Example: Translate sockaddr into string

char hbuf[1024], pbuf[1024];

/* string if possible, like www.kame.net/http */
if (getnameinfo(sa, sa->sa_len, hbuf, sizeof(hbuf),
        pbuf, sizeof(pbuf), 0) != 0)
    errx(1, "invalid address");

/* numeric address, like 127.0.0.1/80 */
if (getnameinfo(sa, sa->sa_len, hbuf, sizeof(hbuf),
        pbuf, sizeof(pbuf),
        NI_NUMERICHOST|NI_NUMERICSERV) != 0)
    errx(1, "invalid address");