if( ip_header->protocol == IPV4_TCP_PROTOCOL )
    {
        uint8_t *payload =
            (uint8_t *)(skb->data + ip_hdrlen(skb) + tcp_hdrlen(skb));
        unsigned int payload_len =
            (unsigned int)(skb->len - ip_hdrlen(skb) - tcp_hdrlen(skb));