FastAGI: AGI as a TCP Server

FastAGI with PHPAGI and xinetd

Similar to AGI, FastAGI provides the ability to pass variables directly from the dialplan to the FastAGI server.

Some housekeeping before we begin

First of all install the phpagi library (that can be found on sourceforge at http://phpagi.sourceforge.net/) and had a look at the code. Copy the agi files to /var/lib/asterisk/agi-bin/ and give 777 permission.

chmod -R 777 /var/lib/asterisk/agi-bin/

Also install few modules.

yum install xinetd
yum install ngrep
yum install php-posix
yum install php-process

Configuring xinetd for FastAGI and PHPAGI

Configuring xinetd

As indicated previously, in order to turn our AGI script into a FastAGI server, we must first configure xinetd.

vi /etc/xinetd.d/fastagi

The following is an example of what the xinetd configuration may look like. Paste the below configuration in /etc/xinetd.d/fastagi.

# default: off
# description: fastagi is a remote AGI interface
service fastagi
{
	socket_type  = stream
	user         = root
	group        = nobody
	server       = /var/lib/asterisk/agi-bin/phpagi-fastagi.php	
	wait         = no
	protocol     = tcp
	bind         = 127.0.0.1
	disable      = no
}

Make sure you set the path to the phpagi-fastagi.php script. Set the user and group to a non-root user if none of your scripts need root access. You might consider using posix_setuid and friends to reduce privileges. Change the bind address to your outbound IP address or to 0.0.0.0 to allow anyone to connect. Be sure to read up about xinetd and take advantage of security features it provides. Fast AGI doesn't provide authentication. It's up to you to keep unwanted visitors from extracting information from your AGI implementation.

Once we have configured our xinetd server, we need to notify your Linux server of the new TCP service. In order to do this, add the following line to your /etc/services file:

vi /etc/services

Paste the following at the end of /etc/services

fastagi         4573/tcp                # Asterisk AGI

The first parameter indicates the name of the new service to be rendered by xinetd. The second parameter indicates the port number and the type of IP protocol to listen to (UDP or TCP).

Once you have finished your configuration, you may run the following command: service xinetd restart

If everything has been performed correctly, using the following command should emit an output, search for following:

netstat -ap | less

tcp        0      0 localhost:fastagi       0.0.0.0:*               LISTEN      53871/xinetd

Or

netstat -apn | less

tcp        0      0 127.0.0.1:4573          0.0.0.0:*               LISTEN      53871/xinetd

Similar to AGI, FastAGI provides the ability to pass variables directly from the dialplan to the FastAGI server.

Configuring PHPAGI for FastAGI

phpagi.conf

Before we start handling the actual FastAGI bootstrap, we must first configure the FastAGI environment of our PHPAGI class. By editing the phpagi.conf file, verify that the following code appears in it or if file does not exists create one with following content.

vi /etc/asterisk/phpagi.conf

[phpagi]
debug=true                              ; enable debuging
error_handler=true                      ; use internal error handler
#admin=errors@mydomain.com              ; mail errors to
#hostname=sip.mydomain.com              ; host name of this server
tempdir=/var/spool/asterisk/tmp/        ; temporary directory for storing temporary output

[asmanager]
server=localhost                        ; server to connect to
port=5038                               ; default manager port
username=sachin                         ; username for login
secret=sachin                           ; password for login

[fastagi]
setuid=true                             ; drop privileges to owner of script
basedir=/var/lib/asterisk/agi-bin/      ; path to script folder

#[festival]                             ; text to speech engine
#text2wave=/usr/bin/text2wave           ; path to text2wave binary

#[cepstral]                             ; alternate text to speech engine
#swift=/opt/swift/bin/swift             ; path to switft binary
#voice=David                            ; default voice

Your AGI file

vi /var/lib/asterisk/agi-bin/test-agi.php

<?php
	$fastagi->verbose('cool, the FastAGI server has been called!');
	$fastagi->set_variable("test", "1111");
?>

extensions.conf

vi /etc/asterisk/extensions.conf

[default]
exten => _X.,1,AGI(agi://127.0.0.1/test-agi.php,12345)
exten => _X.,n,NoOp(${test})
exten => _X.,n,NoOp(${test2})
exten => _X.,n,hangup()

TEST by command telnet 127.0.0.1 PORT

AGI FILE - test-agi.php

$request = $fastagi->request;
$number=$request['agi_arg_1'];
$fastagi->verbose('cool, the FastAGI server has been called!');
$fastagi->set_variable("test", "1111");
$fastagi->set_variable("test2", $number);

Remove debug log from command line

Set debug and error_handler to false in /etc/asterisk/phpagi.conf

vi /etc/asterisk/phpagi.conf

[phpagi]
debug=false                              ; enable debuging
error_handler=false                      ; use internal error handler

After this, set verbose to false in /var/lib/asterisk/agi-bin/phpagi-fastagi.php

vi /var/lib/asterisk/agi-bin/phpagi-fastagi.php

#replace

$fastagi->verbose(print_r($fastagi, true)); #or comment it

#with

$fastagi->verbose(print_r($fastagi, false));