Users can add images to content. They're supposed to be uploading them to the site, but occasionally people will reference an image hosted elsewhere in the src='...'.
What is the best way to prevent these images from working (or even better, redirecting to a "This image is blocked" image)? I imagined using a hook of some sort to modify the content, or possibly a module that adds a filter to weed out these images. But it seems like a situation I could be overthinking.
Any suggestions?
I presume you are allowing the uploading and embedding of images via the WYSIWYG. That being the case you need to write a text filter and apply it to the text format the users are allowed to use (Filtered HTML for example). http://local.example.com/admin/config/content/formats/filtered_html
Have a look at the Examples module for how to do that.
filter_example Defining an input filter
If you're not allowing them to upload and embed via the WYSIWYG (but uploading via a field for example) you could simply remove img from the permitted tags in your Limit allowed HTML tags filter.
