selftests/bpf: Use connect_to_fd in sockopt_inherit

This patch uses public helper connect_to_fd() exported in network_helpers.h
instead of the local defined function connect_to_server() in
prog_tests/sockopt_inherit.c. This can avoid duplicate code.
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Link: https://lore.kernel.org/r/71db79127cc160b0643fd9a12c70ae019ae076a1.1714907662.git.tanggeliang@kylinos.cnSigned-off-by: Martin KaFai Lau <martin.lau@kernel.org>

tools/testing/selftests/bpf/prog_tests/sockopt_inherit.c

@@ -10,35 +10,6 @@
 #define CUSTOM_INHERIT2			1
 #define CUSTOM_LISTENER			2
 
-static int connect_to_server(int server_fd)
-{
-	struct sockaddr_storage addr;
-	socklen_t len = sizeof(addr);
-	int fd;
-
-	fd = socket(AF_INET, SOCK_STREAM, 0);
-	if (fd < 0) {
-		log_err("Failed to create client socket");
-		return -1;
-	}
-
-	if (getsockname(server_fd, (struct sockaddr *)&addr, &len)) {
-		log_err("Failed to get server addr");
-		goto out;
-	}
-
-	if (connect(fd, (const struct sockaddr *)&addr, len) < 0) {
-		log_err("Fail to connect to server");
-		goto out;
-	}
-
-	return fd;
-
-out:
-	close(fd);
-	return -1;
-}
-
 static int verify_sockopt(int fd, int optname, const char *msg, char expected)
 {
 	socklen_t optlen = 1;
@@ -164,7 +135,7 @@ static void run_test(int cgroup_fd)
 	pthread_cond_wait(&server_started, &server_started_mtx);
 	pthread_mutex_unlock(&server_started_mtx);
 
-	client_fd = connect_to_server(server_fd);
+	client_fd = connect_to_fd(server_fd, 0);
 	if (!ASSERT_GE(client_fd, 0, "connect_to_server"))
 		goto close_server_fd;