Unexplained KeyError 'destination_is'

[DMRobertson]

Internal users: https://sentry.matrix.org/sentry/synapse-matrixorg/issues/247960/?query=is%3Aunresolved%20destination_is

StopIteration: DestinationRetryTimings(failure_ts=1568794598907, retry_last_ts=1591706354703, retry_interval=126355483270)
  File "twisted/internet/defer.py", line 1660, in _inlineCallbacks
    result = current_context.run(gen.send, result)

StopIteration: DestinationRetryTimings(failure_ts=1568794598907, retry_last_ts=1591706354703, retry_interval=126355483270)
  File "twisted/internet/defer.py", line 1660, in _inlineCallbacks
    result = current_context.run(gen.send, result)

KeyError: 'destination_is'
  File "synapse/http/server.py", line 298, in _async_render_wrapper
    callback_return = await self._async_render(request)
  File "synapse/http/server.py", line 500, in _async_render
    callback_return = await raw_callback_return
  File "synapse/rest/client/directory.py", line 57, in on_GET
    res = await self.directory_handler.get_association(room_alias_obj)
  File "synapse/handlers/directory.py", line 257, in get_association
    ignore_backoff=True,
  File "synapse/federation/federation_client.py", line 184, in make_query
    ignore_backoff=ignore_backoff,
  File "synapse/federation/transport/client.py", line 272, in make_query
    ignore_backoff=ignore_backoff,
  File "synapse/http/matrixfederationclient.py", line 1068, in get_json
    timeout=timeout,
  File "synapse/http/matrixfederationclient.py", line 389, in _send_request_with_optional_trailing_slash
    response = await self._send_request(request, **send_request_args)
  File "synapse/http/matrixfederationclient.py", line 540, in _send_request
    destination_bytes, method_bytes, url_to_sign_bytes
  File "synapse/http/matrixfederationclient.py", line 748, in build_auth_headers
    request.get("destination") or request["destination_is"],

synapse/synapse/http/matrixfederationclient.py

Lines 695 to 752 in 8dd3e0e

	def build_auth_headers(
	self,
	destination: Optional[bytes],
	method: bytes,
	url_bytes: bytes,
	content: Optional[JsonDict] = None,
	destination_is: Optional[bytes] = None,
	) -> List[bytes]:
	"""
	Builds the Authorization headers for a federation request
	Args:
	destination: The destination homeserver of the request.
	May be None if the destination is an identity server, in which case
	destination_is must be non-None.
	method: The HTTP method of the request
	url_bytes: The URI path of the request
	content: The body of the request
	destination_is: As 'destination', but if the destination is an
	identity server
	Returns:
	A list of headers to be added as "Authorization:" headers
	"""
	if destination is None and destination_is is None:
	raise ValueError("destination and destination_is cannot both be None!")
	request: JsonDict = {
	"method": method.decode("ascii"),
	"uri": url_bytes.decode("ascii"),
	"origin": self.server_name,
	}
	if destination is not None:
	request["destination"] = destination.decode("ascii")
	if destination_is is not None:
	request["destination_is"] = destination_is.decode("ascii")
	if content is not None:
	request["content"] = content
	request = sign_json(request, self.server_name, self.signing_key)
	auth_headers = []
	for key, sig in request["signatures"][self.server_name].items():
	auth_headers.append(
	(
	'X-Matrix origin=%s,key="%s",sig="%s",destination="%s"'
	% (
	self.server_name,
	key,
	sig,
	request.get("destination") or request["destination_is"],
	)
	).encode("ascii")
	)
	return auth_headers

There's logic which is trying to assert we've provided sensible input, but it's failing. I'd guess that destination is an empty bytes object?

[b3s1r]

Yes that seems to be the problem.
I got that error when I tried to GET /_matrix/client/r0/profile/{userId} on my server.
I used it wrong and didn't put the domain in the {userId}. (so just /%40user%3A and not /%40user%3Aexample.com
That caused destination not to be None, but an empty object.

Not sure if this is helpful in any way, but it was my evening. So there you go.