/*=========================================================================
                                                                                
  Program:   gdcm
  Module:    $RCSfile: gdcmUtil.cxx,v $
  Language:  C++
  Date:      $Date: 2005/11/29 13:02:46 $
  Version:   $Revision: 1.179 $
                                                                                
  Copyright (c) CREATIS (Centre de Recherche et d'Applications en Traitement de
  l'Image). All rights reserved. See Doc/License.txt or
  http://www.creatis.insa-lyon.fr/Public/Gdcm/License.html for details.
                                                                                
     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notices for more information.
                                                                                
=========================================================================*/

#include "gdcmUtil.h"
#include "gdcmDebug.h"

#include <iostream>
#include <stdarg.h> // for va_list

// For GetCurrentDate, GetCurrentTime
#include <time.h>
#include <sys/types.h>
#include <sys/stat.h>

#if defined(_MSC_VER) || defined(__BORLANDC__) || defined(__MINGW32__)
#include <sys/timeb.h>
#else
#include <sys/time.h>
#endif

#include <stdarg.h>  //only included in implementation file
#include <stdio.h>   //only included in implementation file

#if defined(_MSC_VER) || defined(__BORLANDC__) || defined(__MINGW32__)
   #include <winsock.h>  // for gethostname and gethostbyname and GetTickCount...
// I haven't find a way to determine wether we need to under GetCurrentTime or not...
// I think the best solution would simply to get rid of this problematic function
// and use a 'less' common name...
#if !defined(__BORLANDC__) || (__BORLANDC__ >= 0x0560)
   #undef GetCurrentTime
#endif
#else
   #include <unistd.h>  // for gethostname
   #include <netdb.h>   // for gethostbyname
#endif

// For GetMACAddress
#ifdef _WIN32
   #include <snmp.h>
   #include <conio.h>
#else
   #include <unistd.h>
   #include <stdlib.h>
   #include <string.h>
   #include <sys/types.h>
#endif

#ifdef CMAKE_HAVE_SYS_IOCTL_H
   #include <sys/ioctl.h>  // For SIOCGIFCONF on Linux
#endif
#ifdef CMAKE_HAVE_SYS_SOCKET_H
   #include <sys/socket.h>
#endif
#ifdef CMAKE_HAVE_SYS_SOCKIO_H
   #include <sys/sockio.h>  // For SIOCGIFCONF on SunOS
#endif
#ifdef CMAKE_HAVE_NET_IF_H
   #include <net/if.h>
#endif
#ifdef CMAKE_HAVE_NETINET_IN_H
   #include <netinet/in.h>   //For IPPROTO_IP
#endif
#ifdef CMAKE_HAVE_NET_IF_DL_H
   #include <net/if_dl.h>
#endif
#if defined(CMAKE_HAVE_NET_IF_ARP_H) && defined(__sun)
   // This is absolutely necessary on SunOS
   #include <net/if_arp.h>
#endif

// For GetCurrentThreadID()
#ifdef __linux__
   #include <sys/types.h>
   #include <linux/unistd.h>
#endif
#ifdef __sun
   #include <thread.h>
#endif

namespace gdcm 
{
//-------------------------------------------------------------------------
const std::string Util::GDCM_UID = "1.2.826.0.1.3680043.2.1143";
std::string Util::RootUID        = GDCM_UID;
/*
 * File Meta Information Version (0002,0001) shall contain a two byte OB 
 * value consisting of a 0x00 byte, followed by 0x01 byte, and not the 
 * value 0x0001 encoded as a little endian 16 bit short value, 
 * which would be the other way around...
 */
const uint16_t Util::FMIV = 0x0100;
uint8_t *Util::FileMetaInformationVersion = (uint8_t *)&FMIV;
std::string Util::GDCM_MAC_ADRESS = GetMACAddress();

//-------------------------------------------------------------------------
// Public
/**
 * \brief Provide a better 'c++' approach for sprintf
 * For example c code is:
 * char result[2048]; // hope 2048 is enough
 * sprintf(result, "%04x|%04x", group , elem);
 *
 * c++ code is 
 * std::ostringstream buf;
 * buf << std::right << std::setw(4) << std::setfill('0') << std::hex
 *     << group << "|" << std::right << std::setw(4) << std::setfill('0') 
 *     << std::hex <<  elem;
 * buf.str();
 *
 * gdcm style code is
 * string result;
 * result = gdcm::Util::Format("%04x|%04x", group , elem);
 */
std::string Util::Format(const char *format, ...)
{
   char buffer[2048]; // hope 2048 is enough
   va_list args;
   va_start(args, format);
   vsprintf(buffer, format, args);  //might be a security flaw
   va_end(args); // Each invocation of va_start should be matched 
                 // by a corresponding invocation of va_end
                 // args is then 'undefined'
   return buffer;
}


/**
 * \brief Because not available in C++ (?)
 * @param str string to check
 * @param tokens std::vector to receive the tokenized substrings
 * @param delimiters string containing the character delimitors
 
 */
void Util::Tokenize (const std::string &str,
                     std::vector<std::string> &tokens,
                     const std::string &delimiters)
{
   std::string::size_type lastPos = str.find_first_not_of(delimiters,0);
   std::string::size_type pos     = str.find_first_of    (delimiters,lastPos);
   while (std::string::npos != pos || std::string::npos != lastPos)
   {
      tokens.push_back(str.substr(lastPos, pos - lastPos));
      lastPos = str.find_first_not_of(delimiters, pos);
      pos     = str.find_first_of    (delimiters, lastPos);
   }
}

/**
 * \brief Because not available in C++ (?)
 *        Counts the number of occurences of a substring within a string
 * @param str string to check
 * @param subStr substring to count
 */
 
int Util::CountSubstring (const std::string &str,
                          const std::string &subStr)
{
   int count = 0;                 // counts how many times it appears
   std::string::size_type x = 0;  // The index position in the string

   do
   {
      x = str.find(subStr,x);     // Find the substring
      if (x != std::string::npos) // If present
      {
         count++;                 // increase the count
         x += subStr.length();    // Skip this word
      }
   }
   while (x != std::string::npos);// Carry on until not present

   return count;
}

/**
 * \brief  Checks whether a 'string' is printable or not (in order
 *         to avoid corrupting the terminal of invocation when printing)
 * @param s string to check
 */
bool Util::IsCleanString(std::string const &s)
{
   //std::cout<< std::endl << s << std::endl;
   for(unsigned int i=0; i<s.size(); i++)
   {
      if (!isprint((unsigned char)s[i]) )
      {
         return false;
      }
   }
   return true;   
}

/**
 * \brief  Checks whether an 'area' is printable or not (in order
 *         to avoid corrupting the terminal of invocation when printing)
 * @param s area to check (uint8_t is just for prototyping. feel free to cast)
 * @param l area length to check
 */
bool Util::IsCleanArea(uint8_t *s, int l)
{
   for( int i=0; i<l; i++)
   {
      if (!isprint((unsigned char)s[i]) )
      {
         return false;
      }
   }
   return true;   
}
/**
 * \brief  Weed out a string from the non-printable characters (in order
 *         to avoid corrupting the terminal of invocation when printing)
 * @param s string to check (uint8_t is just for prototyping. feel free to cast)
 */
std::string Util::CreateCleanString(std::string const &s)
{
   std::string str = s;

   for(unsigned int i=0; i<str.size(); i++)
   {
      if (!isprint((unsigned char)str[i]) )
      {
         str[i] = '.';
      }
   }

   if (str.size() > 0 )
   {
      if (!isprint((unsigned char)s[str.size()-1]) )
      {
         if (s[str.size()-1] == 0 )
         {
            str[str.size()-1] = ' ';
         }
      }
   }

   return str;
}

/**
 * \brief  Weed out a string from the non-printable characters (in order
 *         to avoid corrupting the terminal of invocation when printing)
 * @param s area to process (uint8_t is just for prototyping. feel free to cast)
 * @param l area length to check
 */
std::string Util::CreateCleanString(uint8_t *s, int l)
{
   std::string str;

   for( int i=0; i<l; i++)
   {
      if (!isprint((unsigned char)s[i]) )
      {
         str = str + '.';
      }
   else
      {
         str = str + (char )s[i];
      }
   }

   return str;
}
/**
 * \brief   Add a SEPARATOR to the end of the name is necessary
 * @param   pathname file/directory name to normalize 
 */
std::string Util::NormalizePath(std::string const &pathname)
{
   const char SEPARATOR_X      = '/';
   const char SEPARATOR_WIN    = '\\';
   const std::string SEPARATOR = "/";
   std::string name = pathname;
   int size = name.size();

   if ( name[size-1] != SEPARATOR_X && name[size-1] != SEPARATOR_WIN )
   {
      name += SEPARATOR;
   }
   return name;
}

/**
 * \brief   Get the (directory) path from a full path file name
 * @param   fullName file/directory name to extract Path from
 */
std::string Util::GetPath(std::string const &fullName)
{
   std::string res = fullName;
   int pos1 = res.rfind("/");
   int pos2 = res.rfind("\\");
   if ( pos1 > pos2 )
   {
      res.resize(pos1);
   }
   else
   {
      res.resize(pos2);
   }

   return res;
}

/**
 * \brief   Get the (last) name of a full path file name
 * @param   fullName file/directory name to extract end name from
 */
std::string Util::GetName(std::string const &fullName)
{   
  std::string filename = fullName;

  std::string::size_type slash_pos = filename.rfind("/");
  std::string::size_type backslash_pos = filename.rfind("\\");
  slash_pos = slash_pos > backslash_pos ? slash_pos : backslash_pos;
  if (slash_pos != std::string::npos )
    {
    return filename.substr(slash_pos + 1);
    }
  else
    {
    return filename;
    }
} 

/**
 * \brief   Get the current date of the system in a dicom string
 */
std::string Util::GetCurrentDate()
{
    char tmp[512];
    time_t tloc;
    time (&tloc);    
    strftime(tmp,512,"%Y%m%d", localtime(&tloc) );
    return tmp;
}

/**
 * \brief   Get the current time of the system in a dicom string
 */
std::string Util::GetCurrentTime()
{
    char tmp[512];
    time_t tloc;
    time (&tloc);
    strftime(tmp,512,"%H%M%S", localtime(&tloc) );
    return tmp;  
}

/**
 * \brief  Get both the date and time at the same time to avoid problem 
 * around midnight where the two calls could be before and after midnight
 */
std::string Util::GetCurrentDateTime()
{
   char tmp[40];
   long milliseconds;
   time_t timep;
  
   // We need implementation specific functions to obtain millisecond precision
#if defined(_MSC_VER) || defined(__BORLANDC__) || defined(__MINGW32__)
   struct timeb tb;
   ::ftime(&tb);
   timep = tb.time;
   milliseconds = tb.millitm;
#else
   struct timeval tv;
   gettimeofday (&tv, NULL);
   timep = tv.tv_sec;
   // Compute milliseconds from microseconds.
   milliseconds = tv.tv_usec / 1000;
#endif
   // Obtain the time of day, and convert it to a tm struct.
   struct tm *ptm = localtime (&timep);
   // Format the date and time, down to a single second.
   strftime (tmp, sizeof (tmp), "%Y%m%d%H%M%S", ptm);

   // Add milliseconds
   // Don't use Util::Format to accelerate execution of code
   char tmpAll[80];
   sprintf(tmpAll,"%s%03ld",tmp,milliseconds);

   return tmpAll;
}

unsigned int Util::GetCurrentThreadID()
{
// FIXME the implementation is far from complete
#if defined(_MSC_VER) || defined(__BORLANDC__) || defined(__MINGW32__)
  return (unsigned int)GetCurrentThreadId();
#else
#ifdef __linux__
   return 0;
   // Doesn't work on fedora, but is in the man page...
   //return (unsigned int)gettid();
#else
#ifdef __sun
   return (unsigned int)thr_self();
#else
   //default implementation
   return 0;
#endif // __sun
#endif // __linux__
#endif // Win32
}

unsigned int Util::GetCurrentProcessID()
{
#if defined(_MSC_VER) || defined(__BORLANDC__) || defined(__MINGW32__)
  // NOTE: There is also a _getpid()...
  return (unsigned int)GetCurrentProcessId();
#else
  // get process identification, POSIX
  return (unsigned int)getpid();
#endif
}

/**
 * \brief   tells us whether the processor we are working with is BigEndian or not
 */
bool Util::IsCurrentProcessorBigEndian()
{
#if defined(GDCM_WORDS_BIGENDIAN)
   return true;
#else
   return false;
#endif
}

/**
 * \brief Create a /DICOM/ string:
 * It should a of even length (no odd length ever)
 * It can contain as many (if you are reading this from your
 * editor the following character is backslash followed by zero
 * that needed to be escaped with an extra backslash for doxygen) \\0
 * as you want.
 */
std::string Util::DicomString(const char *s, size_t l)
{
   std::string r(s, s+l);
   gdcmAssertMacro( !(r.size() % 2) ); // == basically 'l' is even
   return r;
}

/**
 * \brief Create a /DICOM/ string:
 * It should a of even length (no odd length ever)
 * It can contain as many (if you are reading this from your
 * editor the following character is backslash followed by zero
 * that needed to be escaped with an extra backslash for doxygen) \\0
 * as you want.
 * This function is similar to DicomString(const char*), 
 * except it doesn't take a length. 
 * It only pad with a null character if length is odd
 */
std::string Util::DicomString(const char *s)
{
   size_t l = strlen(s);
   if ( l%2 )
   {
      l++;
   }
   std::string r(s, s+l);
   gdcmAssertMacro( !(r.size() % 2) );
   return r;
}

/**
 * \brief Safely check the equality of two Dicom String:
 *        - Both strings should be of even length
 *        - We allow padding of even length string by either a null 
 *          character of a space
 */
bool Util::DicomStringEqual(const std::string &s1, const char *s2)
{
  // s2 is the string from the DICOM reference e.g. : 'MONOCHROME1'
  std::string s1_even = s1; //Never change input parameter
  std::string s2_even = DicomString( s2 );
  if ( s1_even[s1_even.size()-1] == ' ' )
  {
    s1_even[s1_even.size()-1] = '\0'; //replace space character by null
  }
  return s1_even == s2_even;
}

/**
 * \brief Safely compare two Dicom String:
 *        - Both strings should be of even length
 *        - We allow padding of even length string by either a null 
 *          character of a space
 */
bool Util::CompareDicomString(const std::string &s1, const char *s2, int op)
{
  // s2 is the string from the DICOM reference e.g. : 'MONOCHROME1'
  std::string s1_even = s1; //Never change input parameter
  std::string s2_even = DicomString( s2 );
  if ( s1_even[s1_even.size()-1] == ' ' )
  {
    s1_even[s1_even.size()-1] = '\0'; //replace space character by null
  }
  switch (op)
  {
     case GDCM_EQUAL :
        return s1_even == s2_even;
     case GDCM_DIFFERENT :  
        return s1_even != s2_even;
     case GDCM_GREATER :  
        return s1_even >  s2_even;  
     case GDCM_GREATEROREQUAL :  
        return s1_even >= s2_even;
     case GDCM_LESS :
        return s1_even <  s2_even;
     case GDCM_LESSOREQUAL :
        return s1_even <= s2_even;
     default :
        gdcmDebugMacro(" Wrong operator : " << op);
        return false;
  }
}

#ifdef _WIN32
   typedef BOOL(WINAPI * pSnmpExtensionInit) (
           IN DWORD dwTimeZeroReference,
           OUT HANDLE * hPollForTrapEvent,
           OUT AsnObjectIdentifier * supportedView);

   typedef BOOL(WINAPI * pSnmpExtensionTrap) (
           OUT AsnObjectIdentifier * enterprise,
           OUT AsnInteger * genericTrap,
           OUT AsnInteger * specificTrap,
           OUT AsnTimeticks * timeStamp,
           OUT RFC1157VarBindList * variableBindings);

   typedef BOOL(WINAPI * pSnmpExtensionQuery) (
           IN BYTE requestType,
           IN OUT RFC1157VarBindList * variableBindings,
           OUT AsnInteger * errorStatus,
           OUT AsnInteger * errorIndex);

   typedef BOOL(WINAPI * pSnmpExtensionInitEx) (
           OUT AsnObjectIdentifier * supportedView);
#endif //_WIN32

/// \brief gets current M.A.C adress (for internal use only)
int GetMacAddrSys ( unsigned char *addr );
int GetMacAddrSys ( unsigned char *addr )
{
#ifdef _WIN32
   WSADATA WinsockData;
   if ( (WSAStartup(MAKEWORD(2, 0), &WinsockData)) != 0 ) 
   {
      std::cerr << "in Get MAC Adress (internal) : This program requires Winsock 2.x!" 
             << std::endl;
      return -1;
   }

   HANDLE PollForTrapEvent;
   AsnObjectIdentifier SupportedView;
   UINT OID_ifEntryType[]  = { 1, 3, 6, 1, 2, 1, 2, 2, 1, 3 };
   UINT OID_ifEntryNum[]   = { 1, 3, 6, 1, 2, 1, 2, 1 };
   UINT OID_ipMACEntAddr[] = { 1, 3, 6, 1, 2, 1, 2, 2, 1, 6 };
   AsnObjectIdentifier MIB_ifMACEntAddr = {
       sizeof(OID_ipMACEntAddr) / sizeof(UINT), OID_ipMACEntAddr };
   AsnObjectIdentifier MIB_ifEntryType = {
       sizeof(OID_ifEntryType) / sizeof(UINT), OID_ifEntryType };
   AsnObjectIdentifier MIB_ifEntryNum = {
       sizeof(OID_ifEntryNum) / sizeof(UINT), OID_ifEntryNum };
   RFC1157VarBindList varBindList;
   RFC1157VarBind varBind[2];
   AsnInteger errorStatus;
   AsnInteger errorIndex;
   AsnObjectIdentifier MIB_NULL = { 0, 0 };
   int ret;
   int dtmp;
   int j = 0;

   // Load the SNMP dll and get the addresses of the functions necessary
   HINSTANCE m_hInst = LoadLibrary("inetmib1.dll");
   if (m_hInst < (HINSTANCE) HINSTANCE_ERROR)
   {
      return -1;
   }
   pSnmpExtensionInit m_Init =
       (pSnmpExtensionInit) GetProcAddress(m_hInst, "SnmpExtensionInit");
   pSnmpExtensionQuery m_Query =
       (pSnmpExtensionQuery) GetProcAddress(m_hInst, "SnmpExtensionQuery");
   m_Init(GetTickCount(), &PollForTrapEvent, &SupportedView);

   /* Initialize the variable list to be retrieved by m_Query */
   varBindList.list = varBind;
   varBind[0].name = MIB_NULL;
   varBind[1].name = MIB_NULL;

   // Copy in the OID to find the number of entries in the
   // Inteface table
   varBindList.len = 1;        // Only retrieving one item
   SNMP_oidcpy(&varBind[0].name, &MIB_ifEntryNum);
   m_Query(ASN_RFC1157_GETNEXTREQUEST, &varBindList, &errorStatus,
                 &errorIndex);
//   printf("# of adapters in this system : %i\n",
//          varBind[0].value.asnValue.number);
   varBindList.len = 2;

   // Copy in the OID of ifType, the type of interface
   SNMP_oidcpy(&varBind[0].name, &MIB_ifEntryType);

   // Copy in the OID of ifPhysAddress, the address
   SNMP_oidcpy(&varBind[1].name, &MIB_ifMACEntAddr);

   do
   {
      // Submit the query.  Responses will be loaded into varBindList.
      // We can expect this call to succeed a # of times corresponding
      // to the # of adapters reported to be in the system
      ret = m_Query(ASN_RFC1157_GETNEXTREQUEST, &varBindList, &errorStatus,
                    &errorIndex); 
      if (!ret)
      {
         ret = 1;
      }
      else
      {
         // Confirm that the proper type has been returned
         ret = SNMP_oidncmp(&varBind[0].name, &MIB_ifEntryType,
                            MIB_ifEntryType.idLength);
      }
      if (!ret)
      {
         j++;
         dtmp = varBind[0].value.asnValue.number;

         // Type 6 describes ethernet interfaces
         if (dtmp == 6)
         {
            // Confirm that we have an address here
            ret = SNMP_oidncmp(&varBind[1].name, &MIB_ifMACEntAddr,
                               MIB_ifMACEntAddr.idLength);
            if ( !ret && varBind[1].value.asnValue.address.stream != NULL )
            {
               if ( (varBind[1].value.asnValue.address.stream[0] == 0x44)
                 && (varBind[1].value.asnValue.address.stream[1] == 0x45)
                 && (varBind[1].value.asnValue.address.stream[2] == 0x53)
                 && (varBind[1].value.asnValue.address.stream[3] == 0x54)
                 && (varBind[1].value.asnValue.address.stream[4] == 0x00) )
               {
                   // Ignore all dial-up networking adapters
                   std::cerr << "in Get MAC Adress (internal) : Interface #" 
                             << j << " is a DUN adapter\n";
                   continue;
               }
               if ( (varBind[1].value.asnValue.address.stream[0] == 0x00)
                 && (varBind[1].value.asnValue.address.stream[1] == 0x00)
                 && (varBind[1].value.asnValue.address.stream[2] == 0x00)
                 && (varBind[1].value.asnValue.address.stream[3] == 0x00)
                 && (varBind[1].value.asnValue.address.stream[4] == 0x00)
                 && (varBind[1].value.asnValue.address.stream[5] == 0x00) )
               {
                  // Ignore NULL addresses returned by other network
                  // interfaces
                  std::cerr << "in Get MAC Adress (internal) :  Interface #" 
                            << j << " is a NULL address\n";
                  continue;
               }
               memcpy( addr, varBind[1].value.asnValue.address.stream, 6);
            }
         }
      }
   } while (!ret);

   // Free the bindings
   SNMP_FreeVarBind(&varBind[0]);
   SNMP_FreeVarBind(&varBind[1]);
   return 0;
#endif //Win32 version


// implementation for POSIX system
#if defined(CMAKE_HAVE_NET_IF_ARP_H) && defined(__sun)
   //The POSIX version is broken anyway on Solaris, plus would require full
   //root power
   struct  arpreq          parpreq;
   struct  sockaddr_in     *psa;
   struct  hostent         *phost;
   char                    hostname[MAXHOSTNAMELEN];
   char                    **paddrs;
   int                     sock, status=0;

   if (gethostname(hostname,  MAXHOSTNAMELEN) != 0 )
   {
      perror("in Get MAC Adress (internal) : gethostname");
      return -1;
   }
   phost = gethostbyname(hostname);
   paddrs = phost->h_addr_list;

   sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
   if (sock == -1 )
   {
      perror("in Get MAC Adress (internal) : sock");
      return -1;
   }
   memset(&parpreq, 0, sizeof(struct arpreq));
   psa = (struct sockaddr_in *) &parpreq.arp_pa;

   memset(psa, 0, sizeof(struct sockaddr_in));
   psa->sin_family = AF_INET;
   memcpy(&psa->sin_addr, *paddrs, sizeof(struct in_addr));

   status = ioctl(sock, SIOCGARP, &parpreq);
   if (status == -1 )
   {
      perror("in Get MAC Adress (internal) : SIOCGARP");
      return -1;
   }
   memcpy(addr, parpreq.arp_ha.sa_data, 6);

   return 0;
#else
#ifdef CMAKE_HAVE_NET_IF_H
   int       sd;
   struct ifreq    ifr, *ifrp;
   struct ifconf    ifc;
   char buf[1024];
   int      n, i;
   unsigned char    *a;
#if defined(AF_LINK) && (!defined(SIOCGIFHWADDR) && !defined(SIOCGENADDR))
   struct sockaddr_dl *sdlp;
#endif

//
// BSD 4.4 defines the size of an ifreq to be
// max(sizeof(ifreq), sizeof(ifreq.ifr_name)+ifreq.ifr_addr.sa_len
// However, under earlier systems, sa_len isn't present, so the size is 
// just sizeof(struct ifreq)
// We should investigate the use of SIZEOF_ADDR_IFREQ
//
#ifdef HAVE_SA_LEN
   #ifndef max
      #define max(a,b) ((a) > (b) ? (a) : (b))
   #endif
   #define ifreq_size(i) max(sizeof(struct ifreq),\
        sizeof((i).ifr_name)+(i).ifr_addr.sa_len)
#else
   #define ifreq_size(i) sizeof(struct ifreq)
#endif // HAVE_SA_LEN

   if ( (sd = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP)) < 0 )
   {
      return -1;
   }
   memset(buf, 0, sizeof(buf));
   ifc.ifc_len = sizeof(buf);
   ifc.ifc_buf = buf;
   if (ioctl (sd, SIOCGIFCONF, (char *)&ifc) < 0)
   {
      close(sd);
      return -1;
   }
   n = ifc.ifc_len;
   for (i = 0; i < n; i+= ifreq_size(*ifrp) )
   {
      ifrp = (struct ifreq *)((char *) ifc.ifc_buf+i);
      strncpy(ifr.ifr_name, ifrp->ifr_name, IFNAMSIZ);
#ifdef SIOCGIFHWADDR
      if (ioctl(sd, SIOCGIFHWADDR, &ifr) < 0)
         continue;
      a = (unsigned char *) &ifr.ifr_hwaddr.sa_data;
#else
#ifdef SIOCGENADDR
      // In theory this call should also work on Sun Solaris, but apparently
      // SIOCGENADDR is not implemented properly thus the call 
      // ioctl(sd, SIOCGENADDR, &ifr) always returns errno=2 
      // (No such file or directory)
      // Furthermore the DLAPI seems to require full root access
      if (ioctl(sd, SIOCGENADDR, &ifr) < 0)
         continue;
      a = (unsigned char *) ifr.ifr_enaddr;
#else
#ifdef AF_LINK
      sdlp = (struct sockaddr_dl *) &ifrp->ifr_addr;
      if ((sdlp->sdl_family != AF_LINK) || (sdlp->sdl_alen != 6))
         continue;
      a = (unsigned char *) &sdlp->sdl_data[sdlp->sdl_nlen];
#else
      perror("in Get MAC Adress (internal) : No way to access hardware");
      close(sd);
      return -1;
#endif // AF_LINK
#endif // SIOCGENADDR
#endif // SIOCGIFHWADDR
      if (!a[0] && !a[1] && !a[2] && !a[3] && !a[4] && !a[5]) continue;

      if (addr) 
      {
         memcpy(addr, a, 6);
         close(sd);
         return 0;
      }
   }
   close(sd);
#endif
   // Not implemented platforms (or no cable !)
   perror("in Get MAC Adress (internal) : There was a configuration problem (or no cable !) on your plateform");
   memset(addr,0,6);
   return -1;
#endif //__sun
}

/**
 * \brief Mini function to return the last digit from a number express in base 256
 *        pre condition data contain an array of 6 unsigned char
 *        post condition carry contain the last digit
 */
inline int getlastdigit(unsigned char *data)
{
  int extended, carry = 0;
  for(int i=0;i<6;i++)
    {
    extended = (carry << 8) + data[i];
    data[i] = extended / 10;
    carry = extended % 10;
    }
  return carry;
}

/**
 * \brief Encode the mac address on a fixed length string of 15 characters.
 * we save space this way.
 */
std::string Util::GetMACAddress()
{
   // This code is the result of a long internet search to find something
   // as compact as possible (not OS independant). We only have to separate
   // 3 OS: Win32, SunOS and 'real' POSIX
   // http://groups-beta.google.com/group/comp.unix.solaris/msg/ad36929d783d63be
   // http://bdn.borland.com/article/0,1410,26040,00.html
   unsigned char addr[6];

   int stat = GetMacAddrSys(addr);
   if (stat == 0)
   {
      // We need to convert a 6 digit number from base 256 to base 10, using integer
      // would requires a 48bits one. To avoid this we have to reimplement the div + modulo 
      // with string only
      bool zero = false;
      int res;
      std::string sres;
      while(!zero)
      {
         res = getlastdigit(addr);
         sres.insert(sres.begin(), '0' + res);
         zero = (addr[0] == 0) && (addr[1] == 0) && (addr[2] == 0) 
             && (addr[3] == 0) && (addr[4] == 0) && (addr[5] == 0);
      }

      return sres;
   }
   else
   {
      gdcmStaticWarningMacro("Problem in finding the MAC Address");
      return "";
   }
}

/**
 * \brief Creates a new UID. As stipulated in the DICOM ref
 *        each time a DICOM image is created it should have 
 *        a unique identifier (URI)
 * @param root is the DICOM prefix assigned by IOS group
 */
std::string Util::CreateUniqueUID(const std::string &root)
{
   std::string prefix;
   std::string append;
   if ( root.empty() )
   {
      // gdcm UID prefix, as supplied by http://www.medicalconnections.co.uk
      prefix = RootUID; 
   }
   else
   {
      prefix = root;
   }

   // A root was specified use it to forge our new UID:
   append += ".";
   //append += Util::GetMACAddress(); // to save CPU time
   append += Util::GDCM_MAC_ADRESS;
   append += ".";
   append += Util::GetCurrentDateTime();
   append += ".";
   //Also add a mini random number just in case:
   char tmp[10];
   int r = (int) (100.0*rand()/RAND_MAX);
   // Don't use Util::Format to accelerate the execution
   sprintf(tmp,"%02d", r);
   append += tmp;

   // If append is too long we need to rehash it
   if ( (prefix + append).size() > 64 )
   {
      gdcmStaticErrorMacro( "Size of UID is too long." );
      // we need a hash function to truncate this number
      // if only md5 was cross plateform
      // MD5(append);
   }

   return prefix + append;
}

void Util::SetRootUID(const std::string &root)
{
   if ( root.empty() )
      RootUID = GDCM_UID;
   else
      RootUID = root;
}

const std::string &Util::GetRootUID()
{
   return RootUID;
}

//-------------------------------------------------------------------------
/**
 * \brief binary_write binary_write
 * @param os ostream to write to 
 * @param val 16 bits value to write
 */ 
std::ostream &binary_write(std::ostream &os, const uint16_t &val)
{
#if defined(GDCM_WORDS_BIGENDIAN) || defined(GDCM_FORCE_BIGENDIAN_EMULATION)
   uint16_t swap;
   swap = ( val << 8 | val >> 8 );

   return os.write(reinterpret_cast<const char*>(&swap), 2);
#else
   return os.write(reinterpret_cast<const char*>(&val), 2);
#endif //GDCM_WORDS_BIGENDIAN
}

/**
 * \brief binary_write binary_write
 * @param os ostream to write to
 * @param val 32 bits value to write
 */ 
std::ostream &binary_write(std::ostream &os, const uint32_t &val)
{
#if defined(GDCM_WORDS_BIGENDIAN) || defined(GDCM_FORCE_BIGENDIAN_EMULATION)
   uint32_t swap;
   swap = (  (val<<24)               | ((val<<8)  & 0x00ff0000) | 
            ((val>>8)  & 0x0000ff00) |  (val>>24)               );
   return os.write(reinterpret_cast<const char*>(&swap), 4);
#else
   return os.write(reinterpret_cast<const char*>(&val), 4);
#endif //GDCM_WORDS_BIGENDIAN
}


/**
 * \brief binary_write binary_write
 * @param os ostream to write to
 * @param val double (64 bits) value to write
 */ 
std::ostream &binary_write(std::ostream &os, const double &val)
{
#if defined(GDCM_WORDS_BIGENDIAN) || defined(GDCM_FORCE_BIGENDIAN_EMULATION)    
   double swap = val;
   
   char *beg = (char *)&swap;
   char *end = beg + 7;
   char t;
   for (unsigned int i = 0; i<7; i++)
   {
      t    = *beg;
      *beg = *end;
      *end = t;
      beg++,
      end--;  
   }  
   return os.write(reinterpret_cast<const char*>(&swap), 8);
#else
   return os.write(reinterpret_cast<const char*>(&val), 8);
#endif //GDCM_WORDS_BIGENDIAN
}


/**
 * \brief  binary_write binary_write
 * @param os ostream to write to
 * @param val 8 bits characters aray to write
 */ 
std::ostream &binary_write(std::ostream &os, const char *val)
{
   return os.write(val, strlen(val));
}

/**
 * \brief  binary_write binary_write
 * @param os ostream to write to
 * @param val std::string value to write
 */ 
std::ostream &binary_write(std::ostream &os, std::string const &val)
{
   return os.write(val.c_str(), val.size());
}

/**
 * \brief  binary_write binary_write
 * @param os ostream to write to
 * @param val 8 bits 'characters' aray to write
 * @param len length of the 'value' to be written
 */ 
std::ostream &binary_write(std::ostream &os, const uint8_t *val, size_t len)
{
   // We are writting sizeof(char) thus no need to swap bytes
   return os.write(reinterpret_cast<const char*>(val), len);
}

/**
 * \brief  binary_write binary_write
 * @param os ostream to write to
 * @param val 16 bits words aray to write
 * @param len length (in bytes) of the 'value' to be written 
 */ 
std::ostream &binary_write(std::ostream &os, const uint16_t *val, size_t len)
{
// This is tricky since we are writting two bytes buffer. 
// Be carefull with little endian vs big endian. 
// Also this other trick is to allocate a small (efficient) buffer that store
// intermediate result before writting it.
#if defined(GDCM_WORDS_BIGENDIAN) || defined(GDCM_FORCE_BIGENDIAN_EMULATION)
   const int BUFFER_SIZE = 4096;
   static char buffer[BUFFER_SIZE];
   uint16_t *binArea16 = (uint16_t*)val; //for the const
 
   // how many BUFFER_SIZE long pieces in binArea ?
   int nbPieces = len/BUFFER_SIZE; //(16 bits = 2 Bytes)
   int remainingSize = len%BUFFER_SIZE;

   for (int j=0;j<nbPieces;j++)
   {
      uint16_t *pbuffer  = (uint16_t*)buffer; //reinitialize pbuffer
      for (int i = 0; i < BUFFER_SIZE/2; i++)
      {
         *pbuffer = *binArea16 >> 8 | *binArea16 << 8;
         pbuffer++;
         binArea16++;
      }
      os.write ( buffer, BUFFER_SIZE );
   }
   if ( remainingSize > 0)
   {
      uint16_t *pbuffer  = (uint16_t*)buffer; //reinitialize pbuffer
      for (int i = 0; i < remainingSize/2; i++)
      {
         *pbuffer = *binArea16 >> 8 | *binArea16 << 8;
         pbuffer++;
         binArea16++;
      }
      os.write ( buffer, remainingSize );
   }
   return os;
#else
   return os.write(reinterpret_cast<const char*>(val), len);
#endif
}

//-------------------------------------------------------------------------
// Protected

//-------------------------------------------------------------------------
// Private
/**
 * \brief   Return the IP adress of the machine writting the DICOM image
 */
std::string Util::GetIPAddress()
{
   // This is a rip from 
   // http://www.codeguru.com/Cpp/I-N/internet/network/article.php/c3445/
#ifndef HOST_NAME_MAX
   // SUSv2 guarantees that `Host names are limited to 255 bytes'.
   // POSIX 1003.1-2001 guarantees that `Host names (not including the
   // terminating NUL) are limited to HOST_NAME_MAX bytes'.
#define HOST_NAME_MAX 255
   // In this case we should maybe check the string was not truncated.
   // But I don't known how to check that...
#if defined(_MSC_VER) || defined(__BORLANDC__) || defined(__MINGW32__)
   // with WinSock DLL we need to initialize the WinSock before using gethostname
   WORD wVersionRequested = MAKEWORD(1,0);
   WSADATA WSAData;
   int err = WSAStartup(wVersionRequested,&WSAData);
   if (err != 0)
   {
      // Tell the user that we could not find a usable
      // WinSock DLL.
      WSACleanup();
      return "127.0.0.1";
   }
#endif
  
#endif //HOST_NAME_MAX

   std::string str;
   char szHostName[HOST_NAME_MAX+1];
   int r = gethostname(szHostName, HOST_NAME_MAX);
 
   if ( r == 0 )
   {
      // Get host adresses
      struct hostent *pHost = gethostbyname(szHostName);
 
      for( int i = 0; pHost!= NULL && pHost->h_addr_list[i]!= NULL; i++ )
      {
         for( int j = 0; j<pHost->h_length; j++ )
         {
            if ( j > 0 ) str += ".";
 
            str += Util::Format("%u", 
                (unsigned int)((unsigned char*)pHost->h_addr_list[i])[j]);
         }
         // str now contains one local IP address 
 
#if defined(_MSC_VER) || defined(__BORLANDC__) || defined(__MINGW32__)
   WSACleanup();
#endif

      }
   }
   // If an error occur r == -1
   // Most of the time it will return 127.0.0.1...
   return str;
}

void Util::hfpswap(double *a, double *b)
{
   double tmp;
   tmp=*a;
   *a=*b;
   *b=tmp;
}

//-------------------------------------------------------------------------
} // end namespace gdcm