pluggable auth with plugin examples

Makefile.am:
  add new API files to the check_abi rule,
  remove duplicates
client/CMakeLists.txt:
  now a client can use dlopen too
client/Makefile.am:
  be csh-friendly
include/my_global.h:
  add dummy plugs for dlopen and co.
  for the code that needs them to work in static builds
mysys/Makefile.am:
  be csh-friendly
plugin/auth/dialog.c:
  typo fixed

1 files changed, 436 insertions, 0 deletions

diff --git a/sql-common/client_plugin.c b/sql-common/client_plugin.c
new file mode 100644
index 00000000000..c609f165d1c
--- /dev/null
+++ b/sql-common/client_plugin.c
@@ -0,0 +1,436 @@
+/* Copyright (C) 2010 Sergei Golubchik and Monty Program Ab
+
+   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 */
+
+/**
+  @file
+  
+  Support code for the client side (libmysql) plugins
+
+  Client plugins are somewhat different from server plugins, they are simpler.
+
+  They do not need to be installed or in any way explicitly loaded on the
+  client, they are loaded automatically on demand.
+  One client plugin per shared object, soname *must* match the plugin name.
+
+  There is no reference counting and no unloading either.
+*/
+
+#include <my_global.h>
+#include "mysql.h"
+#include <my_sys.h>
+#include <m_string.h>
+#ifdef THREAD
+#include <my_pthread.h>
+#else
+#include <my_no_pthread.h>
+#endif
+
+#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];
+#ifdef THREAD
+static pthread_mutex_t LOCK_load_client_plugin;
+#endif
+
+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;
+}
+
+
+/**
+  finds a plugin in the list
+
+  @param name   plugin name to search for
+  @param type   plugin type
+
+  @note this does NOT necessarily need a mutex, take care!
+  
+  @retval a pointer to a found plugin or 0
+*/
+
+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;
+}
+
+
+/**
+  verifies the plugin and adds it to the list
+
+  @param mysql          MYSQL structure (for error reporting)
+  @param plugin         plugin to install
+  @param dlhandle       a handle to the shared object (returned by dlopen)
+                        or 0 if the plugin was not dynamically loaded
+  @param argc           number of arguments in the 'va_list args'
+  @param args           arguments passed to the plugin initialization function
+
+  @retval a pointer to an installed plugin or 0
+*/
+
+static struct st_mysql_client_plugin *
+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;
+  }
+
+  safe_mutex_assert_owner(&LOCK_load_client_plugin);
+
+  p->next= plugin_list[plugin->type];
+  plugin_list[plugin->type]= p;
+
+  return plugin;
+
+err2:
+  if (plugin->deinit)
+    plugin->deinit();
+err1:
+  if (dlhandle)
+    dlclose(dlhandle);
+  set_mysql_extended_error(mysql, CR_AUTH_PLUGIN_CANNOT_LOAD, unknown_sqlstate,
+                           ER(CR_AUTH_PLUGIN_CANNOT_LOAD), plugin->name,
+                           errmsg);
+  return NULL;
+}
+
+
+/**
+  Loads plugins which are specified in the environment variable
+  LIBMYSQL_PLUGINS.
+  
+  Multiple plugins must be separated by semicolon. This function doesn't
+  return or log an error.
+
+  The function is be called by mysql_client_plugin_init
+
+  @todo
+  Support extended syntax, passing parameters to plugins, for example
+  LIBMYSQL_PLUGINS="plugin1(param1,param2);plugin2;..."
+  or
+  LIBMYSQL_PLUGINS="plugin1=int:param1,str:param2;plugin2;..."
+*/
+
+static void load_env_plugins(MYSQL *mysql)
+{
+  char *plugs, *free_env, *s= getenv("LIBMYSQL_PLUGINS");
+
+  /* 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, MYF(0));
+}
+
+/********** extern functions to be used by libmysql *********************/
+
+/**
+  Initializes the client plugin layer.
+
+  This function must be called before any other client plugin function.
+
+  @retval 0    successful
+  @retval != 0 error occured
+*/
+
+int mysql_client_plugin_init()
+{
+  MYSQL mysql;
+  struct st_mysql_client_plugin **builtin;
+
+  if (initialized)
+    return 0;
+
+  bzero(&mysql, sizeof(mysql)); /* dummy mysql for set_mysql_extended_error */
+
+  pthread_mutex_init(&LOCK_load_client_plugin, MY_MUTEX_INIT_SLOW);
+  init_alloc_root(&mem_root, 128, 128);
+
+  bzero(&plugin_list, sizeof(plugin_list));
+
+  initialized= 1;
+
+  pthread_mutex_lock(&LOCK_load_client_plugin);
+
+  for (builtin= mysql_client_builtins; *builtin; builtin++)
+    add_plugin(&mysql, *builtin, 0, 0, 0);
+
+  pthread_mutex_unlock(&LOCK_load_client_plugin);
+
+  load_env_plugins(&mysql);
+
+  return 0;
+}
+
+
+/**
+  Deinitializes the client plugin layer.
+
+  Unloades all client plugins and frees any associated resources.
+*/
+
+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);
+    }
+
+  bzero(&plugin_list, sizeof(plugin_list));
+  initialized= 0;
+  free_root(&mem_root, MYF(0));
+  pthread_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;
+
+  pthread_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(mysql, plugin, 0, 0, 0);
+
+  pthread_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;
+
+  if (is_not_initialized(mysql, name))
+    return NULL;
+
+  pthread_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;
+  }
+
+  /* Compile dll path */
+  strxnmov(dlpath, sizeof(dlpath) - 1,
+           mysql->options.extension && mysql->options.extension->plugin_dir ?
+           mysql->options.extension->plugin_dir : PLUGINDIR, "/",
+           name, SO_EXT, NullS);
+   
+  /* Open new dll handle */
+  if (!(dlhandle= dlopen(dlpath, RTLD_NOW)))
+  {
+    errmsg= dlerror();
+    goto err;
+  }
+
+  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(mysql, plugin, dlhandle, argc, args);
+
+  pthread_mutex_unlock(&LOCK_load_client_plugin);
+
+  return plugin;
+
+err:
+  pthread_mutex_unlock(&LOCK_load_client_plugin);
+  set_mysql_extended_error(mysql, CR_AUTH_PLUGIN_CANNOT_LOAD, unknown_sqlstate,
+                           ER(CR_AUTH_PLUGIN_CANNOT_LOAD), name, errmsg);
+  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;
+
+  if (is_not_initialized(mysql, name))
+    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)))
+    return p;
+
+  /* not found, load it */
+  return mysql_load_plugin(mysql, name, type, 0);
+}
+