pppd/magic.c

   1 /*
   2  * magic.c - PPP Magic Number routines.
   3  *
   4  * Copyright (c) 1989 Carnegie Mellon University.
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms are permitted
   8  * provided that the above copyright notice and this paragraph are
   9  * duplicated in all such forms and that any documentation,
  10  * advertising materials, and other materials related to such
  11  * distribution and use acknowledge that the software was developed
  12  * by Carnegie Mellon University.  The name of the
  13  * University may not be used to endorse or promote products derived
  14  * from this software without specific prior written permission.
  15  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  17  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  18  */
  19
  20 #define RCSID   "$Id: magic.c,v 1.9 1999/08/13 06:46:15 paulus Exp $"
  21
  22 #include <stdio.h>
  23 #include <unistd.h>
  24 #include <sys/types.h>
  25 #include <sys/time.h>
  26
  27 #include "pppd.h"
  28 #include "magic.h"
  29
  30 static const char rcsid[] = RCSID;
  31
  32 extern long mrand48 __P((void));
  33 extern void srand48 __P((long));
  34
  35 /*
  36  * magic_init - Initialize the magic number generator.
  37  *
  38  * Attempts to compute a random number seed which will not repeat.
  39  * The current method uses the current hostid, current process ID
  40  * and current time, currently.
  41  */
  42 void
  43 magic_init()
  44 {
  45     long seed;
  46     struct timeval t;
  47
  48     gettimeofday(&t, NULL);
  49     seed = get_host_seed() ^ t.tv_sec ^ t.tv_usec ^ getpid();
  50     srand48(seed);
  51 }
  52
  53 /*
  54  * magic - Returns the next magic number.
  55  */
  56 u_int32_t
  57 magic()
  58 {
  59     return (u_int32_t) mrand48();
  60 }
  61
  62 #ifdef NO_DRAND48
  63 /*
  64  * Substitute procedures for those systems which don't have
  65  * drand48 et al.
  66  */
  67
  68 double
  69 drand48()
  70 {
  71     return (double)random() / (double)0x7fffffffL; /* 2**31-1 */
  72 }
  73
  74 long
  75 mrand48()
  76 {
  77     return random();
  78 }
  79
  80 void
  81 srand48(seedval)
  82 long seedval;
  83 {
  84     srandom((int)seedval);
  85 }
  86
  87 #endif