I'm trying to restrict a particular folder on my site to only allow certain files to be posted via mobile device.
We are exporting data and movies from iPhones and iPod touches, so I'd like to limit the browser user-agent type to Safari, as well. Is this done through the http handler?
How is the upload being accomplished?
It's probably easiest to do it through your upload page/handler/module.
You could implement Request Filtering to watch for certain keywords when in that path, depending on how your upload page works, but it'd likely not be a "graceful" failure, more just a "Server returned error" type experience.
If the clients are {your own} IOS apps, it might not matter, and the poor experience would be reserved for those faking it, which might be acceptable.