If the user has closed the socket then drop a persisting connection

after a much reduced timeout.

Typically web servers close their sockets quickly under the assumption
that the TCP connections goes away as well.  That is not entirely true
however.  If the peer closed the window we're going to wait for a long
time with lots of data in the send buffer.

MFC after:	2 weeks

1 files changed, 10 insertions, 0 deletions

diff --git a/sys/netinet/tcp_timer.c b/sys/netinet/tcp_timer.c
index 678ce32..71ce426 100644
--- a/sys/netinet/tcp_timer.c
+++ b/sys/netinet/tcp_timer.c
@@ -447,6 +447,16 @@ tcp_timer_persist(void *xtp)
 		tp = tcp_drop(tp, ETIMEDOUT);
 		goto out;
 	}
+	/*
+	 * If the user has closed the socket then drop a persisting
+	 * connection after a much reduced timeout.
+	 */
+	if (tp->t_state > TCPS_CLOSE_WAIT &&
+	    (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) {
+		TCPSTAT_INC(tcps_persistdrop);
+		tp = tcp_drop(tp, ETIMEDOUT);
+		goto out;
+	}
 	tcp_setpersist(tp);
 	tp->t_flags |= TF_FORCEDATA;
 	(void) tcp_output(tp);