res_config_ldap.c

/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2005, Oxymium sarl
 * Manuel Guesdon <mguesdon@oxymium.net> - LDAP RealTime Driver Author/Adaptor
 *
 * Copyright (C) 2007, Digium, Inc.
 * Russell Bryant <russell@digium.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 LDAP plugin for portable configuration engine (ARA)
 *
 * \author Mark Spencer <markster@digium.com>
 * \author Manuel Guesdon
 * \author Carl-Einar Thorner <cthorner@voicerd.com>
 * \author Russell Bryant <russell@digium.com>
 *
 * OpenLDAP http://www.openldap.org
 */

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

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

/*** MODULEINFO
	<depend>ldap</depend>
	<support_level>extended</support_level>
 ***/

#include "asterisk.h"

#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <stdio.h>
#include <ldap.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/strings.h"
#include "asterisk/pbx.h"
#include "asterisk/linkedlists.h"

#define RES_CONFIG_LDAP_CONF "res_ldap.conf"
#define RES_CONFIG_LDAP_DEFAULT_BASEDN "asterisk"

AST_MUTEX_DEFINE_STATIC(ldap_lock);

static LDAP *ldapConn;
static char url[512];
static char user[512];
static char pass[512];
static char base_distinguished_name[512];
static int version;
static time_t connect_time;

static int parse_config(void);
static int ldap_reconnect(void);
static char *realtime_ldap_status(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a);

struct category_and_metric {
	const char *name;
	int metric;
	const char *variable_name;
	const char *variable_value;
	int var_metric; /*!< For organizing variables (particularly includes and switch statements) within a context */
};

/*! \brief Table configuration
 */
struct ldap_table_config {
	char *table_name;		 /*!< table name */
	char *additional_filter;	  /*!< additional filter	*/
	struct ast_variable *attributes;  /*!< attribute names conversion */
	struct ast_variable *delimiters;  /*!< the current delimiter is semicolon, so we are not using this variable */
	AST_LIST_ENTRY(ldap_table_config) entry;
	/*! \todo: Make proxies work */
};

/*! \brief Should be locked before using it
 */
static AST_LIST_HEAD_NOLOCK_STATIC(table_configs, ldap_table_config);
static struct ldap_table_config *base_table_config;
static struct ldap_table_config *static_table_config;

static struct ast_cli_entry ldap_cli[] = {
	AST_CLI_DEFINE(realtime_ldap_status, "Shows connection information for the LDAP RealTime driver"),
};

/*! \brief Create a new table_config
 */
static struct ldap_table_config *table_config_new(const char *table_name)
{
	struct ldap_table_config *p;

	if (!(p = ast_calloc(1, sizeof(*p))))
		return NULL;

	if (table_name) {
		if (!(p->table_name = ast_strdup(table_name))) {
			ast_free(p);
			return NULL;
		}
	}

	return p;
}

/*! \brief Find a table_config
 *
 * Should be locked before using it
 *
 *  \note This function assumes ldap_lock to be locked.
 */
static struct ldap_table_config *table_config_for_table_name(const char *table_name)
{
	struct ldap_table_config *c = NULL;

	AST_LIST_TRAVERSE(&table_configs, c, entry) {
		if (!strcmp(c->table_name, table_name))
			break;
	}

	return c;
}

/*! \brief Find variable by name
 */
static struct ast_variable *variable_named(struct ast_variable *var, const char *name)
{
	for (; var; var = var->next) {
		if (!strcasecmp(name, var->name))
			break;
	}

	return var;
}

/*!
 * \brief Count semicolons in string
 * \param somestr - pointer to a string
 *
 * \return number of occurances of the delimiter(semicolon)
 */
static int semicolon_count_str(const char *somestr)
{
	int count = 0;

	for (; *somestr; somestr++) {
		if (*somestr == ';')
			count++;
	}

	return count;
}

/*!
 * \brief Count semicolons in variables
 *
 * takes a linked list of \a ast_variable variables, finds the one with the name variable_value
 * and returns the number of semicolons in the value for that \a ast_variable
 */
static int semicolon_count_var(struct ast_variable *var)
{
	struct ast_variable *var_value = variable_named(var, "variable_value");

	if (!var_value) {
		return 0;
	}

	ast_debug(2, "semicolon_count_var: %s\n", var_value->value);

	return semicolon_count_str(var_value->value);
}

/*! \brief add attribute to table config
 *
 * Should be locked before using it
 */
static void ldap_table_config_add_attribute(struct ldap_table_config *table_config,
	const char *attribute_name, const char *attribute_value)
{
	struct ast_variable *var;

	if (ast_strlen_zero(attribute_name) || ast_strlen_zero(attribute_value)) {
		return;
	}

	if (!(var = ast_variable_new(attribute_name, attribute_value, table_config->table_name))) {
		return;
	}

	if (table_config->attributes) {
		var->next = table_config->attributes;
	}
	table_config->attributes = var;
}

/*! \brief Free table_config
 *
 * \note assumes ldap_lock to be locked
 */
static void table_configs_free(void)
{
	struct ldap_table_config *c;

	while ((c = AST_LIST_REMOVE_HEAD(&table_configs, entry))) {
		if (c->table_name) {
			ast_free(c->table_name);
		}
		if (c->additional_filter) {
			ast_free(c->additional_filter);
		}
		if (c->attributes) {
			ast_variables_destroy(c->attributes);
		}
		ast_free(c);
	}

	base_table_config = NULL;
	static_table_config = NULL;
}

/*! \brief Convert variable name to ldap attribute name
 *
 * \note Should be locked before using it
 */
static const char *convert_attribute_name_to_ldap(struct ldap_table_config *table_config,
	const char *attribute_name)
{
	int i = 0;
	struct ldap_table_config *configs[] = { table_config, base_table_config };

	for (i = 0; i < ARRAY_LEN(configs); i++) {
		struct ast_variable *attribute;

		if (!configs[i]) {
			continue;
		}

		attribute = configs[i]->attributes;
		for (; attribute; attribute = attribute->next) {
			if (!strcasecmp(attribute_name, attribute->name)) {
				return attribute->value;
			}
		}
	}

	return attribute_name;
}

/*! \brief Convert ldap attribute name to variable name
 *
 * \note Should be locked before using it
 */
static const char *convert_attribute_name_from_ldap(struct ldap_table_config *table_config,
						    const char *attribute_name)
{
	int i = 0;
	struct ldap_table_config *configs[] = { table_config, base_table_config };

	for (i = 0; i < ARRAY_LEN(configs); i++) {
		struct ast_variable *attribute;

		if (!configs[i]) {
			continue;
		}

		attribute = configs[i]->attributes;
		for (; attribute; attribute = attribute->next) {
			if (strcasecmp(attribute_name, attribute->value) == 0) {
				return attribute->name;
			}
		}
	}

	return attribute_name;
}

/*! \brief Get variables from ldap entry attributes
 * \note Should be locked before using it
 * \return a linked list of ast_variable variables.
 */
static struct ast_variable *realtime_ldap_entry_to_var(struct ldap_table_config *table_config,
	LDAPMessage *ldap_entry)
{
	BerElement *ber = NULL;
	struct ast_variable *var = NULL;
	struct ast_variable *prev = NULL;
#if 0
	int is_delimited = 0;
	int i = 0;
#endif
	char *ldap_attribute_name;
	struct berval *value;
	int pos = 0;

	ldap_attribute_name = ldap_first_attribute(ldapConn, ldap_entry, &ber);

	while (ldap_attribute_name) {
		struct berval **values = NULL;
		const char *attribute_name = convert_attribute_name_from_ldap(table_config, ldap_attribute_name);
		int is_realmed_password_attribute = strcasecmp(attribute_name, "md5secret") == 0;

		values = ldap_get_values_len(ldapConn, ldap_entry, ldap_attribute_name); /* these are freed at the end */
		if (values) {
			struct berval **v;
			char *valptr;

			for (v = values; *v; v++) {
				value = *v;
				valptr = value->bv_val;
				ast_debug(2, "attribute_name: %s LDAP value: %s\n", attribute_name, valptr);
				if (is_realmed_password_attribute) {
					if (!strncasecmp(valptr, "{md5}", 5)) {
						valptr += 5;
					}
					ast_debug(2, "md5: %s\n", valptr);
				}
				if (valptr) {
#if 0
					/* ok, so looping through all delimited values except the last one (not, last character is not delimited...) */
					if (is_delimited) {
						i = 0;
						pos = 0;
						while (!ast_strlen_zero(valptr + i)) {
							if (valptr[i] == ';') {
								valptr[i] = '\0';
								if (prev) {
									prev->next = ast_variable_new(attribute_name, &valptr[pos], table_config->table_name);
									if (prev->next) {
										prev = prev->next;
									}
								} else {
									prev = var = ast_variable_new(attribute_name, &valptr[pos], table_config->table_name);
								}
								pos = i + 1;
							}
							i++;
						}
					}
#endif
					/* for the last delimited value or if the value is not delimited: */
					if (prev) {
						prev->next = ast_variable_new(attribute_name, &valptr[pos], table_config->table_name);
						if (prev->next) {
							prev = prev->next;
						}
					} else {
						prev = var = ast_variable_new(attribute_name, &valptr[pos], table_config->table_name);
					}
				}
			}
			ldap_value_free_len(values);
		}
		ldap_memfree(ldap_attribute_name);
		ldap_attribute_name = ldap_next_attribute(ldapConn, ldap_entry, ber);
	}
	ber_free(ber, 0);

	return var;
}

/*! \brief Get variables from ldap entry attributes - Should be locked before using it
 *
 * The results are freed outside this function so is the \a vars array.
 *
 * \return \a vars - an array of ast_variable variables terminated with a null.
 */
static struct ast_variable **realtime_ldap_result_to_vars(struct ldap_table_config *table_config,
	LDAPMessage *ldap_result_msg, unsigned int *entries_count_ptr)
{
	struct ast_variable **vars;
	int i = 0;
	int tot_count = 0;
	int entry_index = 0;
	LDAPMessage *ldap_entry = NULL;
	BerElement *ber = NULL;
	struct ast_variable *var = NULL;
	struct ast_variable *prev = NULL;
	int is_delimited = 0;
	char *delim_value = NULL;
	int delim_tot_count = 0;
	int delim_count = 0;

	/*! \brief First find the total count
	 */
	ldap_entry = ldap_first_entry(ldapConn, ldap_result_msg);

	for (tot_count = 0; ldap_entry; tot_count++) {
		struct ast_variable *tmp = realtime_ldap_entry_to_var(table_config, ldap_entry);
		tot_count += semicolon_count_var(tmp);
		ldap_entry = ldap_next_entry(ldapConn, ldap_entry);
		ast_variables_destroy(tmp);
	}

	if (entries_count_ptr) {
		*entries_count_ptr = tot_count;
	}

	/*! \note Now that we have the total count we allocate space and create the variables
	 * Remember that each element in vars is a linked list that points to realtime variable.
	 * If the we are dealing with a static realtime variable we create a new element in the \a vars array for each delimited
	 * value in \a variable_value; otherwise, we keep \a vars static and increase the length of the linked list of variables in the array element.
	 * This memory must be freed outside of this function.
	 */
	vars = ast_calloc(tot_count + 1, sizeof(struct ast_variable *));

	ldap_entry = ldap_first_entry(ldapConn, ldap_result_msg);

	i = 0;

	/*! \brief For each static realtime variable we may create several entries in the \a vars array if it's delimited
	 */
	for (entry_index = 0; ldap_entry; ) {
		int pos = 0;
		delim_value = NULL;
		delim_tot_count = 0;
		delim_count = 0;

		do { /* while delim_count */

			/* Starting new static var */
			char *ldap_attribute_name = ldap_first_attribute(ldapConn, ldap_entry, &ber);
			struct berval *value;
			while (ldap_attribute_name) {
				const char *attribute_name = convert_attribute_name_from_ldap(table_config, ldap_attribute_name);
				int is_realmed_password_attribute = strcasecmp(attribute_name, "md5secret") == 0;
				struct berval **values = NULL;

				values = ldap_get_values_len(ldapConn, ldap_entry, ldap_attribute_name);
				if (values) {
					struct berval **v;
					char *valptr;

					for (v = values; *v; v++) {
						value = *v;
						valptr = value->bv_val;
						if (is_realmed_password_attribute) {
							if (strncasecmp(valptr, "{md5}", 5) == 0) {
								valptr += 5;
							}
							ast_debug(2, "md5: %s\n", valptr);
						}
						if (valptr) {
							if (delim_value == NULL && !is_realmed_password_attribute
								&& (static_table_config != table_config || strcmp(attribute_name, "variable_value") == 0)) {

								delim_value = ast_strdup(valptr);

								if ((delim_tot_count = semicolon_count_str(delim_value)) > 0) {
									ast_debug(4, "is delimited %d times: %s\n", delim_tot_count, delim_value);
									is_delimited = 1;
								}
							}

							if (is_delimited != 0 && !is_realmed_password_attribute
								&& (static_table_config != table_config || strcmp(attribute_name, "variable_value") == 0) ) {
								/* for non-Static RealTime, first */

								for (i = pos; !ast_strlen_zero(valptr + i); i++) {
									ast_debug(4, "DELIM pos: %d i: %d\n", pos, i);
									if (delim_value[i] == ';') {
										delim_value[i] = '\0';

										ast_debug(2, "DELIM - attribute_name: %s value: %s pos: %d\n", attribute_name, &delim_value[pos], pos);

										if (prev) {
											prev->next = ast_variable_new(attribute_name, &delim_value[pos], table_config->table_name);
											if (prev->next) {
												prev = prev->next;
											}
										} else {
											prev = var = ast_variable_new(attribute_name, &delim_value[pos], table_config->table_name);
										}
										pos = i + 1;

										if (static_table_config == table_config) {
											break;
										}
									}
								}
								if (ast_strlen_zero(valptr + i)) {
									ast_debug(4, "DELIM pos: %d i: %d delim_count: %d\n", pos, i, delim_count);
									/* Last delimited value */
									ast_debug(4, "DELIM - attribute_name: %s value: %s pos: %d\n", attribute_name, &delim_value[pos], pos);
									if (prev) {
										prev->next = ast_variable_new(attribute_name, &delim_value[pos], table_config->table_name);
										if (prev->next) {
											prev = prev->next;
										}
									} else {
										prev = var = ast_variable_new(attribute_name, &delim_value[pos], table_config->table_name);
									}
									/* Remembering to free memory */
									is_delimited = 0;
									pos = 0;
								}
								ast_free(delim_value);
								delim_value = NULL;

								ast_debug(4, "DELIM pos: %d i: %d\n", pos, i);
							} else {
								/* not delimited */
								if (delim_value) {
									ast_free(delim_value);
									delim_value = NULL;
								}
								ast_debug(2, "attribute_name: %s value: %s\n", attribute_name, valptr);

								if (prev) {
									prev->next = ast_variable_new(attribute_name, valptr, table_config->table_name);
									if (prev->next) {
										prev = prev->next;
									}
								} else {
									prev = var = ast_variable_new(attribute_name, valptr, table_config->table_name);
								}
							}
						}
					} /*!< for (v = values; *v; v++) */
					ldap_value_free_len(values);
				}/*!< if (values) */
				ldap_memfree(ldap_attribute_name);
				ldap_attribute_name = ldap_next_attribute(ldapConn, ldap_entry, ber);
			} /*!< while (ldap_attribute_name) */
			ber_free(ber, 0);
			if (static_table_config == table_config) {
				if (DEBUG_ATLEAST(3)) {
					const struct ast_variable *tmpdebug = variable_named(var, "variable_name");
					const struct ast_variable *tmpdebug2 = variable_named(var, "variable_value");
					if (tmpdebug && tmpdebug2) {
						ast_log(LOG_DEBUG, "Added to vars - %s = %s\n", tmpdebug->value, tmpdebug2->value);
					}
				}
				vars[entry_index++] = var;
				prev = NULL;
			}

			delim_count++;
		} while (delim_count <= delim_tot_count && static_table_config == table_config);

		if (static_table_config != table_config) {
			ast_debug(3, "Added to vars - non static\n");

			vars[entry_index++] = var;
			prev = NULL;
		}
		ldap_entry = ldap_next_entry(ldapConn, ldap_entry);
	} /*!< end for loop over ldap_entry */

	return vars;
}


/*! \brief Check if we have a connection error
 */
static int is_ldap_connect_error(int err)
{
	return (err == LDAP_SERVER_DOWN || err == LDAP_TIMEOUT || err == LDAP_CONNECT_ERROR);
}

/*! \brief Get LDAP entry by dn and return attributes as variables
 *
 * Should be locked before using it
 *
 * This is used for setting the default values of an object
 * i.e., with accountBaseDN
*/
static struct ast_variable *ldap_loadentry(struct ldap_table_config *table_config,
					   const char *dn)
{
	if (!table_config) {
		ast_log(LOG_ERROR, "No table config\n");
		return NULL;
	} else {
		struct ast_variable **vars = NULL;
		struct ast_variable *var = NULL;
		int result = -1;
		LDAPMessage *ldap_result_msg = NULL;
		int tries = 0;

		ast_debug(2, "ldap_loadentry dn=%s\n", dn);

		do {
			result = ldap_search_ext_s(ldapConn, dn, LDAP_SCOPE_BASE,
					   "(objectclass=*)", NULL, 0, NULL, NULL, NULL, LDAP_NO_LIMIT, &ldap_result_msg);
			if (result != LDAP_SUCCESS && is_ldap_connect_error(result)) {
				ast_log(LOG_WARNING, "Failed to query directory. Try %d/3\n", tries + 1);
				tries++;
				if (tries < 3) {
					usleep(500000L * tries);
					if (ldapConn) {
						ldap_unbind_ext_s(ldapConn, NULL, NULL);
						ldapConn = NULL;
					}
					if (!ldap_reconnect()) {
						break;
					}
				}
			}
		} while (result != LDAP_SUCCESS && tries < 3 && is_ldap_connect_error(result));

		if (result != LDAP_SUCCESS) {
			ast_log(LOG_WARNING, "Failed to query directory. Error: %s.\n", ldap_err2string(result));
			ast_debug(2, "dn=%s\n", dn);
			ast_mutex_unlock(&ldap_lock);
			return NULL;
		} else {
			int num_entry = 0;
			unsigned int *entries_count_ptr = NULL; /*!< not using this */

			if ((num_entry = ldap_count_entries(ldapConn, ldap_result_msg)) > 0) {
				ast_debug(3, "num_entry: %d\n", num_entry);

				vars = realtime_ldap_result_to_vars(table_config, ldap_result_msg, entries_count_ptr);
				if (num_entry > 1) {
					ast_log(LOG_NOTICE, "More than one entry for dn=%s. Take only 1st one\n", dn);
				}
			} else {
				ast_debug(2, "Could not find any entry dn=%s.\n", dn);
			}
		}
		ldap_msgfree(ldap_result_msg);

		/* Chopping \a vars down to one variable */
		if (vars != NULL) {
			struct ast_variable **p = vars;

			/* Only take the first one. */
			var = *vars;

			/* Destroy the rest. */
			while (*++p) {
				ast_variables_destroy(*p);
			}
			ast_free(vars);
		}

		return var;
	}
}

/*! \note caller should free returned pointer
 */
static char *substituted(struct ast_channel *channel, const char *string)
{
#define MAXRESULT	2048
	char *ret_string = NULL;

	if (!ast_strlen_zero(string)) {
		ret_string = ast_calloc(1, MAXRESULT);
		pbx_substitute_variables_helper(channel, string, ret_string, MAXRESULT - 1);
	}
	ast_debug(2, "substituted: string: '%s' => '%s' \n", string, ret_string);
	return ret_string;
}

/*! \note caller should free returned pointer
 */
static char *cleaned_basedn(struct ast_channel *channel, const char *basedn)
{
	char *cbasedn = NULL;
	if (basedn) {
		char *p = NULL;
		cbasedn = substituted(channel, basedn);
		if (*cbasedn == '"') {
			cbasedn++;
			if (!ast_strlen_zero(cbasedn)) {
				int len = strlen(cbasedn);
				if (cbasedn[len - 1] == '"')
					cbasedn[len - 1] = '\0';

			}
		}
		p = cbasedn;
		while (*p) {
			if (*p == '|')
				*p = ',';
			p++;
		}
	}
	ast_debug(2, "basedn: '%s' => '%s' \n", basedn, cbasedn);
	return cbasedn;
}

/*! \brief Replace \<search\> by \<by\> in string.
 * \note No check is done on string allocated size !
 */
static int replace_string_in_string(char *string, const char *search, const char *by)
{
	int search_len = strlen(search);
	int by_len = strlen(by);
	int replaced = 0;
	char *p = strstr(string, search);

	if (p) {
		replaced = 1;
		while (p) {
			if (by_len == search_len) {
				memcpy(p, by, by_len);
			} else {
				memmove(p + by_len, p + search_len, strlen(p + search_len) + 1);
				memcpy(p, by, by_len);
			}
			p = strstr(p + by_len, search);
		}
	}
	return replaced;
}

/*! \brief Append a name=value filter string. The filter string can grow.
 */
static void append_var_and_value_to_filter(struct ast_str **filter,
	struct ldap_table_config *table_config,
	const char *name, const char *value)
{
	char *new_name = NULL;
	char *new_value = NULL;
	char *like_pos = strstr(name, " LIKE");

	ast_debug(2, "name='%s' value='%s'\n", name, value);

	if (like_pos) {
		int len = like_pos - name;

		name = new_name = ast_strdupa(name);
		new_name[len] = '\0';
		value = new_value = ast_strdupa(value);
		replace_string_in_string(new_value, "\\_", "_");
		replace_string_in_string(new_value, "%", "*");
	}

	name = convert_attribute_name_to_ldap(table_config, name);

	ast_str_append(filter, 0, "(%s=%s)", name, value);
}

/*!
 * \internal
 * \brief Create an LDAP filter using search fields
 *
 * \param config the \c ldap_table_config for this search
 * \param fields the \c ast_variable criteria to include
 *
 * \returns an \c ast_str pointer on success, NULL otherwise.
 */
static struct ast_str *create_lookup_filter(struct ldap_table_config *config, const struct ast_variable *fields)
{
	struct ast_str *filter;
	const struct ast_variable *field;

	filter = ast_str_create(80);
	if (!filter) {
		return NULL;
	}

	/*
	 * Create the filter with the table additional filter and the
	 * parameter/value pairs we were given
	 */
	ast_str_append(&filter, 0, "(&");
	if (config && config->additional_filter) {
		ast_str_append(&filter, 0, "%s", config->additional_filter);
	}
	if (config != base_table_config
		&& base_table_config
		&& base_table_config->additional_filter) {
		ast_str_append(&filter, 0, "%s", base_table_config->additional_filter);
	}
	/* Append the lookup fields */
	for (field = fields; field; field = field->next) {
		append_var_and_value_to_filter(&filter, config, field->name, field->value);
	}
	ast_str_append(&filter, 0, ")");

	return filter;
}

/*! \brief LDAP base function
 * \return a null terminated array of ast_variable (one per entry) or NULL if no entry is found or if an error occured
 * caller should free the returned array and ast_variables
 * \param entries_count_ptr is a pointer to found entries count (can be NULL)
 * \param basedn is the base DN
 * \param table_name is the table_name (used dor attribute convertion and additional filter)
 * \param fields contains list of pairs name/value
*/
static struct ast_variable **realtime_ldap_base_ap(unsigned int *entries_count_ptr,
	const char *basedn, const char *table_name, const struct ast_variable *fields)
{
	struct ast_variable **vars = NULL;
	const struct ast_variable *field = fields;
	struct ldap_table_config *table_config = NULL;
	char *clean_basedn = cleaned_basedn(NULL, basedn);
	struct ast_str *filter = NULL;
	int tries = 0;
	int result = 0;
	LDAPMessage *ldap_result_msg = NULL;

	if (!table_name) {
		ast_log(LOG_ERROR, "No table_name specified.\n");
		ast_free(clean_basedn);
		return NULL;
	}

	if (!field) {
		ast_log(LOG_ERROR, "Realtime retrieval requires at least 1 parameter"
			" and 1 value to search on.\n");
		ast_free(clean_basedn);
		return NULL;
	}

	ast_mutex_lock(&ldap_lock);

	/* We now have our complete statement; Lets connect to the server and execute it.  */
	if (!ldap_reconnect()) {
		ast_mutex_unlock(&ldap_lock);
		ast_free(clean_basedn);
		return NULL;
	}

	table_config = table_config_for_table_name(table_name);
	if (!table_config) {
		ast_log(LOG_WARNING, "No table named '%s'.\n", table_name);
		ast_mutex_unlock(&ldap_lock);
		ast_free(clean_basedn);
		return NULL;
	}

	filter = create_lookup_filter(table_config, fields);
	if (!filter) {
		ast_mutex_unlock(&ldap_lock);
		ast_free(clean_basedn);
		return NULL;
	}

	do {
		/* freeing ldap_result further down */
		result = ldap_search_ext_s(ldapConn, clean_basedn,
				  LDAP_SCOPE_SUBTREE, ast_str_buffer(filter), NULL, 0, NULL, NULL, NULL, LDAP_NO_LIMIT,
				  &ldap_result_msg);
		if (result != LDAP_SUCCESS && is_ldap_connect_error(result)) {
			ast_debug(1, "Failed to query directory. Try %d/10\n", tries + 1);
			if (++tries < 10) {
				usleep(1);
				if (ldapConn) {
					ldap_unbind_ext_s(ldapConn, NULL, NULL);
					ldapConn = NULL;
				}
				if (!ldap_reconnect()) {
					break;
				}
			}
		}
	} while (result != LDAP_SUCCESS && tries < 10 && is_ldap_connect_error(result));

	if (result != LDAP_SUCCESS) {
		ast_log(LOG_WARNING, "Failed to query directory. Error: %s.\n", ldap_err2string(result));
		ast_log(LOG_WARNING, "Query: %s\n", ast_str_buffer(filter));
	} else {
		/* this is where we create the variables from the search result
		 * freeing this \a vars outside this function */
		if (ldap_count_entries(ldapConn, ldap_result_msg) > 0) {
			/* is this a static var or some other? they are handled different for delimited values */
			vars = realtime_ldap_result_to_vars(table_config, ldap_result_msg, entries_count_ptr);
		} else {
			ast_debug(1, "Could not find any entry matching %s in base dn %s.\n", ast_str_buffer(filter), clean_basedn);
		}

		ldap_msgfree(ldap_result_msg);

		/*! \todo get the default variables from the accountBaseDN, not implemented with delimited values
		 */
		if (vars) {
			struct ast_variable **p = vars;
			while (*p) {
				struct ast_variable *append_var = NULL;
				struct ast_variable *tmp = *p;
				while (tmp) {
					if (strcasecmp(tmp->name, "accountBaseDN") == 0) {
						/* Get the variable to compare with for the defaults */
						struct ast_variable *base_var = ldap_loadentry(table_config, tmp->value);

						while (base_var) {
							struct ast_variable *next = base_var->next;
							struct ast_variable *test_var = *p;
							int base_var_found = 0;

							/* run throught the default values and fill it inn if it is missing */
							while (test_var) {
								if (strcasecmp(test_var->name, base_var->name) == 0) {
									base_var_found = 1;
									break;
								} else {
									test_var = test_var->next;
								}
							}
							if (base_var_found) {
								base_var->next = NULL;
								ast_variables_destroy(base_var);
								base_var = next;
							} else {
								/*!
								 * \todo XXX The interactions with base_var and append_var may
								 * cause a memory leak of base_var nodes.  Also the append_var
								 * list and base_var list may get cross linked.
								 */
								if (append_var) {
									base_var->next = append_var;
								} else {
									base_var->next = NULL;
								}
								append_var = base_var;
								base_var = next;
							}
						}
					}
					if (!tmp->next && append_var) {
						tmp->next = append_var;
						tmp = NULL;
					} else {
						tmp = tmp->next;
					}
				}
				p++;
			}
		}
	}

	ast_free(filter);
	ast_free(clean_basedn);

	ast_mutex_unlock(&ldap_lock);

	return vars;
}

static struct ast_variable *realtime_arguments_to_fields(va_list ap)
{
	struct ast_variable *fields = NULL;
	const char *newparam, *newval;

	while ((newparam = va_arg(ap, const char *))) {
		struct ast_variable *field;

		newval = va_arg(ap, const char *);
		if (!(field = ast_variable_new(newparam, newval, ""))) {
			ast_variables_destroy(fields);
			return NULL;
		}

		field->next = fields;
		fields = field;
	}

	return fields;
}

/*! \brief same as realtime_ldap_base_ap but take variable arguments count list
 */
static struct ast_variable **realtime_ldap_base(unsigned int *entries_count_ptr,
	const char *basedn, const char *table_name, ...)
{
	RAII_VAR(struct ast_variable *, fields, NULL, ast_variables_destroy);
	struct ast_variable **vars = NULL;
	va_list ap;

	va_start(ap, table_name);
	fields = realtime_arguments_to_fields(ap);
	va_end(ap);

	vars = realtime_ldap_base_ap(entries_count_ptr, basedn, table_name, fields);

	return vars;
}