Related to https://github.com/element-hq/synapse/issues/17035, when
Synapse receives a request that is larger than the maximum size allowed,
it aborts the connection without ever sending back a HTTP response.
I dug into our usage of twisted and how best to try and report such an
error and this is what I came up with.
It would be ideal to be able to report the status from within
`handleContentChunk` but that is called too early on in the twisted http
handling code, before things have been setup enough to be able to
properly write a response.
I tested this change out locally (both with C-S and S-S apis) and they
do receive a 413 response now in addition to the connection being
closed.
Hopefully this will aid in being able to quickly detect when
https://github.com/element-hq/synapse/issues/17035 is occurring as the
current situation makes it very hard to narrow things down to that
specific issue without making a lot of assumptions.
This PR also responds with more meaningful error codes now in the case
of:
- multiple `Content-Length` headers
- invalid `Content-Length` header value
- request content size being larger than the `Content-Length` value
### Pull Request Checklist
<!-- Please read
https://element-hq.github.io/synapse/latest/development/contributing_guide.html
before submitting your pull request -->
* [X] Pull request is based on the develop branch
* [X] Pull request includes a [changelog
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The entry should:
- Be a short description of your change which makes sense to users.
"Fixed a bug that prevented receiving messages from other servers."
instead of "Moved X method from `EventStore` to `EventWorkerStore`.".
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* [X] [Code
style](https://element-hq.github.io/synapse/latest/code_style.html) is
correct (run the
[linters](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#run-the-linters))
---------
Co-authored-by: Eric Eastwood <erice@element.io>
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