I have an ee site that has tons of forms that are currently live. These forms are submitting data to a third party service using that service's custom submission code (which has nothing to do with ee addon code - I think the service is just using CURL).
I need to implement additional validation for these forms on the PHP side before I pass the data to the service. I kind of need a middle layer which processes the data I guess. The forms are in plain html and are stored as snippets or low variables.
I do not need to save the data. I only need to
- validate form inputs
- filter out bad input characters
- throw back errors and redirect to form if form data is invalid
- send data to the service if the form is valid
How should I do this? Should I write a plugin, extension, module? I only need to process the data not build the form. What should I write?