What if the Matrix was running Windows?

What if the Matrix was running Windows?

What does Neo need to beat the Matrix? - ubuntu

The Art of Laying People Off

By Guy Kawasaki

The Art of Laying People Off

Story of an IT Contractor

An interesting read...

Google's SEO Starter Guide

What does Google intend to do? Put SEO's (Search Engine Optimization) out of job!

Google SEO Starter Guide

SIP and Perl

I have been working with SIP(Session Initiation Protocol) and VoIP in general on and off for many years now. And I have been using perl whenever I could to automate stuff like testing, generate testcases, during performance testing and for recreating scenarios and fixing issues that occur at interops or at remote sites by analyzing the logs.

And uptill now, I had used some very primitive level coding involving string manipulation, sockets and some quick and dirty hard coded stuff in the code to achieve the required functionality asap. I loved this approach because it gave me immense power to simulate any scenario and simulate any proprietary implementations of vendors.

Here is a sample crude perl code I used to use earlier for simulating a SIP UA. Of course on the other end would be a SIP UA we are testing, or some other entity under test. This SIP UA registers with a registrar and waits for an incoming call and establish a call/session. Don't even ask me why this script waits for 2 responses for REGISTER, I don't even remember.

#!/usr/bin/perl -w
use IO::Socket;

#--------------------------------------------------------

$numArgs = $#ARGV + 1;
print "thanks, you gave me $numArgs command-line arguments.\n";

#-------------------------------------------------------

my $sock = new IO::Socket::INET (
                              LocalPort => 8888,
                              PeerAddr => '10.232.14.112',
                       PeerPort => '5060',
                Proto => 'udp',
               );
die "Could not create socket: $!\n" unless $sock;

#-------------------------------------------------------

my $sip_request="";
my $response = "";

# register
$sip_request = "REGISTER sip:10.232.14.112:5060 SIP/2.0\r\nFrom: 1550 ;tag=hrs7fes6\r\n";
$sip_request = $sip_request."To: 1550 \r\nCall-ID: ft36633sdffff7a21111111z7\r\n";
$sip_request = $sip_request."CSeq: 1 REGISTER\r\nContact: 1550 ;q=0.9;expires=3600\r\n";
$sip_request = $sip_request."Via: SIP/2.0/UDP 10.232.15.31:8888;branch=z9hG4bK548s97i77d555458fs\r\n";
$sip_request = $sip_request."Max-Forwards: 70\r\n\r\n";

print "Request to be sent: \n$sip_request\n";

print $sock $sip_request;
#
$sock->recv($sip_request, 5000);
print "Response received: \n$sip_request\n";

$sock->recv($sip_request, 5000);
print "Response received: \n$sip_request\n";

#-------------------------------------------------------

$sip_request = "";
$response = "";


while (TRUE) {

 $sock->recv($sip_request, 5000);
 print "Response received: $sip_request\n";

 @sip_headers = split(/\r\n/, $sip_request);

 print "Number of headers in received message: $#sip_headers\n\n";

 print "\n\n-------------------------------------------------\n\n";


 #-------------------------------------------------------------

 #send 100 Trying
 $response = "SIP/2.0 100 Trying\r\n";

 foreach $header (@sip_headers) {
     if (($header =~ "^From") or ($header =~ "^To") or ($header =~ "^Call-ID") or ($header =~ "^CSeq") or ($header =~ "^Via")) {
         $response = $response.$header."\r\n";
     }
 }

 $response = $response."\r\n";

 print "Response to be sent: $response\n";

 print $sock $response;

 #-----------------------------------------------------------

 #send 180 Ringing
 $response = "SIP/2.0 180 Ringing\r\n";

 foreach $header (@sip_headers) {
     if (($header =~ "^From") or ($header =~ "^To") or
         ($header =~ "^Call-ID") or ($header =~ "^CSeq") or
         ($header =~ "^Via")) {

            if ($header =~ "^To") {
                $header = $header.";tag=rfsdf677566577";
            }
         $response = $response.$header."\r\n";
     }
 }

 $response = $response."Contact: ; isfocus\r\nContent-Length:0\r\n";
 $response = $response."Record-Route: ,,\r\n";
 $response = $response."Require: 100rel\r\nRSeq: 1\r\n";
 $response = $response."Content-Type: application/sdp\r\n";

 $response = $response."\r\n";

 print "Response to be sent: $response\n";

 print $sock $response;

 #---------------------------------------------------------------
 # wait for PRACK

 $sock->recv($sip_request, 5000);
 print "Response received: $sip_request\n";

 @sip_headers = split(/\r\n/, $sip_request);

 print "Number of headers in received message: $#sip_headers\n\n";

 print "\n\n-------------------------------------------------\n\n";

 #-----------------------------------------------------------------

 #send 200 OK
 $response = "SIP/2.0 200 OK\r\n";

 foreach $header (@sip_headers) {
     if (($header =~ "^From") or ($header =~ "^To") or
         ($header =~ "^Call-ID") or ($header =~ "^CSeq") or
         ($header =~ "^Via")
        ) {
         $response = $response.$header."\r\n";
     }
 }

 $response = $response."Contact: ; isfocus\r\nContent-Length:189\r\n";
 $response = $response."Content-Type: application/sdp\r\n";

 $response = $response."\r\n";

 $response = $response."v=0"."\r\n"."o=RV-MCU 2021970 2021970 IN IP4 10.232.15.31"."\r\n"."s=RV MCU Session\r\n"."c=IN IP4 10.232.15.31"."\r\n"."b=CT:64"."\r\n"."t=0 0"."\r\n"."m=audio 6028 RTP/AVP 8"."\r\n"."c=IN IP4 10.232.15.31"."\r\n"."a=rtpmap:8 PCMA/8000"."\r\n"."a=sendrecv"."\r\n";

 print "Response to be sent: $response\n";

 print $sock $response;

 #---------------------------------------------------------------

 #Wait for ACK
 $sip_request = "";
 @sip_headers = "";

 $sock->recv($sip_request, 5000);
 print "Response received: $sip_request\n";

 @sip_headers = split(/\r\n/, $sip_request);

 print "Number of headers in received message: $#sip_headers\n\n";

 print "\n\n-------------------------------------------------\n\n";

 print "CALL SETUP\n";
 sleep 100;

 #----------------------------------------------------------------

}

close $sock;

Of course, I am bringing this up in this post because I have found Net::SIP module for perl. That reminded me of my earlier days and this dirty code I used to write. I don't know how I didn't discover this module earlier. However, my experiments with Net::SIP will be part of another post.

ActivePerl to Strawberry Perl

Activeperl from ActiveState has been the predominant flavour of perl used by many over the years. In addition to the core perl, the package release includes some of the mostly used modules and some win32 specific modules which make the life easier for a developer if he is developing anything for Windows. It also has ppm tool which is quite handful for querying and installing modules and packages from activeperl repository.

However, I have found some irritating issues with activeperl especially if one is developing platform-independant code. First one would be missing packages. For eg support for SSL packages - ssleay and HTTPS support for LWP. I understand that it is not activestate's fault as such since Canadian federal government does not permit distributing of cryptographic software. But it is an annoying thing for a developer since HTTPS is such an important requirement if one is working on any web related programs. Of course, there are work arounds like adding another repository that has them. I have encountered other missing modules like - Net::SIP.

Next in line would be manual compilation on Windows. One can download the source packages from CPAN and try to compile. If the module is a perl only module, then you are in safe land. Compilation and installation will go through. Even for that one needs to have the 'nmake' utility. This is distributed as part of Visual Studio (VS) application by Microsoft. In case one doesn't have VS installed, then one can google for 'nmake' and download it for free else download the express edition of the VS which is free. Probably some tests will fail probably because author made use of *nix specific stuff in the test code, but that's still better than not having anything at all. However if the module has some C code, then you are on your own. It will consume too much effort to proceed.

One of my other grudges is the lack of cpan connectivity. CPAN is one of the reasons why perl is so popular.

Recently I came across strawberryperl. This flavour of win32 perl comes with mingw compiler (gcc for Windows) and other unix utilities for Windows. And has CPAN tool chain with auto-upgrade support. So incase you need a module that's missing, just drop into the cpan shell that's part of the strawberry perl release and install or update the desired module. Incase the module has C source code and needs to be built, then no problem. The mingw compiler and other unix utilities will do the job for you.

Have just started playing around with strawberry perl. If still curious about win32 perl version, then head over to this wiki to quench your thirst.

Update: In the comments, Jan Dubois mentions that most of the issues I have mentioned here have been fixed in the last week's build of the activeperl releases. Thanks Jan for updating. However, I have not tried the latest activeperl releases yet.

Linus family blog

This post is to just communicate to all the penguin lovers about the personal family blog of one of their leaders.

Linus Torvalds has a personal family blog over here, where he talks of mostly non-linux stuff.