Does not discard request body for unnormal close

[fangjian.routon@…]

For the case where the origin is closed without reading the complete request, nginx does not normally discard the request body，call ngx_http_upstream_finalize_request with rc == 0

if (u->length == 0

(upstream->read->eof && u->length == -1))

{

ngx_http_upstream_finalize_request(r, u, 0);
return;

}

This may cause Nginx to send RST to downstream, causing downstream to finish the request abnormally。How to solve this problem elegantly? Thank you.

[Roman Arutyunyan]

With buffered proxying (the default setting) there's no such problem. The request body is read first, and then upstream peers are tried until one of them succeeds.

With unbuffered proxying, things are different. NGINX behaves exactly as the upstream does, like there's no proxy at all.

[Maxim Dounin]

This may cause Nginx to send RST to downstream, causing downstream to finish the request abnormally

If the request is finalized before the whole request body was received from the client, nginx will trigger ​lingering_close to prevent RST (assuming lingering_close on;, which is the default), see ​ngx_http_finalize_connection().

If you are nevertheless seeing RST being sent, please provide more details. In particular, full nginx configuration, a ​debug log, and a network dump showing the RST would be helpful.

[fangjian.routon@…]

This can indeed be solved, but it will strongly depend on this configurationReplying to Maxim Dounin:

This may cause Nginx to send RST to downstream, causing downstream to finish the request abnormally

If the request is finalized before the whole request body was received from the client, nginx will trigger ​lingering_close to prevent RST (assuming lingering_close on;, which is the default), see ​ngx_http_finalize_connection().

If you are nevertheless seeing RST being sent, please provide more details. In particular, full nginx configuration, a ​debug log, and a network dump showing the RST would be helpful.

[fangjian.routon@…]

yes，bug this will affect performance and memory/disk space Replying to Roman Arutyunyan:

With buffered proxying (the default setting) there's no such problem. The request body is read first, and then upstream peers are tried until one of them succeeds.

With unbuffered proxying, things are different. NGINX behaves exactly as the upstream does, like there's no proxy at all.

[Maxim Dounin]

Replying to fangjian.routon@…:

This can indeed be solved, but it will strongly depend on this configuration

Please elaborate. It is expected to work fine with lingering close enabled, which is the default. If you've disabled lingering close for some reason (and/or tuned timeouts so these are not enough for some clients), it's your informed decision and RSTs are expected to appear in many practical cases.

[fangjian.routon@…]

Replying to Maxim Dounin:

Replying to fangjian.routon@…:

This can indeed be solved, but it will strongly depend on this configuration

Please elaborate. It is expected to work fine with lingering close enabled, which is the default. If you've disabled lingering close for some reason (and/or tuned timeouts so these are not enough for some clients), it's your informed decision and RSTs are expected to appear in many practical cases.

OK，Thank you for your reply

[Maxim Dounin]

Closing this. As explained in comment:2, the particular upstream behaviour triggers lingering close in nginx, and RSTs shouldn't appear on the wire.