[tor-bugs] #20823 [Core Tor/Tor]: [controller, prop271] GETINFO support for new guard selection logic

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#20823: [controller, prop271] GETINFO support for new guard selection logic
-------------------------------------------------+-------------------------
 Reporter:  nickm                                |          Owner:  nickm
     Type:  defect                               |         Status:
                                                 |  needs_review
 Priority:  High                                 |      Milestone:  Tor:
                                                 |  0.3.0.x-final
Component:  Core Tor/Tor                         |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  tor-guard regression                 |  Actual Points:  .1 so
  TorCoreTeam201612                              |  far
Parent ID:  #20822                               |         Points:  1
 Reviewer:                                       |        Sponsor:
-------------------------------------------------+-------------------------

Comment (by chelseakomlo):

 Hey,

 This is a small patch, overall it looks good!

 I do get a test failure when I run `make test`:

 {{{
 entrynodes/retry_unreachable: [forking]
   FAIL src/test/test_entrynodes.c:2302: assert(g1->is_reachable OP_EQ
 GUARD_REACHABLE_NO): 2 vs 0
   [retry_unreachable FAILED]

 }}}

 as well as a bug assertion:

 {{{
 dir/purpose_needs_anonymity_returns_true_by_default: Dec 13 20:52:30.319
 [warn] purpose_needs_anonymity(): Bug: Called with dir_purpose=0,
 router_purp
 ose=0 (on Tor 0.3.0.0-alpha-dev 7a7240716eef1f54)
 OK
 }}}

 Not sure if you get these as well? I don't see these on master.

 One point about how we switch on whether we are running the legacy or
 post-271 algorithm.

 If you define two functions- one for the legacy behavior and one for the
 post-271 behavior, then when you remove the legacy algorithm, you won't
 need to change the post-271 method signature or implementation when you
 remove support for legacy in the future.

 So it could look something like:
 {{{
 STATIC char *
 legacy_getinfo_helper_format_single_entry_guard(const entry_guard_t *e)

 STATIC char *
 getinfo_helper_format_single_entry_guard(const entry_guard_t *e)
 }}}

 for the method signatures. The caller would then look like:

 {{{
 SMARTLIST_FOREACH_BEGIN(guards, const entry_guard_t *, e) {
   char *cp;
   #ifdef ENABLE_LEGACY_GUARD_ALGORITHM
     cp = legacy_getinfo_helper_format_single_entry_guard(e);
   #else
     cp = getinfo_helper_format_single_entry_guard(e);
   #endif
   smartlist_add(sl, cp);
 } SMARTLIST_FOREACH_END(e);
 }}}

 Again, this is minor and it might be less work to leave this as is.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/20823#comment:7>
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