Join endpoints are rate-limited even if the user has already joined the room

[freelock]

Description

In the Drupal integration, before sending a message into a room, the API first sends a join to make sure the account is present. Since 1.19.0, this is now resulting in a lot of M_LIMIT_EXCEEDED errors, and interrupting the rest of the processing if not caught/otherwise handled. My assumption is that this end point is idempotent, and by calling it before sending, I'm potentially saving a round trip of having to hit an endpoint to see if the account is already joined, and then again to join if it's not.

In #matrix-dev:matrix.org, @tulir pointed me to #8138 , so I updated the Docker image from the github develop.zip after that PR was merged (I think), but I'm still getting errors.

I think that #8008 is what caused this, and #8138 did not fix the ratelimit_overide user accounts. Needs an additional fix for this table?

Version information

• Homeserver: matrix.freelock.com

If not matrix.org:

• 1.19.0:

• Install method:

Docker image built from release tarball.

• Platform:

Debian stretch container.

[babolivier]

Thanks for your report! As I understanding, your issue isn't so much that the ratelimit_override table is being ignored on joins, but that the idempotency on the join endpoints broke as of #8008. This is a serious regression, which will be fixed by #8153 and released in 1.19.1 (coming out later this week). With this fix, the only operation that'll actually get rate-limited will be actually joining new users to a room.

[babolivier]

If the ratelimiter ignoring the override table (which is currently only used by the message ratelimiter and not the others) is also an issue for you, could you please open a separate issue on this repo?

[freelock]

Reading the PR, this sounds right to me -- the issue is I'm getting a ratelimit error on rooms the account is already a member of.

[babolivier]

#8153 has been merged into the release branch, so I'm closing this issue.

[babolivier]

FYI the fix to this issue has just been released in Synapse v1.19.1 🙂