One thing for sure it`s not the rack boot leaking,the power steering fluid is not contained by the boots, if there is fluid in the boots it is because the high pressure seals in the rack are leaking.
Check for leaks at the external pipework and pump, if none are found it must be the rack leaking high pressure fluid past the rack seals and into the boots.
If it has been driven for any length of time with no fluid in the resevoir the pump may well also have been damaged by cavitation (sucking air instead of fluid)

Colin.