Reverse lookup and printing addresses

Always use getnameinfo().
forget inet_{ntoa, ntop}
do not forget to check errors.

char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];

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);