if the fluid is leaking out at the master cylinder, it points to a bad master cylinder, leaking around the push rod. there should not be any fluid anywhere in the booster, or anywhere outside the high pressure lines of the brake system.
you could rebuild it, or just replace it with a new/rebuilt unit. be sure and do the bench bleed process before installing to save a lot of time bleeding out the air.
edit- AD beat me to it.