/* $OpenBSD: dh_lib.c,v 1.37 2022/06/27 12:31:38 tb Exp $ */
/* 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 <limits.h>
#include <stdio.h>

#include <openssl/opensslconf.h>

#include <openssl/bn.h>
#include <openssl/dh.h>
#include <openssl/err.h>

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

#include "dh_local.h"

static const DH_METHOD *default_DH_method = NULL;

void
DH_set_default_method(const DH_METHOD *meth)
{
        default_DH_method = meth;
}

const DH_METHOD *
DH_get_default_method(void)
{
        if (!default_DH_method)
                default_DH_method = DH_OpenSSL();
        return default_DH_method;
}

int
DH_set_method(DH *dh, const DH_METHOD *meth)
{
        /*
         * NB: The caller is specifically setting a method, so it's not up to us
         * to deal with which ENGINE it comes from.
         */
        const DH_METHOD *mtmp;

        mtmp = dh->meth;
        if (mtmp->finish)
                mtmp->finish(dh);
#ifndef OPENSSL_NO_ENGINE
        ENGINE_finish(dh->engine);
        dh->engine = NULL;
#endif
        dh->meth = meth;
        if (meth->init)
                meth->init(dh);
        return 1;
}

DH *
DH_new(void)
{
        return DH_new_method(NULL);
}

DH *
DH_new_method(ENGINE *engine)
{
        DH *ret;

        ret = malloc(sizeof(DH));
        if (ret == NULL) {
                DHerror(ERR_R_MALLOC_FAILURE);
                return NULL;
        }

        ret->meth = DH_get_default_method();
#ifndef OPENSSL_NO_ENGINE
        if (engine) {
                if (!ENGINE_init(engine)) {
                        DHerror(ERR_R_ENGINE_LIB);
                        free(ret);
                        return NULL;
                }
                ret->engine = engine;
        } else
                ret->engine = ENGINE_get_default_DH();
        if(ret->engine) {
                ret->meth = ENGINE_get_DH(ret->engine);
                if (ret->meth == NULL) {
                        DHerror(ERR_R_ENGINE_LIB);
                        ENGINE_finish(ret->engine);
                        free(ret);
                        return NULL;
                }
        }
#endif

        ret->pad = 0;
        ret->version = 0;
        ret->p = NULL;
        ret->g = NULL;
        ret->length = 0;
        ret->pub_key = NULL;
        ret->priv_key = NULL;
        ret->q = NULL;
        ret->j = NULL;
        ret->seed = NULL;
        ret->seedlen = 0;
        ret->counter = NULL;
        ret->method_mont_p=NULL;
        ret->references = 1;
        ret->flags = ret->meth->flags & ~DH_FLAG_NON_FIPS_ALLOW;
        CRYPTO_new_ex_data(CRYPTO_EX_INDEX_DH, ret, &ret->ex_data);
        if (ret->meth->init != NULL && !ret->meth->init(ret)) {
#ifndef OPENSSL_NO_ENGINE
                ENGINE_finish(ret->engine);
#endif
                CRYPTO_free_ex_data(CRYPTO_EX_INDEX_DH, ret, &ret->ex_data);
                free(ret);
                ret = NULL;
        }
        return ret;
}

void
DH_free(DH *r)
{
        int i;

        if (r == NULL)
                return;
        i = CRYPTO_add(&r->references, -1, CRYPTO_LOCK_DH);
        if (i > 0)
                return;

        if (r->meth->finish)
                r->meth->finish(r);
#ifndef OPENSSL_NO_ENGINE
        ENGINE_finish(r->engine);
#endif

        CRYPTO_free_ex_data(CRYPTO_EX_INDEX_DH, r, &r->ex_data);

        BN_clear_free(r->p);
        BN_clear_free(r->g);
        BN_clear_free(r->q);
        BN_clear_free(r->j);
        free(r->seed);
        BN_clear_free(r->counter);
        BN_clear_free(r->pub_key);
        BN_clear_free(r->priv_key);
        free(r);
}

int
DH_up_ref(DH *r)
{
        int i = CRYPTO_add(&r->references, 1, CRYPTO_LOCK_DH);

        return i > 1 ? 1 : 0;
}

int
DH_get_ex_new_index(long argl, void *argp, CRYPTO_EX_new *new_func,
    CRYPTO_EX_dup *dup_func, CRYPTO_EX_free *free_func)
{
        return CRYPTO_get_ex_new_index(CRYPTO_EX_INDEX_DH, argl, argp, new_func,
            dup_func, free_func);
}

int
DH_set_ex_data(DH *d, int idx, void *arg)
{
        return CRYPTO_set_ex_data(&d->ex_data, idx, arg);
}

void *
DH_get_ex_data(DH *d, int idx)
{
        return CRYPTO_get_ex_data(&d->ex_data, idx);
}

int
DH_size(const DH *dh)
{
        return BN_num_bytes(dh->p);
}

int
DH_bits(const DH *dh)
{
        return BN_num_bits(dh->p);
}

int
DH_security_bits(const DH *dh)
{
        int N = -1;

        if (dh->q != NULL)
                N = BN_num_bits(dh->q);
        else if (dh->length > 0)
                N = dh->length;

        return BN_security_bits(BN_num_bits(dh->p), N);
}

ENGINE *
DH_get0_engine(DH *dh)
{
        return dh->engine;
}

void
DH_get0_pqg(const DH *dh, const BIGNUM **p, const BIGNUM **q, const BIGNUM **g)
{
        if (p != NULL)
                *p = dh->p;
        if (q != NULL)
                *q = dh->q;
        if (g != NULL)
                *g = dh->g;
}

int
DH_set0_pqg(DH *dh, BIGNUM *p, BIGNUM *q, BIGNUM *g)
{
        if ((dh->p == NULL && p == NULL) || (dh->g == NULL && g == NULL))
                return 0;

        if (p != NULL) {
                BN_free(dh->p);
                dh->p = p;
        }
        if (q != NULL) {
                BN_free(dh->q);
                dh->q = q;
                dh->length = BN_num_bits(dh->q);
        }
        if (g != NULL) {
                BN_free(dh->g);
                dh->g = g;
        }

        return 1;
}

void
DH_get0_key(const DH *dh, const BIGNUM **pub_key, const BIGNUM **priv_key)
{
        if (pub_key != NULL)
                *pub_key = dh->pub_key;
        if (priv_key != NULL)
                *priv_key = dh->priv_key;
}

int
DH_set0_key(DH *dh, BIGNUM *pub_key, BIGNUM *priv_key)
{
        if (pub_key != NULL) {
                BN_free(dh->pub_key);
                dh->pub_key = pub_key;
        }
        if (priv_key != NULL) {
                BN_free(dh->priv_key);
                dh->priv_key = priv_key;
        }

        return 1;
}

const BIGNUM *
DH_get0_p(const DH *dh)
{
        return dh->p;
}

const BIGNUM *
DH_get0_q(const DH *dh)
{
        return dh->q;
}

const BIGNUM *
DH_get0_g(const DH *dh)
{
        return dh->g;
}

const BIGNUM *
DH_get0_priv_key(const DH *dh)
{
        return dh->priv_key;
}

const BIGNUM *
DH_get0_pub_key(const DH *dh)
{
        return dh->pub_key;
}

void
DH_clear_flags(DH *dh, int flags)
{
        dh->flags &= ~flags;
}

int
DH_test_flags(const DH *dh, int flags)
{
        return dh->flags & flags;
}

void
DH_set_flags(DH *dh, int flags)
{
        dh->flags |= flags;
}

long
DH_get_length(const DH *dh)
{
        return dh->length;
}

int
DH_set_length(DH *dh, long length)
{
        if (length < 0 || length > INT_MAX)
                return 0;

        dh->length = length;
        return 1;
}