Simple DOS Protection

[yaronyg]

We need some simple protections to tell when we are under attack. What if someone with permission tries to upload a 10 terabyte file? Sure our size hooks will eventually catch them, but when? Do we declare ahead of time what size can be (e.g. when the dl is initiated) or only after it's all dl's (when it's too late). What about someone making infinite connection requests just to run down our battery? What if we are in a concert hall and are being drowned with discovery requests? We need some defensive logic to tell when a situation has gone bad and to shut us down for awhile so we don't cook the phone.