if_nameindex
cp = malloc((ni + 1) * sizeof(struct if_nameindex) + nbytes);
ifni = (struct if_nameindex *)cp;
cp += (ni + 1) * sizeof(struct if_nameindex);
if_freenameindex(struct if_nameindex *ptr)
struct if_nameindex *
struct if_nameindex *ifni, *ifni2;
void if_freenameindex(struct if_nameindex *);
struct if_nameindex *if_nameindex(void);
struct if_nameindex *p;
if ((ifnameindex = if_nameindex()) == NULL)
struct if_nameindex *ifnameindex;