in6_prefixreq
#define SIOCSIFPREFIX_IN6 _IOW('i', 100, struct in6_prefixreq) /* set */
#define SIOCGIFPREFIX_IN6 _IOWR('i', 101, struct in6_prefixreq) /* get */
#define SIOCDIFPREFIX_IN6 _IOW('i', 102, struct in6_prefixreq) /* del */
add_prefix(struct rainfo *rai, struct in6_prefixreq *ipr)
init_prefix(struct in6_prefixreq *ipr)
struct in6_prefixreq ipr;