Specify iframe Link using Regex

Question

Problem:

I need to confirm that iframe have one type of link with the following format:

http://www.example.com/embed/*****11 CHARACTERS MAX.****?rel=0

Starts with: http://www.example.com/embed/
Ends with: ?rel=0
11 CHARACTERS MAX. means in this spot, there can any 11 characters. Don't go beyond 11.

NOTE: none of the specified tags are ensured to be in every post. It depends on how user uses the editor.

I'm using PHP

I used the line below to make sure all tags are excluded except the ones specified:

$rtxt_offer = preg_replace('#<(?!/?(u|br|iframe)\b)[^>]+>#', '', $rtxt_offer);

Please see: [Extract all the text and img tags from HTML in PHP.](http://stackoverflow.com/q/8021543/367456) (closed). — hakre, Nov 13 '11 at 10:38
possible duplicate of [Best methods to parse HTML with PHP](http://stackoverflow.com/questions/3577641/best-methods-to-parse-html-with-php) - Main point: Consider to not use regular expressions to parse HTML. — hakre, Nov 13 '11 at 10:39
Your first regex was basically a reimplementation of `strip_tags()`. You can of course augment it with another assertion just for `|iframe (?=src=)`, but it's not worth the effort. HTMLPurifier might be what you are searching for (though even more effort to do what you want). — mario, Nov 13 '11 at 10:46

score 0 · Answer 1 · answered Nov 13 '11 at 10:51

First of all, there is built-in function in PHP that strips tags for you: http://php.net/manual/en/function.strip-tags.php no need to use slow regex here.

Steps you'll need to solve your problem:

Parse this text as DomDocument
Get iframe node from it
Get src attribute from iframe and parse it with parse_url
Now you can perform easy checks on all components returned by parse_url

Happy coding

score 0 · Accepted Answer · edited May 23 '17 at 11:47

You wrote you only want to validate the link value with a regular expression:

$doesMatch = preg_match('~^http://www.example.com/embed/[^?]{0,11}\?rel=0$~', $link);

This does specifically what you're asking for.

For removing tags please see strip_tags or use a HTML parser to do it, which will also help you to get the link value more properly.

In a similar question/answer I posted some example code how to use strip_tags and SimpleXMLElement together: Extract all the text and img tags from HTML in PHP.

Specify iframe Link using Regex

2 Answers2