/*
Copyright (c) 2017, 2024, Oracle and/or its affiliates.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License, version 2.0,
as published by the Free Software Foundation.

This program is designed to work with certain software (including
but not limited to OpenSSL) that is licensed under separate terms,
as designated in a particular file or component or in included license
documentation.  The authors of MySQL hereby grant you an additional
permission to link the program and your derivative works with the
separately licensed software that they have either included with
the program or referenced in the documentation.

This program 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 General Public License, version 2.0, for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

#ifndef I_SHA2_PASSWORD_COMMON_INCLUDED
#define I_SHA2_PASSWORD_COMMON_INCLUDED

#include <openssl/evp.h>
#include "openssl/ossl_typ.h"
#include "sha2.h" /* SHA256_DIGEST_LENGTH */

#include <string>

/**
  @file sql/auth/i_sha2_password_common.h
  Classes for caching_sha2_authentication plugin
*/

/**
  @defgroup auth_caching_sha2_auth caching_sha2_authentication information
  @{
*/
namespace sha2_password {
/* Digest length for caching_sha2_authentication plugin */
const unsigned int CACHING_SHA2_DIGEST_LENGTH = SHA256_DIGEST_LENGTH;

/**
  Supported digest information
*/

enum class Digest_info { SHA256_DIGEST = 0, DIGEST_LAST };

/**
  Interface for cryptographic digest generation
*/

class Generate_digest {
 public:
  virtual bool update_digest(const void *src, unsigned int length) = 0;
  virtual bool retrieve_digest(unsigned char *digest, unsigned int length) = 0;
  virtual void scrub() = 0;
  virtual ~Generate_digest() = default;
};

/**
  SHA256 digest generator
  @sa Generate_digest
  @sa Digest_info
*/

class SHA256_digest : public Generate_digest {
 public:
  SHA256_digest();
  ~SHA256_digest() override;

  bool update_digest(const void *src, unsigned int length) override;
  bool retrieve_digest(unsigned char *digest, unsigned int length) override;
  void scrub() override;
  bool all_ok() { return m_ok; }

 private:
  void init();
  void deinit();

 private:
  /** Digest output buffer */
  unsigned char m_digest[CACHING_SHA2_DIGEST_LENGTH];
  /** Digest context */
  EVP_MD_CTX *md_context;
  /** Status */
  bool m_ok;
};

/**
  Scramble generator
  Responsible for generating scramble of following format:
  XOR(SHA2(m_src), SHA2(SHA2(SHA2(m_src)), m_rnd))
  @sa SHA256_digest
  @sa Digest_info
*/

class Generate_scramble {
 public:
  Generate_scramble(const std::string source, const std::string rnd,
                    Digest_info digest_type = Digest_info::SHA256_DIGEST);

  ~Generate_scramble();

  bool scramble(unsigned char *scramble, unsigned int scramble_length);

 private:
  /** plaintext source string */
  std::string m_src;
  /** random string */
  std::string m_rnd;
  /** Type of digest */
  Digest_info m_digest_type;
  /** Digest generator class */
  Generate_digest *m_digest_generator;
  /** length of the digest */
  unsigned int m_digest_length;
};

/**
  Scramble validator
  Expects scramble to be:
    XOR(SHA2(m_src), SHA2(SHA2(SHA2(m_src)), m_rnd))
  Validates it against:
    SHA2(SHA2(m_src)) and random string

  @sa Generate_scramble
  @sa SHA256_digest
  @sa Digest_info
*/

class Validate_scramble {
 public:
  Validate_scramble(const unsigned char *scramble, const unsigned char *known,
                    const unsigned char *rnd, unsigned int rnd_length,
                    Digest_info digest_type = Digest_info::SHA256_DIGEST);

  ~Validate_scramble();

  bool validate();

 private:
  /** scramble to be validated */
  const unsigned char *m_scramble;
  /** SHA2(SHA2(plaintext_password)) */
  const unsigned char *m_known;
  /** random string */
  const unsigned char *m_rnd;
  /** random string length*/
  unsigned int m_rnd_length;
  /** Type of digest */
  Digest_info m_digest_type;
  /** Digest generator class */
  Generate_digest *m_digest_generator;
  /** length of the digest */
  unsigned int m_digest_length;
};
}  // namespace sha2_password

/** @} (end of auth_caching_sha2_auth) */

#endif  // !I_SHA2_PASSWORD_INCLUDED