/*
   Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   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 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
*/

/* C Headers */
#include <sys/stat.h>
#include <sys/types.h>
#include <stdint.h>

/* C++ Headers */
#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <string>
#include <sstream>
#include <fstream>
#include <algorithm>

/* MySQL Headers */
#include <my_sys.h>
#include <my_dir.h>
#include <my_default.h>
#include <my_global.h>
#include <my_config.h>
#include <my_getopt.h>
#include <welcome_copyright_notice.h>   /* ORACLE_WELCOME_COPYRIGHT_NOTICE */
#include <mysql_version.h>
#include "path.h"
#include "logger.h"

#if HAVE_CHOWN
#include <pwd.h>
#endif
/* Utility Version */
#define MY_VERSION      "1.0.0"

/* Forward declarations */

using namespace std;
typedef string Sql_string_t;

static Sql_string_t create_string(const char *ptr);

/* Global Variables */
enum certs
{
  CA_CERT=0,
  CA_KEY,
  CA_REQ,
  SERVER_CERT,
  SERVER_KEY,
  SERVER_REQ,
  CLIENT_CERT,
  CLIENT_KEY,
  CLIENT_REQ,
  PRIVATE_KEY,
  PUBLIC_KEY,
  OPENSSL_RND
};

enum extfiles
{
  CAV3_EXT=0,
  CERTV3_EXT
};

Sql_string_t cert_files[] =
{
  create_string("ca.pem"),
  create_string("ca-key.pem"),
  create_string("ca-req.pem"),
  create_string("server-cert.pem"),
  create_string("server-key.pem"),
  create_string("server-req.pem"),
  create_string("client-cert.pem"),
  create_string("client-key.pem"),
  create_string("client-req.pem"),
  create_string("private_key.pem"),
  create_string("public_key.pem"),
  create_string(".rnd")
};

Sql_string_t ext_files[] =
{
  create_string("cav3.ext"),
  create_string("certv3.ext")
};

#define MAX_PATH_LEN  (FN_REFLEN - strlen(FN_DIRSEP) \
                       - cert_files[SERVER_CERT].length() - 1)
/*
  Higest number of fixed characters in subject line is 47:
  MySQL_SERVER_<suffix>_Auto_Generated_Server_Certificate
  Maximum size of subject is 64. So suffix can't be longer
  than 17 characters.
*/
#define MAX_SUFFIX_LEN 17

Log info(cout,"NOTE");
Log error(cerr,"ERROR");

char **defaults_argv= 0;
static char *opt_datadir= 0;
static char default_data_dir[]= MYSQL_DATADIR;
static char *opt_suffix= 0;
static char default_suffix[]= MYSQL_SERVER_VERSION;
#if HAVE_CHOWN
static char *opt_userid= 0;
struct passwd *user_info= 0;
#endif /* HAVE_CHOWN */
Path dir_string;
Sql_string_t suffix_string;
my_bool opt_verbose;

static const char *load_default_groups[]=
{
  "mysql_ssl_rsa_setup",
  "mysql_install_db",
  "mysqld",
  0
};

static struct my_option my_options[]= {
  {"help", '?', "Display this help and exit.", 0, 0, 0, GET_NO_ARG,
   NO_ARG, 0, 0, 0, 0, 0, 0},
  {"verbose", 'v', "Be more verbose when running program",
   &opt_verbose, 0, 0, GET_BOOL, NO_ARG, FALSE, 0, 0, 0, 0, 0},
  {"version", 'V', "Print program version and exit", 0, 0, 0, GET_NO_ARG,
   NO_ARG, 0, 0, 0, 0, 0, 0},
  {"datadir", 'd', "Directory to store generated files.", &opt_datadir, &opt_datadir, 0,
   GET_STR_ALLOC, REQUIRED_ARG, (longlong)&default_data_dir, 0, 0, 0, 0, 0},
  {"suffix", 's',
   "Suffix to be added in certificate subject line", &opt_suffix,
   &opt_suffix, 0, GET_STR_ALLOC, REQUIRED_ARG, (longlong) &default_suffix,
   0, 0, 0, 0, 0},
#if HAVE_CHOWN
   {"uid", 0, "The effective user id to be used for file permission",
    &opt_userid, &opt_userid, 0, GET_STR_ALLOC, REQUIRED_ARG, 0, 0, 0,
    0, 0, 0},
#endif /* HAVE_CHOWN */
  /* END TOKEN */
  {0, 0, 0, 0, 0, 0, GET_NO_ARG, NO_ARG, 0, 0, 0, 0, 0, 0}
};

/* Helper Functions */

/**
  The string class will break if constructed with a NULL pointer. This wrapper
  provides a systematic protection when importing char pointers.
 */
static
Sql_string_t create_string(const char *ptr)
{
  return (ptr ? Sql_string_t(ptr) : Sql_string_t(""));
}


static
int execute_command(const Sql_string_t &command,
                    const Sql_string_t &error_message)
{
  stringstream cmd_string;

  cmd_string << command;
  if (!opt_verbose)
  {
#ifndef _WIN32
    cmd_string << " > /dev/null 2>&1";
#else
    cmd_string << " > NUL 2>&1";
#endif /* _WIN32 */
  }

  info << "Executing : " << cmd_string.str() << endl;
  if (system(cmd_string.str().c_str()))
  {
    error << error_message << endl;
    return 1;
  }

  return 0;
}


static
int set_file_pair_permission(const Sql_string_t &priv,
                             const Sql_string_t &pub)
{
  if (MY_TEST(my_chmod(priv.c_str(),
              USER_READ| USER_WRITE, MYF(MY_FAE+MY_WME))) ||
      MY_TEST(my_chmod(pub.c_str(),
              USER_READ|USER_WRITE|GROUP_READ|OTHERS_READ,
              MYF(MY_FAE+MY_WME))))
  {
    error << "Error setting file permissions for" << priv.c_str()
          << " and " << pub.c_str() << endl;
    return 1;
  }
#if HAVE_CHOWN
  if (user_info)
  {
    if(chown(priv.c_str(), user_info->pw_uid, user_info->pw_gid) ||
       chown(pub.c_str(), user_info->pw_uid, user_info->pw_gid))
    {
      error << "Failed to change file permission" << endl;
      return 1;
    }
  }
#endif /* HAVE_CHOWN */
  return 0;
}


static
bool file_exists(const Sql_string_t &filename)
{
  MY_STAT file_stat;
  if (my_stat(filename.c_str(), &file_stat, MYF(0)) == NULL)
    return false;

  return true;
}


static
int remove_file(const Sql_string_t &filename, bool report_error=true)
{
  if (my_delete(filename.c_str(), MYF(0)))
  {
    if (report_error)
      error << "Error deleting : " << filename << endl;
    return 1;
  }
  return 0;
}


static
void free_resources()
{
  if (opt_datadir)
    my_free(opt_datadir);
  if (opt_suffix)
    my_free(opt_suffix);
#if HAVE_CHOWN
  if (opt_userid)
    my_free(opt_userid);
#endif
  if (defaults_argv && *defaults_argv)
    free_defaults(defaults_argv);
}


class RSA_priv
{
public:
  RSA_priv(uint32_t key_size= 2048)
    : m_key_size(key_size) {};

  ~RSA_priv() {};

  Sql_string_t operator()(const Sql_string_t &key_file)
  {
    stringstream command;
    command << "openssl genrsa " << " -out " << key_file << " " << m_key_size;

    return command.str();
  }
private:
  uint32_t m_key_size;
};


class RSA_pub
{
public:
  Sql_string_t operator()(const Sql_string_t &priv_key_file,
                          const Sql_string_t &pub_key_file)
  {
    stringstream command;
    command << "openssl rsa -in " << priv_key_file << " -pubout -out "
            << pub_key_file;
    return command.str();
  }
};


class X509_key
{
public:
  X509_key(const Sql_string_t &version,
           uint32_t validity= 10*365L)
    : m_validity(validity)
  {
    m_subj_prefix << "-subj /CN=MySQL_Server_" << version;
  }

  Sql_string_t operator()(Sql_string_t suffix,
                          const Sql_string_t &key_file,
                          const Sql_string_t &req_file)
  {
    stringstream command;
    command << "openssl req -newkey rsa:2048 -days " << m_validity
            << " -nodes -keyout " << key_file << " "
            << m_subj_prefix.str() << suffix << " -out " << req_file
            << " && openssl rsa -in " << key_file << " -out " << key_file;

    return command.str();
  }

private:
  uint32_t m_validity;
  stringstream m_subj_prefix;
};

class X509v3_ext_writer
{
public:
  X509v3_ext_writer()
  {
    m_cav3_ext_options << "basicConstraints=CA:TRUE" << std::endl;

    m_certv3_ext_options << "basicConstraints=CA:FALSE" << std::endl;
  }
  ~X509v3_ext_writer() {};

  bool operator()(const Sql_string_t &cav3_ext_file,
                  const Sql_string_t &certv3_ext_file)
  {
    if (!cav3_ext_file.length() ||
        !certv3_ext_file.length())
      return true;

    std::ofstream ext_file;

    ext_file.open(cav3_ext_file.c_str(),
                  std::ios::out|std::ios::trunc);
    if (!ext_file.is_open())
      return true;
    ext_file << m_cav3_ext_options.str();
    ext_file.close();

    ext_file.open(certv3_ext_file.c_str(),
                  std::ios::out|std::ios::trunc);
    if (!ext_file.is_open())
    {
      remove_file(cav3_ext_file.c_str(), false);
      return true;
    }
    ext_file << m_certv3_ext_options.str();
    ext_file.close();

    return false;
  }
private:
  stringstream m_cav3_ext_options;
  stringstream m_certv3_ext_options;
};

class X509_cert
{
public:
  X509_cert(uint32_t validity= 10*365L)
    : m_validity(validity) {};

  ~X509_cert() {};

  Sql_string_t operator()(const Sql_string_t &req_file,
                          const Sql_string_t &cert_file,
                          uint32_t serial,
                          bool self_signed,
                          const Sql_string_t &sign_key_file,
                          const Sql_string_t &sign_cert_file,
                          const Sql_string_t &ext_file)
  {
    stringstream command;
    command << "openssl x509 -sha256 -days " << m_validity;
    command << " -extfile " << ext_file;
    command << " -set_serial " << serial << " -req -in " << req_file;
    if (self_signed)
      command << " -signkey " << sign_key_file;
    else
      command << " -CA " << sign_cert_file << " -CAkey " << sign_key_file;
    command << " -out " << cert_file;

    return command.str();
  }

protected:
  uint32_t m_validity;
};


static
void print_version(void)
{
  cout << my_progname << " Version : " << MY_VERSION
       << " Distribution : " << MYSQL_SERVER_VERSION
       << " For : " << SYSTEM_TYPE << " On : " << MACHINE_TYPE << endl;
}


static
void usage(void)
{
  print_version();
  cout << (ORACLE_WELCOME_COPYRIGHT_NOTICE("2015")) << endl
       << "MySQL SSL Certificate and RSA Key Generation Utility" << endl
       << "Usage : " << my_progname << " [OPTIONS]" << endl;

  my_print_help(my_options);
  my_print_variables(my_options);
}


my_bool
my_arguments_get_one_option(int optid,
                            const struct my_option *opt MY_ATTRIBUTE((unused)),
                            char *argument)
{
  switch(optid){
    case '?':
      usage();
      free_resources();
      exit(0);
    case 'V':
      print_version();
      free_resources();
      exit(0);
  }
  return 0;
}


static inline
bool is_not_alnum_underscore(char c)
{
  return !(isalnum(c) || c == '_');
}

static
bool check_suffix()
{
  return (strcmp(opt_suffix, default_suffix) &&
          (find_if(suffix_string.begin(), suffix_string.end(),
                   is_not_alnum_underscore) != suffix_string.end()));
}


int main(int argc, char *argv[])
{
  int ret_val= 0;
  Sql_string_t openssl_check("openssl version");
  my_bool save_skip_unknown= my_getopt_skip_unknown;

  MY_INIT(argv[0]);
  DBUG_ENTER("main");
  DBUG_PROCESS(argv[0]);

  /* Parse options : Command Line/Config file */

#ifdef _WIN32
  /* Convert command line parameters from UTF16LE to UTF8MB4. */
  my_win_translate_command_line_args(&my_charset_utf8mb4_bin, &argc, &argv);
#endif
  my_getopt_use_args_separator= TRUE;
  if (load_defaults("my", load_default_groups, &argc, &argv))
  {
    my_end(0);
    free_resources();
    exit(1);
  }

  MY_MODE file_creation_mode= get_file_perm(USER_READ | USER_WRITE);
  MY_MODE saved_umask= umask(~(file_creation_mode));

  defaults_argv= argv;
  my_getopt_use_args_separator= FALSE;
  my_getopt_skip_unknown= TRUE;

  if (handle_options(&argc, &argv, my_options,
                     my_arguments_get_one_option))
  {
    error << "Error parsing options" << endl;
    ret_val= 1;
    goto end;
  }

  my_getopt_skip_unknown= save_skip_unknown;

  /* Process opt_verbose */
  if (opt_verbose != TRUE)
    info.enabled(false);

  /* Process opt_datadir */

  dir_string.path(create_string(opt_datadir));
  if (dir_string.to_str().length() > MAX_PATH_LEN)
  {
    error << "Dir path is too long" << endl;
    ret_val= 1;
    goto end;
  }

  if (!dir_string.normalize_path() || !dir_string.exists())
  {
    error << "Failed to access directory pointed by --datadir. "
          << "Please make sure that directory exists and is "
          << "accessible by mysql_ssl_rsa_setup. Supplied value : "
          << dir_string.to_str() << endl;
    ret_val= 1;
    goto end;
  }

  info << "Destination directory: " << dir_string.to_str() << endl;

  /* Process opt_suffix */

  suffix_string.append(opt_suffix);
  if (suffix_string.length() > MAX_SUFFIX_LEN)
  {
    error << "Maximum number of characters allowed as the value for "
          << "--suffix are " << MAX_SUFFIX_LEN << endl;
    ret_val= 1;
    goto end;
  }

  if (check_suffix())
  {
    error << "Invalid string for --suffix option. Either use default value for "
          << "the option or provide a string with alphanumeric characters "
          << "and/or _ only." << endl;
    ret_val= 1;
    goto end;
  }

  if ((ret_val= execute_command(openssl_check, "Could not find OpenSSL on the system")))
  {
    goto end;
  }
  else
  {
    char save_wd[FN_REFLEN];
    bool files_exist= false;
    Sql_string_t verify("openssl verify -CAfile ");

    if (my_getwd(save_wd, FN_REFLEN-1, MYF(MY_WME)))
    {
      error << "Error saving current working directory" << endl;
      ret_val= 1;
      goto end;
    }

    if (my_setwd(dir_string.to_str().c_str(), MYF(MY_WME)))
    {
      error << "Error changing working directory" << endl;
      ret_val= 1;
      goto end;
    }
#if HAVE_CHOWN
    if (opt_userid && geteuid() == 0)
    {
      user_info= getpwnam(opt_userid);
      if (!user_info)
      {
        error << "Error fetching user information" << endl;
        ret_val= 1;
        goto end;
      }
    }
#endif /* HAVE_CHOWN */

    /*
      SSL Certificate Generation.
      1. Check for ca.pem, server_cert.pem and server_key.pem at
         the directory location provided by --dir.
      2. If none of these files are present, generate following
         files:
         ca.pem, ca_key.pem
         server_cert.pem, server_key.pem
         client_cert.pem, client_key.pem
      3. If everything goes smoothly, set permission on files.
    */

    files_exist= file_exists(cert_files[CA_CERT]) ||
                 file_exists(cert_files[SERVER_CERT]) ||
                 file_exists(cert_files[SERVER_KEY]);

    if (files_exist)
    {
      info << "Certificate files are present in given dir. Skipping generation." << endl;
    }
    else
    {
      Sql_string_t empty_string("");
      X509_key x509_key(suffix_string);
      X509_cert x509_cert;
      X509v3_ext_writer x509v3_ext_writer;

      /* Delete existing files if any */
      remove_file(cert_files[CA_REQ], false);
      remove_file(cert_files[SERVER_REQ], false);
      remove_file(cert_files[CLIENT_REQ], false);
      remove_file(cert_files[CLIENT_CERT], false);
      remove_file(cert_files[CLIENT_KEY], false);
      remove_file(cert_files[OPENSSL_RND], false);

      /* Remove existing v3 extension files */
      remove_file(ext_files[CAV3_EXT], false);
      remove_file(ext_files[CERTV3_EXT], false);

      /* Create v3 extension files */
      if (x509v3_ext_writer(ext_files[CAV3_EXT], ext_files[CERTV3_EXT]))
        goto end;

      /* Generate CA Key and Certificate */
      if ((ret_val= execute_command(x509_key("_Auto_Generated_CA_Certificate",
                                             cert_files[CA_KEY], cert_files[CA_REQ]),
                                    "Error generating ca_key.pem and ca_req.pem")))
        goto end;

      if ((ret_val= execute_command(x509_cert(cert_files[CA_REQ], cert_files[CA_CERT], 1,
                                              true, cert_files[CA_KEY], empty_string,
                                              ext_files[CAV3_EXT]),
                                    "Error generating ca_cert.pem")))
        goto end;

      /* Generate Server Key and Certificate */
      if ((ret_val= execute_command(x509_key("_Auto_Generated_Server_Certificate",
                                             cert_files[SERVER_KEY], cert_files[SERVER_REQ]),
                                    "Error generating server_key.pem and server_req.pem")))
        goto end;

      if ((ret_val= execute_command(x509_cert(cert_files[SERVER_REQ], cert_files[SERVER_CERT], 2,
                                              false, cert_files[CA_KEY], cert_files[CA_CERT],
                                              ext_files[CERTV3_EXT]),
                                    "Error generating server_cert.pem")))
        goto end;

      /* Generate Client Key and Certificate */
      if ((ret_val= execute_command(x509_key("_Auto_Generated_Client_Certificate",
                                             cert_files[CLIENT_KEY], cert_files[CLIENT_REQ]),
                                    "Error generating client_key.pem and client_req.pem")))
        goto end;

      if ((ret_val= execute_command(x509_cert(cert_files[CLIENT_REQ], cert_files[CLIENT_CERT], 3,
                                              false, cert_files[CA_KEY], cert_files[CA_CERT],
                                              ext_files[CERTV3_EXT]),
                                    "Error generating client_cert.pem")))
        goto end;

      /* Verify generated certificates */
      verify.append(cert_files[CA_CERT]);
      verify.append(" ");
      verify.append(cert_files[SERVER_CERT]);
      verify.append(" ");
      verify.append(cert_files[CLIENT_CERT]);
      if ((ret_val= execute_command(verify, "Verification of X509 certificates failed.")))
        goto end;

      /* Set permission */
      if ((ret_val= (set_file_pair_permission(cert_files[CA_KEY],
                                              cert_files[CA_CERT]) |
                     set_file_pair_permission(cert_files[SERVER_KEY],
                                              cert_files[SERVER_CERT]) |
                     set_file_pair_permission(cert_files[CLIENT_KEY],
                                              cert_files[CLIENT_CERT]))))
        goto end;

      /* Remove request files : Flag an error if we can't delete them. */
      if ((ret_val= remove_file(cert_files[CA_REQ])))
        goto end;

      if ((ret_val= remove_file(cert_files[SERVER_REQ])))
        goto end;

      if ((ret_val= remove_file(cert_files[CLIENT_REQ])))
        goto end;

      remove_file(cert_files[OPENSSL_RND], false);

      /* Remove existing v3 extension files */
      remove_file(ext_files[CAV3_EXT], false);
      remove_file(ext_files[CERTV3_EXT], false);

    }

    /*
      RSA Key pair generation.
      1. Check if private_key.pem or public_key.pem are present at
         the directory location provided by --dir.
      2. If not, generate private_key.pem, public_key.pem and
         set permission after successful generation.
    */

    files_exist= file_exists(cert_files[PRIVATE_KEY]) ||
                 file_exists(cert_files[PUBLIC_KEY]);

    if (files_exist)
    {
      info << "RSA key files are present in given dir. Skipping generation." << endl;
    }
    else
    {
      RSA_priv rsa_priv;
      RSA_pub rsa_pub;

      /* Remove existing file if any */
      remove_file(cert_files[OPENSSL_RND], false);

      if ((ret_val= execute_command(rsa_priv(cert_files[PRIVATE_KEY]),
              "Error generating private_key.pem")))
        goto end;

      if ((ret_val= execute_command(rsa_pub(cert_files[PRIVATE_KEY],
                                            cert_files[PUBLIC_KEY]),
              "Error generating public_key.pem")))
        goto end;
      /* Set Permission */
      if ((ret_val= set_file_pair_permission(cert_files[PRIVATE_KEY],
                                             cert_files[PUBLIC_KEY])))
        goto end;

      remove_file(cert_files[OPENSSL_RND], false);
    }

    if (my_setwd(save_wd, MYF(MY_WME)))
    {
      error << "Error changing working directory" << endl;
      ret_val= 1;
      goto end;
    }
  }

  info << "Success!" << endl;

end:

  umask(saved_umask);
  free_resources();

  DBUG_RETURN(ret_val);
}