libnet_ptag_t
libnet_build_ntp(u_int8_t leap_indicator, u_int8_t version, u_int8_t mode,
u_int8_t stratum, u_int8_t poll, u_int8_t precision, u_int16_t delay_int,
u_int16_t delay_frac, u_int16_t dispersion_int, u_int16_t dispersion_frac,
u_int32_t reference_id, u_int32_t ref_ts_int, u_int32_t ref_ts_frac,
u_int32_t orig_ts_int, u_int32_t orig_ts_frac, u_int32_t rec_ts_int,
u_int32_t rec_ts_frac, u_int32_t xmt_ts_int, u_int32_t xmt_ts_frac,
u_int8_t *payload, u_int32_t payload_s, libnet_t *l, libnet_ptag_t ptag)
{
    u_int32_t n, h;
    libnet_pblock_t *p;
    struct libnet_ntp_hdr ntp_hdr;

    if (l == NULL)
    { 
        return (-1);
    } 

    n = LIBNET_NTP_H + payload_s;
    h = 0;

    /*
     *  Find the existing protocol block if a ptag is specified, or create
     *  a new one.
     */
    p = libnet_pblock_probe(l, ptag, n, LIBNET_PBLOCK_NTP_H);
    if (p == NULL)
    {
        return (-1);
    }

    memset(&ntp_hdr, 0, sizeof(ntp_hdr));
    ntp_hdr.ntp_li_vn_mode          = LIBNET_NTP_DO_LI_VN_MODE(
                                      leap_indicator, version, mode);
    ntp_hdr.ntp_stratum             = stratum;
    ntp_hdr.ntp_poll                = poll;
    ntp_hdr.ntp_precision           = precision;
    ntp_hdr.ntp_delay.integer       = htons(delay_int);
    ntp_hdr.ntp_delay.fraction      = htons(delay_frac);
    ntp_hdr.ntp_dispersion.integer  = htons(dispersion_int);
    ntp_hdr.ntp_dispersion.fraction = htons(dispersion_frac);
    ntp_hdr.ntp_reference_id        = htonl(reference_id);
    ntp_hdr.ntp_ref_ts.integer      = htonl(ref_ts_int);
    ntp_hdr.ntp_ref_ts.fraction     = htonl(ref_ts_frac);
    ntp_hdr.ntp_orig_ts.integer     = htonl(orig_ts_int);
    ntp_hdr.ntp_orig_ts.fraction    = htonl(orig_ts_frac);
    ntp_hdr.ntp_rec_ts.integer      = htonl(orig_ts_int);
    ntp_hdr.ntp_rec_ts.fraction     = htonl(orig_ts_frac);
    ntp_hdr.ntp_xmt_ts.integer      = htonl(xmt_ts_int);
    ntp_hdr.ntp_xmt_ts.fraction     = htonl(xmt_ts_frac);

    n = libnet_pblock_append(l, p, (u_int8_t *)&ntp_hdr, LIBNET_NTP_H);
    if (n == -1)
    {
        goto bad;
    }

    if ((payload && !payload_s) || (!payload && payload_s))
    {
        snprintf(l->err_buf, LIBNET_ERRBUF_SIZE,
                "%s(): payload inconsistency\n", __func__);
        goto bad;
    }

    if (payload && payload_s)
    {
        n = libnet_pblock_append(l, p, payload, payload_s);
        if (n == -1)
        {
            goto bad;
        }
    }

    return (ptag ? ptag : libnet_pblock_update(l, p, h, LIBNET_PBLOCK_NTP_H));
bad:
    libnet_pblock_delete(l, p);
    return (-1);
}
libnet_ptag_t
libnet_build_ntp(uint8_t leap_indicator, uint8_t version, uint8_t mode,
uint8_t stratum, uint8_t poll, uint8_t precision, uint16_t delay_int,
uint16_t delay_frac, uint16_t dispersion_int, uint16_t dispersion_frac,
uint32_t reference_id, uint32_t ref_ts_int, uint32_t ref_ts_frac,
uint32_t orig_ts_int, uint32_t orig_ts_frac, uint32_t rec_ts_int,
uint32_t rec_ts_frac, uint32_t xmt_ts_int, uint32_t xmt_ts_frac,
const uint8_t *payload, uint32_t payload_s, libnet_t *l, libnet_ptag_t ptag)
{
    uint32_t n, h;
    libnet_pblock_t *p;
    struct libnet_ntp_hdr ntp_hdr;

    if (l == NULL)
    { 
        return (-1);
    } 

    n = LIBNET_NTP_H + payload_s;
    h = 0;

    /*
     *  Find the existing protocol block if a ptag is specified, or create
     *  a new one.
     */
    p = libnet_pblock_probe(l, ptag, n, LIBNET_PBLOCK_NTP_H);
    if (p == NULL)
    {
        return (-1);
    }

    memset(&ntp_hdr, 0, sizeof(ntp_hdr));
    ntp_hdr.ntp_li_vn_mode          = LIBNET_NTP_DO_LI_VN_MODE(
                                      leap_indicator, version, mode);
    ntp_hdr.ntp_stratum             = stratum;
    ntp_hdr.ntp_poll                = poll;
    ntp_hdr.ntp_precision           = precision;
    ntp_hdr.ntp_delay.integer       = htons(delay_int);
    ntp_hdr.ntp_delay.fraction      = htons(delay_frac);
    ntp_hdr.ntp_dispersion.integer  = htons(dispersion_int);
    ntp_hdr.ntp_dispersion.fraction = htons(dispersion_frac);
    ntp_hdr.ntp_reference_id        = htonl(reference_id);
    ntp_hdr.ntp_ref_ts.integer      = htonl(ref_ts_int);
    ntp_hdr.ntp_ref_ts.fraction     = htonl(ref_ts_frac);
    ntp_hdr.ntp_orig_ts.integer     = htonl(orig_ts_int);
    ntp_hdr.ntp_orig_ts.fraction    = htonl(orig_ts_frac);
    ntp_hdr.ntp_rec_ts.integer      = htonl(rec_ts_int);
    ntp_hdr.ntp_rec_ts.fraction     = htonl(rec_ts_frac);
    ntp_hdr.ntp_xmt_ts.integer      = htonl(xmt_ts_int);
    ntp_hdr.ntp_xmt_ts.fraction     = htonl(xmt_ts_frac);

    n = libnet_pblock_append(l, p, (uint8_t *)&ntp_hdr, LIBNET_NTP_H);
    if (n == -1)
    {
        goto bad;
    }

    /* boilerplate payload sanity check / append macro */
    LIBNET_DO_PAYLOAD(l, p);

    return (ptag ? ptag : libnet_pblock_update(l, p, h, LIBNET_PBLOCK_NTP_H));
bad:
    libnet_pblock_delete(l, p);
    return (-1);
}