/_matrix/key/v2/query: 'NoneType' object has no attribute 'registerProducer'

[anoadragon453]

Description

A traceback I saw while skimming my logs:

2020-01-14 15:02:13,505 - synapse.http.server - 109 - ERROR - POST-48708- Failed handle request via 'RemoteKey': <XForwardedForRequest at 0x7f0fa40a9f60 method='POST' uri='/_matrix/key/v2/query' clientproto='HTTP/1.1' site=8008>
  File "/home/synapse/synapse/env/lib/python3.7/site-packages/twisted/internet/defer.py", line 1418, in _inlineCallbacks
    result = g.send(result)
StopIteration: {('mtrx.pro-i-l.de', 'ed25519:a_lehF', None): [{'key_id': 'ed25519:a_lehF', 'from_server': 'matrix.org', 'ts_added_ms': 1576922916596, 'ts_valid_until_ms': 1576921056903, 'key_json': <memory at 0x7f1111544108>}, {'key_id': 'ed25519:a_lehF', 'from_serve

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/synapse/synapse/env/lib/python3.7/site-packages/twisted/internet/defer.py", line 1418, in _inlineCallbacks
    result = g.send(result)
StopIteration: {('mtrx.pro-i-l.de', 'ed25519:a_lehF', None): [{'key_id': 'ed25519:a_lehF', 'from_server': 'matrix.org', 'ts_added_ms': 1576922916596, 'ts_valid_until_ms': 1576921056903, 'key_json': <memory at 0x7f1111544108>}, {'key_id': 'ed25519:a_lehF', 'from_serve

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/synapse/synapse/env/lib/python3.7/site-packages/synapse/http/server.py", line 77, in wrapped_request_handler
    await h(self, request)
  File "/home/synapse/synapse/env/lib/python3.7/site-packages/synapse/rest/key/v2/remote_key_resource.py", line 125, in _async_render_POST
    await self.query_keys(request, query, query_remote_on_cache_miss=True)
  File "/home/synapse/synapse/env/lib/python3.7/site-packages/twisted/internet/defer.py", line 1418, in _inlineCallbacks
    result = g.send(result)
  File "/home/synapse/synapse/env/lib/python3.7/site-packages/synapse/rest/key/v2/remote_key_resource.py", line 230, in query_keys
    respond_with_json_bytes(request, 200, encode_canonical_json(results))
  File "/home/synapse/synapse/env/lib/python3.7/site-packages/synapse/http/server.py", line 507, in respond_with_json_bytes
    producer.start()
  File "/home/synapse/synapse/env/lib/python3.7/site-packages/twisted/web/static.py", line 765, in start
    self.request.registerProducer(self, False)
  File "/home/synapse/synapse/env/lib/python3.7/site-packages/twisted/web/http.py", line 986, in registerProducer
    self.channel.registerProducer(producer, streaming)
AttributeError: 'NoneType' object has no attribute 'registerProducer'

Not sure if this is a bug or a fluke with a broken connection.

Version information

Synapse v1.8.0 via pip

[richvdh]

I think this is a dup of #5304

[richvdh]

ok, it's not quite, but it's closely related

[richvdh]

I've explained what I think is going on here at #5304 (comment), but am going to leave this open too to track the fact that it probably needs fixing in both places.

The trivial fix here is to add if request._disconnected: return to respond_with_json_bytes.

(the error is harmless except for the noise in the log, and that the other end has timed out)

[richvdh]

also, the fact that you're seeing this error means that someone is using your server as a key notary, which is an interesting choice.

[anoadragon453]

also, the fact that you're seeing this error means that someone is using your server as a key notary, which is an interesting choice.

Indeed...