, server_name, from_server, verify_keys):
         """Store a collection of verify keys for a given server
         Args: