# &adminguide;

## 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.

## Dependencies

### &kamailio; Modules

The following modules must be loaded before this module:

- none.

### 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.

## Parameters

### `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.

#### Set `load` parameter

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

### `register` (string)

Use this function to register optional SIP Router 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.

#### Set `register` parameter

    ...
    modparam("app_lua", "register", "sl")
    ...

### `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).

#### Set `reload` parameter

    ...
    modparam("app_lua", "reload", 1)
    ...

## Functions

### `lua_dofile(path)`

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

#### `lua_dofile` usage

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

### `lua_dostring(script)`

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

#### `lua_dostring` usage

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

### `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.

#### `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");
    ...

### `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.

#### `lua_runstring` usage

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

## Exported RPC Commands

### `app_lua.list`

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

Name: app_lua.list

Parameters: none

Example:

                    &sercmd; app_lua.lists

### `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:

                    &sercmd; app_lua.reload 0

## 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");
        }
        ...
    }
    ...