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- /*
- * Asterisk -- An open source telephony toolkit.
- *
- * Copyright (C) 2021, Naveen Albert
- *
- * Naveen Albert <asterisk@phreaknet.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 Sleep until a condition is true
- *
- * \author Naveen Albert <asterisk@phreaknet.org>
- *
- * \ingroup applications
- */
- /*** MODULEINFO
- <support_level>extended</support_level>
- ***/
- #include "asterisk.h"
- #include "asterisk/logger.h"
- #include "asterisk/channel.h"
- #include "asterisk/pbx.h"
- #include "asterisk/module.h"
- #include "asterisk/app.h"
- /*** DOCUMENTATION
- <application name="WaitForCondition" language="en_US">
- <since>
- <version>16.20.0</version>
- <version>18.6.0</version>
- <version>19.0.0</version>
- </since>
- <synopsis>
- Wait (sleep) until the given condition is true.
- </synopsis>
- <syntax>
- <parameter name="replacementchar" required="true">
- <para>Specifies the character in the expression used to replace the <literal>$</literal>
- character. This character should not be used anywhere in the expression itself.</para>
- </parameter>
- <parameter name="expression" required="true">
- <para>A modified logical expression with the <literal>$</literal> characters replaced by
- <replaceable>replacementchar</replaceable>. This is necessary to pass the expression itself
- into the application, rather than its initial evaluation.</para>
- </parameter>
- <parameter name="timeout">
- <para>The maximum amount of time, in seconds, this application should wait for a condition
- to become true before dialplan execution continues automatically to the next priority.
- By default, there is no timeout.</para>
- </parameter>
- <parameter name="interval">
- <para>The frequency, in seconds, of polling the condition, which can be adjusted depending
- on how time-sensitive execution needs to be. By default, this is 0.05.</para>
- </parameter>
- </syntax>
- <description>
- <para>Waits until <replaceable>expression</replaceable> evaluates to true, checking every
- <replaceable>interval</replaceable> seconds for up to <replaceable>timeout</replaceable>. Default
- is evaluate <replaceable>expression</replaceable> every 50 milliseconds with no timeout.</para>
- <example title="Wait for condition dialplan variable/function to become 1 for up to 40 seconds, checking every 500ms">
- same => n,WaitForCondition(#,#["#{condition}"="1"],40,0.5)
- </example>
- <para>Sets <variable>WAITFORCONDITIONSTATUS</variable> to one of the following values:</para>
- <variablelist>
- <variable name="WAITFORCONDITIONSTATUS">
- <value name="TRUE">
- Condition evaluated to true before timeout expired.
- </value>
- <value name="FAILURE">
- Invalid argument.
- </value>
- <value name="TIMEOUT">
- Timeout elapsed without condition evaluating to true.
- </value>
- <value name="HANGUP">
- Channel hung up before condition became true.
- </value>
- </variable>
- </variablelist>
- </description>
- </application>
- ***/
- static char *app = "WaitForCondition";
- static int waitforcond_exec(struct ast_channel *chan, const char *data)
- {
- int ms, i;
- double timeout = 0, poll = 0;
- int timeout_ms = 0;
- int poll_ms = 50; /* default is evaluate the condition every 50ms */
- struct timeval start = ast_tvnow();
- char dollarsignrep;
- int brackets = 0;
- char *pos, *open_bracket, *expression, *optargs = NULL;
- char condition[512];
- AST_DECLARE_APP_ARGS(args,
- AST_APP_ARG(timeout);
- AST_APP_ARG(interval);
- );
- pos = ast_strdupa(data);
- if (ast_strlen_zero(pos)) {
- ast_log(LOG_ERROR, "WaitForCondition requires a condition\n");
- pbx_builtin_setvar_helper(chan, "WAITFORCONDITIONSTATUS", "FAILURE");
- return 0;
- }
- /* is there at least a [ followed by a ] somewhere ? */
- if (!(open_bracket = strchr(pos, '[')) || !strchr(open_bracket, ']')) {
- ast_log(LOG_ERROR, "No expression detected. Did you forget to replace the $ signs?\n");
- pbx_builtin_setvar_helper(chan, "WAITFORCONDITIONSTATUS", "FAILURE");
- return 0;
- }
- dollarsignrep = pos[0];
- if (dollarsignrep == '$' || dollarsignrep == '[' || dollarsignrep == ']'
- || dollarsignrep == '{' || dollarsignrep == '}') {
- ast_log(LOG_ERROR, "Dollar sign replacement cannot be %c.\n", dollarsignrep);
- pbx_builtin_setvar_helper(chan, "WAITFORCONDITIONSTATUS", "FAILURE");
- return 0;
- }
- ++pos;
- if (pos[0] != ',') {
- ast_log(LOG_ERROR, "Invalid separator: %c\n", pos[0]);
- pbx_builtin_setvar_helper(chan, "WAITFORCONDITIONSTATUS", "FAILURE");
- return 0;
- }
- ++pos;
- if (pos[0] != dollarsignrep) {
- ast_log(LOG_ERROR, "Expression start does not match provided replacement: %c\n", pos[0]);
- pbx_builtin_setvar_helper(chan, "WAITFORCONDITIONSTATUS", "FAILURE");
- return 0;
- }
- expression = pos; /* we're at the start of the expression */
- /* commas may appear within the expression, so go until we've encountered as many closing brackets as opening */
- while (++pos) {
- if (pos[0] == '\0') {
- ast_log(LOG_ERROR, "Could not parse end of expression.\n");
- pbx_builtin_setvar_helper(chan, "WAITFORCONDITIONSTATUS", "FAILURE");
- return 0;
- }
- if (pos[0] == '[') {
- brackets++;
- } else if (pos[0] == ']') {
- brackets--;
- }
- if (brackets == 0) { /* reached end of expression */
- break;
- }
- }
- ++pos;
- if (pos[0] != '\0') {
- ++pos; /* eat comma separator */
- if (pos[0] != '\0') {
- optargs = ast_strdupa(pos);
- AST_STANDARD_APP_ARGS(args, optargs);
- if (!ast_strlen_zero(args.timeout)) {
- if (sscanf(args.timeout, "%30lg", &timeout) != 1) {
- ast_log(LOG_WARNING, "Invalid timeout provided: %s. No timeout set.\n", args.timeout);
- return -1;
- }
- timeout_ms = timeout * 1000.0;
- }
- if (!ast_strlen_zero(args.interval)) {
- if (sscanf(args.interval, "%30lg", &poll) != 1) {
- ast_log(LOG_WARNING, "Invalid polling interval provided: %s. Default unchanged.\n", args.interval);
- return -1;
- }
- if (poll < 0.001) {
- ast_log(LOG_WARNING, "Polling interval cannot be less than 1ms. Default unchanged.\n");
- return -1;
- }
- poll_ms = poll * 1000.0;
- }
- }
- }
- for (i = 0; expression[i] != '\0'; i++) {
- if (expression[i] == dollarsignrep) {
- expression[i] = '$'; /* replace $s back into expression for variable parsing */
- }
- }
- if (timeout_ms > 0) {
- ast_debug(1, "Waiting for condition for %f seconds: %s (checking every %d ms)", timeout, expression, poll_ms);
- } else {
- ast_debug(1, "Waiting for condition, forever: %s (checking every %d ms)", expression, poll_ms);
- }
- while (1) {
- /* Substitute variables now */
- pbx_substitute_variables_helper(chan, expression, condition, sizeof(condition) - 1);
- if (pbx_checkcondition(condition)) {
- pbx_builtin_setvar_helper(chan, "WAITFORCONDITIONSTATUS", "TRUE");
- return 0;
- }
- /* If a timeout was specified, check that it hasn't expired */
- if ((timeout_ms > 0) && !(ms = ast_remaining_ms(start, timeout_ms))) {
- pbx_builtin_setvar_helper(chan, "WAITFORCONDITIONSTATUS", "TIMEOUT");
- return 0;
- }
- if (ast_safe_sleep(chan, poll_ms)) { /* don't waste CPU, we don't need a super tight loop */
- pbx_builtin_setvar_helper(chan, "WAITFORCONDITIONSTATUS", "HANGUP");
- return -1; /* channel hung up */
- }
- }
- }
- static int unload_module(void)
- {
- return ast_unregister_application(app);
- }
- static int load_module(void)
- {
- return ast_register_application_xml(app, waitforcond_exec);
- }
- AST_MODULE_INFO_STANDARD_EXTENDED(ASTERISK_GPL_KEY, "Wait until condition is true");
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