Getting preprocessed commands sent by command blocks

I'm essentially trying to register commands per command sender. Certain commands being only available if they're sent from a specific command block or a specific player. I figure the simplest way to do this is to pull all commands via events and if they are available to the sender, run them. This works fine for command senders who actually have command events, but as far as I can tell there is no command event for command blocks. I looked into using the method where I pull all redstone events and check to see if they're being used on a command block, but the problem with that is there is I don't know how to get a reference to the command sender or how to prevent the command from running normally after I'm done with it. Anyone know any work-arounds?

 

Bumping this

 

https://bukkit.org/threads/command-blocks.280462/

From there you can assign some sort of identifier to each command block like location? or int id? or something and test to see if the correct id corresponds to the command block.