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");