/*
 * ftp_control.c
 *
 * Copyright (C) 2016-19 - 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_FTP_CONTROL

#include "ndpi_api.h"

// #define FTP_DEBUG

/* *************************************************************** */

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

/* *************************************************************** */

static void ftp_payload_copy(u_int8_t *dest, u_int dest_len,
			     const u_int8_t *src, u_int src_len) {
  u_int i, j, k = dest_len-1;
  
  for(i=5, j=0; i<src_len; i++) {
    if((j == k) || ((src[i] == '\r')
		    || (src[i] == '\n')
		    || (src[i] == ' ')
		    ))
      break;
    
    dest[j++] = src[i];
  }
  
  dest[k] = '\0';
}

/* *************************************************************** */

static int ndpi_ftp_control_check_request(struct ndpi_flow_struct *flow,
					  const u_int8_t *payload,
					  size_t payload_len) {
#ifdef FTP_DEBUG
  printf("%s() [%s]\n", __FUNCTION__, payload);
#endif

  if(ndpi_match_strprefix(payload, payload_len, "USER")) {
    ftp_payload_copy((u_int8_t*)flow->protos.ftp.username,
		     sizeof(flow->protos.ftp.username),
		     payload, payload_len);
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "PASS")) {
    ftp_payload_copy((u_int8_t*)flow->protos.ftp.password,
		     sizeof(flow->protos.ftp.password),
		     payload, payload_len);
    return 1;
  }

  /* ***************************************************** */

  if(ndpi_match_strprefix(payload, payload_len, "ABOR")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "ACCT")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "ADAT")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "ALLO")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "APPE")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "AUTH")) {
    return 1;
  }
  if(ndpi_match_strprefix(payload, payload_len, "CCC")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "CDUP")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "CONF")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "CWD")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "DELE")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "ENC")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "EPRT")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "EPSV")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "FEAT")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "HELP")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "LANG")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "LIST")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "LPRT")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "LPSV")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "MDTM")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "MIC")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "MKD")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "MLSD")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "MLST")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "MODE")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "NLST")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "NOOP")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "OPTS")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "PASV")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "PBSZ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "PORT")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "PROT")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "PWD")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "QUIT")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "REIN")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "REST")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "RETR")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "RMD")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "RNFR")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "RNTO")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "SITE")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "SIZE")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "SMNT")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "STAT")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "STOR")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "STOU")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "STRU")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "SYST")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "TYPE")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "XCUP")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "XMKD")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "XPWD")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "XRCP")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "XRMD")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "XRSQ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "XSEM")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "XSEN")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "HOST")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "abor")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "acct")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "adat")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "allo")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "appe")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "auth")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "ccc")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "cdup")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "conf")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "cwd")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "dele")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "enc")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "eprt")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "epsv")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "feat")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "help")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "lang")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "list")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "lprt")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "lpsv")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "mdtm")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "mic")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "mkd")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "mlsd")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "mlst")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "mode")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "nlst")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "noop")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "opts")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "pass")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "pasv")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "pbsz")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "port")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "prot")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "pwd")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "quit")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "rein")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "rest")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "retr")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "rmd")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "rnfr")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "rnto")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "site")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "size")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "smnt")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "stat")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "stor")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "stou")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "stru")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "syst")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "type")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "user")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "xcup")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "xmkd")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "xpwd")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "xrcp")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "xrmd")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "xrsq")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "xsem")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "xsen")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "host")) {
    return 1;
  }

  return 0;
}

/* *************************************************************** */

static int ndpi_ftp_control_check_response(struct ndpi_flow_struct *flow,
					   const u_int8_t *payload,
					   size_t payload_len) {
#ifdef FTP_DEBUG
  printf("%s() [%s]\n", __FUNCTION__, payload);
#endif

  if(ndpi_match_strprefix(payload, payload_len, "110-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "120-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "125-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "150-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "202-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "211-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "212-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "213-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "214-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "215-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "220-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "221-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "225-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "226-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "227-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "228-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "229-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "230-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "231-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "232-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "250-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "257-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "331-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "332-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "350-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "421-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "425-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "426-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "430-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "434-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "450-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "451-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "452-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "501-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "502-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "503-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "504-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "530-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "532-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "550-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "551-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "552-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "553-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "631-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "632-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "633-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "10054-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "10060-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "10061-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "10066-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "10068-")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "110 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "120 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "125 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "150 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "202 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "211 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "212 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "213 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "214 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "215 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "220 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "221 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "225 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "226 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "227 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "228 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "229 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "230 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "231 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "232 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "250 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "257 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "331 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "332 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "350 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "421 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "425 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "426 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "430 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "434 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "450 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "451 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "452 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "501 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "502 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "503 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "504 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "530 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "532 ")) {
    return 1;
  }
  if(ndpi_match_strprefix(payload, payload_len, "550 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "551 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "552 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "553 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "631 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "632 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "633 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "10054 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "10060 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "10061 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "10066 ")) {
    return 1;
  }

  if(ndpi_match_strprefix(payload, payload_len, "10068 ")) {
    return 1;
  }

  return 0;
}

/* *************************************************************** */

static void ndpi_check_ftp_control(struct ndpi_detection_module_struct *ndpi_struct,
				   struct ndpi_flow_struct *flow) {
  struct ndpi_packet_struct *packet = &flow->packet;
  u_int32_t payload_len = packet->payload_packet_len;

  /* Check connection over TCP */
  if(packet->tcp) {
    /* Exclude SMTP, which uses similar commands. */
    if(packet->tcp->dest == htons(25) || packet->tcp->source == htons(25)) {
      NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
      return;
    }

    /* Break after 20 packets. */
    if(flow->packet_counter > 20) {
      NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
      return;
    }

    /* Check if we so far detected the protocol in the request or not. */
    if(flow->ftp_control_stage == 0) {
      NDPI_LOG_DBG2(ndpi_struct, "FTP_CONTROL stage 0: \n");

      if((payload_len > 0)
	 && ndpi_ftp_control_check_request(flow, packet->payload, payload_len)) {
	NDPI_LOG_DBG2(ndpi_struct,
		      "Possible FTP_CONTROL request detected, we will look further for the response..\n");

	/* 
	   Encode the direction of the packet in the stage, so we will know when we need
	   to look for the response packet. 
	*/
	flow->ftp_control_stage = packet->packet_direction + 1;
      }
    } else {
      NDPI_LOG_DBG2(ndpi_struct, "FTP_CONTROL stage %u: \n", flow->ftp_control_stage);

      /*
	At first check, if this is for sure a response packet (in another direction.
	If not, do nothing now and return. 
      */
      if((flow->ftp_control_stage - packet->packet_direction) == 1) {
	return;
      }
      
      /* This is a packet in another direction. Check if we find the proper response. */
      if((payload_len > 0)
	 && ndpi_ftp_control_check_response(flow, packet->payload, payload_len)) {
	NDPI_LOG_INFO(ndpi_struct, "found FTP_CONTROL\n");

#ifdef FTP_DEBUG
	printf("%s() [user: %s][pwd: %s]\n", __FUNCTION__,
	       flow->protos.ftp.username, flow->protos.ftp.password);
#endif

	if(flow->protos.ftp.password[0] == '\0')
	  flow->ftp_control_stage = 0;
	else
	  ndpi_int_ftp_control_add_connection(ndpi_struct, flow);
      } else {
	NDPI_LOG_DBG2(ndpi_struct, "The reply did not seem to belong to FTP_CONTROL, "
		      "resetting the stage to 0\n");
	flow->ftp_control_stage = 0;
      }
    }
  }
}

/* *************************************************************** */

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

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

  /* skip marked packets */
  if(packet->detected_protocol_stack[0] != NDPI_PROTOCOL_FTP_CONTROL) {
    if(packet->tcp_retransmission == 0) {
      ndpi_check_ftp_control(ndpi_struct, flow);
    }
  }
}

/* *************************************************************** */

void init_ftp_control_dissector(struct ndpi_detection_module_struct *ndpi_struct,
				u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask) {
  ndpi_set_bitmask_protocol_detection("FTP_CONTROL", ndpi_struct, detection_bitmask, *id,
				      NDPI_PROTOCOL_FTP_CONTROL,
				      ndpi_search_ftp_control,
				      NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_WITHOUT_RETRANSMISSION,
				      SAVE_DETECTION_BITMASK_AS_UNKNOWN,
				      ADD_TO_DETECTION_BITMASK);

  *id += 1;
}