[tor-bugs] #11222 [Tor Launcher]: Inform user if reachable bridges drop below a configurable fraction/number

[Tor Bug Tracker & Wiki]

#11222: Inform user if reachable bridges drop below a configurable fraction/number
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 Reporter:  mikeperry      |          Owner:  brade
     Type:  defect         |         Status:  new
 Priority:  major          |      Milestone:
Component:  Tor Launcher   |        Version:
 Keywords:  tbb-usability  |  Actual Points:
Parent ID:  #11180         |         Points:
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 It would be very useful for a number of reasons if Tor Launcher could pop
 up some kind of alert if some fraction of their bridges become unusable
 (ie when 50% are unreachable, or perhaps min(33%,1)).

 In that case, it should instruct the user to obtain more bridges, and give
 them instructions or a bridgedb link specific to their PT type (ie
 https://bridges.torproject.org/bridges?transport=obfs3).

 The primary motivation for altering the user is that if bridges either go
 down or get blocked, it will be far easier for the user to obtain more if
 the user still has at least one working bridge to work with (to connect to
 gmail or visit a link).

 One way to do this might be to use the control port command 'GETINFO
 entry-guards" on a timer, but an event-based approach using the "GUARD"
 event could also work (but would require substantially more bookkeeping
 and may be error prone in the face of GUARD event state transition
 oddities).

 Tor Launcher probably should also not issue the warning if all bridges
 become unreachable at once, and/or if Tor detects a cease in network
 activity (which does not seem to be directly exported to the control port
 at this point :/). We don't want to alert the user every time they walk
 out of range from a wifi hotspot or similar situation.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/11222>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
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