commit ac67819396ac9e96c3dd65a5b5b23715e11eeec5 Author: Nick Mathewson nickm@torproject.org Date: Wed Nov 23 10:04:23 2016 -0500
Make sure primary-guards are up-to-date when we inspect them.
(Plus some magic to prevent and detect recursive invocation of entry_guards_update_primary(), since that can cause some pretty tricky misbehavior.) --- src/or/entrynodes.c | 58 +++++++++++++++++++++++++++++++++------------- src/or/entrynodes.h | 8 +++++++ src/test/test_entrynodes.c | 3 ++- 3 files changed, 52 insertions(+), 17 deletions(-)
diff --git a/src/or/entrynodes.c b/src/or/entrynodes.c index 9a753e6..bd30078 100644 --- a/src/or/entrynodes.c +++ b/src/or/entrynodes.c @@ -79,9 +79,6 @@ **/ /* DOCDOC -- expand this. * - * XXXX prop271 -- make sure we check all of these properties everywhere we - * should. - * * Information invariants: * * [x] whenever a guard becomes unreachable, clear its usable_filtered flag. @@ -100,11 +97,11 @@ * [x] Whenever we remove a guard from the sample, remove it from the primary * and confirmed lists. * - * [ ] When we make a guard confirmed, update the primary list. + * [x] When we make a guard confirmed, update the primary list. * - * [ ] When we make a guard filtered or unfiltered, update the primary list. + * [x] When we make a guard filtered or unfiltered, update the primary list. * - * [ ] When we are about to pick a guard, make sure that the primary list is + * [x] When we are about to pick a guard, make sure that the primary list is * full. * * [x] Before calling sample_reachable_filtered_entry_guards(), make sure @@ -682,9 +679,12 @@ sampled_guards_update_from_consensus(guard_selection_t *gs) } SMARTLIST_FOREACH_END(guard);
if (n_changes) { - /* Regnerate other things. XXXXXX prop271 */ - // XXXX prop271 rebuild confirmed list. + gs->primary_guards_up_to_date = 0; entry_guards_update_filtered_sets(gs); + /* We don't need to rebuild the confirmed list right here -- we may have + * removed confirmed guards above, but we can't have added any new + * confirmed guards. + */ entry_guards_changed_for_guard_selection(gs); } } @@ -749,6 +749,7 @@ entry_guard_set_filtered_flags(const or_options_t *options, guard_selection_t *gs, entry_guard_t *guard) { + unsigned was_filtered = guard->is_filtered_guard; guard->is_filtered_guard = 0; guard->is_usable_filtered_guard = 0;
@@ -763,6 +764,11 @@ entry_guard_set_filtered_flags(const or_options_t *options, log_debug(LD_GUARD, "Updated sampled guard %s: filtered=%d; " "reachable_filtered=%d.", entry_guard_describe(guard), guard->is_filtered_guard, guard->is_usable_filtered_guard); + + if (!bool_eq(was_filtered, guard->is_filtered_guard)) { + /* This guard might now be primary or nonprimary. */ + gs->primary_guards_up_to_date = 0; + } }
/** @@ -795,6 +801,7 @@ sample_reachable_filtered_entry_guards(guard_selection_t *gs, const unsigned exclude_confirmed = flags & SAMPLE_EXCLUDE_CONFIRMED; const unsigned exclude_primary = flags & SAMPLE_EXCLUDE_PRIMARY; const unsigned exclude_pending = flags & SAMPLE_EXCLUDE_PENDING; + const unsigned no_update_primary = flags & SAMPLE_NO_UPDATE_PRIMARY;
SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) { entry_guard_consider_retry(guard); @@ -810,6 +817,9 @@ sample_reachable_filtered_entry_guards(guard_selection_t *gs, entry_guards_expand_sample(gs); }
+ if (exclude_primary && !gs->primary_guards_up_to_date && !no_update_primary) + entry_guards_update_primary(gs); + /* Build the set of reachable filtered guards. */ smartlist_t *reachable_filtered_sample = smartlist_new(); SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) { @@ -908,24 +918,34 @@ make_guard_confirmed(guard_selection_t *gs, entry_guard_t *guard) guard->confirmed_idx = gs->next_confirmed_idx++; smartlist_add(gs->confirmed_entry_guards, guard);
+ // This confirmed guard might kick something else out of the primary + // guards. + gs->primary_guards_up_to_date = 0; + entry_guards_changed_for_guard_selection(gs); }
/** * Recalculate the list of primary guards (the ones we'd prefer to use) from * the filtered sample and the confirmed list. - * - * XXXXX prop271 are calling this enough ??? */ STATIC void entry_guards_update_primary(guard_selection_t *gs) { tor_assert(gs);
+ // prevent recursion. Recursion is potentially very bad here. + static int running = 0; + tor_assert(!running); + running = 1; + smartlist_t *new_primary_guards = smartlist_new(); smartlist_t *old_primary_guards = smartlist_new(); smartlist_add_all(old_primary_guards, gs->primary_entry_guards);
+ /* Set this flag now, to prevent the calls below from recursing. */ + gs->primary_guards_up_to_date = 1; + /* First, can we fill it up with confirmed guards? */ SMARTLIST_FOREACH_BEGIN(gs->confirmed_entry_guards, entry_guard_t *, guard) { if (smartlist_len(new_primary_guards) >= N_PRIMARY_GUARDS) @@ -964,7 +984,8 @@ entry_guards_update_primary(guard_selection_t *gs) while (smartlist_len(new_primary_guards) < N_PRIMARY_GUARDS) { entry_guard_t *guard = sample_reachable_filtered_entry_guards(gs, SAMPLE_EXCLUDE_CONFIRMED| - SAMPLE_EXCLUDE_PRIMARY); + SAMPLE_EXCLUDE_PRIMARY| + SAMPLE_NO_UPDATE_PRIMARY); if (!guard) break; guard->is_primary = 1; @@ -1007,6 +1028,8 @@ entry_guards_update_primary(guard_selection_t *gs) smartlist_free(old_primary_guards); smartlist_free(gs->primary_entry_guards); gs->primary_entry_guards = new_primary_guards; + gs->primary_guards_up_to_date = 1; + running = 0; }
/** @@ -1104,6 +1127,9 @@ select_entry_guard_for_circuit(guard_selection_t *gs, unsigned *state_out) tor_assert(gs); tor_assert(state_out);
+ if (!gs->primary_guards_up_to_date) + entry_guards_update_primary(gs); + /* "If any entry in PRIMARY_GUARDS has {is_reachable} status of <maybe> or <yes>, return the first such guard." */ SMARTLIST_FOREACH_BEGIN(gs->primary_entry_guards, entry_guard_t *, guard) { @@ -1191,6 +1217,9 @@ entry_guards_note_guard_failure(guard_selection_t *gs, STATIC void mark_primary_guards_maybe_reachable(guard_selection_t *gs) { + if (!gs->primary_guards_up_to_date) + entry_guards_update_primary(gs); + SMARTLIST_FOREACH_BEGIN(gs->primary_entry_guards, entry_guard_t *, guard) { if (guard->is_reachable != GUARD_REACHABLE_NO) continue; @@ -1230,7 +1259,6 @@ entry_guards_note_guard_success(guard_selection_t *gs, guard->is_usable_filtered_guard = 1;
if (guard->confirmed_idx < 0) { - // XXXX prop271 XXXX update primary guards, since we confirmed something? make_guard_confirmed(gs, guard); }
@@ -1248,9 +1276,6 @@ entry_guards_note_guard_success(guard_selection_t *gs, } }
- // XXXX prop271 XXXX update primary guards, since we confirmed something? - // XXXX prop261 XXXX if so, here or above? - log_info(LD_GUARD, "Recorded success for %s%sguard %s", guard->is_primary?"primary ":"", guard->confirmed_idx>=0?"confirmed ":"", @@ -1468,8 +1493,9 @@ entry_guard_chan_failed(guard_selection_t *gs, static int entry_guards_all_primary_guards_are_down(guard_selection_t *gs) { - /* XXXXX prop271 do we have to call entry_guards_update_primary() ?? */ tor_assert(gs); + if (!gs->primary_guards_up_to_date) + entry_guards_update_primary(gs); SMARTLIST_FOREACH_BEGIN(gs->primary_entry_guards, entry_guard_t *, guard) { entry_guard_consider_retry(guard); if (guard->is_reachable != GUARD_REACHABLE_NO) diff --git a/src/or/entrynodes.h b/src/or/entrynodes.h index 4cbfbf5..a514c13 100644 --- a/src/or/entrynodes.h +++ b/src/or/entrynodes.h @@ -223,6 +223,13 @@ struct guard_selection_s { int dirty;
/** + * A value of 1 means that primary_entry_guards is up-to-date; 0 + * means we need to recalculate it before using primary_entry_guards + * or the is_primary flag on any guard. + */ + int primary_guards_up_to_date; + + /** * A list of the sampled entry guards, as entry_guard_t structures. * Not in any particular order. When we 'sample' a guard, we are * noting it as a possible guard to pick in the future. The use of @@ -428,6 +435,7 @@ STATIC void entry_guards_update_filtered_sets(guard_selection_t *gs); #define SAMPLE_EXCLUDE_CONFIRMED (1u<<0) #define SAMPLE_EXCLUDE_PRIMARY (1u<<1) #define SAMPLE_EXCLUDE_PENDING (1u<<2) +#define SAMPLE_NO_UPDATE_PRIMARY (1u<<3) /**@}*/ STATIC entry_guard_t *sample_reachable_filtered_entry_guards( guard_selection_t *gs, diff --git a/src/test/test_entrynodes.c b/src/test/test_entrynodes.c index d8b9ccb..cdf8672 100644 --- a/src/test/test_entrynodes.c +++ b/src/test/test_entrynodes.c @@ -1839,6 +1839,7 @@ test_entry_guard_sample_reachable_filtered(void *arg) g->pb.path_bias_disabled = 1;
entry_guards_update_filtered_sets(gs); + gs->primary_guards_up_to_date = 1; tt_int_op(num_reachable_filtered_guards(gs), OP_EQ, n_guards - 1); tt_int_op(smartlist_len(gs->sampled_entry_guards), OP_EQ, n_guards);
@@ -1851,7 +1852,7 @@ test_entry_guard_sample_reachable_filtered(void *arg) } tests[] = { { 0, -1 }, { SAMPLE_EXCLUDE_CONFIRMED, 1 }, - { SAMPLE_EXCLUDE_PRIMARY, 2 }, + { SAMPLE_EXCLUDE_PRIMARY|SAMPLE_NO_UPDATE_PRIMARY, 2 }, { SAMPLE_EXCLUDE_PENDING, 0 }, { -1, -1}, };