[PATCH net-next 2/4] selftests: net: test IPV6_FL_F_REMOTE

[Marcelo Mendes Spessoto Junior <marcelomspessoto@gmail.com>]

This flag retrieves the latest label received by the socket with
a getsockopt query. Therefore, the validation of this flag requires
a brief connection setup (source code for flow label shows it must
be TCP).

The simple TCP connection logic was wrapped inside two simple helpers,
because there are other uncovered features of flow label mgr that
could benefit from it (such as IPV6_FL_F_REFLECT).

Signed-off-by: Marcelo Mendes Spessoto Junior <marcelospe@proton.me>
---
 .../selftests/net/ipv6_flowlabel_mgr.c        | 71 +++++++++++++++++++
 1 file changed, 71 insertions(+)

diff --git a/tools/testing/selftests/net/ipv6_flowlabel_mgr.c b/tools/testing/selftests/net/ipv6_flowlabel_mgr.c
index cfa7e6270994..383a84ea9385 100644
--- a/tools/testing/selftests/net/ipv6_flowlabel_mgr.c
+++ b/tools/testing/selftests/net/ipv6_flowlabel_mgr.c
@@ -24,10 +24,20 @@
 #ifndef IPV6_FLOWLABEL_MGR
 #define IPV6_FLOWLABEL_MGR	32
 #endif
+#ifndef IPV6_FLOWINFO_SEND
+#define IPV6_FLOWINFO_SEND	33
+#endif
 
 /* from net/ipv6/ip6_flowlabel.c */
 #define FL_MIN_LINGER		6
 
+#define INIT_SIN6_LOOPBACK(name)					\
+	struct sockaddr_in6 name = {					\
+		.sin6_family	= AF_INET6,				\
+		.sin6_addr	= IN6ADDR_LOOPBACK_INIT,		\
+		.sin6_port	= htons(8888),				\
+	}
+
 #define explain(x)							\
 	do { if (cfg_verbose) fprintf(stderr, "       " x "\n"); } while (0)
 
@@ -82,6 +92,52 @@ static int flowlabel_renew(int fd, uint32_t label, uint16_t linger)
 	return setsockopt(fd, SOL_IPV6, IPV6_FLOWLABEL_MGR, &req, sizeof(req));
 }
 
+static int tcp_listen(void)
+{
+	INIT_SIN6_LOOPBACK(addr);
+	const int one = 1;
+	int fd;
+
+	fd = socket(PF_INET6, SOCK_STREAM, 0);
+	if (fd == -1)
+		error(1, errno, "socket listener");
+	if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)))
+		error(1, errno, "setsockopt SO_REUSEADDR");
+	if (bind(fd, (void *)&addr, sizeof(addr)))
+		error(1, errno, "bind");
+	if (listen(fd, 1))
+		error(1, errno, "listen");
+
+	return fd;
+}
+
+static void tcp_connect(int listener, uint32_t flowlabel, int *client, int *accepted)
+{
+	INIT_SIN6_LOOPBACK(addr);
+	const int one = 1;
+	int cfd, afd;
+
+	cfd = socket(PF_INET6, SOCK_STREAM, 0);
+	if (cfd == -1)
+		error(1, errno, "socket client");
+
+	if (flowlabel_get(cfd, flowlabel, IPV6_FL_S_EXCL, IPV6_FL_F_CREATE))
+		error(1, errno, "flowlabel_get");
+	if (setsockopt(cfd, SOL_IPV6, IPV6_FLOWINFO_SEND, &one, sizeof(one)))
+		error(1, errno, "setsockopt flowinfo_send");
+	addr.sin6_flowinfo = htonl(flowlabel);
+
+	if (connect(cfd, (void *)&addr, sizeof(addr)))
+		error(1, errno, "connect");
+
+	afd = accept(listener, NULL, NULL);
+	if (afd == -1)
+		error(1, errno, "accept");
+
+	*client = cfd;
+	*accepted = afd;
+}
+
 static void run_tests(int fd)
 {
 	int wstatus;
@@ -183,6 +239,21 @@ static void run_tests(int fd)
 		expect_fail(flowlabel_get(fd, 5, IPV6_FL_S_ANY, IPV6_FL_F_CREATE));
 	}
 
+	explain("Prepare TCP SYN for REMOTE flag validation");
+	int remote_listener = tcp_listen();
+	int remote_cfd, remote_afd;
+	tcp_connect(remote_listener, 6, &remote_cfd, &remote_afd);
+	struct in6_flowlabel_req freq = {
+		.flr_action = IPV6_FL_A_GET,
+		.flr_flags = IPV6_FL_F_REMOTE,
+	};
+	socklen_t freq_len = sizeof(freq);
+	explain("Query for label sent by client with IPV6_FL_F_REMOTE");
+	expect_pass(getsockopt(remote_afd, SOL_IPV6, IPV6_FLOWLABEL_MGR, &freq, &freq_len));
+	expect_pass(ntohl(freq.flr_label) != 6);
+	close(remote_afd);
+	close(remote_cfd);
+	close(remote_listener);
 }
 
 static void parse_opts(int argc, char **argv)
-- 
2.55.0