[tor-bugs] #18611 [Tor]: Improve semantics for pluggable transports with dummy addresses

[Tor Bug Tracker & Wiki]

#18611: Improve semantics for pluggable transports with dummy addresses
------------------------+--------------------------
     Reporter:  teor    |      Owner:
         Type:  defect  |     Status:  new
     Priority:  Medium  |  Milestone:  Tor: 0.2.???
    Component:  Tor     |    Version:
     Severity:  Normal  |   Keywords:
Actual Points:          |  Parent ID:
       Points:          |   Reviewer:
      Sponsor:          |
------------------------+--------------------------
 In #18517, we noted that some pluggable transports (for example, meek) use
 a dummy IP address in the bridge line, because the actual addresses are
 specified using some other method.

 The address specified in the bridge line is passed by tor to the pluggable
 transport, which then ignores it. But there's no way for tor to know
 whether the address is going to be ignored.

 Ignoring an address has a number of implications:
 * there's no standard IPv4 or IPv6 "dummy" address
 * even if two bridge lines use the same "dummy" address and port,
 bridge_resolve_conflicts should not consider them to be conflicting
 (Are there any more?)
 * anything that checks the address of the bridge will return erroneous
 results

 I'm not sure there's any easy way of fixing this, but I'm writing it down
 so we know about it. Perhaps it needs a change to the semantics of the
 bridge line so we can leave out address and port if they're going to be
 ignored anyway.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/18611>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online