/*

 * Arc4 random number generator for OpenBSD.

 * Copyright 1996 David Mazieres <dm@lcs.mit.edu>.

 *

 * Modification and redistribution in source and binary forms is

 * permitted provided that due credit is given to the author and the

 * OpenBSD project (for instance by leaving this copyright notice

 * intact).

 */

/*

 * This code is derived from section 17.1 of Applied Cryptography,

 * second edition, which describes a stream cipher allegedly

 * compatible with RSA Labs "RC4" cipher (the actual description of

 * which is a trade secret).  The same algorithm is used as a stream

 * cipher called "arcfour" in Tatu Ylonen's ssh package.

 *

 * Here the stream cipher has been modified always to include the time

 * when initializing the state.  That makes it impossible to

 * regenerate the same random sequence twice, so this can't be used

 * for encryption, but will generate good random numbers.

 *

 * RC4 is a registered trademark of RSA Laboratories.

 *

 * * Portions Copyright (c) 2006 Nokia Corporation and/or its subsidiary(-ies).. All rights reserved.

 */

#include <sys/cdefs.h>

__FBSDID("$FreeBSD: src/lib/libc/gen/arc4random.c,v 1.10 2004/03/24 14:44:57 green Exp $");

#include "namespace.h"

#include <sys/types.h>

#include <sys/time.h>

#include <stdlib.h>

#include <pthread.h>

#include <stdio.h>

#include "libc_private.h"

#include "un-namespace.h"

#include <fcntl.h>

#include <unistd.h>

#include "common_def.h"

#if (defined(__SYMBIAN32__) && (defined(__WINSCW__) || defined(__WINS__)))

#include "libc_wsd_defs.h"

#endif

#ifndef EMULATOR

struct arc4_stream {

	u_int8_t i;

	u_int8_t j;

	u_int8_t s[256];

};

#endif //EMUALTOR

#ifndef EMULATOR

static pthread_mutex_t	arc4random_mtx = PTHREAD_MUTEX_INITIALIZER;

#else //EMULATOR

GET_STATIC_VAR_FROM_TLS(arc4random_mtx, pthread_mutex_t)

#define arc4random_mtx (*GET_WSD_VAR_NAME(arc4random_mtx, s)())

#endif //EMULATOR

#define	RANDOMDEV	"/dev/urandom"

#define	THREAD_LOCK()						\

	do {							\

		if (__isthreaded)				\

			_pthread_mutex_lock(&arc4random_mtx);	\

	} while (0)

#define	THREAD_UNLOCK()						\

	do {							\

		if (__isthreaded)				\

			_pthread_mutex_unlock(&arc4random_mtx);	\

	} while (0)

#ifndef EMULATOR

static struct arc4_stream rs;

static int rs_initialized;

static int rs_stired;

#else //EMULATOR

GET_STATIC_VAR_FROM_TLS(rs, struct arc4_stream)

GET_STATIC_VAR_FROM_TLS(rs_initialized, int)

GET_STATIC_VAR_FROM_TLS(rs_stired, int)

#define rs 			(*GET_WSD_VAR_NAME(rs, s)())

#define rs_initialized 	(*GET_WSD_VAR_NAME(rs_initialized, s)())

#define rs_stired 		(*GET_WSD_VAR_NAME(rs_stired, s)())

#endif //EMULATOR

static inline u_int8_t arc4_getbyte(struct arc4_stream *);

static void arc4_stir(struct arc4_stream *);

static inline void

arc4_init(as)

	struct arc4_stream *as;

{

	int     n;

	for (n = 0; n < 256; n++)

		as->s[n] = n;

	as->i = 0;

	as->j = 0;

}

static inline void

arc4_addrandom(as, dat, datlen)

	struct arc4_stream *as;

	u_char *dat;

	int     datlen;

{

	int     n;

	u_int8_t si;

	as->i--;

	for (n = 0; n < 256; n++) {

		as->i = (as->i + 1);

		si = as->s[as->i];

		as->j = (as->j + si + dat[n % datlen]);

		as->s[as->i] = as->s[as->j];

		as->s[as->j] = si;

	}

}

static void

arc4_stir(as)

	struct arc4_stream *as;

{

	int     fd, n;

	struct {

		struct timeval tv;

		pid_t pid;

		u_int8_t rnd[128 - sizeof(struct timeval) - sizeof(pid_t)];

	}       rdat;

	gettimeofday(&rdat.tv, NULL);

	rdat.pid = getpid();

	fd = _open(RANDOMDEV, O_RDONLY, 0);

	if (fd >= 0) {

		(void) _read(fd, rdat.rnd, sizeof(rdat.rnd));

		_close(fd);

	} 

	/* fd < 0?  Ah, what the heck. We'll just take whatever was on the

	 * stack... */

	arc4_addrandom(as, (void *) &rdat, sizeof(rdat));

	/*

	 * Throw away the first N bytes of output, as suggested in the

	 * paper "Weaknesses in the Key Scheduling Algorithm of RC4"

	 * by Fluher, Mantin, and Shamir.  N=1024 is based on

	 * suggestions in the paper "(Not So) Random Shuffles of RC4"

	 * by Ilya Mironov.

	 */

	for (n = 0; n < 1024; n++)

		arc4_getbyte(as);

}

static inline u_int8_t

arc4_getbyte(as)

	struct arc4_stream *as;

{

	u_int8_t si, sj;

	as->i = (as->i + 1);

	si = as->s[as->i];

	as->j = (as->j + si);

	sj = as->s[as->j];

	as->s[as->i] = sj;

	as->s[as->j] = si;

	return (as->s[(si + sj) & 0xff]);

}

static inline u_int32_t

arc4_getword(as)

	struct arc4_stream *as;

{

	u_int32_t val;

	val = arc4_getbyte(as) << 24;

	val |= arc4_getbyte(as) << 16;

	val |= arc4_getbyte(as) << 8;

	val |= arc4_getbyte(as);

	return (val);

}

static void

arc4_check_init(void)

{

	if (!rs_initialized) {

		arc4_init(&rs);

		rs_initialized = 1;

	}

}

static void

arc4_check_stir(void)

{

	if (!rs_stired) {

		arc4_stir(&rs);

		rs_stired = 1;

	}

}

#ifdef __SYMBIAN_COMPILE_UNUSED__

void

arc4random_stir()

{

	THREAD_LOCK();

	arc4_check_init();

	arc4_stir(&rs);

	THREAD_UNLOCK();

}

void

arc4random_addrandom(dat, datlen)

	u_char *dat;

	int     datlen;

{

	THREAD_LOCK();

	arc4_check_init();

	arc4_check_stir();

	arc4_addrandom(&rs, dat, datlen);

	THREAD_UNLOCK();

}

#endif

u_int32_t

arc4random()

{

	u_int32_t rnd;

	THREAD_LOCK();

	arc4_check_init();

	arc4_check_stir();

	rnd = arc4_getword(&rs);

	THREAD_UNLOCK();

	return (rnd);

}

#if 0

/*-------- Test code for i386 --------*/

#include <stdio.h>

#include <machine/pctr.h>

int

main(int argc, char **argv)

{

	const int iter = 1000000;

	int     i;

	pctrval v;

	v = rdtsc();

	for (i = 0; i < iter; i++)

		arc4random();

	v = rdtsc() - v;

	v /= iter;

	printf("%qd cycles\n", v);

}

#endif