how to match a URL inside a HTML comment with regular expressions?

Question

I'm making an automated script with PHP to check if my link exists at my partner website ( link exchange) .. besides making sure my link exists in the source code , I want to make sure he is not placing it in a HTML comment like <!-- http://www.mywebsite.com --> and cheating me ..

I tried to match it with REGEXP , but have failed

Answer 1

Writing a regular expression to look ahead/behind that a link is not within a comment may be more difficult than removing the comments on a page, then searching for your link.

I will point out that there are other ways to hide your link. You should determine what exactly you want to verify, i.e. it must be a <a href="[your_url]">. Just know that there are many crafty ways for the link to be in the code but not be displayed (JS, CSS, etc).

The question is, how crafty do you want to be?

Answer 2

Use the DOM and XPath, it ignores comments:

$doc = new DOMDocument();
$doc->loadHTML($htmlstring);

$xpath = new DOMXPath($doc);

$result = $xpath->query('//a[contains(@href, "mywebsite.com")]');

if (!$result->length) echo "You've been cheated\n";

And then if you still want to know if your website is being commented out

if (strpos($htmlstring, 'mywebsite.com') !== false && !$result->length)
   echo "Your partner is hiding your link in a comment, sneaky bastard\n";

Answer 3

Sounds like a perfect use for an HTML parser like DOMDocument->loadHTML() and look for an anchor tag with your link. He could still remove it via javascript on the browser side, but that's a different issue.

If it's a cat and mouse game of "are you showing a link to my site" using a standard parser is your best bet. There are just too many ways for a regex to fail on html.