Commit 58e10c74 authored by Kurt Zeilenga's avatar Kurt Zeilenga
Browse files

Add a fallback based upon Phil Karn's "practical randomness" idea.

parent d0ad0cf2
......@@ -9,6 +9,7 @@
#include <fcntl.h>
#include <lutil.h>
#include <lutil_md5.h>
/*
* lutil_entropy() provides nbytes of entropy in buf.
......@@ -19,6 +20,7 @@ int lutil_entropy( char *buf, int nbytes )
if( nbytes < 0 ) return -1;
if( nbytes == 0 ) return 0;
#undef URANDOM_DEVICE
#ifdef URANDOM_DEVICE
/* Linux and *BSD offer a urandom device */
{
......@@ -34,6 +36,57 @@ int lutil_entropy( char *buf, int nbytes )
/* should return nbytes */
if( rc < nbytes ) return -1;
return 0;
}
#else
{
/* based upon Phil Karn's "practical randomness" idea
* but implementation 100% OpenLDAP. So don't blame Phil. */
/* worse case is this is a MD5 hash of a counter, if
* MD5 is a strong cryptographic hash, this should
* be fairly resisant to attack
*/
static int initialized = 0;
int n;
struct {
pid_t pid;
#ifdef HAVE_GETTIMEOFDAY
struct timeval *tv;
#else
time_t time;
#endif
unsigned long junk;
} rdata;
if( !initialized ) {
initialized++;
rdata.pid = getpid();
}
for( n = 0; n < nbytes; n += 16 ) {
struct lutil_MD5Context ctx;
char digest[16];
#ifdef HAVE_GETTIMEOFDAY
(void) gettimeofday( &rdata.tv, sizeof( rdata.tv ) );
#else
(void) time( &rdata.time );
#endif
rdata.pid++;
rdata.junk++;
lutil_MD5Init( &ctx );
lutil_MD5Update( &ctx, (char *) &rdata, sizeof( rdata ) );
lutil_MD5Final( digest, &ctx );
memcpy( &buf[n], digest,
nbytes - n > 16 ? 16 : nbytes - n );
}
return 0;
}
#endif
......
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