flow control questions

[Christian Seberino]

Hello Again Tor-landers!

I'm running out of things to ask because the Tor docs are pretty good
overall!
I'm pretty sure about the answers to some of the question below.  I just
wanted to verify I didn't goof somewhere....

So basically ORs have a a limit on number of Relay Data cells they are
willing to send down/up the circuit in **each direction**?

It appears, when an OR can send more cells, it sends a RELAY_SENDME to OP
which may respond with another RELAY_SENDME back to OR right?  Do BOTH of
these RELAY_SENDMEs cause (both?) the OR's windows to increase (by 100)?

So ORs have freedom to send out tons of RELAY_SENDMEs to increase its
windows?  So OPs have freedom to send out tons of RELAY_SENDMEs to
increase OR  windows?  Then why aren't windows vulnerable to attack since
both ORs and OPs can just pump out more RELAY_SENDMEs to increase windows
whenever they want?  What prevents manipulation?

Chris