/*  Copyright (c) 2016, 2021, 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 also distributed 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 included with MySQL.

    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 */

/**
  @file
  Ssl functions wrapper service implementation. For more information please
  check the function comments.
*/

#ifdef WIN32
// In OpenSSL before 1.1.0, we need this first.
#include <winsock2.h>
#endif  // WIN32
#include <openssl/ssl.h>
#include <string.h>

#include "my_compiler.h"
#include "my_io.h"  // IWYU pragma: keep (for Winsock definitions)
#include "mysql/service_ssl_wrapper.h"

namespace ssl_wrapper_service {

int MY_ATTRIBUTE((visibility("default")))
    dummy_function_to_ensure_we_are_linked_into_the_server() {
  return 1;
}

}  // namespace ssl_wrapper_service

static char *my_asn1_time_to_string(ASN1_TIME *time, char *buf, size_t len) {
  int n_read;
  char *res = nullptr;
  BIO *bio = BIO_new(BIO_s_mem());

  if (bio == nullptr) return nullptr;

  if (!ASN1_TIME_print(bio, time)) goto end;

  n_read = BIO_read(bio, buf, (int)(len - 1));

  if (n_read > 0) {
    buf[n_read] = 0;
    res = buf;
  }

end:
  BIO_free(bio);
  return res;
}

void ssl_wrapper_version(Vio *vio, char *buffer, const size_t buffer_size) {
  const char *ssl_version = SSL_get_version((SSL *)vio->ssl_arg);

  strncpy(buffer, ssl_version, buffer_size);
  buffer[buffer_size - 1] = '\0';
}

/**
  Return cipher used in current connection

  @param vio              VIO connection descriptor
  @param buffer           Character buffer in which the cipher name is going to
  be placed
  @param buffer_size      Size of the character buffer
*/
void ssl_wrapper_cipher(Vio *vio, char *buffer, const size_t buffer_size) {
  const char *ssl_version = SSL_get_cipher((SSL *)vio->ssl_arg);

  strncpy(buffer, ssl_version, buffer_size);
  buffer[buffer_size - 1] = '\0';
}

/**
  Return cipher list that can be used for SSL

  @param vio                       VIO connection descriptor
  @param clipher_list              Pointer to an array of c-strings
  @param maximun_num_of_elements   Size of the pointer array
*/
long ssl_wrapper_cipher_list(Vio *vio, const char **clipher_list,
                             const long maximun_num_of_elements) {
  const char *cipher = nullptr;
  int index = 0;
  long element = 0;

  while (element < maximun_num_of_elements) {
    cipher = SSL_get_cipher_list((SSL *)vio->ssl_arg, index++);

    if (nullptr == cipher) break;

    clipher_list[element++] = cipher;
  }

  return element;
}

/**
  Return the verification depth limit set in SSL

  @param vio              VIO connection descriptor

  @return
    -1 default values should be used
    >0 verification depth
*/
long ssl_wrapper_verify_depth(Vio *vio) {
  return SSL_get_verify_depth((SSL *)vio->ssl_arg);
}

long ssl_wrapper_verify_mode(Vio *vio) {
  return SSL_get_verify_mode((SSL *)vio->ssl_arg);
}

/**
  Return issuer name form peers ssl certificate

  @param vio              VIO connection descriptor
  @param issuer           Character buffer in which the issuer name is going to
  be placed
  @param issuer_size      Size of character buffer for the issuer name
*/
void ssl_wrapper_get_peer_certificate_issuer(Vio *vio, char *issuer,
                                             const size_t issuer_size) {
  X509 *cert = nullptr;
  if (!(cert = SSL_get_peer_certificate((SSL *)vio->ssl_arg))) {
    issuer[0] = '\0';
    return;
  }

  X509_NAME_oneline(X509_get_issuer_name(cert), issuer, (int)issuer_size);
  X509_free(cert);
}

/**
  Return subject field form peers ssl certificate

  @param vio              VIO connection descriptor
  @param subject          Character buffer in which the subject is going to be
  placed
  @param subject_size     Size of character buffer for the subject
*/
void ssl_wrapper_get_peer_certificate_subject(Vio *vio, char *subject,
                                              const size_t subject_size) {
  X509 *cert = nullptr;
  if (!(cert = SSL_get_peer_certificate((SSL *)vio->ssl_arg))) {
    subject[0] = '\0';
    return;
  }

  X509_NAME_oneline(X509_get_subject_name(cert), subject, (int)subject_size);
  X509_free(cert);
}

/**
  Check is peer certificate is present and try to verify it

  @param vio                 VIO connection descriptor

  @return
    X509_V_OK verification of peer certificate succeeded
    -1        verification failed
*/
long ssl_wrapper_get_verify_result_and_cert(Vio *vio) {
  long result = 0;

  if (X509_V_OK != (result = SSL_get_verify_result((SSL *)vio->ssl_arg)))
    return result;

  X509 *cert = nullptr;
  if (!(cert = SSL_get_peer_certificate((SSL *)vio->ssl_arg))) return -1;

  X509_free(cert);

  return X509_V_OK;
}

/**
  Return the verification depth limit set in SSL context

  @param vio_ssl              VIO SSL contex descriptor

  @return
    -1 default values should be used
    >0 verification depth
*/
long ssl_wrapper_ctx_verify_depth(struct st_VioSSLFd *vio_ssl) {
  return SSL_CTX_get_verify_depth(vio_ssl->ssl_context);
}

/**
  Return the verification mode set in SSL context

  @param vio_ssl              VIO SSL contex descriptor

  @return
    -1 default values should be used
    >0 verification mode
*/
long ssl_wrapper_ctx_verify_mode(struct st_VioSSLFd *vio_ssl) {
  return SSL_CTX_get_verify_mode(vio_ssl->ssl_context);
}

/**
  Return the last day the server certificate is valid

  @param vio_ssl              VIO SSL contex descriptor
  @param no_after             Character buffer for to be filed with the date in
  human readble format
  @param no_after_size        Size of the character buffer
*/
void ssl_wrapper_ctx_server_not_after(struct st_VioSSLFd *vio_ssl,
                                      char *no_after,
                                      const size_t no_after_size) {
  SSL *ssl = SSL_new(vio_ssl->ssl_context);
  if (nullptr == ssl) {
    no_after[0] = '\0';
    return;
  }

  X509 *cert = SSL_get_certificate(ssl);
  ASN1_TIME *not_after_time = X509_get_notAfter(cert);
  const char *result =
      my_asn1_time_to_string(not_after_time, no_after, no_after_size);

  if (!result) {
    no_after[0] = '\0';
  }

  SSL_free(ssl);
}

/**
  Return the first day the server certificate is valid

  @param vio_ssl              VIO SSL contex descriptor
  @param no_before            Character buffer for to be filed with the date in
  human readble format
  @param no_before_size       Size of the character buffer
*/
void ssl_wrapper_ctx_server_not_before(struct st_VioSSLFd *vio_ssl,
                                       char *no_before,
                                       const size_t no_before_size) {
  SSL *ssl = SSL_new(vio_ssl->ssl_context);
  if (nullptr == ssl) {
    no_before[0] = '\0';
    return;
  }

  X509 *cert = SSL_get_certificate(ssl);
  ASN1_TIME *not_before_time = X509_get_notBefore(cert);
  const char *result =
      my_asn1_time_to_string(not_before_time, no_before, no_before_size);

  if (!result) {
    no_before[0] = '\0';
  }

  SSL_free(ssl);
}

long ssl_wrapper_sess_accept(struct st_VioSSLFd *vio_ssl) {
  return SSL_CTX_sess_accept(vio_ssl->ssl_context);
}

long ssl_wrapper_sess_accept_good(struct st_VioSSLFd *vio_ssl) {
  return SSL_CTX_sess_accept_good(vio_ssl->ssl_context);
}

/**
  Cleanup data allocated by SSL on thread stack

*/
void ssl_wrapper_thread_cleanup() {
  ERR_clear_error();
#if OPENSSL_VERSION_NUMBER < 0x10100000L
  ERR_remove_thread_state(0);
#endif /* OPENSSL_VERSION_NUMBER < 0x10100000L */
}
