/createRoom: "UnicodeEncodeError" and Internal server error when having specific garbage in id_access_token of a 3pid invite

[MTRNord]

Description

When sending some unicode characters in a 3pid invite on /_matrix/client/v3/createRoom the server returns an "Internal server error".

Such an invalid invite can be: {"invite_3pid":[{"address":"localhost","id_access_token":"c��","id_server":"","medium":""}],"name":""}

Confusing enough, the room actually will be created. However, no invite is issued.

Steps to reproduce

• Send an invalid 3pid invite (see above for an example) to the createRoom endpoint.

Homeserver

localhost

Synapse Version

{"server_version":"1.64.0","python_version":"3.9.13"}

Installation Method

Docker (matrixdotorg/synapse)

Platform

Kubernetes with postgres and the official docker image

Relevant log output

2022-08-11 22:41:50,084 - synapse.http.client - 455 - INFO - POST-8133- Error sending request to  GET https:///_matrix/identity/v2/hash_details?access_token=<redacted>: ValueError invalid hostname: 
2022-08-11 22:41:50,084 - synapse.handlers.identity - 632 - WARNING - POST-8133- Error when looking up hashing details: invalid hostname: 
2022-08-11 22:41:50,088 - synapse.http.server - 183 - ERROR - POST-8133- Failed handle request via 'RoomCreateRestServlet': <XForwardedForRequest at 0x7f28acd01190 method='POST' uri='/_matrix/client/v3/createRoom' clientproto='HTTP/1.1' site='8008'>
Traceback (most recent call last):
  File "/usr/local/lib/python3.9/site-packages/twisted/internet/defer.py", line 1660, in _inlineCallbacks
    result = current_context.run(gen.send, result)
StopIteration: {('m.room.create', ''): '$5z43xevRXglYCpB0aEaT8kl_4jLMENhOIGHQGk4E3wE', ('m.room.join_rules', ''): '$4d4a3uZvsS-_7N9QPQjMV7to3svMroxwHDhFBZD-iww', ('m.room.name', ''): '$3KU_XxJUR0mQmOMe64WbSOcohDbBYo0rb7SR7gwKoJA', ('m.room.member', '@fuzzer:localhost'): '$h9EIRCWvHHGChajNL_BLQ5NIo27b6drGsU-YPocIQxU'}

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.9/site-packages/synapse/http/server.py", line 366, in _async_render_wrapper
    callback_return = await self._async_render(request)
  File "/usr/local/lib/python3.9/site-packages/synapse/http/server.py", line 572, in _async_render
    callback_return = await raw_callback_return
  File "/usr/local/lib/python3.9/site-packages/synapse/rest/client/room.py", line 91, in on_POST
    info, _ = await self._room_creation_handler.create_room(
  File "/usr/local/lib/python3.9/site-packages/synapse/handlers/room.py", line 990, in create_room
    ) = await self.hs.get_room_member_handler().do_3pid_invite(
  File "/usr/local/lib/python3.9/site-packages/synapse/handlers/room_member.py", line 1469, in do_3pid_invite
    event, stream_id = await self._make_and_store_3pid_invite(
  File "/usr/local/lib/python3.9/site-packages/synapse/handlers/room_member.py", line 1553, in _make_and_store_3pid_invite
    ) = await self.identity_handler.ask_id_server_for_third_party_invite(
  File "/usr/local/lib/python3.9/site-packages/synapse/handlers/identity.py", line 865, in ask_id_server_for_third_party_invite
    {"Authorization": create_id_access_token_header(id_access_token)},
  File "/usr/local/lib/python3.9/site-packages/synapse/handlers/identity.py", line 944, in create_id_access_token_header
    bearer_token.encode("ascii")
UnicodeEncodeError: 'ascii' codec can't encode characters in position 8-9: ordinal not in range(128)

Anything else that would be useful to know?

No response

[DMRobertson]

https://www.rfc-editor.org/rfc/rfc6750.html#page-5 gives a grammar for bearer tokens. We could enforce this in Synapse, but I'm not sure if it's Synapse's job or the identity server's to enforce t hat.