So i was driving to work today and i pushed my brake pedal and it went to the floor, and then slowly crawled my truck to a stop, i get out and theres no brake flud in the resivor and its running down the big cylinder tube (cant remember what its called) that the master cylinder is hooked up on. what do i need to do, is there a fluid i can use to seal it up or do i have to replace some parts here

 

In short...nope.

 

I see a Master Cylinder in your immediate future!

 

It does sound like your master cylinder is leaking past the seal. Odd that it would just come on like that. Usually you will have tell tale signs before hand, like a slow sinking pedal while stopped....etc.
If you are somewhat mechanically inclined you can buy a MC repair kit and just replace the seals.

Oh and you are referring to the vacuum booster