res_config_mysql.c

/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999-2005, Digium, Inc.
 *
 * Mark Spencer <markster@digium.com>  - Asterisk Author
 * Matthew Boehm <mboehm@cytelcom.com> - MySQL RealTime Driver Author
 *
 * 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 MySQL CDR backend
 */

/*** MODULEINFO
	<depend>mysqlclient</depend>
	<defaultenabled>no</defaultenabled>
	<support_level>extended</support_level>
 ***/

#include "asterisk.h"

#include <sys/stat.h>

#include <mysql/mysql.h>
#include <mysql/errmsg.h>

#include "asterisk/channel.h"
#include "asterisk/logger.h"
#include "asterisk/config.h"
#include "asterisk/module.h"
#include "asterisk/lock.h"
#include "asterisk/options.h"
#include "asterisk/cli.h"
#include "asterisk/utils.h"
#include "asterisk/threadstorage.h"
#include "asterisk/strings.h"

#define RES_CONFIG_MYSQL_CONF "res_config_mysql.conf"
#define RES_CONFIG_MYSQL_CONF_OLD "res_mysql.conf"
#define	READHANDLE	0
#define	WRITEHANDLE	1

#define ESCAPE_STRING(buf, var) \
	do { \
		struct ast_str *semi = ast_str_thread_get(&scratch2_buf, strlen(var) * 3 + 1); \
		const char *chunk = var; \
		ast_str_reset(semi); \
		for (; *chunk; chunk++) { \
			if (strchr(";^", *chunk)) { \
				ast_str_append(&semi, 0, "^%02hhX", *chunk); \
			} else { \
				ast_str_append(&semi, 0, "%c", *chunk); \
			} \
		} \
		if (ast_str_strlen(semi) * 2 + 1 > ast_str_size(buf)) { \
			ast_str_make_space(&(buf), ast_str_strlen(semi) * 2 + 1); \
		} \
		mysql_real_escape_string(&dbh->handle, ast_str_buffer(buf), ast_str_buffer(semi), ast_str_strlen(semi)); \
	} while (0)

AST_THREADSTORAGE(sql_buf);
AST_THREADSTORAGE(sql2_buf);
AST_THREADSTORAGE(find_buf);
AST_THREADSTORAGE(scratch_buf);
AST_THREADSTORAGE(scratch2_buf);
AST_THREADSTORAGE(modify_buf);
AST_THREADSTORAGE(modify2_buf);
AST_THREADSTORAGE(modify3_buf);

enum requirements { RQ_WARN, RQ_CREATECLOSE, RQ_CREATECHAR };

struct mysql_conn {
	AST_RWLIST_ENTRY(mysql_conn) list;
	ast_mutex_t	lock;
	MYSQL       handle;
	char        host[50];
	char        name[50];
	char        user[50];
	char        pass[50];
	char        sock[50];
	char        charset[50];
	int         port;
	int         connected;
	time_t      connect_time;
	enum requirements requirements;
	char        unique_name[0];
};

struct columns {
	char *name;
	char *type;
	char *dflt;
	char null;
	int len;
	AST_LIST_ENTRY(columns) list;
};

struct tables {
	ast_mutex_t lock;
	AST_LIST_HEAD_NOLOCK(mysql_columns, columns) columns;
	AST_LIST_ENTRY(tables) list;
	struct mysql_conn *database;
	char name[0];
};

static AST_LIST_HEAD_STATIC(mysql_tables, tables);
static AST_RWLIST_HEAD_STATIC(databases, mysql_conn);

static int parse_config(int reload);
static int mysql_reconnect(struct mysql_conn *conn);
static char *handle_cli_realtime_mysql_status(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a);
static char *handle_cli_realtime_mysql_cache(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a);
static int load_mysql_config(struct ast_config *config, const char *category, struct mysql_conn *conn);
static int require_mysql(const char *database, const char *tablename, va_list ap);

static struct ast_cli_entry cli_realtime_mysql_status[] = {
	AST_CLI_DEFINE(handle_cli_realtime_mysql_status, "Shows connection information for the MySQL RealTime driver"),
	AST_CLI_DEFINE(handle_cli_realtime_mysql_cache, "Shows cached tables within the MySQL realtime driver"),
};

static struct mysql_conn *find_database(const char *database, int for_write)
{
	char *whichdb;
	const char *ptr;
	struct mysql_conn *cur;

	if ((ptr = strchr(database, '/'))) {
		/* Multiple databases encoded within string */
		if (for_write) {
			whichdb = ast_strdupa(ptr + 1);
		} else {
			whichdb = ast_alloca(ptr - database + 1);
			strncpy(whichdb, database, ptr - database);
			whichdb[ptr - database] = '\0';
		}
	} else {
		whichdb = ast_strdupa(database);
	}

	AST_RWLIST_RDLOCK(&databases);
	AST_RWLIST_TRAVERSE(&databases, cur, list) {
		if (!strcmp(cur->unique_name, whichdb)) {
			ast_mutex_lock(&cur->lock);
			break;
		}
	}
	AST_RWLIST_UNLOCK(&databases);
	return cur;
}

#define release_database(a)	ast_mutex_unlock(&(a)->lock)

static void destroy_table(struct tables *table)
{
	struct columns *column;
	ast_mutex_lock(&table->lock);
	while ((column = AST_LIST_REMOVE_HEAD(&table->columns, list))) {
		ast_free(column);
	}
	ast_mutex_unlock(&table->lock);
	ast_mutex_destroy(&table->lock);
	ast_free(table);
}

static struct tables *find_table(const char *database, const char *tablename)
{
	struct columns *column;
	struct tables *table;
	struct ast_str *sql = ast_str_thread_get(&find_buf, 30);
	char *fname, *ftype, *flen, *fdflt, *fnull;
	struct mysql_conn *dbh;
	MYSQL_RES *result;
	MYSQL_ROW row;

	if (!(dbh = find_database(database, 1))) {
		return NULL;
	}

	AST_LIST_LOCK(&mysql_tables);
	AST_LIST_TRAVERSE(&mysql_tables, table, list) {
		if (!strcasecmp(table->name, tablename)) {
			ast_mutex_lock(&table->lock);
			AST_LIST_UNLOCK(&mysql_tables);
			release_database(dbh);
			return table;
		}
	}

	/* Not found, scan the table */
	ast_str_set(&sql, 0, "DESC %s", tablename);

	if (!mysql_reconnect(dbh)) {
		release_database(dbh);
		AST_LIST_UNLOCK(&mysql_tables);
		return NULL;
	}

	if (mysql_real_query(&dbh->handle, ast_str_buffer(sql), ast_str_strlen(sql))) {
		ast_log(LOG_ERROR, "Failed to query database '%s', table '%s' columns: %s\n", database, tablename, mysql_error(&dbh->handle));
		release_database(dbh);
		AST_LIST_UNLOCK(&mysql_tables);
		return NULL;
	}

	if (!(table = ast_calloc(1, sizeof(*table) + strlen(tablename) + 1))) {
		ast_log(LOG_ERROR, "Unable to allocate memory for new table structure\n");
		release_database(dbh);
		AST_LIST_UNLOCK(&mysql_tables);
		return NULL;
	}
	strcpy(table->name, tablename); /* SAFE */
	table->database = dbh;
	ast_mutex_init(&table->lock);
	AST_LIST_HEAD_INIT_NOLOCK(&table->columns);

	if ((result = mysql_store_result(&dbh->handle))) {
		while ((row = mysql_fetch_row(result))) {
			fname = row[0];
			ftype = row[1];
			fnull = row[2];
			fdflt = row[4];
			ast_verb(4, "Found column '%s' of type '%s'\n", fname, ftype);

			if (fdflt == NULL) {
				fdflt = "";
			}

			if (!(column = ast_calloc(1, sizeof(*column) + strlen(fname) + strlen(ftype) + strlen(fdflt) + 3))) {
				ast_log(LOG_ERROR, "Unable to allocate column element %s for %s\n", fname, tablename);
				destroy_table(table);
				release_database(dbh);
				AST_LIST_UNLOCK(&mysql_tables);
				return NULL;
			}

			if ((flen = strchr(ftype, '('))) {
				sscanf(flen, "(%30d)", &column->len);
			} else {
				/* Columns like dates, times, and timestamps don't have a length */
				column->len = -1;
			}

			column->name = (char *)column + sizeof(*column);
			column->type = (char *)column + sizeof(*column) + strlen(fname) + 1;
			column->dflt = (char *)column + sizeof(*column) + strlen(fname) + 1 + strlen(ftype) + 1;
			strcpy(column->name, fname);
			strcpy(column->type, ftype);
			strcpy(column->dflt, fdflt);
			column->null = (strcmp(fnull, "YES") == 0 ? 1 : 0);
			AST_LIST_INSERT_TAIL(&table->columns, column, list);
		}
		mysql_free_result(result);
	}

	AST_LIST_INSERT_TAIL(&mysql_tables, table, list);
	ast_mutex_lock(&table->lock);
	AST_LIST_UNLOCK(&mysql_tables);
	release_database(dbh);
	return table;
}

static void release_table(struct tables *table)
{
	if (table) {
		ast_mutex_unlock(&table->lock);
	}
}

static struct columns *find_column(struct tables *table, const char *colname)
{
	struct columns *column;

	AST_LIST_TRAVERSE(&table->columns, column, list) {
		if (strcmp(column->name, colname) == 0) {
			break;
		}
	}

	return column;
}

static char *decode_chunk(char *chunk)
{
	char *orig = chunk;
	for (; *chunk; chunk++) {
		if (*chunk == '^' && strchr("0123456789ABCDEFabcdef", chunk[1]) && strchr("0123456789ABCDEFabcdef", chunk[2])) {
			sscanf(chunk + 1, "%02hhX", chunk);
			memmove(chunk + 1, chunk + 3, strlen(chunk + 3) + 1);
		}
	}
	return orig;
}

#define IS_SQL_LIKE_CLAUSE(x) ((x) && ast_ends_with(x, " LIKE"))

/* MySQL requires us to escape the escape... yo dawg */
static char *ESCAPE_CLAUSE = " ESCAPE '\\\\'";

static struct ast_variable *realtime_mysql(const char *database, const char *table, const struct ast_variable *rt_fields)
{
	struct mysql_conn *dbh;
	MYSQL_RES *result;
	MYSQL_ROW row;
	MYSQL_FIELD *fields;
	int numFields, i;
	struct ast_str *sql = ast_str_thread_get(&sql_buf, 16);
	struct ast_str *buf = ast_str_thread_get(&scratch_buf, 16);
	char *stringp;
	char *chunk;
	char *op;
	char *escape = "";
	const struct ast_variable *field = rt_fields;
	struct ast_variable *var=NULL, *prev=NULL;

	if (!(dbh = find_database(database, 0))) {
		ast_log(LOG_WARNING, "MySQL RealTime: Invalid database specified: %s (check res_mysql.conf)\n", database);
		return NULL;
	}

	if (!table) {
		ast_log(LOG_WARNING, "MySQL RealTime: No table specified.\n");
		release_database(dbh);
		return NULL;
	}

	/* Get the first parameter and first value in our list of passed paramater/value pairs */
	if (!field) {
		ast_log(LOG_WARNING, "MySQL RealTime: Realtime retrieval requires at least 1 parameter and 1 value to search on.\n");
		release_database(dbh);
		return NULL;
	}

	/* Must connect to the server before anything else, as the escape function requires the mysql handle. */
	if (!mysql_reconnect(dbh)) {
		release_database(dbh);
		return NULL;
	}

	/* Create the first part of the query using the first parameter/value pairs we just extracted
	   If there is only 1 set, then we have our query. Otherwise, loop thru the list and concat */

	if (!strchr(field->name, ' ')) {
		op = " =";
	} else {
		op = "";
		if (IS_SQL_LIKE_CLAUSE(field->name)) {
			escape = ESCAPE_CLAUSE;
		}
	}

	ESCAPE_STRING(buf, field->value);
	ast_str_set(&sql, 0, "SELECT * FROM %s WHERE %s%s '%s'%s", table, field->name, op, ast_str_buffer(buf), escape);
	while ((field = field->next)) {
		escape = "";
		if (!strchr(field->name, ' ')) {
			op = " =";
		} else {
			op = "";
			if (IS_SQL_LIKE_CLAUSE(field->name)) {
				escape = ESCAPE_CLAUSE;
			}
		}
		ESCAPE_STRING(buf, field->value);
		ast_str_append(&sql, 0, " AND %s%s '%s'%s", field->name, op, ast_str_buffer(buf), escape);
	}

	ast_debug(1, "MySQL RealTime: Retrieve SQL: %s\n", ast_str_buffer(sql));

	/* Execution. */
	if (mysql_real_query(&dbh->handle, ast_str_buffer(sql), ast_str_strlen(sql))) {
		ast_log(LOG_WARNING, "MySQL RealTime: Failed to query database: %s\n", mysql_error(&dbh->handle));
		release_database(dbh);
		return NULL;
	}

	if ((result = mysql_store_result(&dbh->handle))) {
		numFields = mysql_num_fields(result);
		fields = mysql_fetch_fields(result);

		while ((row = mysql_fetch_row(result))) {
			for (i = 0; i < numFields; i++) {
				/* Encode NULL values separately from blank values, for the Realtime API */
				if (row[i] == NULL) {
					row[i] = "";
				} else if (ast_strlen_zero(row[i])) {
					row[i] = " ";
				}
				for (stringp = row[i], chunk = strsep(&stringp, ";"); chunk; chunk = strsep(&stringp, ";")) {
					if (prev) {
						if ((prev->next = ast_variable_new(fields[i].name, decode_chunk(chunk), ""))) {
							prev = prev->next;
						}
					} else {
						prev = var = ast_variable_new(fields[i].name, decode_chunk(chunk), "");
					}
				}
			}
		}
	} else {
		ast_debug(1, "MySQL RealTime: Could not find any rows in table %s.\n", table);
	}

	release_database(dbh);
	mysql_free_result(result);

	return var;
}

static struct ast_config *realtime_multi_mysql(const char *database, const char *table, const struct ast_variable *rt_fields)
{
	struct mysql_conn *dbh;
	MYSQL_RES *result;
	MYSQL_ROW row;
	MYSQL_FIELD *fields;
	int numFields, i;
	struct ast_str *sql = ast_str_thread_get(&sql_buf, 16);
	struct ast_str *buf = ast_str_thread_get(&scratch_buf, 16);
	const char *initfield = NULL;
	char *stringp;
	char *chunk;
	char *op;
	char *escape = "";
	const struct ast_variable *field = rt_fields;
	struct ast_variable *var = NULL;
	struct ast_config *cfg = NULL;
	struct ast_category *cat = NULL;

	if (!(dbh = find_database(database, 0))) {
		ast_log(LOG_WARNING, "MySQL RealTime: Invalid database specified: '%s' (check res_mysql.conf)\n", database);
		return NULL;
	}

	if (!table) {
		ast_log(LOG_WARNING, "MySQL RealTime: No table specified.\n");
		release_database(dbh);
		return NULL;
	}

	if (!(cfg = ast_config_new())) {
		/* If I can't alloc memory at this point, why bother doing anything else? */
		ast_log(LOG_WARNING, "Out of memory!\n");
		release_database(dbh);
		return NULL;
	}

	/* Get the first parameter and first value in our list of passed paramater/value pairs */
	if (!field) {
		ast_log(LOG_WARNING, "MySQL RealTime: Realtime retrieval requires at least 1 parameter and 1 value to search on.\n");
		ast_config_destroy(cfg);
		release_database(dbh);
		return NULL;
	}

	initfield = ast_strdupa(field->name);
	if ((op = strchr(initfield, ' '))) {
		*op = '\0';
	}

	/* Must connect to the server before anything else, as the escape function requires the mysql handle. */
	if (!mysql_reconnect(dbh)) {
		release_database(dbh);
		ast_config_destroy(cfg);
		return NULL;
	}

	/* Create the first part of the query using the first parameter/value pairs we just extracted
	   If there is only 1 set, then we have our query. Otherwise, loop thru the list and concat */

	if (!strchr(field->name, ' ')) {
		op = " =";
	} else {
		op = "";
		if (IS_SQL_LIKE_CLAUSE(field->name)) {
			escape = ESCAPE_CLAUSE;
		}
	}

	ESCAPE_STRING(buf, field->value);
	ast_str_set(&sql, 0, "SELECT * FROM %s WHERE %s%s '%s'%s", table, field->name, op, ast_str_buffer(buf), escape);
	while ((field = field->next)) {
		escape = "";
		if (!strchr(field->name, ' ')) {
			op = " =";
		} else {
			op = "";
			if (IS_SQL_LIKE_CLAUSE(field->name)) {
				escape = ESCAPE_CLAUSE;
			}
		}
		ESCAPE_STRING(buf, field->value);
		ast_str_append(&sql, 0, " AND %s%s '%s'%s", field->name, op, ast_str_buffer(buf), escape);
	}

	if (initfield) {
		ast_str_append(&sql, 0, " ORDER BY %s", initfield);
	}

	ast_debug(1, "MySQL RealTime: Retrieve SQL: %s\n", ast_str_buffer(sql));

	/* Execution. */
	if (mysql_real_query(&dbh->handle, ast_str_buffer(sql), ast_str_strlen(sql))) {
		ast_log(LOG_WARNING, "MySQL RealTime: Failed to query database: %s\n", mysql_error(&dbh->handle));
		release_database(dbh);
		ast_config_destroy(cfg);
		return NULL;
	}

	if ((result = mysql_store_result(&dbh->handle))) {
		numFields = mysql_num_fields(result);
		fields = mysql_fetch_fields(result);

		while ((row = mysql_fetch_row(result))) {
			var = NULL;
			cat = ast_category_new_anonymous();
			if (!cat) {
				continue;
			}
			for (i = 0; i < numFields; i++) {
				if (ast_strlen_zero(row[i]))
					continue;
				for (stringp = row[i], chunk = strsep(&stringp, ";"); chunk; chunk = strsep(&stringp, ";")) {
					if (chunk && !ast_strlen_zero(decode_chunk(ast_strip(chunk)))) {
						if (initfield && !strcmp(initfield, fields[i].name)) {
							ast_category_rename(cat, chunk);
						}
						var = ast_variable_new(fields[i].name, chunk, "");
						ast_variable_append(cat, var);
					}
				}
			}
			ast_category_append(cfg, cat);
		}
	} else {
		ast_debug(1, "MySQL RealTime: Could not find any rows in table %s.\n", table);
	}

	release_database(dbh);
	mysql_free_result(result);

	return cfg;
}

static int update_mysql(const char *database, const char *tablename, const char *keyfield, const char *lookup, const struct ast_variable *rt_fields)
{
	struct mysql_conn *dbh;
	uint64_t numrows;
	const struct ast_variable *field = rt_fields;
	struct ast_str *sql = ast_str_thread_get(&sql_buf, 100), *buf = ast_str_thread_get(&scratch_buf, 100);
	struct tables *table;
	struct columns *column = NULL;

	if (!(dbh = find_database(database, 1))) {
		ast_log(LOG_WARNING, "MySQL RealTime: Invalid database specified: '%s' (check res_mysql.conf)\n", database);
		return -1;
	}

	if (!tablename) {
		ast_log(LOG_WARNING, "MySQL RealTime: No table specified.\n");
		release_database(dbh);
		return -1;
	}

	if (!(table = find_table(database, tablename))) {
		ast_log(LOG_ERROR, "Table '%s' does not exist!!\n", tablename);
		release_database(dbh);
		return -1;
	}

	if (!(column = find_column(table, keyfield))) {
		ast_log(LOG_ERROR, "MySQL RealTime: Updating on column '%s', but that column does not exist within the table '%s' (db '%s')!\n", keyfield, tablename, database);
		release_table(table);
		release_database(dbh);
		return -1;
	}

	/* Get the first parameter and first value in our list of passed paramater/value pairs */
	if (!field) {
		ast_log(LOG_WARNING, "MySQL RealTime: Realtime update requires at least 1 parameter and 1 value to update.\n");
		release_table(table);
		release_database(dbh);
		return -1;
	}

	/* Check that the column exists in the table */
	if (!(column = find_column(table, field->name))) {
		ast_log(LOG_ERROR, "MySQL RealTime: Updating column '%s', but that column does not exist within the table '%s' (first pair MUST exist)!\n", field->name, tablename);
		release_table(table);
		release_database(dbh);
		return -1;
	}

	/* Must connect to the server before anything else, as the escape function requires the mysql handle. */
	if (!mysql_reconnect(dbh)) {
		release_table(table);
		release_database(dbh);
		return -1;
	}

	/* Create the first part of the query using the first parameter/value pairs we just extracted
	   If there is only 1 set, then we have our query. Otherwise, loop thru the list and concat */

	ESCAPE_STRING(buf, field->value);
	ast_str_set(&sql, 0, "UPDATE %s SET `%s` = '%s'", tablename, field->name, ast_str_buffer(buf));

	while ((field = field->next)) {
		/* If the column is not within the table, then skip it */
		if (!(column = find_column(table, field->name))) {
			ast_log(LOG_WARNING, "Attempted to update column '%s' in table '%s', but column does not exist!\n", field->name, tablename);
			continue;
		}

		ESCAPE_STRING(buf, field->value);
		ast_str_append(&sql, 0, ", `%s` = '%s'", field->name, ast_str_buffer(buf));
	}

	ESCAPE_STRING(buf, lookup);
	ast_str_append(&sql, 0, " WHERE `%s` = '%s'", keyfield, ast_str_buffer(buf));

	ast_debug(1, "MySQL RealTime: Update SQL: %s\n", ast_str_buffer(sql));

	/* Execution. */
	if (mysql_real_query(&dbh->handle, ast_str_buffer(sql), ast_str_strlen(sql))) {
		ast_log(LOG_WARNING, "MySQL RealTime: Failed to update database: %s\n", mysql_error(&dbh->handle));
		release_table(table);
		release_database(dbh);
		return -1;
	}

	numrows = mysql_affected_rows(&dbh->handle);
	release_table(table);
	release_database(dbh);

	ast_debug(1, "MySQL RealTime: Updated %" PRIu64 " rows on table: %s\n", numrows, tablename);

	/* From http://dev.mysql.com/doc/mysql/en/mysql-affected-rows.html
	 * An integer greater than zero indicates the number of rows affected
	 * Zero indicates that no records were updated
	 * -1 indicates that the query returned an error (although, if the query failed, it should have been caught above.)
	*/

	return (int)numrows;
}

static int update2_mysql(const char *database, const char *tablename, const struct ast_variable *lookup_fields, const struct ast_variable *update_fields)
{
	struct mysql_conn *dbh;
	uint64_t numrows;
	int first;
	const struct ast_variable *field;
	struct ast_str *sql = ast_str_thread_get(&sql_buf, 100), *buf = ast_str_thread_get(&scratch_buf, 100);
	struct ast_str *where = ast_str_thread_get(&sql2_buf, 100);
	struct tables *table;
	struct columns *column = NULL;

	if (!tablename) {
		ast_log(LOG_WARNING, "MySQL RealTime: No table specified.\n");
		return -1;
	}

	if (!(dbh = find_database(database, 1))) {
		ast_log(LOG_ERROR, "Invalid database specified: %s\n", database);
		return -1;
	}

	if (!(table = find_table(database, tablename))) {
		ast_log(LOG_ERROR, "Table '%s' does not exist!!\n", tablename);
		release_database(dbh);
		return -1;
	}

	if (!sql || !buf || !where) {
		release_database(dbh);
		release_table(table);
		return -1;
	}

	ast_str_set(&sql, 0, "UPDATE %s SET", tablename);
	ast_str_set(&where, 0, "WHERE");

	/* Must connect to the server before anything else, as the escape function requires the mysql handle. */
	if (!mysql_reconnect(dbh)) {
		release_table(table);
		release_database(dbh);
		return -1;
	}

	first = 1;
	for (field = lookup_fields; field; field = field->next) {
		if (!(column = find_column(table, field->name))) {
			ast_log(LOG_ERROR, "Updating on column '%s', but that column does not exist within the table '%s'!\n", field->name, tablename);
			release_table(table);
			release_database(dbh);
			return -1;
		}
		ESCAPE_STRING(buf, field->value);
		ast_str_append(&where, 0, "%s `%s` = '%s'", first ? "" : " AND", field->name, ast_str_buffer(buf));
		first = 0;
	}

	first = 1;
	for (field = update_fields; field; field = field->next) {
		/* If the column is not within the table, then skip it */
		if (!(column = find_column(table, field->name))) {
			ast_log(LOG_WARNING, "Attempted to update column '%s' in table '%s', but column does not exist!\n", field->name, tablename);
			continue;
		}

		ESCAPE_STRING(buf, field->value);
		ast_str_append(&sql, 0, "%s `%s` = '%s'", first ? "" : ",", field->name, ast_str_buffer(buf));
		first = 0;
	}

	release_table(table);

	ast_str_append(&sql, 0, " %s", ast_str_buffer(where));

	ast_debug(1, "MySQL RealTime: Update SQL: %s\n", ast_str_buffer(sql));

	/* Execution. */
	if (mysql_real_query(&dbh->handle, ast_str_buffer(sql), ast_str_strlen(sql))) {
		ast_log(LOG_WARNING, "MySQL RealTime: Failed to update database: %s\n", mysql_error(&dbh->handle));
		release_table(table);
		release_database(dbh);
		return -1;
	}

	numrows = mysql_affected_rows(&dbh->handle);
	release_database(dbh);

	ast_debug(1, "MySQL RealTime: Updated %" PRIu64 " rows on table: %s\n", numrows, tablename);

	/* From http://dev.mysql.com/doc/mysql/en/mysql-affected-rows.html
	 * An integer greater than zero indicates the number of rows affected
	 * Zero indicates that no records were updated
	 * -1 indicates that the query returned an error (although, if the query failed, it should have been caught above.)
	*/

	return (int)numrows;
}

static int store_mysql(const char *database, const char *table, const struct ast_variable *rt_fields)
{
	struct mysql_conn *dbh;
	struct ast_str *sql = ast_str_thread_get(&sql_buf, 16);
	struct ast_str *sql2 = ast_str_thread_get(&sql2_buf, 16);
	struct ast_str *buf = ast_str_thread_get(&scratch_buf, 16);
	const struct ast_variable *field = rt_fields;

	if (!(dbh = find_database(database, 1))) {
		ast_log(LOG_WARNING, "MySQL RealTime: Invalid database specified: '%s' (check res_mysql.conf)\n", database);
		return -1;
	}

	if (!table) {
		ast_log(LOG_WARNING, "MySQL RealTime: No table specified.\n");
		release_database(dbh);
		return -1;
	}
	/* Get the first parameter and first value in our list of passed paramater/value pairs */
	if (!field) {
		ast_log(LOG_WARNING, "MySQL RealTime: Realtime storage requires at least 1 parameter and 1 value to search on.\n");
		release_database(dbh);
		return -1;
	}
	/* Must connect to the server before anything else, as the escape function requires the mysql handle. */
	if (!mysql_reconnect(dbh)) {
		release_database(dbh);
		return -1;
	}
	/* Create the first part of the query using the first parameter/value pairs we just extracted
		If there is only 1 set, then we have our query. Otherwise, loop thru the list and concat */
	ESCAPE_STRING(buf, field->value);
	ast_str_set(&sql, 0, "INSERT INTO %s (`%s`", table, field->name);
	ast_str_set(&sql2, 0, ") VALUES ('%s'", ast_str_buffer(buf));

	while ((field = field->next)) {
		ESCAPE_STRING(buf, field->value);

		ast_str_append(&sql, 0, ", `%s`", field->name);
		ast_str_append(&sql2, 0, ", '%s'", ast_str_buffer(buf));
	}
	ast_str_append(&sql, 0, "%s)", ast_str_buffer(sql2));
	ast_debug(1,"MySQL RealTime: Insert SQL: %s\n", ast_str_buffer(sql));

	/* Execution. */
	if (mysql_real_query(&dbh->handle, ast_str_buffer(sql), ast_str_strlen(sql))) {
		ast_log(LOG_WARNING, "MySQL RealTime: Failed to insert into database: %s\n", mysql_error(&dbh->handle));
		release_database(dbh);
		return -1;
	}

	release_database(dbh);

	ast_debug(1, "MySQL RealTime: row inserted on table: %s\n", table);

	return 1;
}

static int destroy_mysql(const char *database, const char *table, const char *keyfield, const char *lookup, const struct ast_variable *rt_fields)
{
	struct mysql_conn *dbh;
	uint64_t numrows;
	struct ast_str *sql = ast_str_thread_get(&sql_buf, 16);
	struct ast_str *buf = ast_str_thread_get(&scratch_buf, 16);
	const struct ast_variable *field;

	if (!(dbh = find_database(database, 1))) {
		ast_log(LOG_WARNING, "MySQL RealTime: Invalid database specified: '%s' (check res_mysql.conf)\n", database);
		return -1;
	}

	if (!table) {
		ast_log(LOG_WARNING, "MySQL RealTime: No table specified.\n");
		release_database(dbh);
		return -1;
	}

	/* Get the first parameter and first value in our list of passed paramater/value pairs */
	/* newparam = va_arg(ap, const char *);
	newval = va_arg(ap, const char *);*/
	if (ast_strlen_zero(keyfield) || ast_strlen_zero(lookup))  {
		ast_log(LOG_WARNING, "MySQL RealTime: Realtime destroying requires at least 1 parameter and 1 value to search on.\n");
		release_database(dbh);
		return -1;
	}

	/* Must connect to the server before anything else, as the escape function requires the mysql handle. */
	if (!mysql_reconnect(dbh)) {
		release_database(dbh);
		return -1;
	}

	/* Create the first part of the query using the first parameter/value pairs we just extracted
	   If there is only 1 set, then we have our query. Otherwise, loop thru the list and concat */
	ESCAPE_STRING(buf, lookup);
	ast_str_set(&sql, 0, "DELETE FROM %s WHERE `%s` = '%s'", table, keyfield, ast_str_buffer(buf));
	for (field = rt_fields; field; field = field->next) {
		ESCAPE_STRING(buf, field->value);
		ast_str_append(&sql, 0, " AND `%s` = '%s'", field->name, ast_str_buffer(buf));
	}

	ast_debug(1, "MySQL RealTime: Delete SQL: %s\n", ast_str_buffer(sql));

	/* Execution. */
	if (mysql_real_query(&dbh->handle, ast_str_buffer(sql), ast_str_strlen(sql))) {
		ast_log(LOG_WARNING, "MySQL RealTime: Failed to delete from database: %s\n", mysql_error(&dbh->handle));
		release_database(dbh);
		return -1;
	}

	numrows = mysql_affected_rows(&dbh->handle);
	release_database(dbh);

	ast_debug(1, "MySQL RealTime: Deleted %" PRIu64 " rows on table: %s\n", numrows, table);

	/* From http://dev.mysql.com/doc/mysql/en/mysql-affected-rows.html
	 * An integer greater than zero indicates the number of rows affected
	 * Zero indicates that no records were updated
	 * -1 indicates that the query returned an error (although, if the query failed, it should have been caught above.)
	*/

	return (int)numrows;
}

static struct ast_config *config_mysql(const char *database, const char *table, const char *file, struct ast_config *cfg, struct ast_flags config_flags, const char *unused, const char *who_asked)
{
	struct mysql_conn *dbh;
	MYSQL_RES *result;
	MYSQL_ROW row;
	uint64_t num_rows;
	struct ast_variable *new_v;
	struct ast_category *cur_cat = NULL;
	struct ast_str *sql = ast_str_thread_get(&sql_buf, 200);
	char last[80] = "";
	int last_cat_metric = 0;

	ast_clear_flag(&config_flags, CONFIG_FLAG_FILEUNCHANGED);

	if (!file || !strcmp(file, RES_CONFIG_MYSQL_CONF)) {
		ast_log(LOG_WARNING, "MySQL RealTime: Cannot configure myself.\n");
		return NULL;
	}

	if (!(dbh = find_database(database, 0))) {
		ast_log(LOG_WARNING, "MySQL RealTime: Invalid database specified: '%s' (check res_mysql.conf)\n", database);
		return NULL;
	}

	ast_str_set(&sql, 0, "SELECT category, var_name, var_val, cat_metric FROM %s WHERE filename='%s' and commented=0 ORDER BY filename, category, cat_metric desc, var_metric asc, var_name, var_val, id", table, file);

	ast_debug(1, "MySQL RealTime: Static SQL: %s\n", ast_str_buffer(sql));

	/* We now have our complete statement; Lets connect to the server and execute it. */
	if (!mysql_reconnect(dbh)) {
		return NULL;
	}

	if (mysql_real_query(&dbh->handle, ast_str_buffer(sql), ast_str_strlen(sql))) {
		ast_log(LOG_WARNING, "MySQL RealTime: Failed to query database. Check debug for more info.\n");
		ast_debug(1, "MySQL RealTime: Query: %s\n", ast_str_buffer(sql));
		ast_debug(1, "MySQL RealTime: Query Failed because: %s\n", mysql_error(&dbh->handle));
		release_database(dbh);
		return NULL;
	}

	if ((result = mysql_store_result(&dbh->handle))) {
		num_rows = mysql_num_rows(result);
		ast_debug(1, "MySQL RealTime: Found %" PRIu64 " rows.\n", num_rows);

		/* There might exist a better way to access the column names other than counting,
		 * but I believe that would require another loop that we don't need. */

		while ((row = mysql_fetch_row(result))) {
			if (!strcmp(row[1], "#include")) {
				if (!ast_config_internal_load(row[2], cfg, config_flags, "", who_asked)) {
					mysql_free_result(result);
					release_database(dbh);
					return NULL;
				}
				continue;
			}

			if (strcmp(last, row[0]) || last_cat_metric != atoi(row[3])) {
				cur_cat = ast_category_new_dynamic(row[0]);
				if (!cur_cat) {
					break;
				}
				strcpy(last, row[0]);
				last_cat_metric = atoi(row[3]);
				ast_category_append(cfg, cur_cat);
			}
			new_v = ast_variable_new(row[1], row[2], "");
			if (cur_cat)
				ast_variable_append(cur_cat, new_v);
		}
	} else {
		ast_log(LOG_WARNING, "MySQL RealTime: Could not find config '%s' in database.\n", file);
	}

	mysql_free_result(result);
	release_database(dbh);

	return cfg;
}

static int unload_mysql(const char *database, const char *tablename)
{
	struct tables *cur;
	AST_LIST_LOCK(&mysql_tables);
	AST_LIST_TRAVERSE_SAFE_BEGIN(&mysql_tables, cur, list) {
		if (strcmp(cur->name, tablename) == 0) {
			AST_LIST_REMOVE_CURRENT(list);
			destroy_table(cur);
			break;
		}
	}
	AST_LIST_TRAVERSE_SAFE_END
	AST_LIST_UNLOCK(&mysql_tables);
	return cur ? 0 : -1;
}

static int require_mysql(const char *database, const char *tablename, va_list ap)
{
	struct columns *column;
	struct tables *table = find_table(database, tablename);
	char *elm;
	int type;
	int size;
	int res = 0;

	if (!table) {
		ast_log(LOG_WARNING, "Table %s not found in database.  This table should exist if you're using realtime.\n", tablename);
		return -1;
	}

	while ((elm = va_arg(ap, char *))) {
		type = va_arg(ap, require_type);
		size = va_arg(ap, int);

		AST_LIST_TRAVERSE(&table->columns, column, list) {
			if (strcmp(column->name, elm) == 0) {
				/* Char can hold anything, as long as it is large enough */
				if (strncmp(column->type, "char", 4) == 0 || strncmp(column->type, "varchar", 7) == 0) {
					if ((size > column->len) && column->len != -1) {
						ast_log(LOG_WARNING, "Realtime table %s@%s: Column '%s' should be at least %d long, but is only %d long.\n", database, tablename, column->name, size, column->len);
						res = -1;
					}
				} else if (strcasestr(column->type, "unsigned")) {
					if (!ast_rq_is_int(type)) {