/*
 * mssql.c
 *
 * Copyright (C) 2016-18 - 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_MSSQL_TDS

#include "ndpi_api.h"

struct tds_packet_header {
    u_int8_t type;
    u_int8_t status;
    u_int16_t length;
    u_int16_t channel;
    u_int8_t number;
    u_int8_t window;
};

static void ndpi_int_mssql_tds_add_connection(struct ndpi_detection_module_struct
        *ndpi_struct, struct ndpi_flow_struct *flow)
{
    ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_MSSQL_TDS);
}

void ndpi_search_mssql_tds(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
{
    struct ndpi_packet_struct *packet = &flow->packet;
    struct tds_packet_header *h = (struct tds_packet_header*) packet->payload;

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

    if(packet->payload_packet_len < sizeof(struct tds_packet_header)) {
        NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
        return;
    }

    if((h->type >= 1 && h->type <= 8) || (h->type >= 14 && h->type <= 18)) {
        if(h->status == 0x00 || h->status == 0x01 || h->status == 0x02 || h->status == 0x04 || h->status == 0x08 || h->status == 0x09 || h->status == 0x10) {
            if(ntohs(h->length) == packet->payload_packet_len && h->window == 0x00) {
                NDPI_LOG_INFO(ndpi_struct, "found mssql_tds\n");
                ndpi_int_mssql_tds_add_connection(ndpi_struct, flow);
                return;
            }
        }
    }

    NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
}


void init_mssql_tds_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask)
{
    ndpi_set_bitmask_protocol_detection("MsSQL_TDS", ndpi_struct, detection_bitmask, *id,
            NDPI_PROTOCOL_MSSQL_TDS,
            ndpi_search_mssql_tds,
            NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,
            SAVE_DETECTION_BITMASK_AS_UNKNOWN,
            ADD_TO_DETECTION_BITMASK);

    *id += 1;
}
