57 lines
2.3 KiB
Markdown
57 lines
2.3 KiB
Markdown
# MSC2451: Remove the `query_auth` federation endpoint
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This API was added without sufficient thought nor testing. The endpoint isn't
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used in any known implementations, and we do not believe it to be necessary
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for federation to work. The only known implementation (in Synapse) was not fully
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fleshed out and is broken.
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For background, the idea behind this endpoint was that two homeservers would be
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able to share state events with the hope of filling in missing state from one
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of homeservers allowing state resolution to complete. This was to protect
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against a joining server not providing the full (or providing stale) state.
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In addition to the ideas above not coming to fruition, it is unclear whether the
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current design of this endpoint would be sufficient. If this state negotiation
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feature is needed in the future it should be redesigned from scratch via the MSC
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proposal process.
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## Proposal
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Remove the following endpoint:
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* [POST `/_matrix/federation/v1/query_auth/{roomId}/{eventId}`](https://matrix.org/docs/spec/server_server/r0.1.3#post-matrix-federation-v1-query-auth-roomid-eventid)
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## Potential issues
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Removing this endpoint impacts backwards compatibility, in practice removing
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this endpoint should have minimal impact as it was an unused error path in
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Synapse. The federation client code to call this endpoint was removed in Synapse
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v1.5.0rc1.
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There is no evidence of other homeserver implementations having implemented this
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endpoint.
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### History
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This endpoint (and the federation client code) to call it was initially
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added in Synapse v0.7.0 (see [#43](https://github.com/matrix-org/synapse/pull/43)).
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The federation client code was heavily modified for v1.0.0rc1 (see
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[#5227](https://github.com/matrix-org/synapse/pull/5227/)),
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The federation client code to call this endpoint was removed in v1.5.0rc1 of
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Synapse (see [#6214](https://github.com/matrix-org/synapse/pull/6214). After
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that point this endpoint is not called).
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During removal it was noted that the code to call this endpoint was already
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unreachable. It seems that this code was never reachable and was meant for an
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error situation which was never built out (see `git log -S NOT_ANCESTOR`, the
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error condition is never assigned).
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## Alternatives
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The endpoint could be deprecated and removed in a future version of the specification.
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## Security considerations
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None.
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