in6_addrscope
int scope = in6_addrscope(addr);
int dst_scope = in6_addrscope(dst), src_scope, best_scope = 0;
src_scope = in6_addrscope(IFA_IN6(ifa));
in6_addrscope(&ia6_best->ia_addr.sin6_addr);
int in6_addrscope(const struct in6_addr *);