haproxy/include
Amaury Denoyelle 3f07c20fab BUG/MEDIUM: session: only retrieve ready idle conn from session
A bug was introduced by the early insertion of idle connections at the
end of connect_server. It is possible to reuse a connection not yet
ready waiting for an handshake (for example with proxy protocol or ssl).
A wrong duplicate xprt_handshake_io_cb tasklet is thus registered as a
side-effect.

This triggers the BUG_ON statement of xprt_handshake_subscribe :
    BUG_ON(ctx->subs && ctx->subs != es);

To counter this, a check is now present in session_get_conn to only
return a connection without the flag CO_FL_WAIT_XPRT. This might cause
sometimes the creation of dedicated server connections when in theory
reuse could have been used, but probably only occurs rarely in real
condition.

This behavior is present since commit :
    MEDIUM: connection: Add private connections synchronously in session server list
It could also be further exagerated by :
    MEDIUM: backend: add reused conn to sess if mux marked as HOL blocking

It can be backported up to 2.3.

NOTE : This bug seems to be only reproducible with mode tcp, for an
unknown reason. However, reuse should never happen when not in http
mode. This improper behavior will be the subject of a dedicated patch.

This bug can easily be reproducible with the following config (a
webserver is required to accept proxy protocol on port 31080) :

    global

    defaults
      mode tcp
      timeout connect 1s
      timeout server 1s
      timeout client 1s

    listen li
      bind 0.0.0.0:4444
      server bla1 127.0.0.1:31080 check send-proxy-v2

with the inject client :
    $ inject -u 10000 -d 10 -G 127.0.0.1:4444

This should fix the github issue #1058.
2021-01-28 14:16:27 +01:00
..
haproxy BUG/MEDIUM: session: only retrieve ready idle conn from session 2021-01-28 14:16:27 +01:00
import CLEANUP: Fix spelling errors in comments 2021-01-08 14:56:32 +01:00