app_lua Module

Daniel-Constantin Mierla

   asipto.com

Edited by

Daniel-Constantin Mierla

   <miconda@gmail.com>

   Copyright © 2010 Daniel-Constantin Mierla (asipto.com)
     __________________________________________________________________

   Table of Contents

   1. Admin Guide

        1. Overview
        2. Dependencies

              2.1. Kamailio Modules
              2.2. External Libraries or Applications

        3. Parameters

              3.1. load (string)
              3.2. register (string)
              3.3. reload (boolean)

        4. Functions

              4.1. lua_dofile(path)
              4.2. lua_dostring(script)
              4.3. lua_run(function, params)
              4.4. lua_runstring(script)

        5. RPC Commands

              5.1. app_lua.list
              5.2. app_lua.reload

        6. Example of usage

   List of Examples

   1.1. Set load parameter
   1.2. Set register parameter
   1.3. Set reload parameter
   1.4. lua_dofile usage
   1.5. lua_dostring usage
   1.6. lua_run usage
   1.7. lua_runstring usage

Chapter 1. Admin Guide

   Table of Contents

   1. Overview
   2. Dependencies

        2.1. Kamailio Modules
        2.2. External Libraries or Applications

   3. Parameters

        3.1. load (string)
        3.2. register (string)
        3.3. reload (boolean)

   4. Functions

        4.1. lua_dofile(path)
        4.2. lua_dostring(script)
        4.3. lua_run(function, params)
        4.4. lua_runstring(script)

   5. RPC Commands

        5.1. app_lua.list
        5.2. app_lua.reload

   6. Example of usage

1. Overview

   This module allows executing Lua scripts from config file. It exports a
   set of functions to Lua in order to access the current processed SIP
   message. These functions are within Lua module 'sr'.

   Lua (http://www.lua.org) is a fast and easy to embed scripting
   language. Exported API from SIP router to Lua is documented in the
   dokuwiki.

   The module has two Lua contexts:
     * first is used for functions lua_dofile() and lua_dostring().
     * second is used for function lua_run() and parameter 'load'.
       Therefore lua_run() cannot execute functions from scripts loaded
       via lua_dofile() in config. This is kind of caching mode, avoiding
       reading file every time, but you must be sure you do not have
       someting that is executed by default and requires access to SIP
       message.

2. Dependencies

   2.1. Kamailio Modules
   2.2. External Libraries or Applications

2.1. Kamailio Modules

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

2.2. External Libraries or Applications

   The following libraries or applications must be installed before
   running Kamailio with this module loaded:
     * liblua5.1-dev - Lua devel library.

3. Parameters

   3.1. load (string)
   3.2. register (string)
   3.3. reload (boolean)

3.1. load (string)

   Set the path to the Lua script to be loaded at startup. Then you can
   use lua_run(function, params) to execute a function from the script at
   runtime.

   Default value is “null”.

   Example 1.1. Set load parameter
...
modparam("app_lua", "load", "/usr/local/etc/kamailio/lua/myscript.lua")
...

3.2. register (string)

   NOTE: Since Kamailio v5.0, KEMI exports are available in Lua script
   under KSR module. These exports cover most of the modules, a lot more
   that those listed next. The KEMI exports are the recommended to be
   used, the old 'sr' module might be obsoleted soon. To read more about
   KEMI exports and available KSR submodules, see:
     * http://kamailio.org/docs/tutorials/devel/kamailio-kemi-framework/

   Use this parameter to register optional Kamailio submodules to Lua.
   Available submodules are:
     * alias_db - register functions from alias_db module under
       'sr.alias_db'.
     * auth - register functions from auth module under 'sr.auth'.
     * auth_db - register functions from auth_db module under
       'sr.auth_db'.
     * dispatcher - register functions from dispatcher module under
       'sr.dispatcher'.
     * maxfwd - register functions from maxfwd module under 'sr.maxfwd'.
     * msilo - register functions from msilo module under 'sr.msilo'.
     * presence - register functions from presence module under
       'sr.presence'.
     * presence_xml - register functions from presence_xml module under
       'sr.presence_xml'.
     * pua_usrloc - register functions from pua_usrloc module under
       'sr.pua_usrloc'.
     * registrar - register functions from registrar module under
       'sr.registrar'.
     * rls - register functions from rls module under 'sr.rls'.
     * rr - register functions from rr module under 'sr.rr'.
     * sanity - register functions from sanity module under 'sr.sanity'.
     * sdpops - register functions from sdpops module under 'sr.sdpops'.
     * siputils - register functions from siputils module under
       'sr.siputils'.
     * sl - register functions from sl module under 'sr.sl'.
     * sqlops - register functions from sqlops module under 'sr.sqlops'.
     * textops - register functions from textops module under
       'sr.textops'.
     * tm - register functions from tm module under 'sr.tm'.
     * xhttp - register functions from xhttp module under 'sr.xhttp'.

   Note that 'sr', 'sr.hdr' and 'sr.pv' modules are always registered to
   Lua.

   Default value is “null”.

   Example 1.2. Set register parameter
...
modparam("app_lua", "register", "sl")
...

3.3. reload (boolean)

   If reload is 1 enables the ability to reload the scripts using the RPC
   app_lua.reload command.

   Default value is “0 (off)”.

   Example 1.3. Set reload parameter
...
modparam("app_lua", "reload", 1)
...

4. Functions

   4.1. lua_dofile(path)
   4.2. lua_dostring(script)
   4.3. lua_run(function, params)
   4.4. lua_runstring(script)

4.1.  lua_dofile(path)

   Execute the Lua script stored in 'path'. The parameter can be a string
   with pseudo-variables evaluated at runtime.

   Example 1.4. lua_dofile usage
...
lua_dofile("/usr/local/etc/kamailio/lua/myscript.lua");
...

4.2.  lua_dostring(script)

   Execute the Lua script stored in parameter. The parameter can be a
   string with pseudo-variables.

   Example 1.5. lua_dostring usage
...
if(!lua_dostring("sr.log([[err]], [[----------- Hello World from $fU\n]])"))
{
    xdbg("SCRIPT: failed to execute lua script!\n");
}
...

4.3.  lua_run(function, params)

   Execute the Lua function 'func' giving params as parameters. There can
   be up to 3 string parameters. The function must exist in the script
   loaded at startup via parameter 'load'. Parameters can be strings with
   pseudo-variables that are evaluated at runtime.

   Example 1.6. lua_run usage
...
if(!lua_run("sr_append_fu_to_reply"))
{
    xdbg("SCRIPT: failed to execute lua function!\n");
}
...
lua_run("lua_funcx", "$rU", "2");
...

4.4.  lua_runstring(script)

   Execute the Lua script stored in parameter. The parameter can be a
   string with pseudo-variables. The script is executed in Lua context
   specific to loaded Lua files at startup.

   Example 1.7. lua_runstring usage
...
if(!lua_runstring("sr.log([[err]], [[----------- Hello World from $fU\n]])"))
{
    xdbg("SCRIPT: failed to execute lua script!\n");
}
...

5. RPC Commands

   5.1. app_lua.list
   5.2. app_lua.reload

5.1.  app_lua.list

   Lists the id and path for every script loaded by the load parameter.

   Name: app_lua.list

   Parameters: none

   Example:
                kamcmd app_lua.lists

5.2.  app_lua.reload

   Marks the need to reload the selected script. The actual reload is done
   by every working process when the next call to lua_run function is
   executed. If no parameter is added all the scripts are selected to be
   reloaded.

   Name: app_lua.reload

   Parameters: id

   Example:
                kamcmd app_lua.reload 0

6. Example of usage

   Create your Lua script and stored on file system, say:
   '/usr/local/etc/kamailio/lua/myscript.lua'.
...
function sr_append_fu_to_reply()
        sr.hdr.append_to_reply("P-From: " .. sr.pv.get("$fu") .. "\r\n");
end
...

   Load the script via parameter 'load' and execute function via
   lua_run(...).
...
modparam("app_lua", "load", "/usr/local/etc/kamailio/lua/myscript.lua")
...
route {
    ...
    if(!lua_run("sr_append_fu_to_reply"))
    {
        xdbg("SCRIPT: failed to execute lua function!\n");
    }
    ...
}
...