-- C module extracted from ITU-T X.667 (10/2012)

   #include "copyrt.h"
   #include <stdio.h>
   #include <string.h>
   #include "sysdep.h"

   /* system dependent call to get MAC node identifier.
      This sample implementation generates a random node identifier. */
   void get_ieee_node_identifier(uuid_node_t *node)
   {
       static int inited = 0;
       static uuid_node_t saved_node;
       unsigned char seed[16];
       FILE *fp;

       if (!inited) {
           fp = fopen("nodeid", "rb");
           if (fp) {
               fread(&saved_node, sizeof saved_node, 1, fp);
               fclose(fp);
           }
           else {
               get_random_info(seed);
               seed[0] |= 0x80;
               memcpy(&saved_node, seed, sizeof saved_node);
               fp = fopen("nodeid", "wb");
               if (fp) {
                   fwrite(&saved_node, sizeof saved_node, 1, fp);
                   fclose(fp);
               }
           }
           inited = 1;
       }

       *node = saved_node;
   }
   /* system dependent call to get the current system time. Returned as
      100ns ticks since UUID epoch, but resolution may be less than 100ns. */
   #ifdef _WINDOWS_

   void get_system_time(uuid_time_t *uuid_time)
   {
       ULARGE_INTEGER time;

       /* Windows NT keeps time in FILETIME format which is 100ns ticks since
          Jan 1, 1601. UUIDs use time in 100ns ticks since Oct 15, 1582.
          The difference is 17 Days in Oct + 30 (Nov) + 31 (Dec)
          + 18 years and 5 leap days. */
       GetSystemTimeAsFileTime((FILETIME *)&time);
       time.QuadPart +=
             (unsigned __int64) (1000*1000*10)       // seconds
           * (unsigned __int64) (60 * 60 * 24)       // days
           * (unsigned __int64) (17+30+31+365*18+5); // # of days
       *uuid_time = time.QuadPart;
   }

   void get_random_info(unsigned char seed[16])
   {
       MD5_CTX c;
       struct {
           MEMORYSTATUS m;
           SYSTEM_INFO s;
           FILETIME t;
           LARGE_INTEGER pc;
           DWORD tc;
           DWORD l;
           char hostname[MAX_COMPUTERNAME_LENGTH + 1];
       } r;

       MD5Init(&c);
       GlobalMemoryStatus(&r.m);
       GetSystemInfo(&r.s);
       GetSystemTimeAsFileTime(&r.t);
       QueryPerformanceCounter(&r.pc);
       r.tc = GetTickCount();
       r.l = MAX_COMPUTERNAME_LENGTH + 1;
       GetComputerName(r.hostname, &r.l);
       MD5Update(&c, &r, sizeof r);
       MD5Final(seed, &c);
   }

   #else

   void get_system_time(uuid_time_t *uuid_time)

   {
       struct timeval tp;

       gettimeofday(&tp, (struct timezone *)0);

       /* Offset between UUID formatted times and Unix formatted times.
          UUID UTC base time is October 15, 1582.
          Unix base time is January 1, 1970. */
       *uuid_time = (tp.tv_sec * 10000000) + (tp.tv_usec * 10)
           + I64(0x01B21DD213814000);
   }

   void get_random_info(unsigned char seed[16])
   {
       MD5_CTX c;
       struct {
           struct timeval t;
           char hostname[257];
       } r;

       MD5Init(&c);
       gettimeofday(&r.t, (struct timezone *)0);
       gethostname(r.hostname, 256);
       MD5Update(&c, &r, sizeof r);
       MD5Final(seed, &c);
   }

   #endif