HTTP/3: When curl sends request to server, and server takes the initiative to close the connection, then curl will hang and get the CURLE_OPERATION_TIMEDOUT error

[bachue]

I did this

Use libcurl(compiled with quiche) to send more than 10000 h3 requests to one nginx server with quiche h3 patch

I expected the following

All requests are successful to be responded.

But actually some of requests will get CURLE_OPERATION_TIMEDOUT error. I did some debug and realized the nginx server takes the initiative to close the connection via APPLICATION_CLOSE frame(according the nginx h3 patch, one connection could only receive at most 1000 requests, then nginx will close it). Then quiche would receive this frame and set the draining timer, and curl would call Curl_Expire to expire the connection, and finally the request still be timed out.

curl/libcurl version

v7.75.0 with quiche

operating system

Linux 0a60a6fa8cdb 4.19.0-13-amd64 #1 SMP Debian 4.19.160-2 (2020-11-28) x86_64 x86_64 x86_64 GNU/Linux

[bagder]

Is that 1000 requests limit due to the infamous http2_max_requests setting or is there a corresponding one for h3 now? Ie can you force it to happen after say 5 requests to make this easier to reproduce and debug?

[bachue]

@bagder It's a corresponding one for h3, and the source is here: https://github.com/cloudflare/quiche/blob/master/extras/nginx/nginx-1.16.patch#L4391

Now I can change it to 2^31-1 requests to walkaround this bug.

[bagder]

http3_max_requests is thus the name of the config item that is set to 1000 by default (which begs the question why, but that's not really relevant here).