/*
 * netflow.c
 *
 * Copyright (C) 2011-18 - 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"


#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 */
};

void ndpi_search_netflow(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
{
    struct ndpi_packet_struct *packet = &flow->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))
                    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_PROTO(ndpi_struct, flow);
                    return;
                }

                uptime_offset = 8;
                break;
            case 10: /* IPFIX */
                {
                    u_int16_t ipfix_len = n;

                    if(ipfix_len != payload_len)
                        return;
                }
                uptime_offset = 4;
                break;
            default:
                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 <= now))) {
            NDPI_LOG_INFO(ndpi_struct, "found netflow\n");
            ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_NETFLOW);
            return;
        }
    }
}

void init_netflow_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask)
{
    ndpi_set_bitmask_protocol_detection("NetFlow", ndpi_struct, detection_bitmask, *id,
            NDPI_PROTOCOL_NETFLOW,
            ndpi_search_netflow,
            NDPI_SELECTION_BITMASK_PROTOCOL_UDP_WITH_PAYLOAD,
            SAVE_DETECTION_BITMASK_AS_UNKNOWN,
            ADD_TO_DETECTION_BITMASK);

    *id += 1;
}

