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"
);