kamailio/modules/app_lua/doc/app_lua_admin.xml

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<!-- Module User's Guide -->

<chapter>
    
    <title>&adminguide;</title>
    
    <section>
	<title>Overview</title>
	<para>
		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'.
	</para>
	<para>
		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.
	</para>
	<para>
		The module has two Lua contexts:
    	<itemizedlist>
	    <listitem>
		<para>
			<emphasis>first</emphasis> is used for functions lua_dofile()
			and lua_dostring().
		</para>
	    </listitem>
	    <listitem>
		<para>
		    <emphasis>second</emphasis> 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.
		</para>
	    </listitem>
    	</itemizedlist>
	</para>
    </section>
    <section>
	<title>Dependencies</title>
	<section>
	    <title>&kamailio; Modules</title>
	    <para>
		The following modules must be loaded before this module:
	    	<itemizedlist>
		    <listitem>
			<para>
			    <emphasis>none</emphasis>.
			</para>
		    </listitem>
	    	</itemizedlist>
	    </para>
	</section>
	<section>
	    <title>External Libraries or Applications</title>
	    <para>
		The following libraries or applications must be installed before running
		&kamailio; with this module loaded:
	    	<itemizedlist>
		    <listitem>
			<para>
			    <emphasis>liblua5.1-dev</emphasis> - Lua devel library.
			</para>
		    </listitem>
	    	</itemizedlist>
	    </para>
	</section>
    </section>
    <section>
	<title>Exported Parameters</title>
	<section>
	    <title><varname>load</varname> (string)</title>
	    <para>
			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.
	    </para>
	    <para>
		<emphasis>
		    Default value is <quote>null</quote>.
		</emphasis>
	    </para>
	    <example>
		<title>Set <varname>load</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("app_lua", "load", "/usr/local/etc/kamailio/lua/myscript.lua")
...
</programlisting>
	    </example>
	</section>

	<section>
	    <title><varname>register</varname> (string)</title>
	    <para>
			Use this function to register optional SIP Router submodules
			to Lua. Available submodules are:
	    </para>
	    	<itemizedlist>
		    <listitem>
			<para>
				<emphasis>auth</emphasis> - register functions from auth module
				under 'sr.auth'.
			</para>
		    </listitem>
		    <listitem>
			<para>
				<emphasis>auth_db</emphasis> - register functions from auth_db
				module under 'sr.auth_db'.
			</para>
		    </listitem>
		    <listitem>
			<para>
				<emphasis>dispatcher</emphasis> - register functions from
				dispatcher module under 'sr.dispatcher'.
			</para>
		    </listitem>
		    <listitem>
			<para>
				<emphasis>maxfwd</emphasis> - register functions from maxfwd
				module under 'sr.maxfwd'.
			</para>
		    </listitem>
		    <listitem>
			<para>
				<emphasis>registrar</emphasis> - register functions from
				registrar module under 'sr.registrar'.
			</para>
		    </listitem>
		    <listitem>
			<para>
				<emphasis>rr</emphasis> - register functions from rr module
				under 'sr.rr'.
			</para>
		    </listitem>
		    <listitem>
			<para>
				<emphasis>sqlops</emphasis> - register functions from sqlops
				module under 'sr.sqlops'.
			</para>
		    </listitem>
		    <listitem>
			<para>
				<emphasis>sl</emphasis> - register functions from sl module
				under 'sr.sl'.
			</para>
		    </listitem>
		    <listitem>
			<para>
				<emphasis>tm</emphasis> - register functions from tm module
				under 'sr.tm'.
			</para>
		    </listitem>
		    <listitem>
			<para>
				<emphasis>xhttp</emphasis> - register functions from xhttp
				module under 'sr.xhttp'.
			</para>
		    </listitem>
	    	</itemizedlist>
	    <para>
			Note that 'sr', 'sr.hdr' and 'sr.pv' modules are always registered
			to Lua.
	    </para>
	    <para>
		<emphasis>
		    Default value is <quote>null</quote>.
		</emphasis>
	    </para>
	    <example>
		<title>Set <varname>register</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("app_lua", "register", "sl")
...
</programlisting>
	    </example>
	</section>

	</section>
	
    <section>
	<title>Exported Functions</title>
 	<section>
	    <title>
		<function moreinfo="none">lua_dofile(path)</function>
	    </title>
	    <para>
		Execute the Lua script stored in 'path'. The parameter can be
		a string with pseudo-variables evaluated at runtime.
	    </para>
		<example>
		<title><function>lua_dofile</function> usage</title>
		<programlisting format="linespecific">
...
lua_dofile("/usr/local/etc/kamailio/lua/myscript.lua");
...
</programlisting>
	    </example>
	</section>
	
 	<section>
	    <title>
		<function moreinfo="none">lua_dostring(script)</function>
	    </title>
	    <para>i
		Execute the Lua script stored in parameter. The parameter can be
		a string with pseudo-variables.
	    </para>
		<example>
		<title><function>lua_dostring</function> usage</title>
		<programlisting format="linespecific">
...
if(!lua_dostring("sr.log([[err]], [[----------- Hello World from $fU\n]])"))
{
    xdbg("SCRIPT: failed to execute lua script!\n");
}
...
</programlisting>
	    </example>
	</section>

	<section>
	    <title>
		<function moreinfo="none">lua_run(function, params)</function>
	    </title>
	    <para>
		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.
	    </para>
		<example>
		<title><function>lua_run</function> usage</title>
		<programlisting format="linespecific">
...
if(!lua_run("sr_append_fu_to_reply"))
{
    xdbg("SCRIPT: failed to execute lua function!\n");
}
...
lua_run("lua_funcx", "$rU", "2");
...
</programlisting>
	    </example>
	</section>

	<section>
	    <title>
		<function moreinfo="none">lua_runstring(script)</function>
	    </title>
	    <para>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.
	    </para>
		<example>
		<title><function>lua_runstring</function> usage</title>
		<programlisting format="linespecific">
...
if(!lua_runstring("sr.log([[err]], [[----------- Hello World from $fU\n]])"))
{
    xdbg("SCRIPT: failed to execute lua script!\n");
}
...
</programlisting>
	    </example>
	</section>
	
    </section>
	
    <section>
	<title>Example of usage</title>
    <para>
		Create your Lua script and stored on file system,
		say: '/usr/local/etc/kamailio/lua/myscript.lua'.
    </para>
<programlisting format="linespecific">
...
function sr_append_fu_to_reply()
	sr.hdr.append_to_reply("P-From: " .. sr.pv.get("$fu") .. "\r\n");
end
...
</programlisting>
    <para>
		Load the script via parameter 'load' and execute function
		via lua_run(...).
    </para>
<programlisting format="linespecific">
...
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");
    }
    ...
}
...
</programlisting>
    </section>
</chapter>