/*

 * This file is part of the SSH Library

 *

 * Copyright (c) 2017 Sartura d.o.o.

 *

 * Author: Juraj Vijtiuk <juraj.vijtiuk@sartura.hr>

 *

 * The SSH Library is free software; you can redistribute it and/or modify

 * it under the terms of the GNU Lesser General Public License as published by

 * the Free Software Foundation; either version 2.1 of the License, or (at your

 * option) any later version.

 *

 * The SSH Library is distributed in the hope that it will be useful, but

 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY

 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public

 * License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public License

 * along with the SSH Library; see the file COPYING.  If not, write to

 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,

 * MA 02111-1307, USA.

 */

#include "config.h"

#include "libssh/priv.h"

#include "libssh/libmbedcrypto.h"

#ifdef HAVE_LIBMBEDCRYPTO

bignum ssh_mbedcry_bn_new(void)

{

    bignum bn;

    bn = malloc(sizeof(mbedtls_mpi));

    if (bn) {

        mbedtls_mpi_init(bn);

    }

    return bn;

}

void ssh_mbedcry_bn_free(bignum bn)

{

    mbedtls_mpi_free(bn);

    SAFE_FREE(bn);

}

unsigned char *ssh_mbedcry_bn2num(bignum num, int radix)

{

    char *buf = NULL;

    size_t olen;

    int rc;

    rc = mbedtls_mpi_write_string(num, radix, buf, 0, &olen);

    if (rc != 0 && rc != MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL) {

        return NULL;

    }

    buf = malloc(olen);

    if (buf == NULL) {

        return NULL;

    }

    rc = mbedtls_mpi_write_string(num, radix, buf, olen, &olen);

    if (rc != 0) {

        SAFE_FREE(buf);

        return NULL;

    }

    return (unsigned char *) buf;

}

int ssh_mbedcry_rand(bignum rnd, int bits, int top, int bottom)

{

    size_t len;

    int rc;

    int i;

    if (bits <= 0) {

        return 0;

    }

    len = bits / 8 + 1;

    /* FIXME weird bug: over 1024, fill_random function returns an error code

     * MBEDTLS_ERR_MPI_BAD_INPUT_DATA   -0x0004

     */

    if (len > 1024){

        len = 1024;

    }

    rc = mbedtls_mpi_fill_random(rnd,

                                 len,

                                 mbedtls_ctr_drbg_random,

                                 ssh_get_mbedtls_ctr_drbg_context());

    if (rc != 0) {

        return 0;

    }

    for (i = len * 8 - 1; i >= bits; i--) {

        rc = mbedtls_mpi_set_bit(rnd, i, 0);

        if (rc != 0) {

            return 0;

        }

    }

    if (top == 0) {

        rc = mbedtls_mpi_set_bit(rnd, bits - 1, 0);

    }

    if (top == 1) {

        if (bits < 2) {

            return 0;

        }

        rc = mbedtls_mpi_set_bit(rnd, bits - 2, 0);

        if (rc != 0) {

            return 0;

        }

    }

    if (bottom) {

        rc = mbedtls_mpi_set_bit(rnd, 0, 1);

        if (rc != 0) {

            return 0;

        }

    }

    return 1;

}

int ssh_mbedcry_is_bit_set(bignum num, size_t pos)

{

    int bit;

    bit = mbedtls_mpi_get_bit(num, pos);

    return bit;

}

/** @brief generates a random integer between 0 and max

 * @returns 1 in case of success, 0 otherwise

 */

int ssh_mbedcry_rand_range(bignum dest, bignum max)

{

    size_t bits;

    bignum rnd;

    int rc;

    bits = bignum_num_bits(max) + 64;

    rnd = bignum_new();

    if (rnd == NULL){

        return 0;

    }

    rc = bignum_rand(rnd, bits);

    if (rc != 1){

        return rc;

    }

    mbedtls_mpi_mod_mpi(dest, rnd, max);

    bignum_safe_free(rnd);

    return 1;

}

int ssh_mbedcry_hex2bn(bignum *dest, char *data)

{

    int rc;

    *dest = bignum_new();

    if (*dest == NULL){

        return 0;

    }

    rc = mbedtls_mpi_read_string(*dest, 16, data);

    if (rc == 0) {

        return 1;

    }

    return 0;

}

#endif