/* Copyright (c) 2014, Google Inc.

 *

 * Permission to use, copy, modify, and/or distribute this software for any

 * purpose with or without fee is hereby granted, provided that the above

 * copyright notice and this permission notice appear in all copies.

 *

 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES

 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF

 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY

 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES

 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION

 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN

 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */

#include <openssl/aead.h>

#include <assert.h>

#include <string.h>

#include <openssl/cipher.h>

#include <openssl/err.h>

#include <openssl/mem.h>

#include "internal.h"

#include "../../internal.h"

size_t EVP_AEAD_key_length(const EVP_AEAD *aead) { return aead->key_len; }

size_t EVP_AEAD_nonce_length(const EVP_AEAD *aead) { return aead->nonce_len; }

size_t EVP_AEAD_max_overhead(const EVP_AEAD *aead) { return aead->overhead; }

size_t EVP_AEAD_max_tag_len(const EVP_AEAD *aead) { return aead->max_tag_len; }

void EVP_AEAD_CTX_zero(EVP_AEAD_CTX *ctx) {

  OPENSSL_memset(ctx, 0, sizeof(EVP_AEAD_CTX));

}

EVP_AEAD_CTX *EVP_AEAD_CTX_new(const EVP_AEAD *aead, const uint8_t *key,

                               size_t key_len, size_t tag_len) {

  EVP_AEAD_CTX *ctx = OPENSSL_malloc(sizeof(EVP_AEAD_CTX));

  EVP_AEAD_CTX_zero(ctx);

  if (EVP_AEAD_CTX_init(ctx, aead, key, key_len, tag_len, NULL)) {

    return ctx;

  }

  EVP_AEAD_CTX_free(ctx);

  return NULL;

}

void EVP_AEAD_CTX_free(EVP_AEAD_CTX *ctx) {

  if (ctx == NULL) {

    return;

  }

  EVP_AEAD_CTX_cleanup(ctx);

  OPENSSL_free(ctx);

}

int EVP_AEAD_CTX_init(EVP_AEAD_CTX *ctx, const EVP_AEAD *aead,

                      const uint8_t *key, size_t key_len, size_t tag_len,

                      ENGINE *impl) {

  if (!aead->init) {

    OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_NO_DIRECTION_SET);

    ctx->aead = NULL;

    return 0;

  }

  return EVP_AEAD_CTX_init_with_direction(ctx, aead, key, key_len, tag_len,

                                          evp_aead_open);

}

int EVP_AEAD_CTX_init_with_direction(EVP_AEAD_CTX *ctx, const EVP_AEAD *aead,

                                     const uint8_t *key, size_t key_len,

                                     size_t tag_len,

                                     enum evp_aead_direction_t dir) {

  if (key_len != aead->key_len) {

    OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_KEY_SIZE);

    ctx->aead = NULL;

    return 0;

  }

  ctx->aead = aead;

  int ok;

  if (aead->init) {

    ok = aead->init(ctx, key, key_len, tag_len);

  } else {

    ok = aead->init_with_direction(ctx, key, key_len, tag_len, dir);

  }

  if (!ok) {

    ctx->aead = NULL;

  }

  return ok;

}

void EVP_AEAD_CTX_cleanup(EVP_AEAD_CTX *ctx) {

  if (ctx->aead == NULL) {

    return;

  }

  ctx->aead->cleanup(ctx);

  ctx->aead = NULL;

}

// check_alias returns 1 if |out| is compatible with |in| and 0 otherwise. If

// |in| and |out| alias, we require that |in| == |out|.

static int check_alias(const uint8_t *in, size_t in_len, const uint8_t *out,

                       size_t out_len) {

  if (!buffers_alias(in, in_len, out, out_len)) {

    return 1;

  }

  return in == out;

}

int EVP_AEAD_CTX_seal(const EVP_AEAD_CTX *ctx, uint8_t *out, size_t *out_len,

                      size_t max_out_len, const uint8_t *nonce,

                      size_t nonce_len, const uint8_t *in, size_t in_len,

                      const uint8_t *ad, size_t ad_len) {

  if (in_len + ctx->aead->overhead < in_len /* overflow */) {

    OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE);

    goto error;

  }

  if (max_out_len < in_len) {

    OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BUFFER_TOO_SMALL);

    goto error;

  }

  if (!check_alias(in, in_len, out, max_out_len)) {

    OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_OUTPUT_ALIASES_INPUT);

    goto error;

  }

  size_t out_tag_len;

  if (ctx->aead->seal_scatter(ctx, out, out + in_len, &out_tag_len,

                              max_out_len - in_len, nonce, nonce_len, in,

                              in_len, NULL, 0, ad, ad_len)) {

    *out_len = in_len + out_tag_len;

    return 1;

  }

error:

  // In the event of an error, clear the output buffer so that a caller

  // that doesn't check the return value doesn't send raw data.

  OPENSSL_memset(out, 0, max_out_len);

  *out_len = 0;

  return 0;

}

int EVP_AEAD_CTX_seal_scatter(

    const EVP_AEAD_CTX *ctx, uint8_t *out, uint8_t *out_tag, size_t

    *out_tag_len, size_t max_out_tag_len, const uint8_t *nonce, size_t

    nonce_len, const uint8_t *in, size_t in_len, const uint8_t *extra_in,

    size_t extra_in_len, const uint8_t *ad, size_t ad_len) {

  // |in| and |out| may alias exactly, |out_tag| may not alias.

  if (!check_alias(in, in_len, out, in_len) ||

      buffers_alias(out, in_len, out_tag, max_out_tag_len) ||

      buffers_alias(in, in_len, out_tag, max_out_tag_len)) {

    OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_OUTPUT_ALIASES_INPUT);

    goto error;

  }

  if (!ctx->aead->seal_scatter_supports_extra_in && extra_in_len) {

    OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_INVALID_OPERATION);

    goto error;

  }

  if (ctx->aead->seal_scatter(ctx, out, out_tag, out_tag_len, max_out_tag_len,

                              nonce, nonce_len, in, in_len, extra_in,

                              extra_in_len, ad, ad_len)) {

    return 1;

  }

error:

  // In the event of an error, clear the output buffer so that a caller

  // that doesn't check the return value doesn't send raw data.

  OPENSSL_memset(out, 0, in_len);

  OPENSSL_memset(out_tag, 0, max_out_tag_len);

  *out_tag_len = 0;

  return 0;

}

int EVP_AEAD_CTX_open(const EVP_AEAD_CTX *ctx, uint8_t *out, size_t *out_len,

                      size_t max_out_len, const uint8_t *nonce,

                      size_t nonce_len, const uint8_t *in, size_t in_len,

                      const uint8_t *ad, size_t ad_len) {

  if (!check_alias(in, in_len, out, max_out_len)) {

    OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_OUTPUT_ALIASES_INPUT);

    goto error;

  }

  if (ctx->aead->open) {

    if (!ctx->aead->open(ctx, out, out_len, max_out_len, nonce, nonce_len, in,

                        in_len, ad, ad_len)) {

      goto error;

    }

    return 1;

  }

  // AEADs that use the default implementation of open() must set |tag_len| at

  // initialization time.

  assert(ctx->tag_len);

  if (in_len < ctx->tag_len) {

    OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT);

    goto error;

  }

  size_t plaintext_len = in_len - ctx->tag_len;

  if (max_out_len < plaintext_len) {

    OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BUFFER_TOO_SMALL);

    goto error;

  }

  if (EVP_AEAD_CTX_open_gather(ctx, out, nonce, nonce_len, in, plaintext_len,

                               in + plaintext_len, ctx->tag_len, ad, ad_len)) {

    *out_len = plaintext_len;

    return 1;

  }

error:

  // In the event of an error, clear the output buffer so that a caller

  // that doesn't check the return value doesn't try and process bad

  // data.

  OPENSSL_memset(out, 0, max_out_len);

  *out_len = 0;

  return 0;

}

int EVP_AEAD_CTX_open_gather(const EVP_AEAD_CTX *ctx, uint8_t *out,

                             const uint8_t *nonce, size_t nonce_len,

                             const uint8_t *in, size_t in_len,

                             const uint8_t *in_tag, size_t in_tag_len,

                             const uint8_t *ad, size_t ad_len) {

  if (!check_alias(in, in_len, out, in_len)) {

    OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_OUTPUT_ALIASES_INPUT);

    goto error;

  }

  if (!ctx->aead->open_gather) {

    OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_CTRL_NOT_IMPLEMENTED);

    goto error;

  }

  if (ctx->aead->open_gather(ctx, out, nonce, nonce_len, in, in_len, in_tag,

                             in_tag_len, ad, ad_len)) {

    return 1;

  }

error:

  // In the event of an error, clear the output buffer so that a caller

  // that doesn't check the return value doesn't try and process bad

  // data.

  OPENSSL_memset(out, 0, in_len);

  return 0;

}

const EVP_AEAD *EVP_AEAD_CTX_aead(const EVP_AEAD_CTX *ctx) { return ctx->aead; }

int EVP_AEAD_CTX_get_iv(const EVP_AEAD_CTX *ctx, const uint8_t **out_iv,

                        size_t *out_len) {

  if (ctx->aead->get_iv == NULL) {

    OPENSSL_PUT_ERROR(CIPHER, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);

    return 0;

  }

  return ctx->aead->get_iv(ctx, out_iv, out_len);

}

int EVP_AEAD_CTX_tag_len(const EVP_AEAD_CTX *ctx, size_t *out_tag_len,

                         const size_t in_len, const size_t extra_in_len) {

  assert(ctx->aead->seal_scatter_supports_extra_in || !extra_in_len);

  if (ctx->aead->tag_len) {

    *out_tag_len = ctx->aead->tag_len(ctx, in_len, extra_in_len);

    return 1;

  }

  if (extra_in_len + ctx->tag_len < extra_in_len) {

    OPENSSL_PUT_ERROR(CIPHER, ERR_R_OVERFLOW);

    *out_tag_len = 0;

    return 0;

  }

  *out_tag_len = extra_in_len + ctx->tag_len;

  return 1;

}