connect_fd_to_fd
int connect_fd_to_fd(int client_fd, int server_fd, int timeout_ms);
if (!ASSERT_EQ(connect_fd_to_fd(fd, srv_fd, TIMEOUT_MS), 0, "connect_fd_to_fd")) {
err = connect_fd_to_fd(out_sk, serv_sk, 1000);
err = connect_fd_to_fd(*client_fd, *listen_fd, 0);
err = connect_fd_to_fd(*client_fd, *listen_fd, 0);
err = connect_fd_to_fd(sk[i], sk[i + 1], 0);
err = connect_fd_to_fd(reuse_conn_fd, reuse_conn_fd, 0);