Canonical Links Issue

[eluser]Unknown[/eluser]
@boltsabre

I just want to echo out actual url of the current page. Example: When someone visits domain.com/info/about-us.php then in the header it should have

Code:

<link rel="canonical" href="http://domain.com/info/about-us.php" />

so Google does not consider it as duplicate when google finds cdn version http://cdn.domain.com/info/about-us.php