/* Copyright (c) 2016, 2022, 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 */

#include "my_config.h"

/*
  In case of Kerberos authentication we need to fill user name as Kerberos user
  name if it is empty. We need to fill user name inside mysql->user, clients
  uses my_strdup directly to create new string. To use MySQL alloc functions we
  need to include "/mysql/service_mysql_alloc.h". Inside service_mysql_alloc.h
  there is #define which forces all dynamic plugins to use MySQL malloc function
  via services. Client side plugin cannot use any services as of now.   Code
  check in service_mysql_alloc.h #ifdef MYSQL_DYNAMIC_PLUGIN #define my_strdup
  mysql_malloc_service->my_strdup #else extern char *my_strdup(PSI_memory_key
  key, const char *from, myf_t flags); #endif Client authentication plugin
  defines MYSQL_DYNAMIC_PLUGIN. And this forces to use always my_strdup via
  services. To use native direct my_strdup, we need to undefine
  MYSQL_DYNAMIC_PLUGIN. And again define MYSQL_DYNAMIC_PLUGIN once correct
  my_strdup are declared. service_mysql_alloc.h should provide proper fix like
  Instead of #ifdef MYSQL_DYNAMIC_PLUGIN
  #ifdef  MYSQL_DYNAMIC_PLUGIN  &&   ! MYSQL_CLIENT_PLUGIN
*/
#if defined(KERBEROS_LIB_CONFIGURED)
#undef MYSQL_DYNAMIC_PLUGIN
#include <mysql/service_mysql_alloc.h>
#define MYSQL_DYNAMIC_PLUGIN
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "auth_ldap_sasl_client.h"
#ifndef _WIN32
#include <lber.h>
#include <sasl/sasl.h>
#endif

#if defined(SASL_CUSTOM_LIBRARY)
#include <dlfcn.h>
#include <link.h>
#include <string>
#endif

#include <mysql.h>
#include <mysql/client_plugin.h>
#include <sql_common.h>

void Sasl_client::interact(sasl_interact_t *ilist) {
  while (ilist->id != SASL_CB_LIST_END) {
    switch (ilist->id) {
      /*
        the name of the user authenticating
      */
      case SASL_CB_USER:
        ilist->result = m_user_name;
        ilist->len = strlen((const char *)ilist->result);
        break;
      /* the name of the user acting for. (for example postman delivering mail
         for Martin might have an AUTHNAME of postman and a USER of Martin)
      */
      case SASL_CB_AUTHNAME:
        ilist->result = m_user_name;
        ilist->len = strlen((const char *)ilist->result);
        break;
      case SASL_CB_PASS:
        ilist->result = m_user_pwd;
        ilist->len = strlen((const char *)ilist->result);
        break;
      default:
        ilist->result = nullptr;
        ilist->len = 0;
    }
    ilist++;
  }
}

void Sasl_client::set_plugin_info(MYSQL_PLUGIN_VIO *vio, MYSQL *mysql) {
  m_vio = vio;
  m_mysql = mysql;
}

/**
  SASL method is send from the Mysql server, and this is set by the client.
  SASL client and sasl server may support many sasl authentication methods
  and can negotiate in anyone.
  We want to enforce the SASL authentication set by the client.
*/
int Sasl_client::read_method_name_from_server() {
  int rc_server_read = -1;
  unsigned char *packet = nullptr;
  std::stringstream log_stream;
  /*
    We are assuming that there will be only one method name passed by
    server, and length of the method name will not exceed 256 chars.
  */
  const int max_method_name_len = 256;

  if (m_vio == nullptr) {
    return rc_server_read;
  }
  /** Get authentication method from the server. */
  rc_server_read = m_vio->read_packet(m_vio, (unsigned char **)&packet);
  if (rc_server_read >= 0 && rc_server_read <= max_method_name_len) {
    strncpy(m_mechanism, (const char *)packet, rc_server_read);
    m_mechanism[rc_server_read] = '\0';
    if (strcmp(m_mechanism, SASL_GSSAPI) == 0) {
      /*
        If user tries to use kerberos without kerberos libs are installed,
        We should gracefully error out the authentication. Kerberos objects
        will not be built in this case.
      */
#if defined(KERBEROS_LIB_CONFIGURED)
      m_sasl_mechanism = new Sasl_mechanism_kerberos();
#else
      m_sasl_mechanism = NULL;
      log_info("Kerberos lib not installed, not creting kerberos objects.");
#endif
    } else if ((strcmp(m_mechanism, SASL_SCRAM_SHA1) == 0) ||
               (strcmp(m_mechanism, SASL_SCRAM_SHA256) == 0)) {
      m_sasl_mechanism = new Sasl_mechanism();
    } else {
      rc_server_read = SASL_ERROR_INVALID_METHOD;
      log_stream << "SASL METHOD:" << m_mechanism[0];
      log_stream << " is not supported, please make sure correct "
                    "method is set in "
                 << "LDAP SASL server side plug-in";
      m_mechanism[0] = '\0';
      log_error(log_stream.str());
    }
    log_stream << "Sasl_client::read_method_name_from_server : " << m_mechanism;
    log_dbg(log_stream.str());
  } else if (rc_server_read > max_method_name_len) {
    rc_server_read = -1;
    m_mechanism[0] = '\0';
    log_stream << "Sasl_client::read_method_name_from_server : Method name "
               << "is greater then allowed limit of 256 characters.";
    log_error(log_stream.str());
  } else {
    m_mechanism[0] = '\0';
    log_stream << "Sasl_client::read_method_name_from_server : Plugin has "
               << "failed to read the method name, make sure that default "
               << "authentication plugin and method name specified at "
               << "server are correct.";
    log_error(log_stream.str());
  }
  return rc_server_read;
}

Sasl_client::Sasl_client() {
  m_connection = nullptr;
  m_ldap_server_host = "";
  m_mysql = nullptr;
  m_sasl_mechanism = nullptr;
}

int Sasl_client::initilize() {
  std::stringstream log_stream;
  int rc_sasl = SASL_FAIL;
  strncpy(m_service_name, SASL_SERVICE_NAME, sizeof(m_service_name) - 1);
  m_service_name[sizeof(m_service_name) - 1] = '\0';

  if (m_sasl_mechanism) {
    m_sasl_mechanism->set_user_info(m_user_name, m_user_pwd);
    /**
       This method try to get kerberos TGT if user name and password are not
       empty. If method fails, We should not start SASL authentication process.
       Otherwise SASL authentication may consume existing TGT and authentication
       process will start.
    */
    if (!m_sasl_mechanism->pre_authentication()) {
      log_error(
          "Plug-in has failed to obtained Kerberos TGT, authentication process "
          "will be aborted. Please provide valid configuration, user name and "
          "password.");
      return rc_sasl;
    }
    m_sasl_mechanism->get_ldap_host(m_ldap_server_host);
  }
#if defined(KERBEROS_LIB_CONFIGURED)
  if (strcmp(m_mechanism, SASL_GSSAPI) == 0) {
    m_user_name[0] = '\0';
  }
#endif
  /** Creating sasl connection. */
  if (m_ldap_server_host.empty()) {
    rc_sasl = sasl_client_new(m_service_name, nullptr, nullptr, nullptr,
                              callbacks, 0, &m_connection);
  } else {
    log_info(m_ldap_server_host.c_str());
    rc_sasl = sasl_client_new(m_service_name, m_ldap_server_host.c_str(),
                              nullptr, nullptr, callbacks, 0, &m_connection);
  }
  if (rc_sasl != SASL_OK) {
    log_stream << "Sasl_client::initilize failed rc: " << rc_sasl;
    log_error(log_stream.str());
    return rc_sasl;
  }

  /** Set security properties. */
  sasl_setprop(m_connection, SASL_SEC_PROPS, &security_properties);
  return SASL_OK;
}

Sasl_client::~Sasl_client() {
  if (m_connection) {
    sasl_dispose(&m_connection);
    m_connection = nullptr;
  }
  delete m_sasl_mechanism;
  m_sasl_mechanism = nullptr;
}

int Sasl_client::send_sasl_request_to_server(const unsigned char *request,
                                             int request_len,
                                             unsigned char **response,
                                             int *response_len) {
  int rc_server = CR_ERROR;
  std::stringstream log_stream;

  if (m_vio == nullptr) {
    goto EXIT;
  }
  /** Send the request to the MySQL server. */
  log_stream << "Sasl_client::SendSaslRequestToServer length:" << request_len
             << " request: " << request;
  log_dbg(log_stream.str());
  rc_server = m_vio->write_packet(m_vio, request, request_len);
  if (rc_server) {
    log_error(
        "Sasl_client::SendSaslRequestToServer: sasl request write failed");
    goto EXIT;
  }

  /** Get the sasl response from the MySQL server. */
  *response_len = m_vio->read_packet(m_vio, response);
  if ((*response_len) < 0 || (*response == nullptr)) {
    log_error(
        "Sasl_client::SendSaslRequestToServer: sasl response read failed");
    goto EXIT;
  }
  log_stream.str("");
  log_stream << "Sasl_client::SendSaslRequestToServer response:" << *response
             << " length: " << *response_len;
  log_dbg(log_stream.str());
EXIT:
  return rc_server;
}

int Sasl_client::sasl_start(char **client_output, int *client_output_length) {
  int rc_sasl = SASL_FAIL;
  const char *mechanism = nullptr;
  char *sasl_client_output = nullptr;
  sasl_interact_t *interactions = nullptr;
  std::stringstream log_stream;

  if (m_connection == nullptr) {
    log_error("Sasl_client::SaslStart: sasl connection is null");
    return rc_sasl;
  }
  void *sasl_client_output_p = &sasl_client_output;
  do {
    rc_sasl =
        sasl_client_start(m_connection, m_mechanism, &interactions,
                          static_cast<const char **>(sasl_client_output_p),
                          (unsigned int *)client_output_length, &mechanism);
    if (rc_sasl == SASL_INTERACT) interact(interactions);
  } while (rc_sasl == SASL_INTERACT);
  if (rc_sasl == SASL_NOMECH) {
    log_stream << "SASL method '" << m_mechanism << "' sent by server, "
               << "is not supported by the SASL client. Make sure that "
               << "cyrus SASL library is installed.";
    log_error(log_stream.str());
    goto EXIT;
  }
  if (client_output != nullptr) {
    *client_output = sasl_client_output;
    log_stream << "Sasl_client::SaslStart sasl output: " << sasl_client_output;
    log_dbg(log_stream.str());
  }
EXIT:
  return rc_sasl;
}

int Sasl_client::sasl_step(char *server_in, int server_in_length,
                           char **client_out, int *client_out_length) {
  int rc_sasl = SASL_FAIL;
  sasl_interact_t *interactions = nullptr;

  if (m_connection == nullptr) {
    return rc_sasl;
  }
  void *client_out_p = client_out;
  do {
    if (server_in && server_in[0] == 0x0) {
      server_in_length = 0;
      server_in = nullptr;
    }
    rc_sasl = sasl_client_step(
        m_connection, (server_in == nullptr) ? nullptr : server_in,
        (server_in == nullptr) ? 0 : server_in_length, &interactions,
        static_cast<const char **>(client_out_p),
        (unsigned int *)client_out_length);
    if (rc_sasl == SASL_INTERACT) Sasl_client::interact(interactions);
  } while (rc_sasl == SASL_INTERACT);
  return rc_sasl;
}

std::string Sasl_client::get_method() { return m_mechanism; }

#if defined(KERBEROS_LIB_CONFIGURED)
void Sasl_client::read_kerberos_user_name() {
  std::string user_name = "";
  bool ret_kerberos = false;
  auth_ldap_client_kerberos_context::Kerberos kerberos("", "");
  ret_kerberos = kerberos.get_user_name(&user_name);
  if (m_mysql && ret_kerberos && (!user_name.empty())) {
    /*
      MySQL clients/lib uses my_free, my_strdup my_* string function for string
      management. We also need to use same methods as these are used/free inside
      libmysqlclient
    */
    if (m_mysql->user) {
      my_free(m_mysql->user);
      m_mysql->user = nullptr;
    }
    m_mysql->user =
        my_strdup(PSI_NOT_INSTRUMENTED, user_name.c_str(), MYF(MY_WME));
  }
}
#endif

void Sasl_client::set_user_info(std::string name, std::string pwd) {
  strncpy(m_user_name, name.c_str(), sizeof(m_user_name) - 1);
  m_user_name[sizeof(m_user_name) - 1] = '\0';
  strncpy(m_user_pwd, pwd.c_str(), sizeof(m_user_pwd) - 1);
  m_user_pwd[sizeof(m_user_pwd) - 1] = '\0';
}

#ifdef __clang__
// Clang UBSAN false positive?
// Call to function through pointer to incorrect function type
static int sasl_authenticate(MYSQL_PLUGIN_VIO *vio,
                             MYSQL *mysql) SUPPRESS_UBSAN;
static int initialize_plugin(char *, size_t, int, va_list) SUPPRESS_UBSAN;
static int deinitialize_plugin() SUPPRESS_UBSAN;
#endif  // __clang__

static int sasl_authenticate(MYSQL_PLUGIN_VIO *vio, MYSQL *mysql) {
  int rc_sasl = SASL_FAIL;
  int rc_auth = CR_ERROR;
  unsigned char *server_packet = nullptr;
  int server_packet_len = 0;
  char *sasl_client_output = nullptr;
  int sasl_client_output_len = 0;
  std::stringstream log_stream;
  Sasl_client sasl_client;

  sasl_client.set_plugin_info(vio, mysql);

#if defined(KERBEROS_LIB_CONFIGURED)
  /*
    For some cases MySQL user name will be empty as user name is supposed to
    come from kerberos TGT. Get kerberos user name from TGT and assign this as
    MySQL user name.
  */
  if (!mysql->user || mysql->user[0] == '\0') {
    sasl_client.read_kerberos_user_name();
  }
#endif

  server_packet_len = sasl_client.read_method_name_from_server();
  if (server_packet_len < 0) {
    // Callee has already logged the messages.
    goto EXIT;
  }

#if !defined(KERBEROS_LIB_CONFIGURED)
  if (strcmp(sasl_client.get_method().c_str(), SASL_GSSAPI) == 0) {
    log_error(
        "Kerberos library not installed, kerberos authentication will not "
        "work..");
    rc_auth = CR_ERROR;
    goto EXIT;
  }
#endif

  sasl_client.set_user_info(mysql->user, mysql->passwd);
  rc_sasl = sasl_client.initilize();
  if (rc_sasl != SASL_OK) {
    log_error("sasl_authenticate: initialize failed");
    goto EXIT;
  }

  rc_sasl =
      sasl_client.sasl_start(&sasl_client_output, &sasl_client_output_len);
  if ((rc_sasl != SASL_OK) && (rc_sasl != SASL_CONTINUE)) {
    log_error("sasl_authenticate: SaslStart failed");
    goto EXIT;
  }

  /**
    Running SASL authentication step till authentication process is concluded
    MySQL server plug-in working as proxy for SASL / LDAP server.
  */
  do {
    server_packet = nullptr;
    server_packet_len = 0;
    rc_auth = sasl_client.send_sasl_request_to_server(
        (const unsigned char *)sasl_client_output, sasl_client_output_len,
        &server_packet, &server_packet_len);
    if (rc_auth < 0) {
      goto EXIT;
    }
    sasl_client_output = nullptr;
    rc_sasl =
        sasl_client.sasl_step((char *)server_packet, server_packet_len,
                              &sasl_client_output, &sasl_client_output_len);
    if (sasl_client_output_len == 0) {
      log_dbg("sasl_step: empty client output");
    }

  } while (rc_sasl == SASL_CONTINUE);

  if (rc_sasl == SASL_OK) {
    rc_auth = CR_OK;
    log_dbg("sasl_authenticate authentication successful");
    /**
      Kerberos authentication is concluded by the LDAP/SASL server,
      From client side, authentication is succeded and we need to send data to
      server side to conclude the authentication. Other SASL authentication are
      conculded in the client side.
    */
    if (strcmp(sasl_client.get_method().c_str(), SASL_GSSAPI) == 0) {
      server_packet = nullptr;
      rc_auth = sasl_client.send_sasl_request_to_server(
          (const unsigned char *)sasl_client_output, sasl_client_output_len,
          &server_packet, &server_packet_len);
      rc_auth = CR_OK;
    }
  } else {
    log_error("sasl_authenticate client failed");
  }

EXIT:
  if (rc_sasl != SASL_OK) {
    log_stream.str("");
    log_stream << "sasl_authenticate client failed rc: " << rc_sasl;
    log_error(log_stream.str());
  }
  return rc_auth;
}

#if defined(SASL_CUSTOM_LIBRARY) || defined(_WIN32)
static int set_sasl_plugin_path() {
#if defined(_WIN32)
  std::stringstream log_stream;

  char sasl_plugin_dir[MAX_PATH] = "";
  int ret_executable_path = 0;
  /**
    Getting the current executable path, SASL SCRAM dll will be copied in
    executable path. Using/Setting the path from cmake file may not work as
    during installation SASL SCRAM DLL may be copied to any path based on
    installable path.
  */
  ret_executable_path =
      GetModuleFileName(NULL, sasl_plugin_dir, sizeof(sasl_plugin_dir));
  if ((ret_executable_path == 0) ||
      (ret_executable_path == sizeof(sasl_plugin_dir))) {
    log_error(
        "sasl client initialize: failed to find executable path or buffer size "
        "for path is too small.");
    log_stream << "Sasl_client::initialize failed";
    log_error(log_stream.str());
    return 1;
  }
  char *pos = strrchr(sasl_plugin_dir, '\\');
  if (pos != NULL) {
    *pos = '\0';
  }
  /**
    Sasl SCRAM dll default search path is C:\CMU2,
    This is the reason we have copied in the executable folder and setting the
    same from the code.
  */
  sasl_set_path(SASL_PATH_TYPE_PLUGIN, sasl_plugin_dir);
  log_stream << "Sasl_client::initilize sasl scrum plug-in path : "
             << sasl_plugin_dir;
  log_dbg(log_stream.str());
  return 0;
#endif

#if defined(SASL_CUSTOM_LIBRARY)
  /**
    Tell SASL where to look for plugins:

    Custom versions of libsasl2.so and libscram.so will be copied to
      <build directory>/library_output_directory/
    and
      <build directory>/library_output_directory/sasl2
    respectively during build, and to
      <install directory>/lib/private
      <install directory>/lib/private/sasl2
    after 'make install'.

    sasl_set_path() must be called before sasl_client_init(),
    and is not thread-safe.
   */
  char sasl_plugin_dir[PATH_MAX]{};
  // dlopen(NULL, ) should not fail ...
  void *main_handle = dlopen(nullptr, RTLD_LAZY);
  if (main_handle == nullptr) {
    log_error(dlerror());
    return 1;
  }
  struct link_map *lm = nullptr;
  if (0 != dlinfo(main_handle, RTLD_DI_LINKMAP, &lm)) {
    log_error(dlerror());
    dlclose(main_handle);
    return 1;
  }
  size_t find_result = std::string::npos;
  for (; lm; lm = lm->l_next) {
    std::string so_path(lm->l_name);
    find_result = so_path.find("/libsasl");
    if (find_result != std::string::npos) {
      std::string so_dir(lm->l_name, find_result);
      so_dir.append("/sasl2");
      so_dir.copy(sasl_plugin_dir, so_dir.size());
      sasl_set_path(SASL_PATH_TYPE_PLUGIN, sasl_plugin_dir);
      break;
    }
  }
  dlclose(main_handle);
  if (find_result == std::string::npos) {
    log_error("Cannot find SASL plugins");
    return 1;
  }
  return 0;
#endif  // defined(SASL_CUSTOM_LIBRARY)
}
#endif  // defined(SASL_CUSTOM_LIBRARY) || defined(_WIN32)

static int initialize_plugin(char *, size_t, int, va_list) {
  g_logger_client = new Ldap_logger();

  const char *opt = getenv("AUTHENTICATION_LDAP_CLIENT_LOG");
  int opt_val = opt ? atoi(opt) : 0;
  if (opt && opt_val > 0 && opt_val < 6) {
    g_logger_client->set_log_level(static_cast<ldap_log_level>(opt_val));
  }

  int rc_sasl;
#if defined(SASL_CUSTOM_LIBRARY) || defined(_WIN32)
  rc_sasl = set_sasl_plugin_path();
  if (rc_sasl != SASL_OK) {
    // Error already logged.
    return 1;
  }
#endif  // SASL_CUSTOM_LIBRARY

  /** Initialize client-side of SASL. */
  rc_sasl = sasl_client_init(nullptr);
  if (rc_sasl != SASL_OK) {
    std::stringstream log_stream;
    log_stream << "sasl_client_init failed rc: " << rc_sasl;
    log_error(log_stream.str());
    return 1;
  }

  return 0;
}

static int deinitialize_plugin() {
  delete g_logger_client;
  g_logger_client = nullptr;

  return 0;
}

mysql_declare_client_plugin(AUTHENTICATION) "authentication_ldap_sasl_client",
    MYSQL_CLIENT_PLUGIN_AUTHOR_ORACLE, "LDAP SASL Client Authentication Plugin",
    {0, 1, 0}, "PROPRIETARY", nullptr, initialize_plugin, deinitialize_plugin,
    nullptr, nullptr, sasl_authenticate, nullptr mysql_end_client_plugin;
