/*
 * tftp.c
 *
 * Copyright (C) 2009-2011 by ipoque GmbH
 * Copyright (C) 2011-20 - ntop.org
 *
 * This file is part of nDPI, an open source deep packet inspection
 * library based on the OpenDPI and PACE technology by ipoque GmbH
 *
 * nDPI is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * nDPI is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with nDPI.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include "ndpi_protocol_ids.h"

#define NDPI_CURRENT_PROTO NDPI_PROTOCOL_TFTP

#include "ndpi_api.h"

static void ndpi_int_tftp_add_connection(struct ndpi_detection_module_struct
					 *ndpi_struct, struct ndpi_flow_struct *flow)
{
  ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_TFTP, NDPI_PROTOCOL_UNKNOWN);
}

void ndpi_search_tftp(struct ndpi_detection_module_struct
		      *ndpi_struct, struct ndpi_flow_struct *flow)
{
  struct ndpi_packet_struct *packet = &flow->packet;

  NDPI_LOG_DBG(ndpi_struct, "search TFTP\n");

  if ((packet->payload_packet_len > 3)
      && (flow->l4.udp.tftp_stage == 0)
      && (ntohl(get_u_int32_t(packet->payload, 0)) == 0x00030001)) {
    NDPI_LOG_DBG2(ndpi_struct, "maybe tftp. need next packet\n");
    flow->l4.udp.tftp_stage = 1;
    return;
  }

  if(flow->l4.udp.tftp_stage == 1) {
    if (packet->payload_packet_len > 3 && (flow->l4.udp.tftp_stage == 1)
	&& ntohl(get_u_int32_t(packet->payload, 0)) == 0x00040001) {

      NDPI_LOG_INFO(ndpi_struct, "found tftp\n");
      ndpi_int_tftp_add_connection(ndpi_struct, flow);
      return;
    }

    if (packet->payload_packet_len > 1
	&& ((packet->payload[0] == 0 && packet->payload[packet->payload_packet_len - 1] == 0)
	    || (packet->payload_packet_len == 4 && ntohl(get_u_int32_t(packet->payload, 0)) == 0x00040000))) {
      NDPI_LOG_DBG2(ndpi_struct, "skip initial packet\n");
      return;
    }
  }
  
  NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
}


void init_tftp_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask)
{
  ndpi_set_bitmask_protocol_detection("TFTP", ndpi_struct, detection_bitmask, *id,
				      NDPI_PROTOCOL_TFTP,
				      ndpi_search_tftp,
				      NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_UDP_WITH_PAYLOAD,
				      SAVE_DETECTION_BITMASK_AS_UNKNOWN,
				      ADD_TO_DETECTION_BITMASK);

  *id += 1;
}