getipnodebyaddr
he2 = getipnodebyaddr (he->h_addr_list[0], he->h_length,
struct hostent *getipnodebyaddr(const void *, size_t, int, int *);
hp = getipnodebyaddr(addr, afd->a_addrlen, afd->a_af, &h_error);
he = getipnodebyaddr(addr, len, af, &error);
hp2 = getipnodebyaddr(buf, hp->h_length, hp->h_addrtype,