On 06/05/2021 17:13, Leon Atherton wrote:
On 06/05/2021 16:06, Christopher Schultz wrote:
On 5/6/21 09:36, Mark Thomas wrote:
On 06/05/2021 13:33, Christopher Schultz wrote:
Leon,

On 5/6/21 06:25, Leon Atherton wrote:
We are seeing that Firefox triggers the HTTP2 overhead protection with multipart file uploads. About 1MB is uploaded before overhead protection is triggered. I believe a few weeks ago Chrome was triggering this too, but it looks like a recent update may have resolved it.

This is on Tomcat 9.0.45 (though it applies to earlier versions too) using the org.apache.coyote.http11.Http11NioProtocol connector with upgrade to org.apache.coyote.http2.Http2Protocol.

With http2 debug logging enabled, there are occasional Payload size [1] interspersed between larger payloads, though it appears to be a couple of back-to-back Payload size [1]'s which may be triggering the org.apache.coyote.http2.ConnectionException: Connection [0], Too much overhead so the connection will be closed.

I've found earlier Tomcat conversations which seem to indicate it's a client issue. I've searched through the Firefox bug tracker but have not found anything that looks like this (feels like looking for a needle in a haystack).

Is this a known issue in Tomcat or Firefox? It can be resolved by disabling the protection or potentially just tweaking the config values, but if it's a known Firefox issue I'd like to know if something has been raised on their bug tracker I can follow?

Nothing in the tracker that I know of off-hand, but there is this informative answer on SO by markt which may help you a little:

https://stackoverflow.com/a/61454503/276232

Using the information in that answer may allow you to reconfigure your server to allow Firefox's behavior.

It's probably worth us taking some time to adapt markt's SO answer there into a whole section on "Protocol Abuse and Protection Features" in the HTTP/2 configuration guide.

There is an open issue for Chrome:
https://bugs.chromium.org/p/chromium/issues/detail?id=1000809

ACK

but there hasn't been much movement.

I'll add something to my TODO list to see what can be done to avoid false positives like this as it looks like short sequences of small packets can occur depending on how the client buffers data.

Maybe a tweak to the default settings can improve things for "the status quo" for current web browser behavior.

Thanks guys. I'm currently unable to reproduce the problem in Chrome (not seeing any 1 byte payloads). I thought it reproduced a few weeks ago, but perhaps I'm misremembering.

Firefox's market share isn't what it was, but it would be good if this could work out of the box - either by tweaking the Tomcat code or default config to prevent the false-positive or opening a ticket so the Firefox team know what to fix.

Happy to help with the latter, though I'd need some assistance to explain the problem and expected solution. I could bore you to tears with the ins and outs of the PDF spec, but HTTP2 is not one of my specialist subjects.

Leon

Just to confirm that I have been able to reproduce this on an older build of Chromium (88.0.4324.0). Seems like it's the same issue as the current version of Firefox - consequtive 1 byte payloads triggering the overhead protection.

Glad I'm not going crazy.

Leon

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