app_chanisavail.c

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/*
* Asterisk -- An open source telephony toolkit.
*
* Copyright (C) 1999 - 2005, Digium, Inc.
*
* Mark Spencer <[email protected]>
* James Golovich <[email protected]>
*
* 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 Check if Channel is Available
 *
 * \author Mark Spencer <[email protected]>
 * \author James Golovich <[email protected]>

 * \ingroup applications
 */

/*** MODULEINFO
 <support_level>extended</support_level>
 ***/

#include "asterisk.h"

#include <sys/ioctl.h>

#include "asterisk/lock.h"
#include "asterisk/file.h"
#include "asterisk/channel.h"
#include "asterisk/pbx.h"
#include "asterisk/module.h"
#include "asterisk/app.h"
#include "asterisk/devicestate.h"

static const char app[] = "ChanIsAvail";

/*** DOCUMENTATION
 <application name="ChanIsAvail" language="en_US">
 <synopsis>
 Check channel availability
 </synopsis>
 <syntax>
 <parameter name="Technology/Resource" required="false" argsep="&amp;">
 <argument name="Technology/Resource" required="true">
 <para>Specification of the device(s) to check. These must be in the format of
 <literal>Technology/Resource</literal>, where <replaceable>Technology</replaceable>
 represents a particular channel driver, and <replaceable>Resource</replaceable>
 represents a resource available to that particular channel driver.</para>
 </argument>
 <argument name="Technology2/Resource2" multiple="true">
 <para>Optional extra devices to check</para>
 <para>If you need more than one enter them as
 Technology2/Resource2&amp;Technology3/Resource3&amp;.....</para>
 </argument>
 </parameter>
 <parameter name="options" required="false">
 <optionlist>
 <option name="a">
 <para>Check for all available channels, not only the first one</para>
 </option>
 <option name="s">
 <para>Consider the channel unavailable if the channel is in use at all</para>
 </option>
 <option name="t" implies="s">
 <para>Simply checks if specified channels exist in the channel list</para>
 </option>
 </optionlist>
 </parameter>
 </syntax>
 <description>
 <para>This application will check to see if any of the specified channels are available.</para>
 <para>This application sets the following channel variables:</para>
 <variablelist>
 <variable name="AVAILCHAN">
 <para>The name of the available channel, if one exists</para>
 </variable>
 <variable name="AVAILORIGCHAN">
 <para>The canonical channel name that was used to create the channel</para>
 </variable>
 <variable name="AVAILSTATUS">
 <para>The device state for the device</para>
 </variable>
 <variable name="AVAILCAUSECODE">
 <para>The cause code returned when requesting the channel</para>
 </variable>
 </variablelist>
 </description>
 </application>
 ***/

static int chanavail_exec(struct ast_channel *chan, const char *data)
{
 int inuse = -1;
 int option_state = 0;
 int string_compare = 0;
 int option_all_avail = 0;
 int status;
 char *info;
 char trychan[512];
 char *rest;
 char *tech;
 char *number;
 struct ast_str *tmp_availchan = ast_str_alloca(2048);
 struct ast_str *tmp_availorig = ast_str_alloca(2048);
 struct ast_str *tmp_availstat = ast_str_alloca(2048);
 struct ast_str *tmp_availcause = ast_str_alloca(2048);
 struct ast_channel *tempchan;
 struct ast_custom_function *cdr_prop_func = ast_custom_function_find("CDR_PROP");
 AST_DECLARE_APP_ARGS(args,
 AST_APP_ARG(reqchans);
 AST_APP_ARG(options);
 );

 info = ast_strdupa(data ?: "");

 AST_STANDARD_APP_ARGS(args, info);

 if (args.options) {
 if (strchr(args.options, 'a')) {
 option_all_avail = 1;
 }
 if (strchr(args.options, 's')) {
 option_state = 1;
 }
 if (strchr(args.options, 't')) {
 string_compare = 1;
 }
 }

 rest = args.reqchans;
 if (!rest) {
 rest = "";
 }
 while ((tech = strsep(&rest, "&"))) {
 tech = ast_strip(tech);

 number = strchr(tech, '/');
 if (!number) {
 if (!ast_strlen_zero(tech)) {
 ast_log(LOG_WARNING, "Invalid ChanIsAvail technology/resource argument: '%s'\n",
 tech);
 }

 ast_str_append(&tmp_availstat, 0, "%s%d",
 ast_str_strlen(tmp_availstat) ? "&" : "", AST_DEVICE_INVALID);
 continue;
 }
 *number++ = '\0';

 status = AST_DEVICE_UNKNOWN;

 if (string_compare) {
 /* ast_parse_device_state checks for "SIP/1234" as a channel name.
 ast_device_state will ask the SIP driver for the channel state. */

 snprintf(trychan, sizeof(trychan), "%s/%s", tech, number);
 status = inuse = ast_parse_device_state(trychan);
 } else if (option_state) {
 /* If the pbx says in use then don't bother trying further.
 This is to permit testing if someone's on a call, even if the
 channel can permit more calls (ie callwaiting, sip calls, etc). */

 snprintf(trychan, sizeof(trychan), "%s/%s", tech, number);
 status = inuse = ast_device_state(trychan);
 }
 ast_str_append(&tmp_availstat, 0, "%s%d",
 ast_str_strlen(tmp_availstat) ? "&" : "", status);
 if ((inuse <= (int) AST_DEVICE_NOT_INUSE)
 && (tempchan = ast_request(tech, ast_channel_nativeformats(chan), NULL, chan, number, &status))) {
 ast_str_append(&tmp_availchan, 0, "%s%s",
 ast_str_strlen(tmp_availchan) ? "&" : "", ast_channel_name(tempchan));

 ast_str_append(&tmp_availorig, 0, "%s%s/%s",
 ast_str_strlen(tmp_availorig) ? "&" : "", tech, number);

 ast_str_append(&tmp_availcause, 0, "%s%d",
 ast_str_strlen(tmp_availcause) ? "&" : "", status);

 /* Disable CDR for this temporary channel. */
 if (cdr_prop_func) {
 ast_func_write(tempchan, "CDR_PROP(disable)", "1");
 }

 ast_hangup(tempchan);
 tempchan = NULL;

 if (!option_all_avail) {
 break;
 }
 }
 }

 pbx_builtin_setvar_helper(chan, "AVAILCHAN", ast_str_buffer(tmp_availchan));
 /* Store the originally used channel too */
 pbx_builtin_setvar_helper(chan, "AVAILORIGCHAN", ast_str_buffer(tmp_availorig));
 pbx_builtin_setvar_helper(chan, "AVAILSTATUS", ast_str_buffer(tmp_availstat));
 pbx_builtin_setvar_helper(chan, "AVAILCAUSECODE", ast_str_buffer(tmp_availcause));

 return 0;
}

static int unload_module(void)
{
 return ast_unregister_application(app);
}

static int load_module(void)
{
 return ast_register_application_xml(app, chanavail_exec) ?
 AST_MODULE_LOAD_DECLINE : AST_MODULE_LOAD_SUCCESS;
}

AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_DEFAULT, "Check channel availability",
 .support_level = AST_MODULE_SUPPORT_EXTENDED,
 .load = load_module,
 .unload = unload_module,
 .optional_modules = "func_cdr"
);