extern const char *format_host(int af, int len, void *addr, char *buf, int buflen);
extern const char *rt_addr_n2a(int af, int len, void *addr, char *buf, int buflen);
extern const char *format_host(int af, int len, void *addr, char *buf, int buflen);
extern const char *rt_addr_n2a(int af, int len, void *addr, char *buf, int buflen);