func_db.c

/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2005-2006, Russell Bryant <russelb@clemson.edu>
 *
 * func_db.c adapted from the old app_db.c, copyright by the following people
 * Copyright (C) 2005, Mark Spencer <markster@digium.com>
 * Copyright (C) 2003, Jefferson Noxon <jeff@debian.org>
 *
 * 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 Functions for interaction with the Asterisk database
 *
 * \author Russell Bryant <russelb@clemson.edu>
 *
 * \ingroup functions
 */

/*** MODULEINFO
	<support_level>core</support_level>
 ***/

#include "asterisk.h"

#include <regex.h>

#include "asterisk/module.h"
#include "asterisk/channel.h"
#include "asterisk/pbx.h"
#include "asterisk/utils.h"
#include "asterisk/app.h"
#include "asterisk/astdb.h"

/*** DOCUMENTATION
	<function name="DB" language="en_US">
		<synopsis>
			Read from or write to the Asterisk database.
		</synopsis>
		<syntax argsep="/">
			<parameter name="family" required="true" />
			<parameter name="key" required="true" />
		</syntax>
		<description>
			<para>This function will read from or write a value to the Asterisk database.  On a
			read, this function returns the corresponding value from the database, or blank
			if it does not exist.  Reading a database value will also set the variable
			DB_RESULT.  If you wish to find out if an entry exists, use the DB_EXISTS
			function.</para>
		</description>
		<see-also>
			<ref type="application">DBdel</ref>
			<ref type="function">DB_DELETE</ref>
			<ref type="application">DBdeltree</ref>
			<ref type="function">DB_EXISTS</ref>
		</see-also>
	</function>
	<function name="DB_EXISTS" language="en_US">
		<synopsis>
			Check to see if a key exists in the Asterisk database.
		</synopsis>
		<syntax argsep="/">
			<parameter name="family" required="true" />
			<parameter name="key" required="true" />
		</syntax>
		<description>
			<para>This function will check to see if a key exists in the Asterisk
			database. If it exists, the function will return <literal>1</literal>. If not,
			it will return <literal>0</literal>.  Checking for existence of a database key will
			also set the variable DB_RESULT to the key's value if it exists.</para>
		</description>
		<see-also>
			<ref type="function">DB</ref>
		</see-also>
	</function>
	<function name="DB_KEYS" language="en_US">
		<synopsis>
			Obtain a list of keys within the Asterisk database.
		</synopsis>
		<syntax>
			<parameter name="prefix" />
		</syntax>
		<description>
			<para>This function will return a comma-separated list of keys existing
			at the prefix specified within the Asterisk database.  If no argument is
			provided, then a list of key families will be returned.</para>
		</description>
		<see-also>
			<ref type="function">DB_KEYCOUNT</ref>
		</see-also>
	</function>
	<function name="DB_KEYCOUNT" language="en_US">
		<synopsis>
			Obtain the number of keys at a prefix within the Asterisk database.
		</synopsis>
		<syntax>
			<parameter name="prefix" />
		</syntax>
		<description>
			<para>This function will return the number of keys that exist
			at the prefix specified within the Asterisk database.  If no argument is
			provided, then the number of all key families will be returned.</para>
		</description>
		<see-also>
			<ref type="function">DB_KEYS</ref>
		</see-also>
	</function>
	<function name="DB_DELETE" language="en_US">
		<synopsis>
			Return a value from the database and delete it.
		</synopsis>
		<syntax argsep="/">
			<parameter name="family" required="true" />
			<parameter name="key" required="true" />
		</syntax>
		<description>
			<para>This function will retrieve a value from the Asterisk database
			and then remove that key from the database. <variable>DB_RESULT</variable>
			will be set to the key's value if it exists.</para>
			<note>
				<para>If <literal>live_dangerously</literal> in <literal>asterisk.conf</literal>
				is set to <literal>no</literal>, this function can only be read from the
				dialplan, and not directly from external protocols. It can, however, be
				executed as a write operation (<literal>DB_DELETE(family, key)=ignored</literal>)</para>
			</note>
		</description>
		<see-also>
			<ref type="application">DBdel</ref>
			<ref type="function">DB</ref>
			<ref type="application">DBdeltree</ref>
		</see-also>
	</function>
 ***/

static int function_db_read(struct ast_channel *chan, const char *cmd,
			    char *parse, char *buf, size_t len)
{
	AST_DECLARE_APP_ARGS(args,
		AST_APP_ARG(family);
		AST_APP_ARG(key);
	);

	buf[0] = '\0';

	if (ast_strlen_zero(parse)) {
		ast_log(LOG_WARNING, "DB requires an argument, DB(<family>/<key>)\n");
		return -1;
	}

	AST_NONSTANDARD_APP_ARGS(args, parse, '/');

	if (args.argc < 2) {
		ast_log(LOG_WARNING, "DB requires an argument, DB(<family>/<key>)\n");
		return -1;
	}

	if (ast_db_get(args.family, args.key, buf, len - 1)) {
		ast_debug(1, "DB: %s/%s not found in database.\n", args.family, args.key);
	} else {
		pbx_builtin_setvar_helper(chan, "DB_RESULT", buf);
	}

	return 0;
}

static int function_db_write(struct ast_channel *chan, const char *cmd, char *parse,
			     const char *value)
{
	AST_DECLARE_APP_ARGS(args,
		AST_APP_ARG(family);
		AST_APP_ARG(key);
	);

	if (ast_strlen_zero(parse)) {
		ast_log(LOG_WARNING, "DB requires an argument, DB(<family>/<key>)=<value>\n");
		return -1;
	}

	AST_NONSTANDARD_APP_ARGS(args, parse, '/');

	if (args.argc < 2) {
		ast_log(LOG_WARNING, "DB requires an argument, DB(<family>/<key>)=value\n");
		return -1;
	}
	/*
	* When keynames are dynamically created using variables, if the variable is empty, this put bad data into the DB.
	* In particular, a few cases: an empty key name, a key starting or ending with a /, and a key containing // two slashes.
	* If this happens, allow it to go in, but warn the user of the issue and possible data corruption. */
	if (ast_strlen_zero(args.key) || args.key[0] == '/' || args.key[strlen(args.key) - 1] == '/' || strstr(args.key, "//")) {
		ast_log(LOG_WARNING, "DB: key '%s' seems malformed\n", args.key);
	}
	if (ast_db_put(args.family, args.key, value)) {
		ast_log(LOG_WARNING, "DB: Error writing value to database.\n");
	}

	return 0;
}

static struct ast_custom_function db_function = {
	.name = "DB",
	.read = function_db_read,
	.write = function_db_write,
};

static int function_db_exists(struct ast_channel *chan, const char *cmd,
			      char *parse, char *buf, size_t len)
{
	AST_DECLARE_APP_ARGS(args,
		AST_APP_ARG(family);
		AST_APP_ARG(key);
	);

	buf[0] = '\0';

	if (ast_strlen_zero(parse)) {
		ast_log(LOG_WARNING, "DB_EXISTS requires an argument, DB(<family>/<key>)\n");
		return -1;
	}

	AST_NONSTANDARD_APP_ARGS(args, parse, '/');

	if (args.argc < 2) {
		ast_log(LOG_WARNING, "DB_EXISTS requires an argument, DB(<family>/<key>)\n");
		return -1;
	}

	if (ast_db_get(args.family, args.key, buf, len - 1)) {
		strcpy(buf, "0");
	} else {
		pbx_builtin_setvar_helper(chan, "DB_RESULT", buf);
		strcpy(buf, "1");
	}

	return 0;
}

static struct ast_custom_function db_exists_function = {
	.name = "DB_EXISTS",
	.read = function_db_exists,
	.read_max = 2,
};

static int function_db_keys(struct ast_channel *chan, const char *cmd, char *parse, struct ast_str **result, ssize_t maxlen)
{
	size_t parselen = strlen(parse);
	struct ast_db_entry *dbe, *orig_dbe;
	struct ast_str *escape_buf = NULL;
	const char *last = "";

	/* Remove leading and trailing slashes */
	while (parse[0] == '/') {
		parse++;
		parselen--;
	}
	while (parse[parselen - 1] == '/') {
		parse[--parselen] = '\0';
	}

	ast_str_reset(*result);

	/* Nothing within the database at that prefix? */
	if (!(orig_dbe = dbe = ast_db_gettree(parse, NULL))) {
		return 0;
	}

	for (; dbe; dbe = dbe->next) {
		/* Find the current component */
		char *curkey = &dbe->key[parselen + 1], *slash;
		if (*curkey == '/') {
			curkey++;
		}
		/* Remove everything after the current component */
		if ((slash = strchr(curkey, '/'))) {
			*slash = '\0';
		}

		/* Skip duplicates */
		if (!strcasecmp(last, curkey)) {
			continue;
		}
		last = curkey;

		if (orig_dbe != dbe) {
			ast_str_append(result, maxlen, ",");
		}
		ast_str_append_escapecommas(result, maxlen, curkey, strlen(curkey));
	}
	ast_db_freetree(orig_dbe);
	ast_free(escape_buf);
	return 0;
}

static struct ast_custom_function db_keys_function = {
	.name = "DB_KEYS",
	.read2 = function_db_keys,
};

static int function_db_keycount(struct ast_channel *chan, const char *cmd, char *parse, char *buf, size_t len)
{
	size_t parselen = strlen(parse);
	struct ast_db_entry *dbe, *orig_dbe;
	const char *last = "";
	int keycount = 0;

	/* Remove leading and trailing slashes */
	while (parse[0] == '/') {
		parse++;
		parselen--;
	}
	while (parse[parselen - 1] == '/') {
		parse[--parselen] = '\0';
	}

	/* Nothing within the database at that prefix? */
	if (!(orig_dbe = dbe = ast_db_gettree(parse, NULL))) {
		snprintf(buf, len, "%d", keycount);
		return 0;
	}

	for (; dbe; dbe = dbe->next) {
		/* Find the current component */
		char *curkey = &dbe->key[parselen + 1], *slash;
		if (*curkey == '/') {
			curkey++;
		}
		/* Remove everything after the current component */
		if ((slash = strchr(curkey, '/'))) {
			*slash = '\0';
		}

		/* Skip duplicates */
		if (!strcasecmp(last, curkey)) {
			continue;
		}
		last = curkey;

		keycount++;
	}
	ast_db_freetree(orig_dbe);
	snprintf(buf, len, "%d", keycount);
	return 0;
}

static struct ast_custom_function db_keycount_function = {
	.name = "DB_KEYCOUNT",
	.read = function_db_keycount,
};

static int function_db_delete(struct ast_channel *chan, const char *cmd,
			      char *parse, char *buf, size_t len)
{
	AST_DECLARE_APP_ARGS(args,
		AST_APP_ARG(family);
		AST_APP_ARG(key);
	);

	buf[0] = '\0';

	if (ast_strlen_zero(parse)) {
		ast_log(LOG_WARNING, "DB_DELETE requires an argument, DB_DELETE(<family>/<key>)\n");
		return -1;
	}

	AST_NONSTANDARD_APP_ARGS(args, parse, '/');

	if (args.argc < 2) {
		ast_log(LOG_WARNING, "DB_DELETE requires an argument, DB_DELETE(<family>/<key>)\n");
		return -1;
	}

	if (ast_db_get(args.family, args.key, buf, len - 1)) {
		ast_debug(1, "DB_DELETE: %s/%s not found in database.\n", args.family, args.key);
	} else {
		if (ast_db_del(args.family, args.key)) {
			ast_debug(1, "DB_DELETE: %s/%s could not be deleted from the database\n", args.family, args.key);
		}
	}

	pbx_builtin_setvar_helper(chan, "DB_RESULT", buf);

	return 0;
}

/*!
 * \brief Wrapper to execute DB_DELETE from a write operation. Allows execution
 * even if live_dangerously is disabled.
 */
static int function_db_delete_write(struct ast_channel *chan, const char *cmd, char *parse,
	const char *value)
{
	/* Throwaway to hold the result from the read */
	char buf[128];
	return function_db_delete(chan, cmd, parse, buf, sizeof(buf));
}

static struct ast_custom_function db_delete_function = {
	.name = "DB_DELETE",
	.read = function_db_delete,
	.write = function_db_delete_write,
};

static int unload_module(void)
{
	int res = 0;

	res |= ast_custom_function_unregister(&db_function);
	res |= ast_custom_function_unregister(&db_exists_function);
	res |= ast_custom_function_unregister(&db_delete_function);
	res |= ast_custom_function_unregister(&db_keys_function);
	res |= ast_custom_function_unregister(&db_keycount_function);

	return res;
}

static int load_module(void)
{
	int res = 0;

	res |= ast_custom_function_register_escalating(&db_function, AST_CFE_BOTH);
	res |= ast_custom_function_register(&db_exists_function);
	res |= ast_custom_function_register_escalating(&db_delete_function, AST_CFE_READ);
	res |= ast_custom_function_register(&db_keys_function);
	res |= ast_custom_function_register(&db_keycount_function);

	return res;
}

AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Database (astdb) related dialplan functions");