client_plugin.c

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/* Copyright (c) 2010, 2013, 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 */

#include <my_global.h>
#include "mysql.h"
#include <my_sys.h>
#include <m_string.h>
#include <my_pthread.h>

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

struct st_client_plugin_int {
  struct st_client_plugin_int *next;
  void   *dlhandle;
  struct st_mysql_client_plugin *plugin;
};

static my_bool initialized= 0;
static MEM_ROOT mem_root;

static const char *plugin_declarations_sym= "_mysql_client_plugin_declaration_";
static uint plugin_version[MYSQL_CLIENT_MAX_PLUGINS]=
{
  0, /* these two are taken by Connector/C */
  0, /* these two are taken by Connector/C */
  MYSQL_CLIENT_AUTHENTICATION_PLUGIN_INTERFACE_VERSION
};

/*
  Loaded plugins are stored in a linked list.
  The list is append-only, the elements are added to the head (like in a stack).
  The elements are added under a mutex, but the list can be read and traversed
  without any mutex because once an element is added to the list, it stays
  there. The main purpose of a mutex is to prevent two threads from
  loading the same plugin twice in parallel.
*/
struct st_client_plugin_int *plugin_list[MYSQL_CLIENT_MAX_PLUGINS];
static mysql_mutex_t LOCK_load_client_plugin;

static int is_not_initialized(MYSQL *mysql, const char *name)
{
  if (initialized)
    return 0;

  set_mysql_extended_error(mysql, CR_AUTH_PLUGIN_CANNOT_LOAD,
                           unknown_sqlstate, ER(CR_AUTH_PLUGIN_CANNOT_LOAD),
                           name, "not initialized");
  return 1;
}

static struct st_mysql_client_plugin *
find_plugin(const char *name, int type)
{
  struct st_client_plugin_int *p;

  DBUG_ASSERT(initialized);
  DBUG_ASSERT(type >= 0 && type < MYSQL_CLIENT_MAX_PLUGINS);
  if (type < 0 || type >= MYSQL_CLIENT_MAX_PLUGINS)
    return 0;

  for (p= plugin_list[type]; p; p= p->next)
  {
    if (strcmp(p->plugin->name, name) == 0)
      return p->plugin;
  }
  return NULL;
}

static struct st_mysql_client_plugin *
do_add_plugin(MYSQL *mysql, struct st_mysql_client_plugin *plugin,
              void *dlhandle,
              int argc, va_list args)
{
  const char *errmsg;
  struct st_client_plugin_int plugin_int, *p;
  char errbuf[1024];

  DBUG_ASSERT(initialized);

  plugin_int.plugin= plugin;
  plugin_int.dlhandle= dlhandle;

  if (plugin->type >= MYSQL_CLIENT_MAX_PLUGINS)
  {
    errmsg= "Unknown client plugin type";
    goto err1;
  }

  if (plugin->interface_version < plugin_version[plugin->type] ||
      (plugin->interface_version >> 8) >
       (plugin_version[plugin->type] >> 8))
  {
    errmsg= "Incompatible client plugin interface";
    goto err1;
  }

  /* Call the plugin initialization function, if any */
  if (plugin->init && plugin->init(errbuf, sizeof(errbuf), argc, args))
  {
    errmsg= errbuf;
    goto err1;
  }

  p= (struct st_client_plugin_int *)
    memdup_root(&mem_root, &plugin_int, sizeof(plugin_int));

  if (!p)
  {
    errmsg= "Out of memory";
    goto err2;
  }

  mysql_mutex_assert_owner(&LOCK_load_client_plugin);

  p->next= plugin_list[plugin->type];
  plugin_list[plugin->type]= p;
  net_clear_error(&mysql->net);

  return plugin;

err2:
  if (plugin->deinit)
    plugin->deinit();
err1:
  set_mysql_extended_error(mysql, CR_AUTH_PLUGIN_CANNOT_LOAD, unknown_sqlstate,
                           ER(CR_AUTH_PLUGIN_CANNOT_LOAD), plugin->name,
                           errmsg);
  if (dlhandle)
    dlclose(dlhandle);
  return NULL;
}


static struct st_mysql_client_plugin *
add_plugin_noargs(MYSQL *mysql, struct st_mysql_client_plugin *plugin,
                  void *dlhandle,
                  int argc, ...)
{
  struct st_mysql_client_plugin *retval= NULL;
  va_list ap;
  va_start(ap, argc);
  retval= do_add_plugin(mysql, plugin, dlhandle, argc, ap);
  va_end(ap);
  return retval;
}


static struct st_mysql_client_plugin *
add_plugin_withargs(MYSQL *mysql, struct st_mysql_client_plugin *plugin,
                    void *dlhandle,
                    int argc, va_list args)
{
  return do_add_plugin(mysql, plugin, dlhandle, argc, args);
}



static void load_env_plugins(MYSQL *mysql)
{
  char *plugs, *free_env, *s= getenv("LIBMYSQL_PLUGINS");
  char *enable_cleartext_plugin= getenv("LIBMYSQL_ENABLE_CLEARTEXT_PLUGIN");

  if (enable_cleartext_plugin && strchr("1Yy", enable_cleartext_plugin[0]))
    libmysql_cleartext_plugin_enabled= 1;

  /* no plugins to load */
  if(!s)
    return;

  free_env= plugs= my_strdup(s, MYF(MY_WME));

  do {
    if ((s= strchr(plugs, ';')))
      *s= '\0';
    mysql_load_plugin(mysql, plugs, -1, 0);
    plugs= s + 1;
  } while (s);

  my_free(free_env);

}

/********** extern functions to be used by libmysql *********************/

int mysql_client_plugin_init()
{
  MYSQL mysql;
  struct st_mysql_client_plugin **builtin;

  if (initialized)
    return 0;

  memset(&mysql, 0, sizeof(mysql)); /* dummy mysql for set_mysql_extended_error */

  mysql_mutex_init(0, &LOCK_load_client_plugin, MY_MUTEX_INIT_SLOW);
  init_alloc_root(&mem_root, 128, 128);

  memset(&plugin_list, 0, sizeof(plugin_list));

  initialized= 1;

  mysql_mutex_lock(&LOCK_load_client_plugin);

  for (builtin= mysql_client_builtins; *builtin; builtin++)
    add_plugin_noargs(&mysql, *builtin, 0, 0);

  mysql_mutex_unlock(&LOCK_load_client_plugin);

  load_env_plugins(&mysql);

  return 0;
}

void mysql_client_plugin_deinit()
{
  int i;
  struct st_client_plugin_int *p;

  if (!initialized)
    return;

  for (i=0; i < MYSQL_CLIENT_MAX_PLUGINS; i++)
    for (p= plugin_list[i]; p; p= p->next)
    {
      if (p->plugin->deinit)
        p->plugin->deinit();
      if (p->dlhandle)
        dlclose(p->dlhandle);
    }

  memset(&plugin_list, 0, sizeof(plugin_list));
  initialized= 0;
  free_root(&mem_root, MYF(0));
  mysql_mutex_destroy(&LOCK_load_client_plugin);
}

/************* public facing functions, for client consumption *********/

/* see <mysql/client_plugin.h> for a full description */
struct st_mysql_client_plugin *
mysql_client_register_plugin(MYSQL *mysql,
                             struct st_mysql_client_plugin *plugin)
{
  if (is_not_initialized(mysql, plugin->name))
    return NULL;

  mysql_mutex_lock(&LOCK_load_client_plugin);

  /* make sure the plugin wasn't loaded meanwhile */
  if (find_plugin(plugin->name, plugin->type))
  {
    set_mysql_extended_error(mysql, CR_AUTH_PLUGIN_CANNOT_LOAD,
                             unknown_sqlstate, ER(CR_AUTH_PLUGIN_CANNOT_LOAD),
                             plugin->name, "it is already loaded");
    plugin= NULL;
  }
  else
    plugin= add_plugin_noargs(mysql, plugin, 0, 0);

  mysql_mutex_unlock(&LOCK_load_client_plugin);
  return plugin;
}

/* see <mysql/client_plugin.h> for a full description */
struct st_mysql_client_plugin *
mysql_load_plugin_v(MYSQL *mysql, const char *name, int type,
                    int argc, va_list args)
{
  const char *errmsg;
  char dlpath[FN_REFLEN+1];
  void *sym, *dlhandle;
  struct st_mysql_client_plugin *plugin;
  const char *plugindir;
#ifdef _WIN32
  char win_errormsg[2048];
#endif

  DBUG_ENTER ("mysql_load_plugin_v");
  DBUG_PRINT ("entry", ("name=%s type=%d int argc=%d", name, type, argc));
  if (is_not_initialized(mysql, name))
  {
    DBUG_PRINT ("leave", ("mysql not initialized"));
    DBUG_RETURN (NULL);
  }

  mysql_mutex_lock(&LOCK_load_client_plugin);

  /* make sure the plugin wasn't loaded meanwhile */
  if (type >= 0 && find_plugin(name, type))
  {
    errmsg= "it is already loaded";
    goto err;
  }

  if (mysql->options.extension && mysql->options.extension->plugin_dir)
  {
    plugindir= mysql->options.extension->plugin_dir;
  }
  else
  {
    plugindir= getenv("LIBMYSQL_PLUGIN_DIR");
    if (!plugindir)
    {
      plugindir= PLUGINDIR;
    }
  }

  /* Compile dll path */
  strxnmov(dlpath, sizeof(dlpath) - 1,
           plugindir, "/",
           name, SO_EXT, NullS);
   
  DBUG_PRINT ("info", ("dlopeninig %s", dlpath));
  /* Open new dll handle */
  if (!(dlhandle= dlopen(dlpath, RTLD_NOW)))
  {
#if defined(__APPLE__)
    /* Apple supports plugins with .so also, so try this as well */
    strxnmov(dlpath, sizeof(dlpath) - 1,
             mysql->options.extension && mysql->options.extension->plugin_dir ?
             mysql->options.extension->plugin_dir : PLUGINDIR, "/",
             name, ".so", NullS);
    if ((dlhandle= dlopen(dlpath, RTLD_NOW)))
      goto have_plugin;
#endif

#ifdef _WIN32
    /* There should be no win32 calls between failed dlopen() and GetLastError() */
    if(FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM,
                  0, GetLastError(), 0, win_errormsg, 2048, NULL))
      errmsg= win_errormsg;
    else
      errmsg= "";
#else
    errmsg= dlerror();
#endif
    DBUG_PRINT ("info", ("failed to dlopen"));
    goto err;
  }

#if defined(__APPLE__)
have_plugin:  
#endif
  if (!(sym= dlsym(dlhandle, plugin_declarations_sym)))
  {
    errmsg= "not a plugin";
    dlclose(dlhandle);
    goto err;
  }

  plugin= (struct st_mysql_client_plugin*)sym;

  if (type >=0 && type != plugin->type)
  {
    errmsg= "type mismatch";
    goto err;
  }

  if (strcmp(name, plugin->name))
  {
    errmsg= "name mismatch";
    goto err;
  }

  if (type < 0 && find_plugin(name, plugin->type))
  {
    errmsg= "it is already loaded";
    goto err;
  }

  plugin= add_plugin_withargs(mysql, plugin, dlhandle, argc, args);

  mysql_mutex_unlock(&LOCK_load_client_plugin);

  DBUG_PRINT ("leave", ("plugin loaded ok"));
  DBUG_RETURN (plugin);

err:
  mysql_mutex_unlock(&LOCK_load_client_plugin);
  DBUG_PRINT ("leave", ("plugin load error : %s", errmsg));
  set_mysql_extended_error(mysql, CR_AUTH_PLUGIN_CANNOT_LOAD, unknown_sqlstate,
                           ER(CR_AUTH_PLUGIN_CANNOT_LOAD), name, errmsg);
  DBUG_RETURN (NULL);
}

/* see <mysql/client_plugin.h> for a full description */
struct st_mysql_client_plugin *
mysql_load_plugin(MYSQL *mysql, const char *name, int type, int argc, ...)
{
  struct st_mysql_client_plugin *p;
  va_list args;
  va_start(args, argc);
  p= mysql_load_plugin_v(mysql, name, type, argc, args);
  va_end(args);
  return p;
}

/* see <mysql/client_plugin.h> for a full description */
struct st_mysql_client_plugin *
mysql_client_find_plugin(MYSQL *mysql, const char *name, int type)
{
  struct st_mysql_client_plugin *p;

  DBUG_ENTER ("mysql_client_find_plugin");
  DBUG_PRINT ("entry", ("name=%s, type=%d", name, type));
  if (is_not_initialized(mysql, name))
    DBUG_RETURN (NULL);

  if (type < 0 || type >= MYSQL_CLIENT_MAX_PLUGINS)
  {
    set_mysql_extended_error(mysql, CR_AUTH_PLUGIN_CANNOT_LOAD, unknown_sqlstate,
                             ER(CR_AUTH_PLUGIN_CANNOT_LOAD), name,
                             "invalid type");
  }

  if ((p= find_plugin(name, type)))
  {
    DBUG_PRINT ("leave", ("found %p", p));
    DBUG_RETURN (p);
  }

  /* not found, load it */
  p= mysql_load_plugin(mysql, name, type, 0);
  DBUG_PRINT ("leave", ("loaded %p", p));
  DBUG_RETURN (p);
}


/* see <mysql/client_plugin.h> for a full description */
int mysql_plugin_options(struct st_mysql_client_plugin *plugin,
                                 const char *option,
                                 const void *value)
{
  DBUG_ENTER("mysql_plugin_options");
  /* does the plugin support options call? */
  if (!plugin || !plugin->options)
    DBUG_RETURN(1);
  DBUG_RETURN(plugin->options(option, value));
}