# &adminguide;

## Overview

The time needed when writing a new OpenSIPS module unfortunately is quite high, while the options provided by the configuration file are limited to the features implemented in the modules.

With this Lua module, you can easily implement your own OpenSIPS extensions in Lua.

## Installing the module

This Lua module is loaded in opensips.cfg (just like all the other modules) with loadmodule("/path/to/lua.so");.

For the Lua module to compile, you need a recent version of Lua (tested with 5.1) linked dynamically. The default version of your favorite Linux distribution should work fine.

## Using the module

With the Lua module, you can access to lua function on the OpenSIPS side. You need to define a file to load and call a function from it. Write a function "mongo_alias" and then write in your opensips.cfg

    ...
    if (lua_exec("mongo_alias")) {
    	...
    }
    ...

On the Lua side, you have access to opensips functions and variables (AVP, pseudoVar, ...). Read the documentation below for further informations.

## Dependencies

### OpenSIPS Modules

None ;-)

### External Libraries or Applications

The following libraries or applications must be installed before running OpenSIPS with this module loaded:

- Lua 5.1.x or later

- memcached

This module has been developed and tested with Lua 5.1.?, but should work with any 5.1.x release. Earlier versions do not work.

On current Debian systems, at least the following packages should be installed:

- lua5.1

- liblua5.1-0-dev

- libmemcached-dev

- libmysqlclient-dev

It was reported that other Debian-style distributions (such as Ubuntu) need the same packages.

On OpenBSD systems, at least the following packages should be installed:

- Lua

## Exported Parameters

### luafilename (string)

This is the file name of your script. This may be set once only, but it may include an arbitary number of functions and "use" as many Lua module as necessary.

The default value is "/etc/opensips/opensips.lua"

#### Set luafilename parameter

    ...
    modparam("lua", "luafilename", "/etc/opensips/opensips.lua")
    ...

### lua_auto_reload (int)

Define this value to 1 if you want to reload automatically the lua script. Disabled by default.

### warn_missing_free_fixup (int)

When you call a function via moduleFunc() you could have a memleak. Enable this warns you when you're doing it. Enabled by default.

### lua_allocator (string)

Change the default memory allocator for the lua module. Possible values are :

- opensips (default)

- malloc

### lua_user_debug (int)

Disable by default

## Exported Functions

### lua_exec(func, [param])

Calls a Lua function with passing it the current SIP message. This function can be used from REQUEST_ROUTE, FAILURE_ROUTE, ONREPLY_ROUTE and BRANCH_ROUTE.

#### lua_exec() usage

    ...
    if (lua_exec("mongo_alias")) {
    	...
    }
    ...

### lua_meminfo()

Logs informations about memory.