Addrinfo#getnameinfo

static VALUE
addrinfo_getnameinfo(int argc, VALUE *argv, VALUE self)
{
    rb_addrinfo_t *rai = get_addrinfo(self);
    VALUE vflags;
    char hbuf[1024], pbuf[1024];
    int flags, error;

    rb_scan_args(argc, argv, "01", &vflags);

    flags = NIL_P(vflags) ? 0 : NUM2INT(vflags);

    if (rai->socktype == SOCK_DGRAM)
        flags |= NI_DGRAM;

    error = rb_getnameinfo(&rai->addr.addr, rai->sockaddr_len,
                           hbuf, (socklen_t)sizeof(hbuf), pbuf, (socklen_t)sizeof(pbuf),
                           flags);
    if (error) {
        rsock_raise_resolution_error("getnameinfo", error);
    }

    return rb_assoc_new(rb_str_new2(hbuf), rb_str_new2(pbuf));
}