/*

 * This file is part of the SSH Library

 *

 * Copyright (c) 2014 by Aris Adamantiadis <aris@badcode.be>

 *

 * 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 <stdio.h>

#include "libssh/priv.h"

#include "libssh/bignum.h"

#include "libssh/string.h"

static ssh_string make_bignum_string(bignum num, size_t pad_to_len)

{

    ssh_string ptr = NULL;

    size_t pad = 0;

    size_t len = bignum_num_bytes(num);

    size_t bits = bignum_num_bits(num);

    if (pad_to_len == 0) {

        /* If the first bit is set we have a negative number */

        if (!(bits % 8) && bignum_is_bit_set(num, bits - 1)) {

            pad++;

        }

    } else {

        if (len > pad_to_len) {

            return NULL;

        }

        pad = pad_to_len - len;

    }

#ifdef DEBUG_CRYPTO

    SSH_LOG(SSH_LOG_TRACE, "%zu bits, %zu bytes, %zu padding", bits, len, pad);

#endif /* DEBUG_CRYPTO */

    ptr = ssh_string_new(len + pad);

    if (ptr == NULL) {

        return NULL;

    }

    /* We have a negative number so we need a leading zero */

    if (pad) {

        memset(ptr->data, 0, pad);

    }

    bignum_bn2bin(num, len, ptr->data + pad);

    return ptr;

}

ssh_string ssh_make_bignum_string(bignum num)

{

    return make_bignum_string(num, 0);

}

ssh_string ssh_make_padded_bignum_string(bignum num, size_t pad_len)

{

    return make_bignum_string(num, pad_len);

}

bignum ssh_make_string_bn(ssh_string string)

{

    bignum bn = NULL;

    size_t len = ssh_string_len(string);

#ifdef DEBUG_CRYPTO

    SSH_LOG(SSH_LOG_TRACE,

            "Importing a %zu bits, %zu bytes object ...",

            len * 8,

            len);

#endif /* DEBUG_CRYPTO */

    bignum_bin2bn(string->data, (int)len, &bn);

    return bn;

}

/* prints the bignum on stderr */

void ssh_print_bignum(const char *name, const_bignum num)

{

    unsigned char *hex = NULL;

    if (num != NULL) {

        bignum_bn2hex(num, &hex);

    }

    SSH_LOG(SSH_LOG_DEBUG,

            "%s value: %s",

            name,

            (hex == NULL) ? "(null)" : (char *)hex);

    ssh_crypto_free(hex);

}