ICT

I bug dei big

Sun, 24 Apr 2011 23:00:00 GMT

Con l'ultimo aggiornamento della sicurezza di Windows XP (quello del 12 aprile 2011) è inclusa una simpatica sorpresa... e visto che siamo in tempo di Pasqua effettivamente, non guasta.

More...

...fondata sul lavoro.

Thu, 25 Sep 2008 08:38:58 GMT

Questi sono gli annunci di lavoro che si trovano a Cosenza. Ti spari prima una bella laurea di 5 anni, poi trovi un lavoro (anche a gratis) che ti permetta di imparare tutto quello che l'università non ti ha dato ma il mercato richiede: PHP, ASP, .NET, MySQL, SQL Server e, perchè no, anche Ajax.

Poi... un bel giorno (dopo 3/5 anni) leggi questo annuncio e decidi di fare il salto di qualità... una botta di vita... ragazzi si passa a 450 euro al mese (NETTI!!! Questa è una svolta!!).

Io purtroppo non conosco PHP... peccato... se vi interessa vi passo il link, và.

RevokeCertificate, two's complement and unchecked

Thu, 18 Oct 2007 13:56:30 GMT

Those of you working with Microsoft Certification Authority in a .NET environment probably noticed that during the use of a specific Win32 dll in .NET an anomalous situation arises.

Prologue

CertAdm.dll library expose, among other ca administrative methods, the RevokeCertificate method of the ICertAdmin2 interface. Those method, as explained in documentation, accept the LONG Reason input parameter (We could argue why a LONG, given that allowed values are 0..6).
However, from the documentation we can read that in case of certificates revoked with CRL_REASON_CERTIFICATE_HOLD reason (Reason=6) it is possible to invoke again RevokeCertificate method to do a certificate resume using MAXDWORD (0xffffffff as defined in Winnt.h) as Reason value. After it is reinstated, the certificate will not appear in future CRLs.

The anomaly

When importing CertAdm.dll in your .NET project, Visual Studio provide to create the wrapper Interop.CERTADMINLib.dll. With this wrapper you can create a CCertAdmin object that expose:

objAdmin.RevokeCertificate(string Config, string SN, int Reason, DateTime Date);

Note that Reason is now an int, no more a LONG.

int Reason = 0xffffffff;

rises the following error:

Cannot implicitly convert type 'uint' to 'int'

So, how to assign a uint value to an int?

The solution ?

Another try could be this one:

int Reason = (int)0xffffffff;

but it rises the following error:

Constant value '4294967295' cannot be converted to a 'int' (use 'unchecked' syntax to override)

In fact, giving a look at some articles around the internet, comes out that one method to do the trick could be the use of unchecked keyword:

"Conversions between numeric types, where the value to be converted overflows the destination type, can also be checked/unchecked."

So this seems to be the solution:

int Reason = unchecked((int)0xffffffff);

Egg of Columbus

The problem is indeed simpler than how it seems.
In fact, it's enough to remember that int type is a representation of signed integers in two's complement. And which is the representation of 0xffffffff in two's complement?

 ffffffff (exadecimal)
 00000000 (One's complement)
+       1
----------
 00000001 (Two's complement)
 ^
 sign -

0xffffffff equivals to -1 in decimal when we are representing a 4 byte signed integer value.
So, the smartest solutions is:

int Reason = -1;

Error BC30560

Mon, 16 Jul 2007 10:12:14 GMT

Few days ago, early in the morning, connecting to my DotNetNuke site I found it completely crashed!
Apparently without a valid reason, given that I left it in good health the night before... everything was ok and I didn't make any config changes.
Giving a look at the log, the main exception (at which many other followed) seemed to be this:

"System.Web.HttpCompileException: \Portals\_default\Skins\Tranquility\Basic.ascx(32): error BC30560: 'admin_skins_solpartmenu_ascx' is ambiguous in the namespace 'ASP'."

After 5 minutes of panic, I started to look for a known solution on the internet and on dotnetnuke.com forums.
I didn't find many solutions... and the few ones I found didn't match my case.

For someone the exception arises due to the existence of an "admin" virtual path

Others state that is a naming conflict and a renaming is enough to fix the bug

In some other cases seems to be a lower-upper case problem

However, in all situations above everything started after a modify, an external input... thing not true in my case. My provider too assured me that no modifies or patching activities was done during that night.

At the end I solved this way:

set to true the debug mode in web.config:
restart the application connecting to the home page
re-set to false the debug mode in web.config:

The mistery about the exception remains... if someone know a clear explanation, please, post it on the blog.. just to avoid the "An error occurred" panic! ;-)