[tor-dev] Proposal 205: Remove global client-side DNS caching

[Roger Dingledine]

On Thu, Nov 29, 2012 at 06:14:23PM +0000, Julian Yon wrote:
> (3) Don't bother trying to ascertain the full exit policy, but rather
> maintain a simple table of exit/IP/port combinations that have been
> rejected and consult it when building/using circuits. This requires no
> protocol changes (win!) at the cost of no longer blacklisting dishonest
> exits entirely. Some mechanism for expiring entries would probably be a
> good idea, and/or maybe hold it in a circular list so that there's a
> maximum number.

I had this same thought while rereading my earlier message: just prepend
a reject rule for this ip:port to our local version of the relay's
exit policy.

It does let the exit "tag" you with an IP:port combo that you'll never
come back to it with. But that seems a small risk compared to the risk
of an exit relay with a complex enough policy that it causes clients to
spend two circuits for fetching each component of web pages.

--Roger