app_system.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2005, Digium, Inc.
 *
 * Mark Spencer <markster@digium.com>
 *
 * 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 <markster@digium.com>
 *
 * \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");