getaddrinfo

Input
Host name (numeric IPv4/v6 addr string, FQDN string)
Service name ("80" or "http")
Type of service you wish to use
Output
All information needed for socket/bind/connect
sockaddr, protocol number, socket type, etc

int getaddrinfo(host, port, hints, res)
    const char *host;
    const char *port;
    const struct addrinfo *hints;
    struct addrinfo **res;

struct addrinfo {
    int ai_flags;
    int ai_family;     /* PF_xxx */
    int ai_socktype;   /* SOCK_xxx */
    int ai_protocol;
    size_t ai_addrlen;
    char *ai_canonname;
    struct sockaddr *ai_addr;
    struct addrinfo *ai_next;
};