[tor-bugs] #20853 [Core Tor/Tor]: rend_config_services should use service_is_ephemeral rather than old/new->directory

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#20853: rend_config_services should use service_is_ephemeral rather than
old/new->directory
------------------------------------+------------------------------------
 Reporter:  teor                    |          Owner:  jryans
     Type:  defect                  |         Status:  needs_revision
 Priority:  Medium                  |      Milestone:  Tor: 0.3.0.x-final
Component:  Core Tor/Tor            |        Version:  Tor: 0.2.9.5-alpha
 Severity:  Normal                  |     Resolution:
 Keywords:  easy refactor intro hs  |  Actual Points:
Parent ID:                          |         Points:  0.1
 Reviewer:                          |        Sponsor:
------------------------------------+------------------------------------
Changes (by teor):

 * status:  needs_review => needs_revision


Comment:

 Replying to [comment:8 jryans]:
 > Thanks for the quick review!  Updated patch at:
 >
 > https://github.com/jryans/tor/commits/service_is_ephemeral
 >
 > Replying to [comment:6 teor]:
 > > rend_service_verify_single_onion_poison() needs an explicit check for
 the directory, because rend_service_private_key_exists() requires there to
 be a directory, or tor asserts. And we want to be able to vary how we
 check for ephemeral services in future. (But you're right that we should
 check for ephemeral services.)
 > >
 > > So I think we can fix this by adding a check for s->directory as well
 as the ephemeral check.
 > >
 > > Similarly, we can't change this part of rend_config_services:
 > > {{{
 > >         if (new->directory && old->directory &&
 > >             !strcmp(old->directory, new->directory)) {
 > > }}}
 > > without adding explicit checks for the directories being valid before
 doing a strcmp on them.
 >
 > Okay, I added explicit `BUG` checks for the directory in addition to the
 ephemeral check for both of these cases.

 Thanks for this change.
 The `BUG(new->directory)` and the old check are inverted, they will log a
 message when the directory exists, but we want to log a message when it
 doesn't.

 Oh, and can we do them in the same order in
 rend_service_verify_single_onion_poison?
 (That is, the ephemeral check first, then the directory check?)
 Let's not log a BUG unless we really have to.

 > > > Not sure if a changes file was needed for this, but I added one
 anyway just to get familiar with the process.
 > >
 > > Thanks! Minor comment changes don't get a changes file, everything
 else does.
 > > (I've submitted a number of code changes that were "Refactoring, no
 behaviour change", and then ended up being "unexpected bug in ticket XXXXX
 because behaviour changed during refactor".)
 > >
 > > One nitpick:
 > >
 > > the changes file format starts with
 > > `Minor bugfix (optional categories):`
 > >
 https://gitweb.torproject.org/tor.git/tree/doc/HACKING/CodingStandards.md#n56
 >
 > I wasn't sure if you wanted me to add an optional category or change to
 "Minor bugfix".  The current file (using the group "Code simplification
 and refactoring") passes the `lintChanges.py` script.  Let me know if
 there's still a change needed.

 Yes, please change it to 'Minor bugfix (hidden services)'.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/20853#comment:9>
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