BUG/MEDIUM: peers: set NOLINGER on the outgoing stream interface
Since peers were ported to an applet in 1.5, an issue appeared which
is that certain attempts to close an outgoing connection are a bit
"too nice". Specifically, protocol errors and stream timeouts result
in a clean shutdown to be sent, waiting for the other side to confirm.
This is particularly problematic in the case of timeouts since by
definition the other side will not confirm as it has disappeared.
As found by Fred, this issue was further emphasized in 1.8 by commit
f9ce57e ("MEDIUM: connection: make conn_sock_shutw() aware of
lingering") which causes clean shutdowns not to be sent if the fd is
marked as linger_risk, because now even a clean timeout will not be
sent on an idle peers session, and the other one will have nothing
to respond to.
The solution here is to set NOLINGER on the outgoing stream interface
to ensure we always close whenever we attempt a simple shutdown.
However it is important to keep in mind that this also underlines
some weaknesses of the shutr/shutw processing inside process_stream()
and that all this part needs to be reworked to clearly consider the
abort case, and to stop the confusion between linger_risk and NOLINGER.
This fix needs to be backported as far as 1.5 (all versions are affected).
However, during testing of the backport it was found that 1.5 never tries
to close the peers connection on timeout, so it suffers for another issue.
diff --git a/src/peers.c b/src/peers.c
index 155f334..988cd71 100644
--- a/src/peers.c
+++ b/src/peers.c
@@ -1912,6 +1912,7 @@
appctx_wakeup(appctx);
/* initiate an outgoing connection */
+ s->si[1].flags |= SI_FL_NOLINGER;
si_set_state(&s->si[1], SI_ST_ASS);
/* automatically prepare the stream interface to connect to the