[tor-bugs] #20667 [Core Tor/Tor]: Make FetchUselessDescriptors actually fetch all flavours on clients (was: Clarify FetchUselessDescriptors and UseMicrodescriptors in 0.3.0)

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#20667: Make FetchUselessDescriptors actually fetch all flavours on clients
--------------------------+----------------------------------------
 Reporter:  teor          |          Owner:
     Type:  defect        |         Status:  new
 Priority:  Medium        |      Milestone:  Tor: 0.3.0.x-final
Component:  Core Tor/Tor  |        Version:  Tor: 0.3.0.0-alpha-dev
 Severity:  Normal        |     Resolution:
 Keywords:  easy, intro   |  Actual Points:
Parent ID:                |         Points:  0.5
 Reviewer:                |        Sponsor:
--------------------------+----------------------------------------
Changes (by teor):

 * keywords:  doc => easy, intro
 * points:  0.1 => 0.5


Old description:

> `FetchUselessDescriptors 1` used to imply `UseMicrodescriptors 0`, but
> due to #6769, it doesn't in 0.3.0 and later.
>
> Therefore, clients that want to download a full consensus have to
> explictly set `UseMicrodescriptors 0`.
>
> We should document this in the man page and probably the changelog
> summary, as it is a breaking change for many configs that used to obtain
> a full consensus.
>
> (Alternately, we could fix this bug by FetchUselessDescriptors download a
> full consensus, even on clients, and document that behaviour.)
>
> Discovered when running a test bandwidth authority - see #20621.

New description:

 `FetchUselessDescriptors 1` used to imply `UseMicrodescriptors 0`, but due
 to #6769, it doesn't in 0.3.0 and later.

 Therefore, clients that want to download a full consensus have to
 explictly set `UseMicrodescriptors 0`.

 ~~We should document this in the man page and probably the changelog
 summary, as~~ it is a breaking change for many configs that used to obtain
 a full consensus.

 ~~(Alternately,~~ we could fix this bug by FetchUselessDescriptors
 download a full consensus, even on clients, and document that behaviour.)

 Discovered when running a test bandwidth authority - see #20621.

--

Comment:

 Replying to [comment:1 arma]:
 > I think we should make FetchUselessDescriptors fetch all the consensus
 flavors and all the descriptor flavors. That's what most people seem to
 use it for at least.

 I don't think it has done this for quite some time, at least on clients -
 unless the download schedule for the useless descriptors is minutes long.

 I tested with 0.2.7, 0.2.8, and 0.2.9, and FetchUselessDescriptors only
 fetched the full consensus and descriptors, not microdescriptors

 And I tested with 0.3.0, and FetchUselessDescriptors only fetched the
 micro consensus and microdescriptors.

 Since this is not a regression in 0.2.9, I'm keeping it in 0.3.0, and I've
 retitled the bug and edited the description.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/20667#comment:3>
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