Max says…

At work, I have a Snom 360 IP phone that is hooked up to our internal Asterisk PBX.  If I’m listening to music with my headphones in, I’m not always aware that my phone is ringing – some Perl and PHP hacking later, I’ve got a crude (and work-in-progress) solution.

The phone has an internal web server that lets the user customise a number of options.  The one I’m interested in is ‘Action URI’.  When a call comes through to my phone, I can enter a URI that my phone will request.  I can send arbitrary parameters in the query string, e.g. a message or the phone number of the caller.  My solution involves a PHP script that the phone can request, a simple Perl socket server sitting listening on my laptop, and a simpel Perl Tk script that will open a window to alert me to the call.

The PHP script that my phone requests is quite simple:

// Hostname of machine
$host = 'somehost';
// Port to connect to
$port = '7890';
$timeout = 30;
$message = $_GET['message'];

$socket = fsockopen($host, $port, $errnum, $errstr, $timeout);
if (!is_resource($socket))
{
exit("Cannot connect: " . $errnum . " " . $errstr);
}
else
{
fputs($socket, $message);
}
fclose($socket);

This script is called from my phone and connects to the socket server listening on my laptop. The code for the corresponding socket server follows:

use strict;
use IO::Socket;
use Net::hostent;

my $PORT = 7890;
my $IP = '192.168.0.1';

my $serverSocket = IO::Socket::INET->new(
    Proto => 'tcp',
    LocalHost => $IP,
    LocalPort => $PORT,
    Listen => SOMAXCONN,
    Reuse => 1,
) or die("Cannot create socket: $!\n");

while (my $clientSocket = $serverSocket->accept())
{
    $clientSocket->autoflush(1);
    while (<$clientSocket>)
    {
        `/path/to/tk/script/showMessage.pl "$_"`;
    }
    close($clientSocket);
}

This Perl script listens in the background for incoming connections and passes any data it receives to a Perl TK script that displays this data in the form of a simple window on display 0:0. Here’s the code for th Perl Tk srcript:

use strict;
use Tk;
use Tk::Font;

my $message = $ARGV[0];

my $mainWindow = MainWindow->new();
$mainWindow->minsize(qw(500 200));
$mainWindow->title("Incoming Call");
$mainWindow->configure(-background => 'white');

my $font = $mainWindow->Font(
    -family => 'Arial',
    -size => '24',
);

my $acceptButton = $mainWindow->Button(
    -text => $message,
    -background => 'red',
    -command => \&exit,
    -foreground => 'white',
    -font => $font,
);

$acceptButton->pack(
    -side => 'bottom',
    -expand => 1,
    -fill => 'both'
);

$mainWindow->withdraw();
$mainWindow->update();
my $winXPos = int(($mainWindow->screenwidth - $mainWindow->width) / 2);
my $winYPos = int(($mainWindow->screenheight - $mainWindow->height) / 2);
$mainWindow->geometry("+$winXPos+$winYPos");
$mainWindow->deiconify();

MainLoop();

There’s no doubt about it, this combination of scripts is crude, insecure, and really more of a proof of concept. Nonetheless, it serves my purposes and hopefully can tidy it up as time allows.