/*
 * netbios.c
 *
 * Copyright (C) 2009-2011 by ipoque GmbH
 * Copyright (C) 2011-18 - 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_NETBIOS

#include "ndpi_api.h"


struct netbios_header {
  u_int16_t transaction_id, flags, questions, answer_rrs, authority_rrs, additional_rrs;
};

/* The function below has been inherited by tcpdump */
int ndpi_netbios_name_interpret(char *in, char *out, u_int out_len) {
  int ret = 0, len;
  char *b;
  
  len = (*in++)/2;
  b  = out;
  *out=0;

  if(len > (out_len-1) || len < 1)
    return(-1);  
  
  while (len--) {
    if(in[0] < 'A' || in[0] > 'P' || in[1] < 'A' || in[1] > 'P') {
      *out = 0;
      break;
    }

    *out = ((in[0]-'A')<<4) + (in[1]-'A');
        
    in += 2;

    if(isprint(*out))
      out++, ret++;
  }

  *out = 0;

  /* Courtesy of Roberto F. De Luca <deluca@tandar.cnea.gov.ar> */
  /* Trim trailing whitespace from the returned string */
  for(out--; out>=b && *out==' '; out--) *out = '\0';

  return(ret);
}


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


void ndpi_search_netbios(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
{
  struct ndpi_packet_struct *packet = &flow->packet;
  u_int16_t dport;
  char name[64];
  
  NDPI_LOG_DBG(ndpi_struct, "search netbios\n");
  if(packet->udp != NULL) {
    dport = ntohs(packet->udp->dest);


    /*check standard NETBIOS over udp to port 137  */
    if((dport == 137 || 0) && packet->payload_packet_len >= 50) {
      struct netbios_header h;

      memcpy(&h, packet->payload, sizeof(struct netbios_header));
      h.transaction_id = ntohs(h.transaction_id), h.flags = ntohs(h.flags),
	h.questions = ntohs(h.questions), h.answer_rrs = ntohs(h.answer_rrs),
	h.authority_rrs = ntohs(h.authority_rrs), h.additional_rrs = ntohs(h.additional_rrs);
      
      NDPI_LOG_DBG(ndpi_struct, "found netbios port 137 and payload_packet_len 50\n");

      if(h.flags == 0 &&
	  h.questions == 1 &&
	  h.answer_rrs == 0 &&
	  h.authority_rrs == 0 && h.additional_rrs == 0) {

	NDPI_LOG_INFO(ndpi_struct, "found netbios with questions = 1 and answers = 0, authority = 0  \n");

	ndpi_int_netbios_add_connection(ndpi_struct, flow);
	return;
      }
      if(((h.flags & 0x8710) == 0x10) &&
	  h.questions == 1 &&
	  h.answer_rrs == 0 &&
	  h.authority_rrs == 0) {

	NDPI_LOG_INFO(ndpi_struct, "found netbios with questions = 1 and answers = 0, authority = 0 and broadcast \n");
	
	if(ndpi_netbios_name_interpret((char*)&packet->payload[12], name, sizeof(name)) > 0) {
	  if(!ndpi_struct->disable_metadata_export) {
	    snprintf((char*)flow->host_server_name, sizeof(flow->host_server_name)-1, "%s", name);
	  }
	}
	
	ndpi_int_netbios_add_connection(ndpi_struct, flow);
	return;
      }
      if(packet->payload[2] == 0x80 &&
	  h.questions == 1 &&
	  h.answer_rrs == 0 &&
	  h.authority_rrs == 0 && h.additional_rrs == 1) {

	NDPI_LOG_INFO(ndpi_struct, "found netbios with questions = 1 and answers, authority, additional = 0  \n");

	ndpi_int_netbios_add_connection(ndpi_struct, flow);
	return;
      }
      if(h.flags == 0x4000 &&
	  h.questions == 1 &&
	  h.answer_rrs == 0 &&
	  h.authority_rrs == 0 && h.additional_rrs == 1) {

	NDPI_LOG_INFO(ndpi_struct, "found netbios with questions = 1 and answers = 0, authority = 0  \n");

	ndpi_int_netbios_add_connection(ndpi_struct, flow);
	return;
      }
      if(h.flags == 0x8400 &&
	  h.questions == 0 &&
	  h.answer_rrs == 1 &&
	  h.authority_rrs == 0 && h.additional_rrs == 0) {

	NDPI_LOG_INFO(ndpi_struct,
		 "found netbios with flag 8400 questions = 0 and answers = 1, authority, additional = 0  \n");

	ndpi_int_netbios_add_connection(ndpi_struct, flow);
	return;
      }
      if(h.flags == 0x8500 &&
	  h.questions == 0 &&
	  h.answer_rrs == 1 &&
	  h.authority_rrs == 0 && h.additional_rrs == 0) {

	NDPI_LOG_INFO(ndpi_struct,
		 "found netbios with flag 8500 questions = 0 and answers = 1, authority, additional = 0  \n");

	ndpi_int_netbios_add_connection(ndpi_struct, flow);
	return;
      }
      if(h.flags == 0x2910 &&
	  h.questions == 1 &&
	  h.answer_rrs == 0 &&
	  h.authority_rrs == 0 && h.additional_rrs == 1) {

	NDPI_LOG_INFO(ndpi_struct,
		 "found netbios with flag 2910, questions = 1 and answers, authority=0, additional = 1  \n");

	ndpi_int_netbios_add_connection(ndpi_struct, flow);
	return;
      }
      if(h.flags == 0xAD86 &&
	  h.questions == 0 &&
	  h.answer_rrs == 1 &&
	  h.authority_rrs == 0 && h.additional_rrs == 0) {

	NDPI_LOG_INFO(ndpi_struct,
		 "found netbios with flag ad86 questions = 0 and answers = 1, authority, additional = 0  \n");

	ndpi_int_netbios_add_connection(ndpi_struct, flow);
	return;
      }
      if(h.flags == 0x0110 &&
	  h.questions == 1 &&
	  h.answer_rrs == 0 &&
	  h.authority_rrs == 0 && h.additional_rrs == 0) {

	NDPI_LOG_INFO(ndpi_struct,
		 "found netbios with flag 0110 questions = 1 and answers = 0, authority, additional = 0  \n");

	ndpi_int_netbios_add_connection(ndpi_struct, flow);
	return;
      }

      if((h.flags & 0xf800) == 0) {

	NDPI_LOG_DBG2(ndpi_struct, "possible netbios name query request\n");

	if(get_u_int16_t(packet->payload, 4) == htons(1) &&
	    get_u_int16_t(packet->payload, 6) == 0 &&
	    get_u_int16_t(packet->payload, 8) == 0 && get_u_int16_t(packet->payload, 10) == 0) {

	  /* name is encoded as described in rfc883 */
	  u_int8_t name_length = packet->payload[12];

	  NDPI_LOG_DBG2(ndpi_struct,
		   "possible netbios name query request, one question\n");

	  if(packet->payload_packet_len == 12 + 1 + name_length + 1 + 2 + 2) {

	    NDPI_LOG_DBG2(ndpi_struct,
		     "possible netbios name query request, length matches\n");

	    /* null terminated? */
	    if(packet->payload[12 + name_length + 1] == 0 &&
		get_u_int16_t(packet->payload, 12 + name_length + 2) == htons(0x0020) &&
		get_u_int16_t(packet->payload, 12 + name_length + 4) == htons(0x0001)) {

	      NDPI_LOG_INFO(ndpi_struct,
		       "found netbios name query request\n");
	      ndpi_int_netbios_add_connection(ndpi_struct, flow);
	      return;
	    }
	  }
	}
      } else if((h.flags & 0xf800) == 0x8000) {
	NDPI_LOG_DBG2(ndpi_struct,
		 "possible netbios name query response\n");

	if(get_u_int16_t(packet->payload, 4) == 0 &&
	    get_u_int16_t(packet->payload, 6) == htons(1) &&
	    get_u_int16_t(packet->payload, 8) == 0 && get_u_int16_t(packet->payload, 10) == 0) {

	  /* name is encoded as described in rfc883 */
	  u_int8_t name_length = packet->payload[12];

	  NDPI_LOG_DBG2(ndpi_struct,
		   "possible netbios positive name query response, one answer\n");

	  if(packet->payload_packet_len >= 12 + 1 + name_length + 1 + 2 + 2) {

	    NDPI_LOG_DBG2(ndpi_struct,
		     "possible netbios name query response, length matches\n");

	    /* null terminated? */
	    if(packet->payload[12 + name_length + 1] == 0 &&
		get_u_int16_t(packet->payload, 12 + name_length + 2) == htons(0x0020) &&
		get_u_int16_t(packet->payload, 12 + name_length + 4) == htons(0x0001)) {

	      NDPI_LOG_INFO(ndpi_struct,
		       "found netbios name query response\n");
	      ndpi_int_netbios_add_connection(ndpi_struct, flow);
	      return;
	    }
	  }
	} else if(get_u_int16_t(packet->payload, 4) == 0 &&
		   get_u_int16_t(packet->payload, 6) == 0 &&
		   get_u_int16_t(packet->payload, 8) == 0 && get_u_int16_t(packet->payload, 10) == 0) {

	  /* name is encoded as described in rfc883 */
	  u_int8_t name_length = packet->payload[12];

	  NDPI_LOG_DBG2(ndpi_struct,
		   "possible netbios negative name query response, one answer\n");

	  if(packet->payload_packet_len >= 12 + 1 + name_length + 1 + 2 + 2) {

	    NDPI_LOG_DBG2(ndpi_struct,
		     "possible netbios name query response, length matches\n");

	    /* null terminated? */
	    if(packet->payload[12 + name_length + 1] == 0 &&
		get_u_int16_t(packet->payload, 12 + name_length + 2) == htons(0x000A) &&
		get_u_int16_t(packet->payload, 12 + name_length + 4) == htons(0x0001)) {

	      NDPI_LOG_INFO(ndpi_struct,
		       "found netbios name query response\n");
	      ndpi_int_netbios_add_connection(ndpi_struct, flow);
	      return;
	    }
	  }
	} else if(get_u_int16_t(packet->payload, 4) == 0 &&
		   get_u_int16_t(packet->payload, 6) == 0 &&
		   get_u_int16_t(packet->payload, 8) == htons(1) && get_u_int16_t(packet->payload, 10) == htons(1)) {

	  /* name is encoded as described in rfc883 */
	  u_int8_t name_length = packet->payload[12];

	  NDPI_LOG_DBG2(ndpi_struct,
		   "possible netbios redirect name query response, one answer\n");

	  if(packet->payload_packet_len >= 12 + 1 + name_length + 1 + 2 + 2) {

	    NDPI_LOG_DBG2(ndpi_struct,
		     "possible netbios name query response, length matches\n");

	    /* null terminated? */
	    if(packet->payload[12 + name_length + 1] == 0 &&
		get_u_int16_t(packet->payload, 12 + name_length + 2) == htons(0x0002) &&
		get_u_int16_t(packet->payload, 12 + name_length + 4) == htons(0x0001)) {

	      NDPI_LOG_INFO(ndpi_struct,
		       "found netbios name query response\n");
	      ndpi_int_netbios_add_connection(ndpi_struct, flow);
	      return;
	    }
	  }
	}
      }
      /* TODO: extend according to rfc1002 */
    }

    /*check standard NETBIOS over udp to port 138 */

    /*netbios header token from http://www.protocolbase.net/protocols/protocol_NBDGM.php */

    if((dport == 138) &&
	packet->payload_packet_len >= 14 &&
	ntohs(get_u_int16_t(packet->payload, 10)) == packet->payload_packet_len - 14) {

      NDPI_LOG_DBG2(ndpi_struct, "found netbios port 138 and payload length >= 112 \n");

      if(packet->payload[0] >= 0x10 && packet->payload[0] <= 0x16) {
	NDPI_LOG_DBG2(ndpi_struct, "found netbios with MSG-type 0x10,0x11,0x12,0x13,0x14,0x15 or 0x16\n");

	if(ntohl(get_u_int32_t(packet->payload, 4)) == ntohl(packet->iph->saddr)) {
	  NDPI_LOG_INFO(ndpi_struct, "found netbios with checked ip-address\n");

	  if(ndpi_netbios_name_interpret((char*)&packet->payload[12], name, sizeof(name)) > 0) {
	    if(!ndpi_struct->disable_metadata_export) {
	      snprintf((char*)flow->host_server_name, sizeof(flow->host_server_name)-1, "%s", name);
	    }
	  }
	  
	  ndpi_int_netbios_add_connection(ndpi_struct, flow);
	  return;
	}
      }
    }
  }

  if(packet->tcp != NULL) {
    dport = ntohs(packet->tcp->dest);

    /* destination port must be 139 */
    if(dport == 139) {

      NDPI_LOG_DBG2(ndpi_struct, "found netbios with destination port 139\n");

      /* payload_packet_len must be 72 */
      if(packet->payload_packet_len == 72) {
	NDPI_LOG_DBG2(ndpi_struct, "found netbios with payload_packen_len = 72. \n");

	if(packet->payload[0] == 0x81 && packet->payload[1] == 0 && ntohs(get_u_int16_t(packet->payload, 2)) == 68) {
	  NDPI_LOG_INFO(ndpi_struct,
		   "found netbios with session request = 81, flags=0 and length od following bytes = 68. \n");

	  ndpi_int_netbios_add_connection(ndpi_struct, flow);
	  return;
	}
      }
    }

  }

  NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
}

void init_netbios_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask)
{
  ndpi_set_bitmask_protocol_detection("NETBIOS", ndpi_struct, detection_bitmask, *id,
				      NDPI_PROTOCOL_NETBIOS,
				      ndpi_search_netbios,
				      NDPI_SELECTION_BITMASK_PROTOCOL_TCP_OR_UDP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,
				      SAVE_DETECTION_BITMASK_AS_UNKNOWN,
				      ADD_TO_DETECTION_BITMASK);

  *id += 1;
}
