/* crypto/rand/rand_lib.c */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 *
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 *
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 *
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */

#include <stdio.h>
#include <time.h>
#include "cryptlib.h"
#include <openssl/rand.h>

#ifndef OPENSSL_NO_ENGINE
# include <openssl/engine.h>
#endif

#ifdef OPENSSL_FIPS
# include <openssl/fips.h>
# include <openssl/fips_rand.h>
# include "rand_lcl.h"
#endif

#ifndef OPENSSL_NO_ENGINE
/* non-NULL if default_RAND_meth is ENGINE-provided */
static ENGINE *funct_ref = NULL;
#endif
static const RAND_METHOD *default_RAND_meth = NULL;

int RAND_set_rand_method(const RAND_METHOD *meth)
{
#ifndef OPENSSL_NO_ENGINE
    if (funct_ref) {
        ENGINE_finish(funct_ref);
        funct_ref = NULL;
    }
#endif
    default_RAND_meth = meth;
    return 1;
}

const RAND_METHOD *RAND_get_rand_method(void)
{
    if (!default_RAND_meth) {
#ifndef OPENSSL_NO_ENGINE
        ENGINE *e = ENGINE_get_default_RAND();
        if (e) {
            default_RAND_meth = ENGINE_get_RAND(e);
            if (!default_RAND_meth) {
                ENGINE_finish(e);
                e = NULL;
            }
        }
        if (e)
            funct_ref = e;
        else
#endif
            default_RAND_meth = RAND_SSLeay();
    }
    return default_RAND_meth;
}

#ifndef OPENSSL_NO_ENGINE
int RAND_set_rand_engine(ENGINE *engine)
{
    const RAND_METHOD *tmp_meth = NULL;
    if (engine) {
        if (!ENGINE_init(engine))
            return 0;
        tmp_meth = ENGINE_get_RAND(engine);
        if (!tmp_meth) {
            ENGINE_finish(engine);
            return 0;
        }
    }
    /* This function releases any prior ENGINE so call it first */
    RAND_set_rand_method(tmp_meth);
    funct_ref = engine;
    return 1;
}
#endif

void RAND_cleanup(void)
{
    const RAND_METHOD *meth = RAND_get_rand_method();
    if (meth && meth->cleanup)
        meth->cleanup();
    RAND_set_rand_method(NULL);
}

void RAND_seed(const void *buf, int num)
{
    const RAND_METHOD *meth = RAND_get_rand_method();
    if (meth && meth->seed)
        meth->seed(buf, num);
}

void RAND_add(const void *buf, int num, double entropy)
{
    const RAND_METHOD *meth = RAND_get_rand_method();
    if (meth && meth->add)
        meth->add(buf, num, entropy);
}

int RAND_bytes(unsigned char *buf, int num)
{
    const RAND_METHOD *meth = RAND_get_rand_method();
    if (meth && meth->bytes)
        return meth->bytes(buf, num);
    return (-1);
}

int RAND_pseudo_bytes(unsigned char *buf, int num)
{
    const RAND_METHOD *meth = RAND_get_rand_method();
    if (meth && meth->pseudorand)
        return meth->pseudorand(buf, num);
    return (-1);
}

int RAND_status(void)
{
    const RAND_METHOD *meth = RAND_get_rand_method();
    if (meth && meth->status)
        return meth->status();
    return 0;
}

#ifdef OPENSSL_FIPS

/*
 * FIPS DRBG initialisation code. This sets up the DRBG for use by the rest
 * of OpenSSL.
 */

/*
 * Entropy gatherer: use standard OpenSSL PRNG to seed (this will gather
 * entropy internally through RAND_poll()).
 */

static size_t drbg_get_entropy(DRBG_CTX *ctx, unsigned char **pout,
                               int entropy, size_t min_len, size_t max_len)
{
    /* Round up request to multiple of block size */
    min_len = ((min_len + 19) / 20) * 20;
    *pout = OPENSSL_malloc(min_len);
    if (!*pout)
        return 0;

    /* Enforces a reseed of the SSLEAY PRNG before generating random bytes */
    if (ssleay_rand_bytes_from_system(*pout, min_len) <= 0) {
        OPENSSL_free(*pout);
        *pout = NULL;
        return 0;
    }
    return min_len;
}

static size_t drbg_get_nonce(DRBG_CTX *ctx, unsigned char **pout,
                               int entropy, size_t min_len, size_t max_len)
{
    /* Round up request to multiple of block size */
    min_len = ((min_len + 19) / 20) * 20;
    *pout = OPENSSL_malloc(min_len);
    if (!*pout)
        return 0;
    if (ssleay_rand_bytes(*pout, min_len, 0, 0) <= 0) {
        OPENSSL_free(*pout);
        *pout = NULL;
        return 0;
    }
    return min_len;
}

static void drbg_free_entropy(DRBG_CTX *ctx, unsigned char *out, size_t olen)
{
    if (out) {
        OPENSSL_cleanse(out, olen);
        OPENSSL_free(out);
    }
}

/*
 * Set "additional input" when generating random data. This uses the current
 * PID, a time value and a counter.
 */

static size_t drbg_get_adin(DRBG_CTX *ctx, unsigned char **pout)
{
    /* Use of static variables is OK as this happens under a lock */
    static unsigned char buf[16];
    static unsigned long counter;
    FIPS_get_timevec(buf, &counter);
    *pout = buf;
    return sizeof(buf);
}

/*
 * RAND_add() and RAND_seed() pass through to OpenSSL PRNG so it is
 * correctly seeded by RAND_poll().
 */

static int drbg_rand_add(DRBG_CTX *ctx, const void *in, int inlen,
                         double entropy)
{
    RAND_SSLeay()->add(in, inlen, entropy);
    return 1;
}

static int drbg_rand_seed(DRBG_CTX *ctx, const void *in, int inlen)
{
    RAND_SSLeay()->seed(in, inlen);
    return 1;
}

# ifndef OPENSSL_DRBG_DEFAULT_TYPE
#  define OPENSSL_DRBG_DEFAULT_TYPE       NID_aes_256_ctr
# endif
# ifndef OPENSSL_DRBG_DEFAULT_FLAGS
#  define OPENSSL_DRBG_DEFAULT_FLAGS      DRBG_FLAG_CTR_USE_DF
# endif

static int fips_drbg_type = OPENSSL_DRBG_DEFAULT_TYPE;
static int fips_drbg_flags = OPENSSL_DRBG_DEFAULT_FLAGS;

void RAND_set_fips_drbg_type(int type, int flags)
{
    fips_drbg_type = type;
    fips_drbg_flags = flags;
}

int RAND_init_fips(void)
{
    DRBG_CTX *dctx;
    size_t plen;
    unsigned char pers[32], *p;
# ifndef OPENSSL_ALLOW_DUAL_EC_DRBG
    if (fips_drbg_type >> 16) {
        RANDerr(RAND_F_RAND_INIT_FIPS, RAND_R_DUAL_EC_DRBG_DISABLED);
        return 0;
    }
# endif

    dctx = FIPS_get_default_drbg();
    if (FIPS_drbg_init(dctx, fips_drbg_type, fips_drbg_flags) <= 0) {
        RANDerr(RAND_F_RAND_INIT_FIPS, RAND_R_ERROR_INITIALISING_DRBG);
        return 0;
    }

    FIPS_drbg_set_callbacks(dctx,
                            drbg_get_entropy, drbg_free_entropy, 20,
                            drbg_get_nonce, drbg_free_entropy);
    FIPS_drbg_set_rand_callbacks(dctx, drbg_get_adin, 0,
                                 drbg_rand_seed, drbg_rand_add);
    /* Personalisation string: a string followed by date time vector */
    strcpy((char *)pers, "OpenSSL DRBG2.0");
    plen = drbg_get_adin(dctx, &p);
    memcpy(pers + 16, p, plen);

    if (FIPS_drbg_instantiate(dctx, pers, sizeof(pers)) <= 0) {
        RANDerr(RAND_F_RAND_INIT_FIPS, RAND_R_ERROR_INSTANTIATING_DRBG);
        return 0;
    }
    FIPS_rand_set_method(FIPS_drbg_method());
    return 1;
}

#endif
