From: Geliang Tang <tanggeliang@kylinos.cn>

Implement tests for transparent socket options:
- IP_TRANSPARENT (IPv4) and IPV6_TRANSPARENT (IPv6)
- Setsockopt and getsockopt helpers
- State verification after setting
- IPv4/IPv6 coverage in test script

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 .../selftests/net/mptcp/mptcp_sockopt.c       | 27 +++++++++++++++++++
 .../selftests/net/mptcp/mptcp_sockopt.sh      |  4 +--
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/net/mptcp/mptcp_sockopt.c b/tools/testing/selftests/net/mptcp/mptcp_sockopt.c
index e9ef908dc270..ccc072005118 100644
--- a/tools/testing/selftests/net/mptcp/mptcp_sockopt.c
+++ b/tools/testing/selftests/net/mptcp/mptcp_sockopt.c
@@ -243,6 +243,16 @@ static void do_setsockopt_freebind(int fd)
 		perror("setsockopt(IP(V6)_FREEBIND)");
 }
 
+static void do_setsockopt_transparent(int fd)
+{
+	int optname = (pf == AF_INET ? IP_TRANSPARENT : IPV6_TRANSPARENT);
+	int level = (pf == AF_INET ? SOL_IP : SOL_IPV6);
+	int enable = 1;
+
+	if (setsockopt(fd, level, optname, &enable, sizeof(enable)))
+		perror("setsockopt(IP(V6)_TRANSPARENT)");
+}
+
 static void do_setsockopts(int fd)
 {
 	do_setsockopt_reuseaddr(fd);
@@ -250,6 +260,7 @@ static void do_setsockopts(int fd)
 	do_setsockopt_bindtodevice(fd);
 	do_setsockopt_bindtoifindex(fd);
 	do_setsockopt_freebind(fd);
+	do_setsockopt_transparent(fd);
 }
 
 static int sock_listen_mptcp(const char * const listenaddr,
@@ -686,6 +697,20 @@ static void do_getsockopt_freebind(int fd)
 	assert(enable == 1);
 }
 
+static void do_getsockopt_transparent(int fd)
+{
+	int optname = (pf == AF_INET ? IP_TRANSPARENT : IPV6_TRANSPARENT);
+	int level = (pf == AF_INET ? SOL_IP : SOL_IPV6);
+	socklen_t len;
+	int enable;
+
+	len = sizeof(enable);
+	if (getsockopt(fd, level, optname, &enable, &len))
+		die_perror("getsockopt(IP(V6)_TRANSPARENT)");
+
+	assert(enable == 1);
+}
+
 static void do_getsockopts(struct so_state *s, int fd, size_t r, size_t w)
 {
 	do_getsockopt_mptcp_info(s, fd, w);
@@ -706,6 +731,8 @@ static void do_getsockopts(struct so_state *s, int fd, size_t r, size_t w)
 	do_getsockopt_bindtoifindex(fd);
 
 	do_getsockopt_freebind(fd);
+
+	do_getsockopt_transparent(fd);
 }
 
 static void connect_one_server(int fd, int pipefd)
diff --git a/tools/testing/selftests/net/mptcp/mptcp_sockopt.sh b/tools/testing/selftests/net/mptcp/mptcp_sockopt.sh
index 193f4d4dc41a..da02769fbb2b 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_sockopt.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_sockopt.sh
@@ -272,7 +272,7 @@ do_mptcp_sockopt_tests()
 	for opt in "SOL_MPTCP" \
 		   "SO_REUSEADDR" "SO_REUSEPORT" \
 		   "SO_BINDTODEVICE" "SO_BINDTOIFINDEX" \
-		   "IP_FREEBIND"; do
+		   "IP_FREEBIND" "IP_TRANSPARENT"; do
 		print_title "$opt sockopt v4"
 		mptcp_lib_pr_ok
 		mptcp_lib_result_pass "$opt sockopt v4"
@@ -292,7 +292,7 @@ do_mptcp_sockopt_tests()
 	for opt in "SOL_MPTCP" \
 		   "SO_REUSEADDR" "SO_REUSEPORT" \
 		   "SO_BINDTODEVICE" "SO_BINDTOIFINDEX" \
-		   "IPV6_FREEBIND"; do
+		   "IPV6_FREEBIND" "IPV6_TRANSPARENT"; do
 		print_title "$opt sockopt v6"
 		mptcp_lib_pr_ok
 		mptcp_lib_result_pass "$opt sockopt v6"
-- 
2.48.1