Imgur image validation using preg_match

Question

I'd like to use the preg_match function (procedural, not oop) to validate user provided urls for images hosted on imgur.com

The purpose is to include the called image into a php page (hotlink) where users can use the image as their avatar/profile image.

As far as I know, a valid imgur hotlink is:

https://i.imgur.com/FILENAME.XYZ

Where "FILENAME" is something like "2lcqfvJ" and "XYZ" is the image format like "jpg". Example:

https://i.sstatic.net/2UXVL.jpg

I've some difficulties to figure out the pattern for the validation. I use this method yet to identify valid tinypic and imageshack valid urls

I tried this to check the url provided by the user, but it seems to not work:

if ( !preg_match('/^(http|https):\/\/(.*?)\.(imgur)\.(com)\/.(png|jpg|gif|PNG|JPG|GIF)$/i',$url) )

Passing the url above (https://i.sstatic.net/2UXVL.jpg) the function doesn't recognize it as a valid imgur link. So I can imagine I've done something wrong with the regular expression.

Answer 1

(Posted answer on behalf of the question author).

The pattern below works:

!preg_match('/^(http|https):\/\/(.*?)\.(imgur)\.(com)\/(.*?)\.(png|jpg|gif|PNG|JPG|GIF)$/i',$url)

Answer 2

Your regex can be simplified:

!preg_match('~^https?://i\.imgur\.com/\w+\.(png|jpe?g|gif)$~i', $url)