static int ipnetns_have_nsid(void)
{
	struct {
		struct nlmsghdr n;
		struct rtgenmsg g;
		char            buf[1024];
	} req = {
		.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtgenmsg)),
		.n.nlmsg_flags = NLM_F_REQUEST,
		.n.nlmsg_type = RTM_GETNSID,
		.g.rtgen_family = AF_UNSPEC,
	};
	int fd;

	if (have_rtnl_getnsid < 0) {
		fd = open("/proc/self/ns/net", O_RDONLY);
		if (fd < 0) {
			have_rtnl_getnsid = 0;
			return 0;
		}

		addattr32(&req.n, 1024, NETNSA_FD, fd);

		if (rtnl_send(&rth, &req.n, req.n.nlmsg_len) < 0) {
			perror("request send failed");
			exit(1);
		}
		rtnl_listen(&rth, ipnetns_accept_msg, NULL);
		close(fd);
	}

	return have_rtnl_getnsid;
}
Unknown