app_system.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2005, Digium, Inc.
 *
 * Mark Spencer <[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 Execute arbitrary system commands
 *
 * \author Mark Spencer <[email protected]>
 *
 * \ingroup applications
 */

/*** MODULEINFO
   <support_level>core</support_level>
 ***/

#include "asterisk.h"

#include "asterisk/pbx.h"
#include "asterisk/module.h"
#include "asterisk/app.h"
#include "asterisk/channel.h" /* autoservice */
#include "asterisk/strings.h"
#include "asterisk/threadstorage.h"

/*** DOCUMENTATION
   <application name="System" language="en_US">
      <synopsis>
         Execute a system command.
      </synopsis>
      <syntax>
         <parameter name="command" required="true">
            <para>Command to execute</para>
            <warning><para>Do not use untrusted strings such as <variable>CALLERID(num)</variable>
            or <variable>CALLERID(name)</variable> as part of the command parameters.  You
            risk a command injection attack executing arbitrary commands if the untrusted
            strings aren't filtered to remove dangerous characters.  See function
            <variable>FILTER()</variable>.</para></warning>
         </parameter>
      </syntax>
      <description>
         <para>Executes a command  by  using  system(). If the command
         fails, the console should report a fallthrough.</para>
         <para>Result of execution is returned in the <variable>SYSTEMSTATUS</variable> channel variable:</para>
         <variablelist>
            <variable name="SYSTEMSTATUS">
               <value name="FAILURE">
                  Could not execute the specified command.
               </value>
               <value name="SUCCESS">
                  Specified command successfully executed.
               </value>
            </variable>
         </variablelist>
      </description>
   </application>
   <application name="TrySystem" language="en_US">
      <synopsis>
         Try executing a system command.
      </synopsis>
      <syntax>
         <parameter name="command" required="true">
            <para>Command to execute</para>
            <warning><para>Do not use untrusted strings such as <variable>CALLERID(num)</variable>
            or <variable>CALLERID(name)</variable> as part of the command parameters.  You
            risk a command injection attack executing arbitrary commands if the untrusted
            strings aren't filtered to remove dangerous characters.  See function
            <variable>FILTER()</variable>.</para></warning>
         </parameter>
      </syntax>
      <description>
         <para>Executes a command  by  using  system().</para>
         <para>Result of execution is returned in the <variable>SYSTEMSTATUS</variable> channel variable:</para>
         <variablelist>
            <variable name="SYSTEMSTATUS">
               <value name="FAILURE">
                  Could not execute the specified command.
               </value>
               <value name="SUCCESS">
                  Specified command successfully executed.
               </value>
               <value name="APPERROR">
                  Specified command successfully executed, but returned error code.
               </value>
            </variable>
         </variablelist>
      </description>
   </application>

 ***/

AST_THREADSTORAGE(buf_buf);

static char *app = "System";

static char *app2 = "TrySystem";

static char *chanvar = "SYSTEMSTATUS";

static int system_exec_helper(struct ast_channel *chan, const char *data, int failmode)
{
   int res = 0;
   struct ast_str *buf = ast_str_thread_get(&buf_buf, 16);
   char *cbuf;

   if (ast_strlen_zero(data)) {
      ast_log(LOG_WARNING, "System requires an argument(command)\n");
      pbx_builtin_setvar_helper(chan, chanvar, "FAILURE");
      return failmode;
   }

   ast_autoservice_start(chan);

   /* Do our thing here */
   ast_str_get_encoded_str(&buf, 0, (char *) data);
   cbuf = ast_str_buffer(buf);

   if (strchr("\"'", cbuf[0]) && cbuf[ast_str_strlen(buf) - 1] == cbuf[0]) {
      cbuf[ast_str_strlen(buf) - 1] = '\0';
      cbuf++;
      ast_log(LOG_NOTICE, "It is not necessary to quote the argument to the System application.\n");
   }

   res = ast_safe_system(cbuf);

   if ((res < 0) && (errno != ECHILD)) {
      ast_log(LOG_WARNING, "Unable to execute '%s'\n", (char *)data);
      pbx_builtin_setvar_helper(chan, chanvar, "FAILURE");
      res = failmode;
   } else if (res == 127) {
      ast_log(LOG_WARNING, "Unable to execute '%s'\n", (char *)data);
      pbx_builtin_setvar_helper(chan, chanvar, "FAILURE");
      res = failmode;
   } else {
      if (res < 0)
         res = 0;
      if (res != 0)
         pbx_builtin_setvar_helper(chan, chanvar, "APPERROR");
      else
         pbx_builtin_setvar_helper(chan, chanvar, "SUCCESS");
      res = 0;
   }

   ast_autoservice_stop(chan);

   return res;
}

static int system_exec(struct ast_channel *chan, const char *data)
{
   return system_exec_helper(chan, data, -1);
}

static int trysystem_exec(struct ast_channel *chan, const char *data)
{
   return system_exec_helper(chan, data, 0);
}

static int unload_module(void)
{
   int res;

   res = ast_unregister_application(app);
   res |= ast_unregister_application(app2);

   return res;
}

static int load_module(void)
{
   int res;

   res = ast_register_application_xml(app2, trysystem_exec);
   res |= ast_register_application_xml(app, system_exec);

   return res;
}

AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Generic System() application");