[BUG] stream_sock: always shutdown(SHUT_WR) before closing

When we close a socket with unread data in the buffer, or when the
nolinger option is set, we regularly lose the last fragment, which
often contains the error message. This typically occurs when sending
too large a request. Only the RST is seen due to the close() (since
not all data were read) and the output message never reaches the
network.

Doing a shutdown() before the close() solves this annoying issue
because the data are really pushed before the system sends the RST.

src/stream_sock.c

@@ -834,17 +834,16 @@ void stream_sock_shutw(struct stream_interface *si)
 
 	switch (si->state) {
 	case SI_ST_EST:
-		if (!(si->ib->flags & BF_SHUTR)) {
-			EV_FD_CLR(si->fd, DIR_WR);
-			shutdown(si->fd, SHUT_WR);
-			return;
-		}
+		/* we have to shut before closing, otherwise some short messages
+		 * may never leave the system, especially when there are remaining
+		 * unread data in the socket input buffer, or when nolinger is set.
+		 */
+		EV_FD_CLR(si->fd, DIR_WR);
+		shutdown(si->fd, SHUT_WR);
+
+		if (!(si->ib->flags & BF_SHUTR))
+			return;
 
-		if (fdtab[si->fd].flags & FD_FL_TCP_NOLING) {
-			/* we have to shut before closing if we disable lingering */
-			EV_FD_CLR(si->fd, DIR_WR);
-			shutdown(si->fd, SHUT_WR);
-		}
 		/* fall through */
 	case SI_ST_CON:
 		/* we may have to close a pending connection, and mark the