Reverse lookup, printing addresses

Use getnameinfo()
Always check errors

Don't use inet_{ntoa,ntop} - they do not support scoped IPv6 address

if (getnameinfo(sa, sa->sa_len, hbuf, sizeof(hbuf),
    sbuf, sizeof(sbuf), 0) != 0)
        printf("invalid\n");
printf("host=%s serv=%s\n", hbuf, sbuf);

if (getnameinfo(sa, sa->sa_len, hbuf, sizeof(hbuf),
    sbuf, sizeof(sbuf), NI_NUMERICHOST|NI_NUMERICSERV) != 0)
        printf("invalid\n");
printf("host=%s serv=%s\n", hbuf, sbuf);