/* Copyright (C) 2007 MySQL AB, 2008-2009 Sun Microsystems, Inc

   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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

#include "mysql_priv.h"
#include "sql_audit.h"

extern int initialize_audit_plugin(st_plugin_int *plugin);
extern int finalize_audit_plugin(st_plugin_int *plugin);

#ifndef EMBEDDED_LIBRARY

unsigned long mysql_global_audit_mask[MYSQL_AUDIT_CLASS_MASK_SIZE];

static mysql_mutex_t LOCK_audit_mask;

static void event_class_dispatch(THD *thd, const struct mysql_event *event);


static inline
void set_audit_mask(unsigned long *mask, uint event_class)
{
  mask[0]= 1;
  mask[0]<<= event_class;
}

static inline
void add_audit_mask(unsigned long *mask, const unsigned long *rhs)
{
  mask[0]|= rhs[0];
}

static inline
bool check_audit_mask(const unsigned long *lhs,
                      const unsigned long *rhs)
{
  return !(lhs[0] & rhs[0]);
}


typedef void (*audit_handler_t)(THD *thd, uint event_subtype, va_list ap);

/**
  MYSQL_AUDIT_GENERAL_CLASS handler
  
  @param[in] thd
  @param[in] event_subtype
  @param[in] error_code
  @param[in] ap
  
*/

static void general_class_handler(THD *thd, uint event_subtype, va_list ap)
{
  mysql_event_general event;
  event.event_class= MYSQL_AUDIT_GENERAL_CLASS;
  event.general_error_code= va_arg(ap, int);
  event.general_thread_id= thd ? thd->thread_id : 0;
  event.general_time= va_arg(ap, time_t);
  event.general_user= va_arg(ap, const char *);
  event.general_user_length= va_arg(ap, unsigned int);
  event.general_command= va_arg(ap, const char *);
  event.general_command_length= va_arg(ap, unsigned int);
  event.general_query= va_arg(ap, const char *);
  event.general_query_length= va_arg(ap, unsigned int);
  event.general_charset= va_arg(ap, struct charset_info_st *);
  event.general_rows= (unsigned long long) va_arg(ap, ha_rows);
  event_class_dispatch(thd, (const mysql_event*) &event);
}


static audit_handler_t audit_handlers[] =
{
  general_class_handler
};

static const uint audit_handlers_count=
  (sizeof(audit_handlers) / sizeof(audit_handler_t));


/**
  Acquire and lock any additional audit plugins as required
  
  @param[in] thd
  @param[in] plugin
  @param[in] arg

  @retval FALSE Always  
*/

static my_bool acquire_plugins(THD *thd, plugin_ref plugin, void *arg)
{
  uint event_class= *(uint*) arg;
  unsigned long event_class_mask[MYSQL_AUDIT_CLASS_MASK_SIZE];
  st_mysql_audit *data= plugin_data(plugin, struct st_mysql_audit *);

  set_audit_mask(event_class_mask, event_class);

  /* Check if this plugin is interested in the event */
  if (check_audit_mask(data->class_mask, event_class_mask))
    return 0;

  /*
    Check if this plugin may already be registered. This will fail to
    acquire a newly installed plugin on a specific corner case where
    one or more event classes already in use by the calling thread
    are an event class of which the audit plugin has interest.
  */
  if (!check_audit_mask(data->class_mask, thd->audit_class_mask))
    return 0;
  
  /* Check if we need to initialize the array of acquired plugins */
  if (unlikely(!thd->audit_class_plugins.buffer))
  {
    /* specify some reasonable initialization defaults */
    my_init_dynamic_array(&thd->audit_class_plugins,
                          sizeof(plugin_ref), 16, 16);
  }
  
  /* lock the plugin and add it to the list */
  plugin= my_plugin_lock(NULL, &plugin);
  insert_dynamic(&thd->audit_class_plugins, (uchar*) &plugin);

  return 0;
}


/**
  Notify the audit system of an event
  
  @param[in] thd
  @param[in] event_class
  @param[in] event_subtype
  @param[in] error_code

*/

void mysql_audit_notify(THD *thd, uint event_class, uint event_subtype, ...)
{
  va_list ap;
  audit_handler_t *handlers= audit_handlers + event_class;
  unsigned long event_class_mask[MYSQL_AUDIT_CLASS_MASK_SIZE];
  
  DBUG_ASSERT(event_class < audit_handlers_count);

  set_audit_mask(event_class_mask, event_class);
  /*
    Check to see if we have acquired the audit plugins for the
    required audit event classes.
  */
  if (thd && check_audit_mask(thd->audit_class_mask, event_class_mask))
  {
    plugin_foreach(thd, acquire_plugins, MYSQL_AUDIT_PLUGIN, &event_class);
    add_audit_mask(thd->audit_class_mask, event_class_mask);
  }

  va_start(ap, event_subtype);  
  (*handlers)(thd, event_subtype, ap);
  va_end(ap);
}


/**
  Release any resources associated with the current thd.
  
  @param[in] thd

*/

void mysql_audit_release(THD *thd)
{
  plugin_ref *plugins, *plugins_last;
  
  if (!thd || !(thd->audit_class_plugins.elements))
    return;
  
  plugins= (plugin_ref*) thd->audit_class_plugins.buffer;
  plugins_last= plugins + thd->audit_class_plugins.elements;
  for (; plugins < plugins_last; plugins++)
  {
    st_mysql_audit *data= plugin_data(*plugins, struct st_mysql_audit *);
	
    /* Check to see if the plugin has a release method */
    if (!(data->release_thd))
      continue;

    /* Tell the plugin to release its resources */
    data->release_thd(thd);
  }

  /* Now we actually unlock the plugins */  
  plugin_unlock_list(NULL, (plugin_ref*) thd->audit_class_plugins.buffer,
                     thd->audit_class_plugins.elements);
  
  /* Reset the state of thread values */
  reset_dynamic(&thd->audit_class_plugins);
  bzero(thd->audit_class_mask, sizeof(thd->audit_class_mask));
}


/**
  Initialize thd variables used by Audit
  
  @param[in] thd

*/

void mysql_audit_init_thd(THD *thd)
{
  bzero(&thd->audit_class_plugins, sizeof(thd->audit_class_plugins));
  bzero(thd->audit_class_mask, sizeof(thd->audit_class_mask));
}


/**
  Free thd variables used by Audit
  
  @param[in] thd
  @param[in] plugin
  @param[in] arg

  @retval FALSE Always  
*/

void mysql_audit_free_thd(THD *thd)
{
  mysql_audit_release(thd);
  DBUG_ASSERT(thd->audit_class_plugins.elements == 0);
  delete_dynamic(&thd->audit_class_plugins);
}

#ifdef HAVE_PSI_INTERFACE
static PSI_mutex_key key_LOCK_audit_mask;

static PSI_mutex_info all_audit_mutexes[]=
{
  { &key_LOCK_audit_mask, "LOCK_audit_mask", PSI_FLAG_GLOBAL}
};

static void init_audit_psi_keys(void)
{
  const char* category= "sql";
  int count;

  if (PSI_server == NULL)
    return;

  count= array_elements(all_audit_mutexes);
  PSI_server->register_mutex(category, all_audit_mutexes, count);
}
#endif /* HAVE_PSI_INTERFACE */

/**
  Initialize Audit global variables
*/

void mysql_audit_initialize()
{
#ifdef HAVE_PSI_INTERFACE
  init_audit_psi_keys();
#endif

  mysql_mutex_init(key_LOCK_audit_mask, &LOCK_audit_mask, MY_MUTEX_INIT_FAST);
  bzero(mysql_global_audit_mask, sizeof(mysql_global_audit_mask));
}


/**
  Finalize Audit global variables  
*/

void mysql_audit_finalize()
{
  mysql_mutex_destroy(&LOCK_audit_mask);
}


/**
  Initialize an Audit plug-in
  
  @param[in] plugin

  @retval FALSE  OK
  @retval TRUE   There was an error.
*/

int initialize_audit_plugin(st_plugin_int *plugin)
{
  st_mysql_audit *data= (st_mysql_audit*) plugin->plugin->info;
  
  if (!data->class_mask || !data->event_notify ||
      !data->class_mask[0])
  {
    sql_print_error("Plugin '%s' has invalid data.",
                    plugin->name.str);
    return 1;
  }
  
  if (plugin->plugin->init && plugin->plugin->init(NULL))
  {
    sql_print_error("Plugin '%s' init function returned error.",
                    plugin->name.str);
    return 1;
  }

  /* Make the interface info more easily accessible */
  plugin->data= plugin->plugin->info;
  
  /* Add the bits the plugin is interested in to the global mask */
  mysql_mutex_lock(&LOCK_audit_mask);
  add_audit_mask(mysql_global_audit_mask, data->class_mask);
  mysql_mutex_unlock(&LOCK_audit_mask);

  return 0;
}


/**
  Performs a bitwise OR of the installed plugins event class masks

  @param[in] thd
  @param[in] plugin
  @param[in] arg

  @retval FALSE  always
*/
static my_bool calc_class_mask(THD *thd, plugin_ref plugin, void *arg)
{
  st_mysql_audit *data= plugin_data(plugin, struct st_mysql_audit *);
  if ((data= plugin_data(plugin, struct st_mysql_audit *)))
    add_audit_mask((unsigned long *) arg, data->class_mask);
  return 0;
}


/**
  Finalize an Audit plug-in
  
  @param[in] plugin

  @retval FALSE  OK
  @retval TRUE   There was an error.
*/
int finalize_audit_plugin(st_plugin_int *plugin)
{
  unsigned long event_class_mask[MYSQL_AUDIT_CLASS_MASK_SIZE];
  
  if (plugin->plugin->deinit && plugin->plugin->deinit(NULL))
  {
    DBUG_PRINT("warning", ("Plugin '%s' deinit function returned error.",
                            plugin->name.str));
    DBUG_EXECUTE("finalize_audit_plugin", return 1; );
  }
  
  plugin->data= NULL;
  bzero(&event_class_mask, sizeof(event_class_mask));

  /* Iterate through all the installed plugins to create new mask */

  /*
    LOCK_audit_mask/LOCK_plugin order is not fixed, but serialized with table
    lock on mysql.plugin.
  */
  mysql_mutex_lock(&LOCK_audit_mask);
  plugin_foreach(current_thd, calc_class_mask, MYSQL_AUDIT_PLUGIN,
                 &event_class_mask);

  /* Set the global audit mask */
  bmove(mysql_global_audit_mask, event_class_mask, sizeof(event_class_mask));
  mysql_mutex_unlock(&LOCK_audit_mask);

  return 0;
}


/**
  Dispatches an event by invoking the plugin's event_notify method.  

  @param[in] thd
  @param[in] plugin
  @param[in] arg

  @retval FALSE  always
*/

static my_bool plugins_dispatch(THD *thd, plugin_ref plugin, void *arg)
{
  const struct mysql_event *event= (const struct mysql_event *) arg;
  unsigned long event_class_mask[MYSQL_AUDIT_CLASS_MASK_SIZE];
  st_mysql_audit *data= plugin_data(plugin, struct st_mysql_audit *);

  set_audit_mask(event_class_mask, event->event_class);

  /* Check to see if the plugin is interested in this event */
  if (check_audit_mask(data->class_mask, event_class_mask))
    return 0;

  /* Actually notify the plugin */
  data->event_notify(thd, event);

  return 0;
}


/**
  Distributes an audit event to plug-ins
  
  @param[in] thd
  @param[in] event
*/

static void event_class_dispatch(THD *thd, const struct mysql_event *event)
{
  /*
    Check if we are doing a slow global dispatch. This event occurs when
    thd == NULL as it is not associated with any particular thread.
  */
  if (unlikely(!thd))
  {
    plugin_foreach(thd, plugins_dispatch, MYSQL_AUDIT_PLUGIN, (void*) event);
  }
  else
  {
    plugin_ref *plugins, *plugins_last;

    /* Use the cached set of audit plugins */
    plugins= (plugin_ref*) thd->audit_class_plugins.buffer;
    plugins_last= plugins + thd->audit_class_plugins.elements;

    for (; plugins < plugins_last; plugins++)
      plugins_dispatch(thd, *plugins, (void*) event);
  }
}


#else /* EMBEDDED_LIBRARY */


void mysql_audit_initialize()
{
}


void mysql_audit_finalize()
{
}


int initialize_audit_plugin(st_plugin_int *plugin)
{
  return 1;
}


int finalize_audit_plugin(st_plugin_int *plugin)
{
  return 0;
}


void mysql_audit_release(THD *thd)
{
}


#endif /* EMBEDDED_LIBRARY */