a2tun
ret->force_tun_device = a2tun(opt, NULL);
return (a2tun(s, NULL));
*remote = a2tun(ep, NULL);
tun = a2tun(sp, NULL);
int a2tun(const char *, int *);
value = a2tun(arg, &value2);
options.tun_local = a2tun(optarg, &options.tun_remote);