kamailio/modules/app_lua/README

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. Exported Parameters

              3.1. load (string)
              3.2. register (string)

        4. Exported Functions

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

        5. Example of usage

   List of Examples

   1.1. Set load parameter
   1.2. Set register parameter
   1.3. lua_dofile usage
   1.4. lua_dostring usage
   1.5. lua_run usage
   1.6. 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. Exported Parameters

        3.1. load (string)
        3.2. register (string)

   4. Exported Functions

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

   5. 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. Exported Parameters

   3.1. load (string)
   3.2. register (string)

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("lua", "load", "/usr/local/etc/kamailio/lua/myscript.lua")
...

3.2. register (string)

   Use this function to register optional SIP Router submodules to Lua.
   Available submodules are:
     * sl - register functions from sl module under 'sr.sl'.

   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("lua", "register", "sr")
...

4. Exported 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 1.3. lua_dofile usage
...
lua_dofile("/usr/local/etc/kamailio/lua/myscript.lua");
...

4.2.  lua_dostring(script)

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

   Example 1.4. 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 1.5. 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)

   i 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 1.6. lua_runstring usage
...
if(!lua_runstring("sr.log([[err]], [[----------- Hello World from $fU\n]])"))
{
    xdbg("SCRIPT: failed to execute lua script!\n");
}
...

5. 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");
    }
    ...
}
...