flooding attacks to discover hidden services

[Wikileaks]

Does the public nature of tor routers makes hidden services  
vulnerable to
discovery using flooding attacks?

Open an onion connection to the hidden service, asking for echos. Now  
flood each
router. If the "ping" is overly delayed, the router is on the hidden  
path.

Since the rendezvous node is known and the other nodes vary over  
time, this will
eventually reveal the entry node.