Federation tries to use ipv6 even if ipv6 is not available

[turt2live]

Description

2018-02-05 19:14:51,585 - synapse.access.http.8008 - 59 - INFO - GET-131021- - - 8008 - Received request: GET /_matrix/client/r0/directory/room/%23test%3Amatrix.org?access_token=<redacted>
2018-02-05 19:14:51,589 - synapse.http.outbound - 154 - INFO - GET-131021- {GET-O-1317} [matrix.org] Sending request: GET matrix://matrix.org/_matrix/federation/v1/query/directory?room_alias=%23test%3Amatrix.org
2018-02-05 19:14:51,590 - synapse.http.endpoint - 264 - INFO - - Connecting to 2a04:3541:1000:500:6866:a4ff:fe4c:21ac:8448
2018-02-05 19:14:51,592 - twisted - 131 - INFO - - Starting factory _HTTP11ClientFactory(<function quiescentCallback at 0x7f9d7826ad70>, <synapse.http.endpoint._WrappingEndpointFac object at 0x7f9d9c993190>)
2018-02-05 19:14:51,593 - twisted - 131 - INFO - - Stopping factory _HTTP11ClientFactory(<function quiescentCallback at 0x7f9d7826ad70>, <synapse.http.endpoint._WrappingEndpointFac object at 0x7f9d9c993190>)
2018-02-05 19:14:51,892 - synapse.http.matrixfederationclient - 212 - WARNING - GET-131021- {GET-O-1317} Sending request failed to matrix.org: GET matrix://matrix.org/_matrix/federation/v1/query/directory?room_alias=%23test%3Amatrix.org: NoRouteError('Network is unreachable',)
2018-02-05 19:14:51,892 - synapse.http.outbound - 236 - INFO - GET-131021- {GET-O-1317} [matrix.org] Result: NoRouteError('Network is unreachable',)
2018-02-05 19:14:51,893 - synapse.http.server - 183 - ERROR - GET-131021- Failed handle request synapse.http.server._async_render on <synapse.rest.ClientRestResource object at 0x7f9dae55b590>: <XForwardedForRequest at 0x7f9d78220bd8 method=GET uri=/_matrix/client/r0/directory/room/%23test%3Amatrix.org?access_token=<redacted> clientproto=HTTP/1.1 site=8008>: Traceback (most recent call last): Failure: twisted.internet.error.NoRouteError: No route to host: 101: Network is unreachable.
2018-02-05 19:14:51,895 - synapse.access.http.8008 - 93 - INFO - GET-131021- - - 8008 - {None} Processed request: 309ms (4ms, 0ms) (1ms/1ms/1) 69B 500 "GET /_matrix/client/r0/directory/room/%23test%3Amatrix.org?access_token=<redacted> HTTP/1.1" "curl/7.47.0"

The homeserver that received this request doesn't have ipv6 enabled, and failed to reach matrix.org. Instead of automatically falling back to ipv4, it returned a 500 error at the client. After 5 or so requests for the same alias, synapse eventually started relying on the ipv4 address of matrix.org though.

Version information

• Homeserver: dev.t2bot.io
• Version: 0.26.0
• Install method: pip
• Platform: Ubuntu 16.04 VM

[ara4n]

this sounds like federation in general trying to connect to v6 even if the box has no v6 :/

[turt2live]

fwiw, the federation_sender has a similar problem: it fails endlessly trying to reach ipv6 addresses until it eventually decides to use ipv4 for a while.

[turt2live]

I've managed to confirm this for more than the room directory by simply scrolling through the logs. Backfilling, getting missing events, and everything else tries ipv6 first.

[ara4n]

i'm getting this too on arasphere.net atm; very annoying.

[git-minix]

2018-04-01 10:57:21,243 - synapse.http.endpoint - 264 - INFO - - Connecting to 2400:cb00:2048:1::6818:cf1b:8443
...
2018-04-01 10:57:21,545 - synapse.http.matrixfederationclient - 223 - WARNING - None- {PUT-O-1} Sending request failed to matrix.org: PUT matrix://matrix.org/_matrix/federation/v1/send/????????????/: ConnectBindError('Address family not supported by protocol',)
2018-04-01 10:57:25,058 - synapse.handlers.presence - 328 - INFO - - Handling presence timeouts
2018-04-01 10:57:25,059 - synapse.handlers.typing - 78 - INFO - - Checking for typing timeouts
2018-04-01 10:57:25,060 - synapse.handlers.presence - 243 - INFO - - Performing _persist_unpersisted_changes. Persisting 1 unpersisted changes

Same here.

[ansorg]

Slightly different error message but actually the same issue?

018-05-15 15:00:33,863 - synapse.http.matrixfederationclient - 223 - WARNING - POST-101 - {GET-O-2} Sending request failed to matrix.org: GET matrix://matrix.org/_matrix/federation/v1/publicRooms?include_all_networks=true&limit=20: ConnectError('Cannot assign requested address',)

[ara4n]

i thought this was fixed by #3016? i think @ansorg's issue might be different (or might have been on an old synapse?)

[ansorg]

@ara4n My issue seems gone. server was on 0.2x and is up to 0.30 by now.

[turt2live]

Yea... I'm going to go ahead and close this because I haven't seen the issue since 0.28 landed (with #3016). If someone is still seeing this, please mention it here so this issue can be reopened or open a new issue.