[tor-bugs] #1852 [Tor Client]: Project: Tor clients remember bridge info across restarts

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#1852: Project: Tor clients remember bridge info across restarts
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 Reporter:  arma         |       Owner:                     
     Type:  enhancement  |      Status:  new                
 Priority:  normal       |   Milestone:  Deliverable-Mar2011
Component:  Tor Client   |     Version:                     
 Keywords:               |      Parent:                     
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 In Tor 0.2.2.x if you stop your Tor client, it forgets everything it's
 learned about its bridges. So when you start it again, it just goes back
 to the torrc file to learn which bridges it should try.

 We need to teach Tor how to remember bridge fingerprints, reachability,
 longevity, IP addresses, etc across restarts.

 Step one is to brainstorm about the range of information we might
 remember, and how we can learn it, and how we might use it productively.
 This part will be tricky -- for example, right now we remember bridge
 descriptors across restarts, but we don't use them because we don't know
 whether they're fresh enough.

 Step two is to design a format for the state file, so we can capture
 everything we want to capture in a future-compatible way.

 Step three is to design a protocol (i.e. write a proposal) by which Tor
 clients can learn new bridge lines in-band, e.g. by asking the bridge
 authority for some more (perhaps the new bridges will be a function of the
 current bridges; but that's a separate proposal). We should make sure the
 results of this project are compatible with that protocol.

 Step four is to prioritize the items from step one, and implement the key
 ones (learning, storing, and using).

 Part of step four might turn out to be "refactor Tor's use of entry guards
 and bridges in circuitbuild.c", since right now it's increasingly turning
 into a hacked together mess.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/1852>
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