/*
 * %CopyrightBegin%
 *
 * Copyright Ericsson AB 2010-2018. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * %CopyrightEnd%
 */

#include "block.h"
#include "aes.h"
#include "cipher.h"

ERL_NIF_TERM block_crypt_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{/* (Type, Key, Ivec, Text, IsEncrypt) or (Type, Key, Text, IsEncrypt) */
    struct cipher_type_t *cipherp = NULL;
    const EVP_CIPHER     *cipher;
    ErlNifBinary         key, ivec, text;
    EVP_CIPHER_CTX       *ctx = NULL;
    ERL_NIF_TERM         ret;
    unsigned char        *out;
    int                  ivec_size, out_size = 0;
    int                  cipher_len;

    if (argc != 4 && argc != 5)
        goto bad_arg;
    if (!enif_inspect_iolist_as_binary(env, argv[1], &key))
        goto bad_arg;
    if (key.size > INT_MAX)
        goto bad_arg;
    if ((cipherp = get_cipher_type(argv[0], key.size)) == NULL)
        goto bad_arg;
    if (!enif_inspect_iolist_as_binary(env, argv[argc - 2], &text))
        goto bad_arg;
    if (text.size > INT_MAX)
        goto bad_arg;

    if ((cipher = cipherp->cipher.p) == NULL)
        return enif_raise_exception(env, atom_notsup);

    if (argv[0] == atom_aes_cfb8
        && (key.size == 24 || key.size == 32)) {
        /* Why do EVP_CIPHER_CTX_set_key_length() fail on these key sizes?
         * Fall back on low level API
         */
        return aes_cfb_8_crypt(env, argc-1, argv+1);
    }
    else if (argv[0] == atom_aes_cfb128
        && (key.size == 24 || key.size == 32)) {
        /* Why do EVP_CIPHER_CTX_set_key_length() fail on these key sizes?
         * Fall back on low level API
         */
        return aes_cfb_128_crypt_nif(env, argc-1, argv+1);
   }

    ivec_size  = EVP_CIPHER_iv_length(cipher);

#ifdef HAVE_ECB_IVEC_BUG
    if (argv[0] == atom_aes_ecb || argv[0] == atom_blowfish_ecb ||
	argv[0] == atom_des_ecb)
	ivec_size = 0; /* 0.9.8l returns faulty ivec_size */
#endif
    if (ivec_size < 0)
        goto bad_arg;

    if ((cipher_len = EVP_CIPHER_block_size(cipher)) < 0)
        goto bad_arg;
    if (text.size % (size_t)cipher_len != 0)
        goto bad_arg;

    if (ivec_size == 0) {
        if (argc != 4)
            goto bad_arg;
    } else {
        if (argc != 5)
            goto bad_arg;
        if (!enif_inspect_iolist_as_binary(env, argv[2], &ivec))
            goto bad_arg;
        if (ivec.size != (size_t)ivec_size)
            goto bad_arg;
    }

    if ((out = enif_make_new_binary(env, text.size, &ret)) == NULL)
        goto err;
    if ((ctx = EVP_CIPHER_CTX_new()) == NULL)
        goto err;

    if (!EVP_CipherInit_ex(ctx, cipher, NULL, NULL, NULL,
                           (argv[argc - 1] == atom_true)))
        goto err;
    if (!EVP_CIPHER_CTX_set_key_length(ctx, (int)key.size))
        goto err;

    if (EVP_CIPHER_type(cipher) == NID_rc2_cbc) {
        if (key.size > INT_MAX / 8)
            goto err;
        if (!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_SET_RC2_KEY_BITS, (int)key.size * 8, NULL))
            goto err;
    }

    if (!EVP_CipherInit_ex(ctx, NULL, NULL, key.data,
                           ivec_size ? ivec.data : NULL, -1))
        goto err;
    if (!EVP_CIPHER_CTX_set_padding(ctx, 0))
        goto err;

    /* OpenSSL 0.9.8h asserts text.size > 0 */
    if (text.size > 0) {
        if (!EVP_CipherUpdate(ctx, out, &out_size, text.data, (int)text.size))
            goto err;
        if (ASSERT(out_size == text.size), 0)
            goto err;
        if (!EVP_CipherFinal_ex(ctx, out + out_size, &out_size))
            goto err;
    }

    ASSERT(out_size == 0);
    CONSUME_REDS(env, text);
    goto done;

 bad_arg:
    ret = enif_make_badarg(env);
    goto done;

 err:
    ret = enif_raise_exception(env, atom_notsup);

 done:
    if (ctx)
        EVP_CIPHER_CTX_free(ctx);
    return ret;
}