/*

 * Copyright 2000-2026 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the Apache License 2.0 (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

 */

/*

 * DH low level APIs are deprecated for public use, but still ok for

 * internal use.

 */

#include "internal/deprecated.h"

#include <stdio.h>

#include "internal/cryptlib.h"

#include <openssl/bn.h>

#include "dh_local.h"

#include <openssl/objects.h>

#include <openssl/asn1t.h>

#include "crypto/dh.h"

/* Override the default free and new methods */

static int dh_cb(int operation, ASN1_VALUE **pval, const ASN1_ITEM *it,

    void *exarg)

{

    if (operation == ASN1_OP_NEW_PRE) {

        *pval = (ASN1_VALUE *)DH_new();

        if (*pval != NULL)

            return 2;

        return 0;

    } else if (operation == ASN1_OP_FREE_PRE) {

        DH_free((DH *)*pval);

        *pval = NULL;

        return 2;

    } else if (operation == ASN1_OP_D2I_POST) {

        DH *dh = (DH *)*pval;

        DH_clear_flags(dh, DH_FLAG_TYPE_MASK);

        DH_set_flags(dh, DH_FLAG_TYPE_DH);

        ossl_dh_cache_named_group(dh);

        dh->dirty_cnt++;

    }

    return 1;

}

ASN1_SEQUENCE_cb(DHparams, dh_cb) = {

    ASN1_SIMPLE(DH, params.p, BIGNUM),

    ASN1_SIMPLE(DH, params.g, BIGNUM),

    ASN1_OPT_EMBED(DH, length, ZINT32),

} ASN1_SEQUENCE_END_cb(DH, DHparams)

IMPLEMENT_ASN1_ENCODE_FUNCTIONS_fname(DH, DHparams, DHparams)

/*

 * Internal only structures for handling X9.42 DH: this gets translated to or

 * from a DH structure straight away.

 */

typedef struct {

    ASN1_BIT_STRING *seed;

    BIGNUM *counter;

} int_dhvparams;

typedef struct {

    BIGNUM *p;

    BIGNUM *q;

    BIGNUM *g;

    BIGNUM *j;

    int_dhvparams *vparams;

} int_dhx942_dh;

ASN1_SEQUENCE(DHvparams) = {

    ASN1_SIMPLE(int_dhvparams, seed, ASN1_BIT_STRING),

    ASN1_SIMPLE(int_dhvparams, counter, BIGNUM)

} static_ASN1_SEQUENCE_END_name(int_dhvparams, DHvparams)

ASN1_SEQUENCE(DHxparams)

    = {

          ASN1_SIMPLE(int_dhx942_dh, p, BIGNUM),

          ASN1_SIMPLE(int_dhx942_dh, g, BIGNUM),

          ASN1_SIMPLE(int_dhx942_dh, q, BIGNUM),

          ASN1_OPT(int_dhx942_dh, j, BIGNUM),

          ASN1_OPT(int_dhx942_dh, vparams, DHvparams),

      } static_ASN1_SEQUENCE_END_name(int_dhx942_dh, DHxparams)

int_dhx942_dh *d2i_int_dhx(int_dhx942_dh **a, const unsigned char **pp, long length);

int i2d_int_dhx(const int_dhx942_dh *a, unsigned char **pp);

IMPLEMENT_ASN1_ENCODE_FUNCTIONS_fname(int_dhx942_dh, DHxparams, int_dhx)

DH *d2i_DHxparams(DH **a, const unsigned char **pp, long length)

{

    FFC_PARAMS *params;

    int_dhx942_dh *dhx = NULL;

    DH *dh = NULL;

    dh = DH_new();

    if (dh == NULL)

        return NULL;

    dhx = d2i_int_dhx(NULL, pp, length);

    if (dhx == NULL) {

        DH_free(dh);

        return NULL;

    }

    if (a != NULL) {

        DH_free(*a);

        *a = dh;

    }

    params = &dh->params;

    DH_set0_pqg(dh, dhx->p, dhx->q, dhx->g);

    ossl_ffc_params_set0_j(params, dhx->j);

    if (dhx->vparams != NULL) {

        /* The counter has a maximum value of 4 * numbits(p) - 1 */

        int counter = (int)BN_get_word(dhx->vparams->counter);

        ossl_ffc_params_set_validate_params(params, dhx->vparams->seed->data,

            dhx->vparams->seed->length,

            counter);

        ASN1_BIT_STRING_free(dhx->vparams->seed);

        BN_free(dhx->vparams->counter);

        OPENSSL_free(dhx->vparams);

        dhx->vparams = NULL;

    }

    OPENSSL_free(dhx);

    DH_clear_flags(dh, DH_FLAG_TYPE_MASK);

    DH_set_flags(dh, DH_FLAG_TYPE_DHX);

    return dh;

}

int i2d_DHxparams(const DH *dh, unsigned char **pp)

{

    int ret = 0;

    int_dhx942_dh dhx;

    int_dhvparams dhv = { NULL, NULL };

    ASN1_BIT_STRING seed;

    size_t seedlen = 0;

    const FFC_PARAMS *params = &dh->params;

    int counter;

    ossl_ffc_params_get0_pqg(params, (const BIGNUM **)&dhx.p,

        (const BIGNUM **)&dhx.q, (const BIGNUM **)&dhx.g);

    dhx.j = params->j;

    ossl_ffc_params_get_validate_params(params, &seed.data, &seedlen, &counter);

    seed.length = (int)seedlen;

    if (counter != -1 && seed.data != NULL && seed.length > 0) {

        seed.flags = ASN1_STRING_FLAG_BITS_LEFT;

        dhv.seed = &seed;

        dhv.counter = BN_new();

        if (dhv.counter == NULL)

            return 0;

        if (!BN_set_word(dhv.counter, (BN_ULONG)counter))

            goto err;

        dhx.vparams = &dhv;

    } else {

        dhx.vparams = NULL;

    }

    ret = i2d_int_dhx(&dhx, pp);

err:

    BN_free(dhv.counter);

    return ret;

}