[tor-bugs] #2355 [Tor Bridge]: change the meaning of UseBridges

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#2355: change the meaning of UseBridges
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    Reporter:  anonym            |        Type:  enhancement
      Status:  needs_review      |    Priority:  minor      
   Milestone:  Tor: unspecified  |   Component:  Tor Bridge 
     Version:                    |    Keywords:             
      Parent:                    |      Points:             
Actualpoints:                    |  
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Comment(by anonym):

 New patch.

 Replying to [comment:11 anonym]:
 > Replying to nickm:
 > > In the new check, we give the warning if UseBridges? is 0. But
 previously, we gave it if it was nonzero. Maybe a strcmp mistake?

 Fixed.


 > > I'm not sure about launching the bridge descriptor fetch from config.c
 ; the more stuff we launch from configuration parsing, the more
 spaghettiish our code has gotten historically. We already retry launching
 downloads every 10 or 60 seconds from main.c; perhaps what we need is a
 function to tell main that it needs to retry downloads right away.
 >
 > Do you think this any of these approaches are viable?

 I chose approach 2 from above.


 > > The any_bridge_descriptors_known() logic is fragile in depending on
 have_bridge_descriptors anc choose_random_entry; instead IMO it should
 probably just iterate through bridge_list and see whether we have a
 descriptor for any member.

 I instead iterate over entry_guards (since any bridge who's got a
 descriptor will be put there) as it seemed the easiest way to implement
 it. Time complexity for any_bridge_descriptors_known() is O(E*B), where E
 is the number of bridges and B the number of configured bridges, so really
 it's O(E^2), but that should be ok since E shouldn't ever grow very big,
 right?

 BTW, are previously used bridges ever purged from your entry guards pool?
 If not, it could be a good idea, I guess.

 I've done some pretty frequent bridge switching with ~40 bridges, and I
 didn't encounter the problem I mentioned before with me previous patch.

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/2355#comment:12>
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