rtsock: fix socket closure.

Currently `close(2)` erroneously return `EOPNOTSUPP` for `PF_ROUTE` sockets.
It happened after making rtsock socket implementation self-contained (
36b10ac2cd ). Rtsock code marks socket as connected in `rts_attach()`.
`soclose()` tries to disconnect such socket using `.pr_disconnect` callback.
Rtsock does not implement this callback, resulting in the default method being
substituted. This default method returns `ENOTSUPP`, failing `soclose()` logic.

This diff restores the previous behaviour by adding custom `pr_disconnect()`
returning `ENOTCONN`.

Reviewed by:	glebius
Differential Revision: https://reviews.freebsd.org/D38059

sys/net/rtsock.c

@@ -446,6 +446,13 @@ rts_detach(struct socket *so)
 	so->so_pcb = NULL;
 }
 
+static int
+rts_disconnect(struct socket *so)
+{
+
+	return (ENOTCONN);
+}
+
 static int
 rts_shutdown(struct socket *so)
 {
@@ -2702,6 +2709,7 @@ static struct protosw routesw = {
 	.pr_detach =		rts_detach,
 	.pr_send =		rts_send,
 	.pr_shutdown =		rts_shutdown,
+	.pr_disconnect =	rts_disconnect,
 	.pr_close =		rts_close,
 };
 

tests/sys/net/routing/Makefile

@@ -7,6 +7,7 @@ TESTSDIR=       ${TESTSBASE}/sys/net/routing
 
 ATF_TESTS_C +=	test_rtsock_l3
 ATF_TESTS_C +=	test_rtsock_lladdr
+ATF_TESTS_C +=	test_rtsock_ops
 ATF_TESTS_PYTEST +=	test_routing_l3.py
 ATF_TESTS_PYTEST +=	test_rtsock_multipath.py
 

tests/sys/net/routing/test_rtsock_ops.c

@@ -0,0 +1,56 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2023 Alexander V. Chernikov
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/types.h>
+#include <sys/errno.h>
+#include <sys/socket.h>
+#include <net/route.h>
+
+#include <atf-c.h>
+
+ATF_TC(socket_rtsock_openclose);
+ATF_TC_HEAD(socket_rtsock_openclose, tc)
+{
+	atf_tc_set_md_var(tc, "descr", "test successful open/close");
+}
+
+ATF_TC_BODY(socket_rtsock_openclose, tc)
+{
+	int s = socket(PF_ROUTE, SOCK_RAW, 0);
+	ATF_CHECK(s >= 0);
+	ATF_CHECK_ERRNO(0, close(s) == 0);
+}
+
+ATF_TP_ADD_TCS(tp)
+{
+	ATF_TP_ADD_TC(tp, socket_rtsock_openclose);
+
+	return (atf_no_error());
+}