/*
 * Adaped from libtomcrypt by Tom St Denis.
 *
 * by Nathan Wagner, and released into the public domain
 */

#include <stdio.h>

#define LTC_ARGCHK(x)
#define TRY_URANDOM_FIRST 1

#ifndef WIN32
#define LTC_DEVRANDOM 1
#endif

#ifdef LTC_DEVRANDOM
/* on *NIX read /dev/random */
static unsigned long rng_nix(unsigned char *buf, unsigned long len) {
#ifdef LTC_NO_FILE
	return 0;
#else
	FILE           *f;
	unsigned long   x;
#ifdef TRY_URANDOM_FIRST
	f = fopen("/dev/urandom", "rb");
	if (f == NULL)
#endif
		f = fopen("/dev/random", "rb");

	if (f == NULL) {
		return 0;
	}
	/* disable buffering */
	if (setvbuf(f, NULL, _IONBF, 0) != 0) {
		fclose(f);
		return 0;
	}
	x = (unsigned long) fread(buf, 1, (size_t) len, f);
	fclose(f);
	return x;
#endif
}

#endif

/* TODO remove this.  It's too slow really (I think) */
/* on ANSI C platforms with 100 < CLOCKS_PER_SEC < 10000 */
#if defined(CLOCKS_PER_SEC) && !defined(WINCE)

#define ANSI_RNG

static unsigned long rng_ansic(unsigned char *buf, unsigned long len) {
	clock_t         t1;
	int             l, acc, bits, a, b;

	if (XCLOCKS_PER_SEC < 100 || XCLOCKS_PER_SEC > 10000) {
		return 0;
	}
	l = len;
	bits = 8;
	acc = a = b = 0;
	while (len--) {
		while (bits--) {
			do {
				t1 = XCLOCK();
				while (t1 == XCLOCK())
					a ^= 1;
				t1 = XCLOCK();
				while (t1 == XCLOCK())
					b ^= 1;
			} while (a == b);
			acc = (acc << 1) | a;
		}
		*buf++ = acc;
		acc = 0;
		bits = 8;
	}
	acc = bits = a = b = 0;
	return l;
}

#endif

/* Try the Microsoft CSP */
#if defined(WIN32) || defined(WINCE)
#warning using WIN32
#define _WIN32_WINNT 0x0400
#ifdef WINCE
#define UNDER_CE
#define ARM
#endif
#include <windows.h>
#include <wincrypt.h>

static unsigned long rng_win32(unsigned char *buf, unsigned long len) {
	HCRYPTPROV      hProv = 0;

	if (!CryptAcquireContext(&hProv, NULL, MS_DEF_PROV, PROV_RSA_FULL,
			    (CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET)) &&
	    !CryptAcquireContext(&hProv, NULL, MS_DEF_PROV, PROV_RSA_FULL,
	      CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET | CRYPT_NEWKEYSET))
		return 0;

	if (CryptGenRandom(hProv, len, buf) == TRUE) {
		CryptReleaseContext(hProv, 0);
		return len;
	} else {
		CryptReleaseContext(hProv, 0);
		return 0;
	}
}

#endif

unsigned long   pd_uuid_rng_get_bytes(unsigned char *out, unsigned long outlen) {
	unsigned long   x;

	LTC_ARGCHK(out != NULL);

#if defined(LTC_DEVRANDOM)
	x = rng_nix(out, outlen);
	if (x != 0) {
		return x;
	}
#endif
#ifdef WIN32
	x = rng_win32(out, outlen);
	if (x != 0) {
		return x;
	}
#endif
#ifdef ANSI_RNG
	x = rng_ansic(out, outlen);
	if (x != 0) {
		return x;
	}
#endif
	return 0;
}