[tor-bugs] #20262 [- Select a component]: Onion services startup time always gets revealed

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#20262: Onion services startup time always gets revealed
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     Reporter:  twim                  |      Owner:
         Type:  defect                |     Status:  new
     Priority:  Medium                |  Milestone:
    Component:  - Select a component  |    Version:
     Severity:  Normal                |   Keywords:
Actual Points:                        |  Parent ID:
       Points:                        |   Reviewer:
      Sponsor:                        |
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 Due to dead code in `rend_consider_services_upload()` startup time of
 onion services always gets revealed.

 If service descriptor is not uploaded yet we add random delay from
 [rendinitialpostdelay;rendinitialpostdelay+rand(2*rendpostperiod)] (
 [30s;30s+2h] ):
 {{{
 if (!service->next_upload_time) {
   service->next_upload_time =
         now + rendinitialpostdelay + crypto_rand_int(2*rendpostperiod);

 }}}

 But this delay is useless when we're checking whether we should upload:

 {{{
     if (intro_points_ready &&
         (service->next_upload_time < now ||
         (service->desc_is_dirty &&
          service->desc_is_dirty < now-rendinitialpostdelay))) {
       /* Upload */
 }}}

 Because descriptor is dirty for never-yet-uploaded services it always gets
 uploaded after being stable for `rendinitialpostdelay` seconds.
 `next_upload_time` is further in future than `rendinitialpostdelay`
 stabilization stuff.
 So it goes.

 I made a patch to unbork this function to work properly.
 But it raised a problem. We got used to expect that descriptors are going
 to be uploaded pretty soon. But 'now' they will be uploaded with delay up
 to 2h. That's not okay. Should we make a `torrc` option like
 `RevealOnionServiceStartupTime` that defaults to 1?

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/20262>
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