/*

 * netflow.c

 *

 * Copyright (C) 2011-26 - ntop.org

 *

 * 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_NETFLOW

#include "ndpi_api.h"

#include "ndpi_private.h"

#ifdef WIN32

extern int gettimeofday(struct timeval * tp, struct timezone * tzp);

#endif

#define do_gettimeofday(a) gettimeofday(a, NULL)

struct flow_ver1_rec {

  u_int32_t srcaddr;    /* Source IP Address */

  u_int32_t dstaddr;    /* Destination IP Address */

  u_int32_t nexthop;    /* Next hop router's IP Address */

  u_int16_t input;      /* Input interface index */

  u_int16_t output;     /* Output interface index */

  u_int32_t dPkts;      /* Packets sent in Duration */

  u_int32_t dOctets;    /* Octets sent in Duration */

  u_int32_t first;      /* SysUptime at start of flow */

  u_int32_t last;       /* and of last packet of the flow */

  u_int16_t srcport;    /* TCP/UDP source port number (.e.g, FTP, Telnet, etc.,or equivalent) */

  u_int16_t dstport;    /* TCP/UDP destination port number (.e.g, FTP, Telnet, etc.,or equivalent) */

  u_int16_t pad;        /* pad to word boundary */

  u_int8_t  proto;      /* IP protocol, e.g., 6=TCP, 17=UDP, etc... */

  u_int8_t  tos;        /* IP Type-of-Service */

  u_int8_t  pad2[7];    /* pad to word boundary */

};

struct flow_ver5_rec {

  u_int32_t srcaddr;    /* Source IP Address */

  u_int32_t dstaddr;    /* Destination IP Address */

  u_int32_t nexthop;    /* Next hop router's IP Address */

  u_int16_t input;      /* Input interface index */

  u_int16_t output;     /* Output interface index */

  u_int32_t dPkts;      /* Packets sent in Duration (milliseconds between 1st

         & last packet in this flow)*/

  u_int32_t dOctets;    /* Octets sent in Duration (milliseconds between 1st

         & last packet in  this flow)*/

  u_int32_t first;      /* SysUptime at start of flow */

  u_int32_t last;       /* and of last packet of the flow */

  u_int16_t srcport;    /* TCP/UDP source port number (.e.g, FTP, Telnet, etc.,or equivalent) */

  u_int16_t dstport;    /* TCP/UDP destination port number (.e.g, FTP, Telnet, etc.,or equivalent) */

  u_int8_t pad1;        /* pad to word boundary */

  u_int8_t tcp_flags;   /* Cumulative OR of tcp flags */

  u_int8_t proto;        /* IP protocol, e.g., 6=TCP, 17=UDP, etc... */

  u_int8_t tos;         /* IP Type-of-Service */

  u_int16_t src_as;     /* source peer/origin Autonomous System */

  u_int16_t dst_as;     /* dst peer/origin Autonomous System */

  u_int8_t src_mask;    /* source route's mask bits */

  u_int8_t dst_mask;    /* destination route's mask bits */

  u_int16_t pad2;       /* pad to word boundary */

};

struct flow_ver7_rec {

  u_int32_t srcaddr;    /* Source IP Address */

  u_int32_t dstaddr;    /* Destination IP Address */

  u_int32_t nexthop;    /* Next hop router's IP Address */

  u_int16_t input;      /* Input interface index */

  u_int16_t output;     /* Output interface index */

  u_int32_t dPkts;      /* Packets sent in Duration */

  u_int32_t dOctets;    /* Octets sent in Duration */

  u_int32_t first;      /* SysUptime at start of flow */

  u_int32_t last;       /* and of last packet of the flow */

  u_int16_t srcport;    /* TCP/UDP source port number (.e.g, FTP, Telnet, etc.,or equivalent) */

  u_int16_t dstport;    /* TCP/UDP destination port number (.e.g, FTP, Telnet, etc.,or equivalent) */

  u_int8_t  flags;      /* Shortcut mode(dest only,src only,full flows*/

  u_int8_t  tcp_flags;  /* Cumulative OR of tcp flags */

  u_int8_t  proto;      /* IP protocol, e.g., 6=TCP, 17=UDP, etc... */

  u_int8_t  tos;        /* IP Type-of-Service */

  u_int16_t dst_as;     /* dst peer/origin Autonomous System */

  u_int16_t src_as;     /* source peer/origin Autonomous System */

  u_int8_t  dst_mask;   /* destination route's mask bits */

  u_int8_t  src_mask;   /* source route's mask bits */

  u_int16_t pad2;       /* pad to word boundary */

  u_int32_t router_sc;  /* Router which is shortcut by switch */

};

static void ndpi_search_netflow(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)

{

  struct ndpi_packet_struct *packet = &ndpi_struct->packet;

  // const u_int8_t *packet_payload = packet->payload;

  u_int32_t payload_len = packet->payload_packet_len;

  time_t now;

  struct timeval now_tv;

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

  if((packet->udp != NULL) && (payload_len >= 24)) {

    u_int16_t version = (packet->payload[0] << 8) + packet->payload[1], uptime_offset;

    u_int32_t when, *_when;

    u_int16_t n = (packet->payload[2] << 8) + packet->payload[3], expected_len = 0;

    switch(version) {

    case 1:

    case 5:

    case 7:

    case 9:

      if((n == 0) || (n > 30)) {

  NDPI_EXCLUDE_DISSECTOR(ndpi_struct, flow);

  return;

      }

      switch(version) {

      case 1:

  expected_len = n * sizeof(struct flow_ver1_rec) + 16 /* header */;

  break;

      case 5:

  expected_len = n * sizeof(struct flow_ver5_rec) + 24 /* header */;

  break;

      case 7:

  expected_len = n * sizeof(struct flow_ver7_rec) + 24 /* header */;

  break;

      case 9:

  /* We need to check the template */

  break;

      }

      if((expected_len > 0) && (expected_len != payload_len)) {

  NDPI_EXCLUDE_DISSECTOR(ndpi_struct, flow);

  return;

      }

      uptime_offset = 8;

      break;

    case 10: /* IPFIX */

      {      

  u_int16_t ipfix_len = n;

  if(ipfix_len != payload_len) {

    NDPI_EXCLUDE_DISSECTOR(ndpi_struct, flow);

    return;

  }

      }    

      uptime_offset = 4;

      break;

    default:

      NDPI_EXCLUDE_DISSECTOR(ndpi_struct, flow);

      return;

    }

    _when = (u_int32_t*)&packet->payload[uptime_offset]; /* Sysuptime */

    when = ntohl(*_when);

    do_gettimeofday(&now_tv);

    now = now_tv.tv_sec;

    if(((version == 1) && (when == 0))

       || ((when >= 946684800 /* 1/1/2000 */) && (when <= (u_int32_t)now))) {

      NDPI_LOG_INFO(ndpi_struct, "found netflow\n");

      ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_NETFLOW, NDPI_PROTOCOL_UNKNOWN, NDPI_CONFIDENCE_DPI);

      return;

    }

  } else

    NDPI_EXCLUDE_DISSECTOR(ndpi_struct, flow);

}

void init_netflow_dissector(struct ndpi_detection_module_struct *ndpi_struct)

{

  ndpi_register_dissector("NetFlow", ndpi_struct,

                     ndpi_search_netflow,

                     NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_UDP_WITH_PAYLOAD,

                     1, NDPI_PROTOCOL_NETFLOW);

}