Wed Apr 6 11:29:37 2011

Asterisk developer's documentation


app_chanisavail.c

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00001 /*
00002 * Asterisk -- An open source telephony toolkit.
00003 *
00004 * Copyright (C) 1999 - 2005, Digium, Inc.
00005 *
00006 * Mark Spencer <markster@digium.com>
00007 * James Golovich <james@gnuinter.net>
00008 *
00009 * See http://www.asterisk.org for more information about
00010 * the Asterisk project. Please do not directly contact
00011 * any of the maintainers of this project for assistance;
00012 * the project provides a web site, mailing lists and IRC
00013 * channels for your use.
00014 *
00015 * This program is free software, distributed under the terms of
00016 * the GNU General Public License Version 2. See the LICENSE file
00017 * at the top of the source tree.
00018 */
00019 
00020 /*! \file
00021  *
00022  * \brief Check if Channel is Available
00023  *
00024  * \author Mark Spencer <markster@digium.com>
00025  * \author James Golovich <james@gnuinter.net>
00026 
00027  * \ingroup applications
00028  */
00029 
00030 #include "asterisk.h"
00031 
00032 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 229970 $")
00033 
00034 #include <sys/ioctl.h>
00035 
00036 #include "asterisk/lock.h"
00037 #include "asterisk/file.h"
00038 #include "asterisk/channel.h"
00039 #include "asterisk/pbx.h"
00040 #include "asterisk/module.h"
00041 #include "asterisk/app.h"
00042 #include "asterisk/devicestate.h"
00043 
00044 static const char app[] = "ChanIsAvail";
00045 
00046 /*** DOCUMENTATION
00047    <application name="ChanIsAvail" language="en_US">
00048       <synopsis>
00049          Check channel availability
00050       </synopsis>
00051       <syntax>
00052          <parameter name="Technology/Resource" required="true" argsep="&amp;">
00053             <argument name="Technology2/Resource2" multiple="true">
00054                <para>Optional extra devices to check</para>
00055                <para>If you need more then one enter them as
00056                Technology2/Resource2&amp;Technology3/Resourse3&amp;.....</para>
00057             </argument>
00058             <para>Specification of the device(s) to check.  These must be in the format of 
00059             <literal>Technology/Resource</literal>, where <replaceable>Technology</replaceable>
00060             represents a particular channel driver, and <replaceable>Resource</replaceable>
00061             represents a resource available to that particular channel driver.</para>
00062          </parameter>
00063          <parameter name="options" required="false">
00064             <optionlist>
00065                <option name="a">
00066                   <para>Check for all available channels, not only the first one</para>
00067                </option>
00068                <option name="s">
00069                   <para>Consider the channel unavailable if the channel is in use at all</para>
00070                </option>
00071                <option name="t" implies="s">
00072                   <para>Simply checks if specified channels exist in the channel list</para>
00073                </option>
00074             </optionlist>
00075          </parameter>
00076       </syntax>
00077       <description>
00078          <para>This application will check to see if any of the specified channels are available.</para>
00079          <para>This application sets the following channel variables:</para>
00080          <variablelist>
00081             <variable name="AVAILCHAN">
00082                <para>The name of the available channel, if one exists</para>
00083             </variable>
00084             <variable name="AVAILORIGCHAN">
00085                <para>The canonical channel name that was used to create the channel</para>
00086             </variable>
00087             <variable name="AVAILSTATUS">
00088                <para>The device state for the device</para>
00089             </variable>
00090             <variable name="AVAILCAUSECODE">
00091                     <para>The cause code returned when requesting the channel</para>
00092             </variable> 
00093          </variablelist>
00094       </description>
00095    </application>
00096  ***/
00097 
00098 static int chanavail_exec(struct ast_channel *chan, const char *data)
00099 {
00100    int inuse=-1, option_state=0, string_compare=0, option_all_avail=0;
00101    int status;
00102    char *info, tmp[512], trychan[512], *peers, *tech, *number, *rest, *cur;
00103    struct ast_str *tmp_availchan = ast_str_alloca(2048);
00104    struct ast_str *tmp_availorig = ast_str_alloca(2048);
00105    struct ast_str *tmp_availstat = ast_str_alloca(2048);
00106    struct ast_str *tmp_availcause = ast_str_alloca(2048);
00107    struct ast_channel *tempchan;
00108    AST_DECLARE_APP_ARGS(args,
00109       AST_APP_ARG(reqchans);
00110       AST_APP_ARG(options);
00111    );
00112 
00113    if (ast_strlen_zero(data)) {
00114       ast_log(LOG_WARNING, "ChanIsAvail requires an argument (DAHDI/1&DAHDI/2)\n");
00115       return -1;
00116    }
00117 
00118    info = ast_strdupa(data);
00119 
00120    AST_STANDARD_APP_ARGS(args, info);
00121 
00122    if (args.options) {
00123       if (strchr(args.options, 'a')) {
00124          option_all_avail = 1;
00125       }
00126       if (strchr(args.options, 's')) {
00127          option_state = 1;
00128       }
00129       if (strchr(args.options, 't')) {
00130          string_compare = 1;
00131       }
00132    }
00133    peers = args.reqchans;
00134    if (peers) {
00135       cur = peers;
00136       do {
00137          /* remember where to start next time */
00138          rest = strchr(cur, '&');
00139          if (rest) {
00140             *rest = 0;
00141             rest++;
00142          }
00143          tech = cur;
00144          number = strchr(tech, '/');
00145          if (!number) {
00146             ast_log(LOG_WARNING, "ChanIsAvail argument takes format ([technology]/[device])\n");
00147             return -1;
00148          }
00149          *number = '\0';
00150          number++;
00151          
00152          if (string_compare) {
00153             /* ast_parse_device_state checks for "SIP/1234" as a channel name.
00154                ast_device_state will ask the SIP driver for the channel state. */
00155 
00156             snprintf(trychan, sizeof(trychan), "%s/%s",cur,number);
00157             status = inuse = ast_parse_device_state(trychan);
00158          } else if (option_state) {
00159             /* If the pbx says in use then don't bother trying further.
00160                This is to permit testing if someone's on a call, even if the
00161                channel can permit more calls (ie callwaiting, sip calls, etc).  */
00162 
00163             snprintf(trychan, sizeof(trychan), "%s/%s",cur,number);
00164             status = inuse = ast_device_state(trychan);
00165          }
00166          snprintf(tmp, sizeof(tmp), "%d", status);
00167          ast_str_append(&tmp_availstat, 0, "%s%s", ast_str_strlen(tmp_availstat) ? "&" : "", tmp);
00168          if ((inuse <= 1) && (tempchan = ast_request(tech, chan->nativeformats, chan, number, &status))) {
00169                ast_str_append(&tmp_availchan, 0, "%s%s", ast_str_strlen(tmp_availchan) ? "&" : "", tempchan->name);
00170                
00171                snprintf(tmp, sizeof(tmp), "%s/%s", tech, number);
00172                ast_str_append(&tmp_availorig, 0, "%s%s", ast_str_strlen(tmp_availorig) ? "&" : "", tmp);
00173 
00174                snprintf(tmp, sizeof(tmp), "%d", status);
00175                ast_str_append(&tmp_availcause, 0, "%s%s", ast_str_strlen(tmp_availcause) ? "&" : "", tmp);
00176 
00177                ast_hangup(tempchan);
00178                tempchan = NULL;
00179 
00180                if (!option_all_avail) {
00181                   break;
00182                }
00183          }
00184          cur = rest;
00185       } while (cur);
00186    }
00187 
00188    pbx_builtin_setvar_helper(chan, "AVAILCHAN", ast_str_buffer(tmp_availchan));
00189    /* Store the originally used channel too */
00190    pbx_builtin_setvar_helper(chan, "AVAILORIGCHAN", ast_str_buffer(tmp_availorig));
00191    pbx_builtin_setvar_helper(chan, "AVAILSTATUS", ast_str_buffer(tmp_availstat));
00192    pbx_builtin_setvar_helper(chan, "AVAILCAUSECODE", ast_str_buffer(tmp_availcause));
00193 
00194    return 0;
00195 }
00196 
00197 static int unload_module(void)
00198 {
00199    return ast_unregister_application(app);
00200 }
00201 
00202 static int load_module(void)
00203 {
00204    return ast_register_application_xml(app, chanavail_exec) ?
00205       AST_MODULE_LOAD_DECLINE : AST_MODULE_LOAD_SUCCESS;
00206 }
00207 
00208 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Check channel availability");

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