[tor-bugs] #24110 [Core Tor/Tor]: NS_CONTROL_PORT formats change when using microdescriptors

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#24110: NS_CONTROL_PORT formats change when using microdescriptors
-------------------------------------------------+-------------------------
 Reporter:  teor                                 |          Owner:  (none)
     Type:  defect                               |         Status:  new
 Priority:  Medium                               |      Milestone:  Tor:
                                                 |  0.3.3.x-final
Component:  Core Tor/Tor                         |        Version:  Tor:
                                                 |  0.3.0.1-alpha
 Severity:  Normal                               |     Resolution:
 Keywords:  bwauth-needs, tor-control, tor-spec  |  Actual Points:
Parent ID:                                       |         Points:  1
 Reviewer:                                       |        Sponsor:
                                                 |  SponsorV-can
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Changes (by catalyst):

 * keywords:  bwauth-needs => bwauth-needs, tor-control, tor-spec


Old description:

> In Tor 0.3.0 (or earlier?), we made clients use microdescriptors by
> default. This changes the format of NS_CONTROL_PORT routerstatus lines,
> which breaks pytorctl, and therefore the bandwidth authorities.
>
> Apparently, this issue can be resolved by setting UseMicrodescriptors 0
> or using 0.2.9.

New description:

 In Tor 0.3.0 (or earlier?), we made clients use microdescriptors by
 default. This changes the format of NS_CONTROL_PORT routerstatus lines,
 which breaks pytorctl, and therefore the bandwidth authorities.

 Apparently, this issue can be resolved by setting UseMicrodescriptors 0 or
 using 0.2.9.

 edit: Let's update control-spec.txt to document the current (surprising)
 behavior and track further behavior improvements in other tickets.

--

Comment:

 Summarizing an IRC conversation with arma and Sebastian:

 * The `UseMicrodescriptors=0` workaround seems to work for pytorctl (and
 thus bwauths) for now.
 * We probably should keep the `GETINFO ns/*` keys and `NS` async events
 the same for backward compatibility, i.e., continue making them in the ns-
 flavored format with a truncated SHA-256 hash in the descriptor digest
 field if tor is using microdescriptors.
 * There should probably be a new set of `GETINFO` keys and async events
 that generalize router statuses in the control protocol, maybe `GETINFO
 rs/*` and `RS` async events.  The controller could explicitly request ns
 and microdesc flavors of each.
 * TODO: check whether it's possible for a single instance of tor to
 download both ns- and microdescriptor-flavored consensuses.

 I'm also thinking that we should scope this ticket to updating control-
 spec.txt to describe the current (somewhat surprising) behavior and open
 new tickets for the other related issues.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/24110#comment:12>
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