/*
 * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the OpenSSL license (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <stdio.h>
#include "internal/cryptlib.h"
#include <openssl/bn.h>
#include "dh_locl.h"
#include <openssl/engine.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 = OPENSSL_zalloc(sizeof(*ret));

    if (ret == NULL) {
        DHerr(DH_F_DH_NEW_METHOD, ERR_R_MALLOC_FAILURE);
        return NULL;
    }

    ret->references = 1;
    ret->lock = CRYPTO_THREAD_lock_new();
    if (ret->lock == NULL) {
        DHerr(DH_F_DH_NEW_METHOD, ERR_R_MALLOC_FAILURE);
        OPENSSL_free(ret);
        return NULL;
    }

    ret->meth = DH_get_default_method();
#ifndef OPENSSL_NO_ENGINE
    ret->flags = ret->meth->flags;  /* early default init */
    if (engine) {
        if (!ENGINE_init(engine)) {
            DHerr(DH_F_DH_NEW_METHOD, ERR_R_ENGINE_LIB);
            goto err;
        }
        ret->engine = engine;
    } else
        ret->engine = ENGINE_get_default_DH();
    if (ret->engine) {
        ret->meth = ENGINE_get_DH(ret->engine);
        if (ret->meth == NULL) {
            DHerr(DH_F_DH_NEW_METHOD, ERR_R_ENGINE_LIB);
            goto err;
        }
    }
#endif

    ret->flags = ret->meth->flags;

    if (!CRYPTO_new_ex_data(CRYPTO_EX_INDEX_DH, ret, &ret->ex_data))
        goto err;

    if ((ret->meth->init != NULL) && !ret->meth->init(ret)) {
        DHerr(DH_F_DH_NEW_METHOD, ERR_R_INIT_FAIL);
err:
        DH_free(ret);
        ret = NULL;
    }

    return ret;
}

void DH_free(DH *r)
{
    int i;

    if (r == NULL)
        return;

    CRYPTO_atomic_add(&r->references, -1, &i, r->lock);
    REF_PRINT_COUNT("DH", r);
    if (i > 0)
        return;
    REF_ASSERT_ISNT(i < 0);

    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);

    CRYPTO_THREAD_lock_free(r->lock);

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

int DH_up_ref(DH *r)
{
    int i;

    if (CRYPTO_atomic_add(&r->references, 1, &i, r->lock) <= 0)
        return 0;

    REF_PRINT_COUNT("DH", r);
    REF_ASSERT_ISNT(i < 2);
    return ((i > 1) ? 1 : 0);
}

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

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

int DH_security_bits(const DH *dh)
{
    int N;
    if (dh->q)
        N = BN_num_bits(dh->q);
    else if (dh->length)
        N = dh->length;
    else
        N = -1;
    return BN_security_bits(BN_num_bits(dh->p), N);
}


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 the fields p and g in d are NULL, the corresponding input
     * parameters MUST be non-NULL.  q may remain NULL.
     */
    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;
    }
    if (g != NULL) {
        BN_free(dh->g);
        dh->g = g;
    }

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

    return 1;
}

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

int DH_set_length(DH *dh, long length)
{
    dh->length = length;
    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 the field pub_key in dh is NULL, the corresponding input
     * parameters MUST be non-NULL.  The priv_key field may
     * be left NULL.
     */
    if (dh->pub_key == NULL && pub_key == NULL)
        return 0;

    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;
}

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;
}

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