exec Module

Jiri Kuthan

   FhG FOKUS

Edited by

Jan Janak

   Copyright © 2003 FhG FOKUS
   Revision History
   Revision $Revision$ $Date: 2009-07-21 10:45:05 +0300
                              (Tue, 21 Jul 2009) $
     __________________________________________________________

   Table of Contents

   1. Admin Guide

        1.1. Overview
        1.2. Dependencies

              1.2.1. OpenSIPS Modules
              1.2.2. External Libraries or Applications

        1.3. Exported Parameters

              1.3.1. setvars (integer)
              1.3.2. time_to_kill (integer)
              1.3.3. async (integer)

        1.4. Exported Functions

              1.4.1. exec_dset(command)
              1.4.2. exec_msg(command)
              1.4.3. exec_avp(command [, avplist])
              1.4.4. exec_getenv(environment_variable [, avp])

        1.5. Known Issues

   List of Examples

   1.1. Set “setvars” parameter
   1.2. Set “time_to_kill” parameter
   1.3. Set “async” parameter
   1.4. exec_dset usage
   1.5. exec_msg usage
   1.6. exec_avp usage
   1.7. exec_getenv usage

Chapter 1. Admin Guide

1.1. Overview

   Exec module allows to start an external command from a OpenSIPS
   script. The commands may be any valid shell commands--the
   command string is passed to shell using “popen” command.
   OpenSIPS passes additionally lot of information about request
   in environment variables:
     * SIP_HF_<hf_name> contains value of each header field in
       request. If a header field occurred multiple times, values
       are concatenated and comma-separated. <hf_name> is in
       capital letters. Ff a header-field name occurred in compact
       form, <hf_name> is canonical.
     * SIP_TID is transaction identifier. All request
       retransmissions or CANCELs/ACKs associated with a previous
       INVITE result in the same value.
     * SIP_DID is dialog identifier, which is the same as to-tag.
       Initially, it is empty.
     * SIP_SRCIP is source IP address from which request came.
     * SIP_ORURI is original request URI.
     * SIP_RURI is current request URI (if unchanged, equal to
       original).
     * SIP_USER is userpart of current request URI.
     * SIP_OUSER is userpart of original request URI.

   NOTE: The envirnment variables must be specified with double $
   (e.g., $$SIP_OUSER) in the parameters given to exec functions.
   Otherwise they will be evaluated as OpenSIPS pseudo-variables,
   throwing errors.

1.2. Dependencies

1.2.1. OpenSIPS Modules

   The following modules must be loaded before this module:
     * No dependencies on other OpenSIPS modules.

1.2.2. External Libraries or Applications

   The following libraries or applications must be installed
   before running OpenSIPS with this module loaded:
     * None.

1.3. Exported Parameters

1.3.1. setvars (integer)

   Turn off to disable setting environment variables for executed
   commands.

   Default value is 1.

   Example 1.1. Set “setvars” parameter
...
modparam("exec", "setvars", 1)
...

1.3.2.  time_to_kill (integer)

   Specifies the longest time a program is allowed to execute. If
   the time is exceeded, the program is killed.

   Default value is 0.

   Example 1.2. Set “time_to_kill” parameter
...
modparam("exec", "time_to_kill", 20)
...

1.3.3. async (integer)

   Turns on the asynchronous mode for 'exec_msg' function. All
   commands will be executed by a different process and the caller
   will continue it's flow, without waiting for a response.

   Default value is 0.

   Example 1.3. Set “async” parameter
...
modparam("exec", "async", 1)
...

1.4. Exported Functions

1.4.1.  exec_dset(command)

   Executes an external command. Current URI is passed to the
   command as parameter. Output of the command is considered URI
   set (separated by lines).

   Meaning of the parameters is as follows:
     * command - Command to be executed. It can include pseudo-
       variabes;

   WARNING: if the var you are passing out has a bash special
   character in it, the var needs to be placed inside quotes, for
   ex: exec_dset("print-contact.sh '$ct'");

   This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.

   Example 1.4. exec_dset usage
...
exec_dset("echo TEST > /tmp/test.txt");
exec_dset("echo TEST > /tmp/$rU.txt");
...

1.4.2.  exec_msg(command)

   Executes an external command. The whole message is passed to it
   in input, no command-line parameters are added, output of the
   command is not processed.

   See sip-server/modules/exec/etc/exec.cfg in the source tarball
   for information on usage.

   Meaning of the parameters is as follows:
     * command - Command to be executed. It can include
       pseudo-variables.

   WARNING: if the var you are passing out has a bash special
   character in it, the var needs to be placed inside quotes, for
   ex: exec_msg("print-contact.sh '$ct'");

   This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.

   Example 1.5. exec_msg usage
...
exec_msg("echo TEST > /tmp/test.txt");
exec_msg("echo TEST > /tmp/$rU.txt");
...

1.4.3.  exec_avp(command [, avplist])

   Executes an external command. Each line from output of the
   command is saved in an AVP from 'avplist'. If 'avplist' is
   missing, the AVP are named 1, 2, 3, ...

   Meaning of the parameters is as follows:
     * command - Command to be executed. It can include pseudo-
       variabes;
     * avplist - comma separated list with AVP names to store the
       result in;

   WARNING: if the var you are passing out has a bash special
   character in it, the var needs to be placed inside quotes, for
   ex: exec_avp("print-contact.sh '$ct'");

   This function can be used from REQUEST_ROUTE, FAILURE_ROUTE,
   LOCAL_ROUTE, STARTUP_ROUTE.

   Example 1.6. exec_avp usage
...
exec_avp("echo TEST");
exec_avp("echo TEST", "$avp(test)");
...

1.4.4.  exec_getenv(environment_variable [, avp])

   Get the value of an evironment_variable. The value is saved in
   'avp'. If 'avp' is missing, the AVP is named 1. If there is no
   such environment variable no value is returned.

   Meaning of the parameters is as follows:
     * environment_variable - Environent variable name. It can
       include pseudo- variabes;
     * avp - an AVP names to store the result in;

   WARNING: if the var you are passing out has a bash special
   character in it, the var needs to be placed inside quotes, for
   ex: exec_getenv("'$ct'");

   This function can be used from REQUEST_ROUTE, FAILURE_ROUTE,
   LOCAL_ROUTE, STARTUP_ROUTE.

   Example 1.7. exec_getenv usage
...
exec_getenv("HOSTNAME");
exec_getenv("HOSTNAME", "$avp(test)");
...

1.5. Known Issues

   There is currently no guarantee that scripts ever return and
   stop blocking SIP server. (There is kill.c but it is not used
   along with the current mechanisms based on popen. Besides that
   kill.c is ugly).
