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/*
* arc4wrap.c - wrapper for libevent's ARCFOUR random number generator
*
* Written by Juergen Perlinger (perlinger@ntp.org) for the NTP project.
* The contents of 'html/copyright.html' apply.
* --------------------------------------------------------------------
* This is an inclusion wrapper for the ARCFOUR implementation in
* libevent. It's main usage is to enable a openSSL-free build on Win32
* without a full integration of libevent. This provides Win32 specific
* glue to make the PRNG working. Porting to POSIX should be easy, but
* on most POSIX systems using openSSL is no problem and falling back to
* using ARCFOUR instead of the openSSL PRNG is not necessary. And even
* if it is, there's a good chance that ARCFOUR is a system library.
*/
#include <config.h>
#ifdef _WIN32
# include <wincrypt.h>
# include <process.h>
#else
# error this is currently a pure windows port
#endif
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include "ntp_types.h"
#include "ntp_stdlib.h"
/* ARCFOUR implementation glue */
/* export type is empty, since this goes into a static library*/
#define ARC4RANDOM_EXPORT
/* we use default uint32_t as UINT32 */
#define ARC4RANDOM_UINT32 uint32_t
/* do not use ARCFOUR's default includes - we gobble it all up here. */
#define ARC4RANDOM_NO_INCLUDES
/* And the locking. Could probably be left empty. */
#define ARC4_LOCK_() private_lock_()
#define ARC4_UNLOCK_() private_unlock_()
/* support code */
static void
evutil_memclear_(
void *buf,
size_t len)
{
memset(buf, 0, len);
}
/* locking uses a manual thread-safe ONCE pattern. There's no static
* initialiser pattern that can be used for critical sections, and
* we must make sure we do the creation exactly once on the first call.
*/
static long once_ = 0;
static CRITICAL_SECTION csec_;
static void
private_lock_(void)
{
again:
switch (InterlockedCompareExchange(&once_, 1, 0)) {
case 0:
InitializeCriticalSection(&csec_);
InterlockedExchange(&once_, 2);
case 2:
EnterCriticalSection(&csec_);
break;
default:
YieldProcessor();
goto again;
}
}
static void
private_unlock_(void)
{
if (InterlockedExchangeAdd(&once_, 0) == 2)
LeaveCriticalSection(&csec_);
}
#pragma warning(disable : 4244)
#include "../../../sntp/libevent/arc4random.c"
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