exec Module

Jiri Kuthan

FhG FOKUS

Edited by

Jan Janak

Revision History
Revision $Revision: 5901 $$Date$

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, LOCAL_ROUTE, TIMER_ROUTE, EVENT_ROUTE, ONREPLY_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, TIMER_ROUTE, EVENT_ROUTE, ONREPLY_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, TIMER_ROUTE, EVENT_ROUTE, ONREPLY_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).