res_odbc.c

Go to the documentation of this file.

/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2012, Digium, Inc.
 *
 * Mark Spencer <markster@digium.com>
 *
 * res_odbc.c <ODBC resource manager>
 * Copyright (C) 2004 - 2005 Anthony Minessale II <anthmct@yahoo.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief ODBC resource manager
 *
 * \author Mark Spencer <markster@digium.com>
 * \author Anthony Minessale II <anthmct@yahoo.com>
 * \author Tilghman Lesher <tilghman@digium.com>
 *
 * \arg See also: \ref cdr_odbc
 */

/*! \li \ref res_odbc.c uses the configuration file \ref res_odbc.conf
 * \addtogroup configuration_file Configuration Files
 */

/*!
 * \page res_odbc.conf res_odbc.conf
 * \verbinclude res_odbc.conf.sample
 */

/*** MODULEINFO
   <depend>generic_odbc</depend>
   <depend>res_odbc_transaction</depend>
   <support_level>core</support_level>
 ***/

#include "asterisk.h"

#include "asterisk/file.h"
#include "asterisk/channel.h"
#include "asterisk/config.h"
#include "asterisk/pbx.h"
#include "asterisk/module.h"
#include "asterisk/cli.h"
#include "asterisk/lock.h"
#include "asterisk/res_odbc.h"
#include "asterisk/time.h"
#include "asterisk/astobj2.h"
#include "asterisk/app.h"
#include "asterisk/strings.h"
#include "asterisk/threadstorage.h"

struct odbc_class
{
   AST_LIST_ENTRY(odbc_class) list;
   char name[80];
   char dsn[80];
   char *username;
   char *password;
   char *sanitysql;
   SQLHENV env;
   unsigned int delme:1;                /*!< Purge the class */
   unsigned int backslash_is_escape:1;  /*!< On this database, the backslash is a native escape sequence */
   unsigned int forcecommit:1;          /*!< Should uncommitted transactions be auto-committed on handle release? */
   unsigned int isolation;              /*!< Flags for how the DB should deal with data in other, uncommitted transactions */
   unsigned int conntimeout;            /*!< Maximum time the connection process should take */
   unsigned int maxconnections;         /*!< Maximum number of allowed connections */
   /*! When a connection fails, cache that failure for how long? */
   struct timeval negative_connection_cache;
   /*! When a connection fails, when did that last occur? */
   struct timeval last_negative_connect;
   /*! A pool of available connections */
   AST_LIST_HEAD_NOLOCK(, odbc_obj) connections;
   /*! Lock to protect the connections */
   ast_mutex_t lock;
   /*! Condition to notify any pending connection requesters */
   ast_cond_t cond;
   /*! The total number of current connections */
   size_t connection_cnt;
   /*! Whether logging is enabled on this class or not */
   unsigned int logging;
   /*! The number of prepares executed on this class (total from all connections */
   int prepares_executed;
   /*! The number of queries executed on this class (total from all connections) */
   int queries_executed;
   /*! The longest execution time for a query executed on this class */
   long longest_query_execution_time;
   /*! The SQL query that took the longest to execute */
   char *sql_text;
   /*! Slow query limit (in milliseconds) */
   unsigned int slowquerylimit;
};

static struct ao2_container *class_container;

static AST_RWLIST_HEAD_STATIC(odbc_tables, odbc_cache_tables);

static odbc_status odbc_obj_connect(struct odbc_obj *obj);
static odbc_status odbc_obj_disconnect(struct odbc_obj *obj);
static void odbc_register_class(struct odbc_class *class, int connect);

AST_THREADSTORAGE(errors_buf);

struct odbc_txn_frame {
   AST_LIST_ENTRY(odbc_txn_frame) list;
   struct ast_channel *owner;
   struct odbc_obj *obj;        /*!< Database handle within which transacted statements are run */
   /*!\brief Is this record the current active transaction within the channel?
    * Note that the active flag is really only necessary for statements which
    * are triggered from the dialplan, as there isn't a direct correlation
    * between multiple statements.  Applications wishing to use transactions
    * may simply perform each statement on the same odbc_obj, which keeps the
    * transaction persistent.
    */
   unsigned int active:1;
   unsigned int forcecommit:1;     /*!< Should uncommitted transactions be auto-committed on handle release? */
   unsigned int isolation;         /*!< Flags for how the DB should deal with data in other, uncommitted transactions */
   char name[0];                   /*!< Name of this transaction ID */
};

const char *ast_odbc_isolation2text(int iso)
{
   if (iso == SQL_TXN_READ_COMMITTED) {
      return "read_committed";
   } else if (iso == SQL_TXN_READ_UNCOMMITTED) {
      return "read_uncommitted";
   } else if (iso == SQL_TXN_SERIALIZABLE) {
      return "serializable";
   } else if (iso == SQL_TXN_REPEATABLE_READ) {
      return "repeatable_read";
   } else {
      return "unknown";
   }
}

int ast_odbc_text2isolation(const char *txt)
{
   if (strncasecmp(txt, "read_", 5) == 0) {
      if (strncasecmp(txt + 5, "c", 1) == 0) {
         return SQL_TXN_READ_COMMITTED;
      } else if (strncasecmp(txt + 5, "u", 1) == 0) {
         return SQL_TXN_READ_UNCOMMITTED;
      } else {
         return 0;
      }
   } else if (strncasecmp(txt, "ser", 3) == 0) {
      return SQL_TXN_SERIALIZABLE;
   } else if (strncasecmp(txt, "rep", 3) == 0) {
      return SQL_TXN_REPEATABLE_READ;
   } else {
      return 0;
   }
}

static void odbc_class_destructor(void *data)
{
   struct odbc_class *class = data;
   struct odbc_obj *obj;

   /* Due to refcounts, we can safely assume that any objects with a reference
    * to us will prevent our destruction, so we don't need to worry about them.
    */
   if (class->username) {
      ast_free(class->username);
   }
   if (class->password) {
      ast_free(class->password);
   }
   if (class->sanitysql) {
      ast_free(class->sanitysql);
   }

   while ((obj = AST_LIST_REMOVE_HEAD(&class->connections, list))) {
      ao2_ref(obj, -1);
   }

   SQLFreeHandle(SQL_HANDLE_ENV, class->env);
   ast_mutex_destroy(&class->lock);
   ast_cond_destroy(&class->cond);
   ast_free(class->sql_text);
}

static void odbc_obj_destructor(void *data)
{
   struct odbc_obj *obj = data;

   odbc_obj_disconnect(obj);
}

static void destroy_table_cache(struct odbc_cache_tables *table)
{
   struct odbc_cache_columns *col;

   ast_debug(1, "Destroying table cache for %s\n", table->table);

   AST_RWLIST_WRLOCK(&table->columns);
   while ((col = AST_RWLIST_REMOVE_HEAD(&table->columns, list))) {
      ast_free(col);
   }
   AST_RWLIST_UNLOCK(&table->columns);
   AST_RWLIST_HEAD_DESTROY(&table->columns);

   ast_free(table);
}

/*!
 * \brief Find or create an entry describing the table specified.
 * \param database Name of an ODBC class on which to query the table
 * \param tablename Tablename to describe
 * \retval A structure describing the table layout, or NULL, if the table is not found or another error occurs.
 * When a structure is returned, the contained columns list will be
 * rdlock'ed, to ensure that it will be retained in memory.
 *
 * XXX This creates a connection and disconnects it. In some situations, the caller of
 * this function has its own connection and could donate it to this function instead of
 * needing to create another one.
 *
 * XXX The automatic readlock of the columns is awkward. It's done because it's possible for
 * multiple threads to have references to the table, and the table is not refcounted. Possible
 * changes here would be
 * * Eliminate the table cache entirely. The use of ast_odbc_find_table() is generally
 *   questionable. The only real good use right now is from ast_realtime_require_field() in
 *   order to make sure the DB has the expected columns in it. Since that is only used sparingly,
 *   the need to cache tables is questionable. Instead, the table structure can be fetched from
 *   the DB directly each time, resulting in a single owner of the data.
 * * Make odbc_cache_tables a refcounted object.
 *
 * \since 1.6.1
 */
struct odbc_cache_tables *ast_odbc_find_table(const char *database, const char *tablename)
{
   struct odbc_cache_tables *tableptr;
   struct odbc_cache_columns *entry;
   char columnname[80];
   SQLLEN sqlptr;
   SQLHSTMT stmt = NULL;
   int res = 0, error = 0;
   struct odbc_obj *obj;

   AST_RWLIST_RDLOCK(&odbc_tables);
   AST_RWLIST_TRAVERSE(&odbc_tables, tableptr, list) {
      if (strcmp(tableptr->connection, database) == 0 && strcmp(tableptr->table, tablename) == 0) {
         break;
      }
   }
   if (tableptr) {
      AST_RWLIST_RDLOCK(&tableptr->columns);
      AST_RWLIST_UNLOCK(&odbc_tables);
      return tableptr;
   }

   if (!(obj = ast_odbc_request_obj(database, 0))) {
      ast_log(LOG_WARNING, "Unable to retrieve database handle for table description '%s@%s'\n", tablename, database);
      AST_RWLIST_UNLOCK(&odbc_tables);
      return NULL;
   }

   /* Table structure not already cached; build it now. */
   do {
      res = SQLAllocHandle(SQL_HANDLE_STMT, obj->con, &stmt);
      if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO)) {
         ast_log(LOG_WARNING, "SQL Alloc Handle failed on connection '%s'!\n", database);
         break;
      }

      res = SQLColumns(stmt, NULL, 0, NULL, 0, (unsigned char *)tablename, SQL_NTS, (unsigned char *)"%", SQL_NTS);
      if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO)) {
         SQLFreeHandle(SQL_HANDLE_STMT, stmt);
         ast_log(LOG_ERROR, "Unable to query database columns on connection '%s'.\n", database);
         break;
      }

      if (!(tableptr = ast_calloc(sizeof(char), sizeof(*tableptr) + strlen(database) + 1 + strlen(tablename) + 1))) {
         ast_log(LOG_ERROR, "Out of memory creating entry for table '%s' on connection '%s'\n", tablename, database);
         break;
      }

      tableptr->connection = (char *)tableptr + sizeof(*tableptr);
      tableptr->table = (char *)tableptr + sizeof(*tableptr) + strlen(database) + 1;
      strcpy(tableptr->connection, database); /* SAFE */
      strcpy(tableptr->table, tablename); /* SAFE */
      AST_RWLIST_HEAD_INIT(&(tableptr->columns));

      while ((res = SQLFetch(stmt)) != SQL_NO_DATA && res != SQL_ERROR) {
         SQLGetData(stmt,  4, SQL_C_CHAR, columnname, sizeof(columnname), &sqlptr);

         if (!(entry = ast_calloc(sizeof(char), sizeof(*entry) + strlen(columnname) + 1))) {
            ast_log(LOG_ERROR, "Out of memory creating entry for column '%s' in table '%s' on connection '%s'\n", columnname, tablename, database);
            error = 1;
            break;
         }
         entry->name = (char *)entry + sizeof(*entry);
         strcpy(entry->name, columnname);

         SQLGetData(stmt,  5, SQL_C_SHORT, &entry->type, sizeof(entry->type), NULL);
         SQLGetData(stmt,  7, SQL_C_LONG, &entry->size, sizeof(entry->size), NULL);
         SQLGetData(stmt,  9, SQL_C_SHORT, &entry->decimals, sizeof(entry->decimals), NULL);
         SQLGetData(stmt, 10, SQL_C_SHORT, &entry->radix, sizeof(entry->radix), NULL);
         SQLGetData(stmt, 11, SQL_C_SHORT, &entry->nullable, sizeof(entry->nullable), NULL);
         SQLGetData(stmt, 16, SQL_C_LONG, &entry->octetlen, sizeof(entry->octetlen), NULL);

         /* Specification states that the octenlen should be the maximum number of bytes
          * returned in a char or binary column, but it seems that some drivers just set
          * it to NULL. (Bad Postgres! No biscuit!) */
         if (entry->octetlen == 0) {
            entry->octetlen = entry->size;
         }

         ast_debug(3, "Found %s column with type %hd with len %ld, octetlen %ld, and numlen (%hd,%hd)\n", entry->name, entry->type, (long) entry->size, (long) entry->octetlen, entry->decimals, entry->radix);
         /* Insert column info into column list */
         AST_LIST_INSERT_TAIL(&(tableptr->columns), entry, list);
      }
      SQLFreeHandle(SQL_HANDLE_STMT, stmt);

      AST_RWLIST_INSERT_TAIL(&odbc_tables, tableptr, list);
      AST_RWLIST_RDLOCK(&(tableptr->columns));
      break;
   } while (1);

   AST_RWLIST_UNLOCK(&odbc_tables);

   if (error) {
      destroy_table_cache(tableptr);
      tableptr = NULL;
   }
   ast_odbc_release_obj(obj);
   return tableptr;
}

struct odbc_cache_columns *ast_odbc_find_column(struct odbc_cache_tables *table, const char *colname)
{
   struct odbc_cache_columns *col;
   AST_RWLIST_TRAVERSE(&table->columns, col, list) {
      if (strcasecmp(col->name, colname) == 0) {
         return col;
      }
   }
   return NULL;
}

int ast_odbc_clear_cache(const char *database, const char *tablename)
{
   struct odbc_cache_tables *tableptr;

   AST_RWLIST_WRLOCK(&odbc_tables);
   AST_RWLIST_TRAVERSE_SAFE_BEGIN(&odbc_tables, tableptr, list) {
      if (strcmp(tableptr->connection, database) == 0 && strcmp(tableptr->table, tablename) == 0) {
         AST_LIST_REMOVE_CURRENT(list);
         destroy_table_cache(tableptr);
         break;
      }
   }
   AST_RWLIST_TRAVERSE_SAFE_END
   AST_RWLIST_UNLOCK(&odbc_tables);
   return tableptr ? 0 : -1;
}

SQLHSTMT ast_odbc_direct_execute(struct odbc_obj *obj, SQLHSTMT (*exec_cb)(struct odbc_obj *obj, void *data), void *data)
{
   struct timeval start;
   SQLHSTMT stmt;

   if (obj->parent->logging) {
      start = ast_tvnow();
   }

   stmt = exec_cb(obj, data);

   if (obj->parent->logging) {
      long execution_time = ast_tvdiff_ms(ast_tvnow(), start);

      if (obj->parent->slowquerylimit && execution_time > obj->parent->slowquerylimit) {
         ast_log(LOG_WARNING, "SQL query '%s' took %ld milliseconds to execute on class '%s', this may indicate a database problem\n",
            obj->sql_text, execution_time, obj->parent->name);
      }

      ast_mutex_lock(&obj->parent->lock);
      if (execution_time > obj->parent->longest_query_execution_time || !obj->parent->sql_text) {
         obj->parent->longest_query_execution_time = execution_time;
         /* Due to the callback nature of the res_odbc API it's not possible to ensure that
          * the SQL text is removed from the connection in all cases, so only if it becomes the
          * new longest executing query do we steal the SQL text. In other cases what will happen
          * is that the SQL text will be freed if the connection is released back to the class or
          * if a new query is done on the connection.
          */
         ast_free(obj->parent->sql_text);
         obj->parent->sql_text = obj->sql_text;
         obj->sql_text = NULL;
      }
      ast_mutex_unlock(&obj->parent->lock);
   }

   return stmt;
}

SQLHSTMT ast_odbc_prepare_and_execute(struct odbc_obj *obj, SQLHSTMT (*prepare_cb)(struct odbc_obj *obj, void *data), void *data)
{
   struct timeval start;
   int res = 0;
   SQLHSTMT stmt;

   if (obj->parent->logging) {
      start = ast_tvnow();
   }

   /* This prepare callback may do more than just prepare -- it may also
    * bind parameters, bind results, etc.  The real key, here, is that
    * when we disconnect, all handles become invalid for most databases.
    * We must therefore redo everything when we establish a new
    * connection. */
   stmt = prepare_cb(obj, data);
   if (!stmt) {
      return NULL;
   }

   res = SQLExecute(stmt);
   if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO) && (res != SQL_NO_DATA)) {
      if (res == SQL_ERROR) {
         ast_odbc_print_errors(SQL_HANDLE_STMT, stmt, "SQL Execute");
      }

      ast_log(LOG_WARNING, "SQL Execute error %d!\n", res);
      SQLFreeHandle(SQL_HANDLE_STMT, stmt);
      stmt = NULL;
   } else if (obj->parent->logging) {
      long execution_time = ast_tvdiff_ms(ast_tvnow(), start);

      if (obj->parent->slowquerylimit && execution_time > obj->parent->slowquerylimit) {
         ast_log(LOG_WARNING, "SQL query '%s' took %ld milliseconds to execute on class '%s', this may indicate a database problem\n",
            obj->sql_text, execution_time, obj->parent->name);
      }

      ast_mutex_lock(&obj->parent->lock);

      /* If this takes the record on longest query execution time, update the parent class
       * with the information.
       */
      if (execution_time > obj->parent->longest_query_execution_time || !obj->parent->sql_text) {
         obj->parent->longest_query_execution_time = execution_time;
         ast_free(obj->parent->sql_text);
         obj->parent->sql_text = obj->sql_text;
         obj->sql_text = NULL;
      }
      ast_mutex_unlock(&obj->parent->lock);

      ast_atomic_fetchadd_int(&obj->parent->queries_executed, +1);
   }

   return stmt;
}

int ast_odbc_prepare(struct odbc_obj *obj, SQLHSTMT *stmt, const char *sql)
{
   if (obj->parent->logging) {
      /* It is possible for this connection to be reused without being
       * released back to the class, so we free what may already exist
       * and place the new SQL in.
       */
      ast_free(obj->sql_text);
      obj->sql_text = ast_strdup(sql);
      ast_atomic_fetchadd_int(&obj->parent->prepares_executed, +1);
   }

   return SQLPrepare(stmt, (unsigned char *)sql, SQL_NTS);
}

SQLRETURN ast_odbc_execute_sql(struct odbc_obj *obj, SQLHSTMT *stmt, const char *sql)
{
   if (obj->parent->logging) {
      ast_free(obj->sql_text);
      obj->sql_text = ast_strdup(sql);
      ast_atomic_fetchadd_int(&obj->parent->queries_executed, +1);
   }

   return SQLExecDirect(stmt, (unsigned char *)sql, SQL_NTS);
}

int ast_odbc_smart_execute(struct odbc_obj *obj, SQLHSTMT stmt)
{
   int res = 0;

   res = SQLExecute(stmt);
   if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO) && (res != SQL_NO_DATA)) {
      if (res == SQL_ERROR) {
         ast_odbc_print_errors(SQL_HANDLE_STMT, stmt, "SQL Execute");
      }
   }

   if (obj->parent->logging) {
      ast_atomic_fetchadd_int(&obj->parent->queries_executed, +1);
   }

   return res;
}

SQLRETURN ast_odbc_ast_str_SQLGetData(struct ast_str **buf, int pmaxlen, SQLHSTMT StatementHandle, SQLUSMALLINT ColumnNumber, SQLSMALLINT TargetType, SQLLEN *StrLen_or_Ind)
{
   SQLRETURN res;

   if (pmaxlen == 0) {
      if (SQLGetData(StatementHandle, ColumnNumber, TargetType, ast_str_buffer(*buf), 0, StrLen_or_Ind) == SQL_SUCCESS_WITH_INFO) {
         ast_str_make_space(buf, *StrLen_or_Ind + 1);
      }
   } else if (pmaxlen > 0) {
      ast_str_make_space(buf, pmaxlen);
   }
   res = SQLGetData(StatementHandle, ColumnNumber, TargetType, ast_str_buffer(*buf), ast_str_size(*buf), StrLen_or_Ind);
   ast_str_update(*buf);

   return res;
}

struct ast_str *ast_odbc_print_errors(SQLSMALLINT handle_type, SQLHANDLE handle, const char *operation)
{
   struct ast_str *errors = ast_str_thread_get(&errors_buf, 16);
   SQLINTEGER nativeerror = 0;
   SQLSMALLINT diagbytes = 0;
   SQLSMALLINT i;
   unsigned char state[10];
   unsigned char diagnostic[256];

   ast_str_reset(errors);
   i = 0;
   while (SQLGetDiagRec(handle_type, handle, ++i, state, &nativeerror,
      diagnostic, sizeof(diagnostic), &diagbytes) == SQL_SUCCESS) {
      ast_str_append(&errors, 0, "%s%s", ast_str_strlen(errors) ? "," : "", state);
      ast_log(LOG_WARNING, "%s returned an error: %s: %s\n", operation, state, diagnostic);
      /* XXX Why is this here? */
      if (i > 10) {
         ast_log(LOG_WARNING, "There are more than 10 diagnostic records! Ignore the rest.\n");
         break;
      }
   }

   return errors;
}

unsigned int ast_odbc_class_get_isolation(struct odbc_class *class)
{
   return class->isolation;
}

unsigned int ast_odbc_class_get_forcecommit(struct odbc_class *class)
{
   return class->forcecommit;
}

const char *ast_odbc_class_get_name(struct odbc_class *class)
{
   return class->name;
}

static int load_odbc_config(void)
{
   static char *cfg = "res_odbc.conf";
   struct ast_config *config;
   struct ast_variable *v;
   char *cat;
   const char *dsn, *username, *password, *sanitysql;
   int enabled, bse, conntimeout, forcecommit, isolation, maxconnections, logging, slowquerylimit;
   struct timeval ncache = { 0, 0 };
   int preconnect = 0, res = 0;
   struct ast_flags config_flags = { 0 };

   struct odbc_class *new;

   config = ast_config_load(cfg, config_flags);
   if (config == CONFIG_STATUS_FILEMISSING || config == CONFIG_STATUS_FILEINVALID) {
      ast_log(LOG_WARNING, "Unable to load config file res_odbc.conf\n");
      return -1;
   }
   for (cat = ast_category_browse(config, NULL); cat; cat=ast_category_browse(config, cat)) {
      if (!strcasecmp(cat, "ENV")) {
         for (v = ast_variable_browse(config, cat); v; v = v->next) {
            setenv(v->name, v->value, 1);
            ast_log(LOG_NOTICE, "Adding ENV var: %s=%s\n", v->name, v->value);
         }
      } else {
         /* Reset all to defaults for each class of odbc connections */
         dsn = username = password = sanitysql = NULL;
         enabled = 1;
         preconnect = 0;
         bse = 1;
         conntimeout = 10;
         forcecommit = 0;
         isolation = SQL_TXN_READ_COMMITTED;
         maxconnections = 1;
         logging = 0;
         slowquerylimit = 5000;
         for (v = ast_variable_browse(config, cat); v; v = v->next) {
            if (!strcasecmp(v->name, "pooling") ||
                  !strncasecmp(v->name, "share", 5) ||
                  !strcasecmp(v->name, "limit") ||
                  !strcasecmp(v->name, "idlecheck")) {
               ast_log(LOG_WARNING, "The 'pooling', 'shared_connections', 'limit', and 'idlecheck' options were replaced by 'max_connections'.  See res_odbc.conf.sample.\n");
            } else if (!strcasecmp(v->name, "enabled")) {
               enabled = ast_true(v->value);
            } else if (!strcasecmp(v->name, "pre-connect")) {
               preconnect = ast_true(v->value);
            } else if (!strcasecmp(v->name, "dsn")) {
               dsn = v->value;
            } else if (!strcasecmp(v->name, "username")) {
               username = v->value;
            } else if (!strcasecmp(v->name, "password")) {
               password = v->value;
            } else if (!strcasecmp(v->name, "sanitysql")) {
               sanitysql = v->value;
            } else if (!strcasecmp(v->name, "backslash_is_escape")) {
               bse = ast_true(v->value);
            } else if (!strcasecmp(v->name, "connect_timeout")) {
               if (sscanf(v->value, "%d", &conntimeout) != 1 || conntimeout < 1) {
                  ast_log(LOG_WARNING, "connect_timeout must be a positive integer\n");
                  conntimeout = 10;
               }
            } else if (!strcasecmp(v->name, "negative_connection_cache")) {
               double dncache;
               if (sscanf(v->value, "%lf", &dncache) != 1 || dncache < 0) {
                  ast_log(LOG_WARNING, "negative_connection_cache must be a non-negative integer\n");
                  /* 5 minutes sounds like a reasonable default */
                  ncache.tv_sec = 300;
                  ncache.tv_usec = 0;
               } else {
                  ncache.tv_sec = (int)dncache;
                  ncache.tv_usec = (dncache - ncache.tv_sec) * 1000000;
               }
            } else if (!strcasecmp(v->name, "forcecommit")) {
               forcecommit = ast_true(v->value);
            } else if (!strcasecmp(v->name, "isolation")) {
               if ((isolation = ast_odbc_text2isolation(v->value)) == 0) {
                  ast_log(LOG_ERROR, "Unrecognized value for 'isolation': '%s' in section '%s'\n", v->value, cat);
                  isolation = SQL_TXN_READ_COMMITTED;
               }
            } else if (!strcasecmp(v->name, "max_connections")) {
               if (sscanf(v->value, "%30d", &maxconnections) != 1 || maxconnections < 1) {
                  ast_log(LOG_WARNING, "max_connections must be a positive integer\n");
                  maxconnections = 1;
                                        }
            } else if (!strcasecmp(v->name, "logging")) {
               logging = ast_true(v->value);
            } else if (!strcasecmp(v->name, "slow_query_limit")) {
               if (sscanf(v->value, "%30d", &slowquerylimit) != 1) {
                  ast_log(LOG_WARNING, "slow_query_limit must be a positive integer\n");
                  slowquerylimit = 5000;
               }
            }
         }

         if (enabled && !ast_strlen_zero(dsn)) {
            new = ao2_alloc(sizeof(*new), odbc_class_destructor);

            if (!new) {
               res = -1;
               break;
            }

            SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &new->env);
            res = SQLSetEnvAttr(new->env, SQL_ATTR_ODBC_VERSION, (void *) SQL_OV_ODBC3, 0);

            if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO)) {
               ast_log(LOG_WARNING, "res_odbc: Error SetEnv\n");
               ao2_ref(new, -1);
               return res;
            }

            new->backslash_is_escape = bse ? 1 : 0;
            new->forcecommit = forcecommit ? 1 : 0;
            new->isolation = isolation;
            new->conntimeout = conntimeout;
            new->negative_connection_cache = ncache;
            new->maxconnections = maxconnections;
            new->logging = logging;
            new->slowquerylimit = slowquerylimit;

            if (cat)
               ast_copy_string(new->name, cat, sizeof(new->name));
            if (dsn)
               ast_copy_string(new->dsn, dsn, sizeof(new->dsn));
            if (username && !(new->username = ast_strdup(username))) {
               ao2_ref(new, -1);
               break;
            }
            if (password && !(new->password = ast_strdup(password))) {
               ao2_ref(new, -1);
               break;
            }
            if (sanitysql && !(new->sanitysql = ast_strdup(sanitysql))) {
               ao2_ref(new, -1);
               break;
            }

            ast_mutex_init(&new->lock);
            ast_cond_init(&new->cond, NULL);

            odbc_register_class(new, preconnect);
            ast_log(LOG_NOTICE, "Registered ODBC class '%s' dsn->[%s]\n", cat, dsn);
            ao2_ref(new, -1);
            new = NULL;
         }
      }
   }
   ast_config_destroy(config);
   return res;
}

static char *handle_cli_odbc_show(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
   struct ao2_iterator aoi;
   struct odbc_class *class;
   int length = 0;
   int which = 0;
   char *ret = NULL;

   switch (cmd) {
   case CLI_INIT:
      e->command = "odbc show";
      e->usage =
            "Usage: odbc show [class]\n"
            "       List settings of a particular ODBC class or,\n"
            "       if not specified, all classes.\n";
      return NULL;
   case CLI_GENERATE:
      if (a->pos != 2)
         return NULL;
      length = strlen(a->word);
      aoi = ao2_iterator_init(class_container, 0);
      while ((class = ao2_iterator_next(&aoi))) {
         if (!strncasecmp(a->word, class->name, length) && ++which > a->n) {
            ret = ast_strdup(class->name);
         }
         ao2_ref(class, -1);
         if (ret) {
            break;
         }
      }
      ao2_iterator_destroy(&aoi);
      if (!ret && !strncasecmp(a->word, "all", length) && ++which > a->n) {
         ret = ast_strdup("all");
      }
      return ret;
   }

   ast_cli(a->fd, "\nODBC DSN Settings\n");
   ast_cli(a->fd,   "-----------------\n\n");
   aoi = ao2_iterator_init(class_container, 0);
   while ((class = ao2_iterator_next(&aoi))) {
      if ((a->argc == 2) || (a->argc == 3 && !strcmp(a->argv[2], "all")) || (!strcmp(a->argv[2], class->name))) {
         char timestr[80];
         struct ast_tm tm;

         ast_cli(a->fd, "  Name:   %s\n  DSN:    %s\n", class->name, class->dsn);

         if (class->last_negative_connect.tv_sec > 0) {
            ast_localtime(&class->last_negative_connect, &tm, NULL);
            ast_strftime(timestr, sizeof(timestr), "%Y-%m-%d %T", &tm);
            ast_cli(a->fd, "    Last fail connection attempt: %s\n", timestr);
         }

         ast_cli(a->fd, "    Number of active connections: %zd (out of %d)\n", class->connection_cnt, class->maxconnections);
         ast_cli(a->fd, "    Logging: %s\n", class->logging ? "Enabled" : "Disabled");
         if (class->logging) {
            ast_cli(a->fd, "    Number of prepares executed: %d\n", class->prepares_executed);
            ast_cli(a->fd, "    Number of queries executed: %d\n", class->queries_executed);
            ast_mutex_lock(&class->lock);
            if (class->sql_text) {
               ast_cli(a->fd, "    Longest running SQL query: %s (%ld milliseconds)\n", class->sql_text, class->longest_query_execution_time);
            }
            ast_mutex_unlock(&class->lock);
         }
         ast_cli(a->fd, "\n");
      }
      ao2_ref(class, -1);
   }
   ao2_iterator_destroy(&aoi);

   return CLI_SUCCESS;
}

static struct ast_cli_entry cli_odbc[] = {
   AST_CLI_DEFINE(handle_cli_odbc_show, "List ODBC DSN(s)")
};

static void odbc_register_class(struct odbc_class *class, int preconnect)
{
   struct odbc_obj *obj;

   ao2_link(class_container, class);
   /* I still have a reference in the caller, so a deref is NOT missing here. */

   if (!preconnect) {
      return;
   }

   /* Request and release builds a connection */
   obj = ast_odbc_request_obj(class->name, 0);
   if (obj) {
      ast_odbc_release_obj(obj);
   }

   return;
}

void ast_odbc_release_obj(struct odbc_obj *obj)
{
   struct odbc_class *class = obj->parent;

   ast_debug(2, "Releasing ODBC handle %p into pool\n", obj);

   /* The odbc_obj only holds a reference to the class when it is
    * actively being used. This guarantees no circular reference
    * between odbc_class and odbc_obj. Since it is being released
    * we also release our class reference. If a reload occurred before
    * the class will go away automatically once all odbc_obj are
    * released back.
    */
   obj->parent = NULL;

   /* Free the SQL text so that the next user of this connection has
    * a fresh start.
    */
   ast_free(obj->sql_text);
   obj->sql_text = NULL;

   ast_mutex_lock(&class->lock);
   AST_LIST_INSERT_HEAD(&class->connections, obj, list);
   ast_cond_signal(&class->cond);
   ast_mutex_unlock(&class->lock);

   ao2_ref(class, -1);
}

int ast_odbc_backslash_is_escape(struct odbc_obj *obj)
{
   return obj->parent->backslash_is_escape;
}

static int aoro2_class_cb(void *obj, void *arg, int flags)
{
   struct odbc_class *class = obj;
   char *name = arg;
   if (!strcmp(class->name, name) && !class->delme) {
      return CMP_MATCH | CMP_STOP;
   }
   return 0;
}

unsigned int ast_odbc_get_max_connections(const char *name)
{
   struct odbc_class *class;
   unsigned int max_connections;

   class = ao2_callback(class_container, 0, aoro2_class_cb, (char *) name);
   if (!class) {
      return 0;
   }

   max_connections = class->maxconnections;
   ao2_ref(class, -1);

   return max_connections;
}

/*
 * \brief Determine if the connection has died.
 *
 * \param connection The connection to check
 * \param class The ODBC class
 * \retval 1 Yep, it's dead
 * \retval 0 It's alive and well
 */
static int connection_dead(struct odbc_obj *connection, struct odbc_class *class)
{
   char *test_sql = "select 1";
   SQLINTEGER dead;
   SQLRETURN res;
   SQLHSTMT stmt;

   res = SQLGetConnectAttr(connection->con, SQL_ATTR_CONNECTION_DEAD, &dead, 0, 0);
   if (SQL_SUCCEEDED(res)) {
      return dead == SQL_CD_TRUE ? 1 : 0;
   }

   /* If the Driver doesn't support SQL_ATTR_CONNECTION_DEAD do a
    * probing query instead
    */
   res = SQLAllocHandle(SQL_HANDLE_STMT, connection->con, &stmt);
   if (!SQL_SUCCEEDED(res)) {
      return 1;
   }

   if (!ast_strlen_zero(class->sanitysql)) {
      test_sql = class->sanitysql;
   }

   res = SQLPrepare(stmt, (unsigned char *)test_sql, SQL_NTS);
   if (!SQL_SUCCEEDED(res)) {
      SQLFreeHandle(SQL_HANDLE_STMT, stmt);
      return 1;
   }

   res = SQLExecute(stmt);
   SQLFreeHandle(SQL_HANDLE_STMT, stmt);

   return SQL_SUCCEEDED(res) ? 0 : 1;
}

struct odbc_obj *_ast_odbc_request_obj2(const char *name, struct ast_flags flags, const char *file, const char *function, int lineno)
{
   struct odbc_obj *obj = NULL;
   struct odbc_class *class;

   if (!(class = ao2_callback(class_container, 0, aoro2_class_cb, (char *) name))) {
      ast_debug(1, "Class '%s' not found!\n", name);
      return NULL;
   }

   ast_mutex_lock(&class->lock);

   while (!obj) {
      obj = AST_LIST_REMOVE_HEAD(&class->connections, list);

      if (!obj) {
         if (class->connection_cnt < class->maxconnections) {
            /* If no connection is immediately available establish a new
             * one if allowed. If we try and fail we give up completely as
             * we could go into an infinite loop otherwise.
             */
            obj = ao2_alloc(sizeof(*obj), odbc_obj_destructor);
            if (!obj) {
               break;
            }

            obj->parent = ao2_bump(class);
            if (odbc_obj_connect(obj) == ODBC_FAIL) {
               ao2_ref(obj->parent, -1);
               ao2_ref(obj, -1);
               obj = NULL;
               break;
            }

            class->connection_cnt++;
            ast_debug(2, "Created ODBC handle %p on class '%s', new count is %zd\n", obj,
               name, class->connection_cnt);
         } else {
            /* Otherwise if we're not allowed to create a new one we
             * wait for another thread to give up the connection they
             * own.
             */
            ast_cond_wait(&class->cond, &class->lock);
         }
      } else if (connection_dead(obj, class)) {
         /* If the connection is dead try to grab another functional one from the
          * pool instead of trying to resurrect this one.
          */
         ao2_ref(obj, -1);
         obj = NULL;
         class->connection_cnt--;
         ast_debug(2, "ODBC handle %p dead - removing from class '%s', new count is %zd\n",
            obj, name, class->connection_cnt);
      } else {
         /* We successfully grabbed a connection from the pool and all is well!
          */
         obj->parent = ao2_bump(class);
         ast_debug(2, "Reusing ODBC handle %p from class '%s'\n", obj, name);
      }
   }

   ast_mutex_unlock(&class->lock);
   ao2_ref(class, -1);

   return obj;
}

struct odbc_obj *_ast_odbc_request_obj(const char *name, int check, const char *file, const char *function, int lineno)
{
   struct ast_flags flags = { check ? RES_ODBC_SANITY_CHECK : 0 };
   /* XXX New flow means that the "check" parameter doesn't do anything. We're requesting
    * a connection from ODBC. We'll either get a new one, which obviously is already connected, or
    * we'll get one from the ODBC connection pool. In that case, it will ensure to only give us a
    * live connection
    */
   return _ast_odbc_request_obj2(name, flags, file, function, lineno);
}

static odbc_status odbc_obj_disconnect(struct odbc_obj *obj)
{
   int res;
   SQLINTEGER err;
   short int mlen;
   unsigned char msg[200], state[10];
   SQLHDBC con;

   /* Nothing to disconnect */
   if (!obj->con) {
      return ODBC_SUCCESS;
   }

   con = obj->con;
   obj->con = NULL;
   res = SQLDisconnect(con);

   if ((res = SQLFreeHandle(SQL_HANDLE_DBC, con)) == SQL_SUCCESS) {
      ast_debug(3, "Database handle %p (connection %p) deallocated\n", obj, con);
   } else {
      SQLGetDiagRec(SQL_HANDLE_DBC, con, 1, state, &err, msg, 100, &mlen);
      ast_log(LOG_WARNING, "Unable to deallocate database handle %p? %d errno=%d %s\n", con, res, (int)err, msg);
   }

   return ODBC_SUCCESS;
}

static odbc_status odbc_obj_connect(struct odbc_obj *obj)
{
   int res;
   SQLINTEGER err;
   short int mlen;
   unsigned char msg[200], state[10];
#ifdef NEEDTRACE
   SQLINTEGER enable = 1;
   char *tracefile = "/tmp/odbc.trace";
#endif
   SQLHDBC con;
   long int negative_cache_expiration;

   ast_assert(obj->con == NULL);
   ast_debug(3, "Connecting %s(%p)\n", obj->parent->name, obj);

   /* Dont connect while server is marked as unreachable via negative_connection_cache */
   negative_cache_expiration = obj->parent->last_negative_connect.tv_sec + obj->parent->negative_connection_cache.tv_sec;
   if (time(NULL) < negative_cache_expiration) {
      ast_log(LOG_WARNING, "Not connecting to %s. Negative connection cache for %ld seconds\n", obj->parent->name, negative_cache_expiration - time(NULL));
      return ODBC_FAIL;
   }

   res = SQLAllocHandle(SQL_HANDLE_DBC, obj->parent->env, &con);

   if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO)) {
      ast_log(LOG_WARNING, "res_odbc: Error AllocHDB %d\n", res);
      obj->parent->last_negative_connect = ast_tvnow();
      return ODBC_FAIL;
   }
   SQLSetConnectAttr(con, SQL_LOGIN_TIMEOUT, (SQLPOINTER *)(long) obj->parent->conntimeout, 0);
   SQLSetConnectAttr(con, SQL_ATTR_CONNECTION_TIMEOUT, (SQLPOINTER *)(long) obj->parent->conntimeout, 0);
#ifdef NEEDTRACE
   SQLSetConnectAttr(con, SQL_ATTR_TRACE, &enable, SQL_IS_INTEGER);
   SQLSetConnectAttr(con, SQL_ATTR_TRACEFILE, tracefile, strlen(tracefile));
#endif

   res = SQLConnect(con,
         (SQLCHAR *) obj->parent->dsn, SQL_NTS,
         (SQLCHAR *) obj->parent->username, SQL_NTS,
         (SQLCHAR *) obj->parent->password, SQL_NTS);

   if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO)) {
      SQLGetDiagRec(SQL_HANDLE_DBC, con, 1, state, &err, msg, 100, &mlen);
      obj->parent->last_negative_connect = ast_tvnow();
      ast_log(LOG_WARNING, "res_odbc: Error SQLConnect=%d errno=%d %s\n", res, (int)err, msg);
      if ((res = SQLFreeHandle(SQL_HANDLE_DBC, con)) != SQL_SUCCESS) {
         SQLGetDiagRec(SQL_HANDLE_DBC, con, 1, state, &err, msg, 100, &mlen);
         ast_log(LOG_WARNING, "Unable to deallocate database handle %p? %d errno=%d %s\n", con, res, (int)err, msg);
      }
      return ODBC_FAIL;
   } else {
      ast_debug(3, "res_odbc: Connected to %s [%s (%p)]\n", obj->parent->name, obj->parent->dsn, obj);
   }

   obj->con = con;
   return ODBC_SUCCESS;
}

static int reload(void)
{
   struct odbc_cache_tables *table;
   struct odbc_class *class;
   struct ao2_iterator aoi = ao2_iterator_init(class_container, 0);

   /* First, mark all to be purged */
   while ((class = ao2_iterator_next(&aoi))) {
      class->delme = 1;
      ao2_ref(class, -1);
   }
   ao2_iterator_destroy(&aoi);

   load_odbc_config();

   aoi = ao2_iterator_init(class_container, 0);
   while ((class = ao2_iterator_next(&aoi))) {
      if (class->delme) {
         ao2_unlink(class_container, class);
      }
      ao2_ref(class, -1);
   }
   ao2_iterator_destroy(&aoi);

   /* Empty the cache; it will get rebuilt the next time the tables are needed. */
   AST_RWLIST_WRLOCK(&odbc_tables);
   while ((table = AST_RWLIST_REMOVE_HEAD(&odbc_tables, list))) {
      destroy_table_cache(table);
   }
   AST_RWLIST_UNLOCK(&odbc_tables);

   return 0;
}

static int unload_module(void)
{
   ao2_cleanup(class_container);
   ast_cli_unregister_multiple(cli_odbc, ARRAY_LEN(cli_odbc));

   return 0;
}

static int load_module(void)
{
   class_container = ao2_container_alloc_list(AO2_ALLOC_OPT_LOCK_MUTEX, 0, NULL, ao2_match_by_addr);
   if (!class_container) {
      return AST_MODULE_LOAD_DECLINE;
   }

   if (load_odbc_config() == -1) {
      return AST_MODULE_LOAD_DECLINE;
   }

   ast_module_shutdown_ref(ast_module_info->self);
   ast_cli_register_multiple(cli_odbc, ARRAY_LEN(cli_odbc));

   return AST_MODULE_LOAD_SUCCESS;
}

AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_GLOBAL_SYMBOLS | AST_MODFLAG_LOAD_ORDER, "ODBC resource",
   .support_level = AST_MODULE_SUPPORT_CORE,
   .load = load_module,
   .unload = unload_module,
   .reload = reload,
   .load_pri = AST_MODPRI_REALTIME_DEPEND,
   .requires = "res_odbc_transaction",
);