struct addrinfo  *ai_next;

typedef struct addrinfo {
int             ai_flags;
int             ai_family;
int             ai_socktype;
int             ai_protocol;
size_t          ai_addrlen;
char            *ai_canonname;
struct sockaddr  *ai_addr;
struct addrinfo  *ai_next;
}ADDRINFOA, *PADDRINFOA;