Python Module

Maxim Sobolev

   Sippy Software, Inc.

Edited by

Razvan Crainea

   Copyright © 2009 Sippy Software, Inc.
     __________________________________________________________

   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. script_name (string)
              1.3.2. mod_init_function (string)
              1.3.3. child_init_method (string)

        1.4. Exported Functions

              1.4.1. python_exec(method_name [, extra_args])

   List of Examples

   1.1. Set script_name parameter
   1.2. Set mod_init_function parameter
   1.3. Set child_init_method parameter

Chapter 1. Admin Guide

1.1. Overview

   This module can be used to efficiently run Python code directly
   from the OpenSIPS script, without executing the python
   interpreter.

   The module provides the means to load a python module and run
   its functions. Each function has to receive the SIP message as
   parameter, and optionally some extra arguments passed from the
   script.

   In order to run Python functions, one has to load the module
   that contains them, by specifying the script name using the
   script_name parameter. The module has to contain the following
   components:
     * A class that contains all the methods that can be invoked
       from the script.
     * A method within the class that is called when a SIP child
       is created. The method should receive an integer parameter,
       which represents the rank of the child, and must return 0
       or positive in case the function was executed successfully,
       or negative otherwise. The name of this method is specified
       by the child_init_method parameter.
     * A global function that initializes the Python module and
       returns an object from the class whose functions will be
       invoked by the script. The name of the global function is
       indicated by the mod_init_method parameter.

   A minimal example of a Python script that satisfies these
   requirements is:
        def mod_init():
                return SIPMsg()

        class SIPMsg:
        def child_init(self, rank):
                return 0

   A function from the object returned above can be executed from
   the script using the python_exec() script function. The python
   method has to receive the following parameters:
     * The SIP message, that has the structure detailed below
     * Optionally, a string passed from the script

   The SIP message received as parameter by the function has the
   following fields and methods:
     * Type - the type of the message, either SIP_REQUEST or
       SIP_REPLY
     * Method - the method of the message
     * Status - the status of the message, available only for
       replies
     * RURI - the R-URI of the message, available only for
       requests
     * src_address - the (IP, port) tuple representing source
       address of the message
     * dst_address - the (IP, port) tuple representing the
       destination address (OpenSIPS address) of the message
     * copy() - copies the current SIP message in a new object
     * rewrite_ruri() - changes the R-URI of the message;
       available only for requests
     * set_dst_uri() - sets the destination URI of the message;
       available only for requests
     * getHeader() - returns the header of a message the
       destination address (OpenSIPS address) of the message
     * call_function() - calls a function from the script

1.2. Dependencies

1.2.1. OpenSIPS Modules

   The following modules must be loaded before this module:
     * None.

1.2.2. External Libraries or Applications

   The following libraries or applications must be installed
   before running OpenSIPS with this module loaded:
     * python-dev - provides the Python bindings.

1.3. Exported Parameters

1.3.1. script_name (string)

   The script that contains the Python module.

   Default value is “/usr/local/etc/opensips/handler.py”.

   Example 1.1. Set script_name parameter
...
modparam("python", "script_name", "/usr/local/bin/opensips_handler.py")
...

1.3.2. mod_init_function (string)

   The method used to initialize the Python module and return the
   object.

   Default value is “mod_init”.

   Example 1.2. Set mod_init_function parameter
...
modparam("python", "mod_init_function", "module_initializer")
...

1.3.3. child_init_method (string)

   The method called for each child process.

   Default value is “child_init”.

   Example 1.3. Set child_init_method parameter
...
modparam("python", "child_init_method", "child_initializer")
...

1.4. Exported Functions

1.4.1.  python_exec(method_name [, extra_args])

   Thhis function is used to execute a method from the Python
   module loaded.

   This function can be used from REQUEST_ROUTE, ONREPLY_ROUTE,
   FAILURE_ROUTE and BRANCH_ROUTE.

   Meaning of the parameters is as follows:
     * method_name - name of the method called
     * extra_args(optional) - extra arguments that can be passed
       from the script to the python function.
