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read rng seed from random number source device

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Linux and BSD system have random number source devices that can be used
as source for a unguessable seed source.

Other platforms fall back to generate the seed with gettime().
This commit is contained in:
Patric Mueller
2019-01-11 19:08:22 +01:00
parent 1083971228
commit 86d694c61b
4 changed files with 56 additions and 13 deletions
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51
src/hacklib.c
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@@ -848,12 +848,23 @@ extern struct tm *FDECL(localtime, (time_t *));
#endif
STATIC_DCL struct tm *NDECL(getlt);
void
setrandom()
/* Returns a number suitable as seed for the random number generator. */
static unsigned long
get_random_seed()
{
unsigned long seed = (unsigned long) getnow(); /* time((TIME_type) 0) */
unsigned long seed = 0;
#ifdef DEV_RANDOM
FILE *fptr = NULL;
#if defined(UNIX) || defined(VMS)
fptr = fopen(DEV_RANDOM, "r");
if (fptr) {
fread(&seed, sizeof(long), 1, fptr);
}
fclose(fptr);
#else
seed = (unsigned long) getnow(); /* time((TIME_type) 0) */
# if defined(UNIX) || defined(VMS)
{
unsigned long pid = (unsigned long) getpid();
@@ -864,28 +875,46 @@ setrandom()
seed *= pid;
}
}
# endif
#endif
return seed;
}
/* Sets the seed for the random number generator */
static void
set_random(unsigned long seed)
{
/* the types are different enough here that sweeping the different
* routine names into one via #defines is even more confusing
*/
#ifdef RANDOM /* srandom() from sys/share/random.c */
srandom((unsigned int) seed);
#else
#if defined(__APPLE__) || defined(BSD) || defined(LINUX) || defined(ULTRIX) \
# if defined(__APPLE__) || defined(BSD) || defined(LINUX) || defined(ULTRIX) \
|| defined(CYGWIN32) /* system srandom() */
#if defined(BSD) && !defined(POSIX_TYPES) && defined(SUNOS4)
# if defined(BSD) && !defined(POSIX_TYPES) && defined(SUNOS4)
(void)
#endif
# endif
srandom((int) seed);
#else
#ifdef UNIX /* system srand48() */
# else
# ifdef UNIX /* system srand48() */
srand48((long) seed);
#else /* poor quality system routine */
# else /* poor quality system routine */
srand((int) seed);
# endif
#endif
#endif
#endif
}
/*
* Initializes the random number generator.
* Only call once.
*/
void
init_random()
{
unsigned long seed = get_random_seed();
set_random(seed);
}
time_t