[tor-bugs] #32604 [Core Tor/Tor]: Add HiddenServiceExportRendPoint and HiddenServiceExportInstanceID directive

[Tor Bug Tracker & Wiki]

#32604: Add HiddenServiceExportRendPoint and HiddenServiceExportInstanceID
directive
-----------------------------------------+---------------------------------
 Reporter:  moonsikpark                  |          Owner:  (none)
     Type:  enhancement                  |         Status:  needs_revision
 Priority:  Medium                       |      Milestone:  Tor:
                                         |  0.4.3.x-final
Component:  Core Tor/Tor                 |        Version:
 Severity:  Normal                       |     Resolution:
 Keywords:  tor-hs tor-dos extra-review  |  Actual Points:
Parent ID:  #32511                       |         Points:
 Reviewer:  dgoulet, ahf, teor           |        Sponsor:  Sponsor27-can
-----------------------------------------+---------------------------------

Comment (by moonsikpark):

 OK, made CI happy by letting `circuit_free_()` free
 `or_circ->build_state->chosen_exit`.

 Before extending the exposure range of rp fingerprint, I think there might
 be other metrics we can export that can help onion services. Potentially
 `circ->rend_data->nr_streams` or `circ->hs_ident->intro_auth_pk` or
 `circ->hs_ident->rendezvous_cookie`.

 If we can't export all 20 bytes, exporting part of it and exporting other
 things like `which intro point did the client choose?` or `what was the
 rendezvous cookie?` or `how many streams is the client opening now?` might
 help.

 Also I think `INSTANCE_ID` don't have to be that long, we can change it to
 1 byte and move it to the front(`fdAA` where `AA=INSTANCE_ID`).

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/32604#comment:21>
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