/*
 * smb.c
 *
 * Copyright (C) 2016-22 - 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_SMBV23
#include "ndpi_api.h"
#include "ndpi_private.h"


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

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

  /* Check connection over TCP */
  if(packet->tcp) {
    u_int16_t fourfourfive =  htons(445);
    
    if(((packet->tcp->dest == fourfourfive) || (packet->tcp->source == fourfourfive))
       && packet->payload_packet_len > (32 + 4 + 4)
       && packet->payload[0] == 0x00) {
      u_int32_t length;

      length = (packet->payload[1] << 16) + (packet->payload[2] << 8) + packet->payload[3];
      /* If the message is split into multiple TCP segments, let's hope that
         the first message we receive is the first segment */
      if(length >= (uint32_t)packet->payload_packet_len - 4) {
        u_int8_t smbv1[] = { 0xff, 0x53, 0x4d, 0x42 };
        u_int8_t smbv2[] = { 0xfe, 0x53, 0x4d, 0x42 };

        if(memcmp(&packet->payload[4], smbv1, sizeof(smbv1)) == 0) {
          if(packet->payload[8] != 0x72) /* Skip Negotiate request */ {
            NDPI_LOG_INFO(ndpi_struct, "found SMBv1\n");
            ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_SMBV1, NDPI_PROTOCOL_NETBIOS, NDPI_CONFIDENCE_DPI);
            ndpi_set_risk(ndpi_struct, flow, NDPI_SMB_INSECURE_VERSION, "Found SMBv1");
          }
          return;
        } else if(memcmp(&packet->payload[4], smbv2, sizeof(smbv2)) == 0) {
          NDPI_LOG_INFO(ndpi_struct, "found SMBv23\n");
          ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_SMBV23, NDPI_PROTOCOL_NETBIOS, NDPI_CONFIDENCE_DPI);
          return;
        }
      }
    }
  }

  NDPI_EXCLUDE_PROTO_EXT(ndpi_struct, flow, NDPI_PROTOCOL_SMBV1);
  NDPI_EXCLUDE_PROTO_EXT(ndpi_struct, flow, NDPI_PROTOCOL_SMBV23);
}


void init_smb_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id)
{
  ndpi_set_bitmask_protocol_detection("SMB", ndpi_struct, *id,
				      NDPI_PROTOCOL_SMBV23,
				      ndpi_search_smb_tcp,
				      NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,
				      SAVE_DETECTION_BITMASK_AS_UNKNOWN,
				      ADD_TO_DETECTION_BITMASK);

  *id += 1;
}