app_chanisavail.c

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/*
* Asterisk -- An open source telephony toolkit.
*
* Copyright (C) 1999 - 2005, Digium, Inc.
*
* Mark Spencer <markster@digium.com>
* James Golovich <james@gnuinter.net>
*
* 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 <markster@digium.com>
 * \author James Golovich <james@gnuinter.net>
 
 * \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");
    struct ast_format_cap *caps = NULL;
    AST_DECLARE_APP_ARGS(args,
        AST_APP_ARG(reqchans);
        AST_APP_ARG(options);
    );
 
    info = ast_strdupa(data ?: "");
 
    AST_STANDARD_APP_ARGS(args, info);
 
    ao2_lock(chan);
    caps = ao2_bump(ast_channel_nativeformats(chan));
    ao2_unlock(chan);
 
    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, caps, 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;
            }
        }
 
    }
 
    ao2_cleanup(caps);
 
    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"
);