int in_addr_prefix_next(unsigned family, union in_addr_union *u, unsigned prefixlen);
int in_addr_to_string(unsigned family, const union in_addr_union *u, char **ret);
int in_addr_from_string(unsigned family, const char *s, union in_addr_union *ret);
int in_addr_prefix_next(unsigned family, union in_addr_union *u, unsigned prefixlen);
int in_addr_to_string(unsigned family, const union in_addr_union *u, char **ret);
int in_addr_from_string(unsigned family, const char *s, union in_addr_union *ret);