/*
 * Secure eXtended Message Passing framework
 * Secure eXtended Transport layer implementation: (libsxt)
 * - very similar to SSH2/TLS
 * - using already proven and tested crypto algos
 * - better than TLS for message passing
 *
 * libressl/openssl wrappers
 *
 * (c) Alexander Vdolainen 2016 <avdolainen@zoho.com>
 *
 * libsxmp 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.
 *
 * libsxmp 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 this program.  If not, see <http://www.gnu.org/licenses/>.";
 *
 */

#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>

#include <sodium.h>

#include <openssl/aes.h>
#include <openssl/blowfish.h>
#include <openssl/rand.h>

#include <sxt/errno.h>
#include <sxt/ciphers.h>
#include <sxt/lcrypt.h>

/* internals */
static int __alloc_keybuf(sxt_cipher_t *c)
{
  if(!c->lcp) return -1;
  if(!(c->lcp->key = malloc(c->keylen))) return -1;

  return 0;
}

void lcrypt_cleanup_keystub(sxt_cipher_t *c)
{
  if(!c || !c->lcp) return;

  memset(c->lcp->key, 0, sizeof(c->keylen));
  free(c->lcp->key);

  memset(c->lcp, 0, sizeof(struct _lcrypt_cipher_priv));
  free(c->lcp);

  return;
}

int lcrypt_alloc_keystub(sxt_cipher_t *c)
{
  if(!c) return -1;

  if(!(c->lcp = malloc(sizeof(struct _lcrypt_cipher_priv)))) return -1;
  else memset(c->lcp, 0, sizeof(struct _lcrypt_cipher_priv));

  return 0;
}

/* AES */
static int aes_set_encrypt_key(sxt_cipher_t *cipher, void *key, void *ivec)
{
  if (cipher->lcp->key == NULL) {
    if (__alloc_keybuf(cipher) < 0) return -1;

    if(AES_set_encrypt_key(key, cipher->keysize, cipher->lcp->key) < 0) {
      if(cipher->lcp->key) {
        memset(cipher->lcp->key, 0, cipher->keylen);
        free(cipher->lcp->key);
        cipher->lcp->key = NULL;
      }
      return -1;
    }
  }

  cipher->lcp->ivec = ivec;

  return 0;
}

static int aes_set_decrypt_key(sxt_cipher_t *cipher, void *key, void *ivec)
{
  if (cipher->lcp->key == NULL) {
    if (__alloc_keybuf(cipher) < 0) return -1;

    if (AES_set_decrypt_key(key, cipher->keysize, cipher->lcp->key) < 0) {
      if(cipher->lcp->key) {
        memset(cipher->lcp->key, 0, cipher->keylen);
        free(cipher->lcp->key);
        cipher->lcp->key = NULL;
      }
      return -1;
    }
  }

  cipher->lcp->ivec = ivec;

  return 0;
}

static void aes_encrypt(sxt_cipher_t *cipher, void *in, void *out,
                        unsigned long len)
{
  AES_cbc_encrypt(in, out, len, cipher->lcp->key, cipher->lcp->ivec, AES_ENCRYPT);
}

static void aes_decrypt(sxt_cipher_t *cipher, void *in, void *out,
                        unsigned long len)
{
  AES_cbc_encrypt(in, out, len, cipher->lcp->key, cipher->lcp->ivec, AES_DECRYPT);
}

static struct _cipher_ops aes_ops = {
  .set_encrypt_key = aes_set_encrypt_key,
  .set_decrypt_key = aes_set_decrypt_key,
  .encrypt = aes_encrypt,
  .decrypt = aes_decrypt,
};

/* blow fish */
static int blowfish_set_key(sxt_cipher_t *cipher, void *key, void *ivec)
{
  if (cipher->lcp->key == NULL) {
    if (__alloc_keybuf(cipher) < 0) return -1;

    BF_set_key(cipher->lcp->key, 16, key);
  }
  cipher->lcp->ivec = ivec;

  return 0;
}

static void blowfish_encrypt(sxt_cipher_t *cipher, void *in,
                             void *out, unsigned long len)
{
  BF_cbc_encrypt(in, out, len, cipher->lcp->key, cipher->lcp->ivec, BF_ENCRYPT);
}

static void blowfish_decrypt(sxt_cipher_t *cipher, void *in,
                             void *out, unsigned long len)
{
  BF_cbc_encrypt(in, out, len, cipher->lcp->key, cipher->lcp->ivec, BF_DECRYPT);
}

static struct _cipher_ops bf_ops = {
  .set_encrypt_key = blowfish_set_key,
  .set_decrypt_key = blowfish_set_key,
  .encrypt = blowfish_encrypt,
  .decrypt = blowfish_decrypt,
};

int lcrypt_init_ciphers(void)
{
  int r = 0;

  r = sxt_cipher_add("blowfish-cbc", 8, sizeof(BF_KEY), 128, &bf_ops);
  r = sxt_cipher_add("aes128-cbc", 16, sizeof(AES_KEY), 128, &aes_ops);
  r = sxt_cipher_add("aes192-cbc", 16, sizeof(AES_KEY), 192, &aes_ops);
  r = sxt_cipher_add("aes256-cbc", 16, sizeof(AES_KEY), 256, &aes_ops);

  return r;
}

/* misc */
int lcrypt_reseed(void)
{
  randombytes_stir();

  return SXT_SUCCESS;
}