commit 02da24f8e5b2ce34da941cc25ce9808b447065ac Author: Nick Mathewson <nickm@torproject.org> Date: Tue Jan 31 12:30:33 2017 -0500 Don't (usually) return any guards that are missing descriptors. Actually, it's _fine_ to use a descriptorless guard for fetching directory info -- we just shouldn't use it when building circuits. Fortunately, we already have a "usage" flag that we can use here. Partial fix for bug 21242. --- src/or/entrynodes.c | 25 ++++++++++++++++++++++++- src/or/entrynodes.h | 1 + 2 files changed, 25 insertions(+), 1 deletion(-) diff --git a/src/or/entrynodes.c b/src/or/entrynodes.c index 344b69d..1cf1ff2 100644 --- a/src/or/entrynodes.c +++ b/src/or/entrynodes.c @@ -185,6 +185,16 @@ should_apply_guardfraction(const networkstatus_t *ns) return options->UseGuardFraction; } +/** Return true iff we know a descriptor for <b>guard</b> */ +static int +guard_has_descriptor(const entry_guard_t *guard) +{ + const node_t *node = node_get_by_id(guard->identity); + if (!node) + return 0; + return node_has_descriptor(node); +} + /** * Try to determine the correct type for a selection named "name", * if <b>type</b> is GS_TYPE_INFER. @@ -1447,6 +1457,7 @@ sample_reachable_filtered_entry_guards(guard_selection_t *gs, 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; + const unsigned need_descriptor = flags & SAMPLE_EXCLUDE_NO_DESCRIPTOR; SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) { entry_guard_consider_retry(guard); @@ -1480,6 +1491,8 @@ sample_reachable_filtered_entry_guards(guard_selection_t *gs, continue; if (exclude_pending && guard->is_pending) continue; + if (need_descriptor && !guard_has_descriptor(guard)) + continue; smartlist_add(reachable_filtered_sample, guard); } SMARTLIST_FOREACH_END(guard); @@ -1777,6 +1790,7 @@ select_entry_guard_for_circuit(guard_selection_t *gs, const entry_guard_restriction_t *rst, unsigned *state_out) { + const int need_descriptor = (usage == GUARD_USAGE_TRAFFIC); tor_assert(gs); tor_assert(state_out); @@ -1793,6 +1807,9 @@ select_entry_guard_for_circuit(guard_selection_t *gs, if (! entry_guard_obeys_restriction(guard, rst)) continue; if (guard->is_reachable != GUARD_REACHABLE_NO) { + if (need_descriptor && BUG(!guard_has_descriptor(guard))) { + continue; + } *state_out = GUARD_CIRC_STATE_USABLE_ON_COMPLETION; guard->last_tried_to_connect = approx_time(); smartlist_add(usable_primary_guards, guard); @@ -1821,6 +1838,8 @@ select_entry_guard_for_circuit(guard_selection_t *gs, continue; entry_guard_consider_retry(guard); if (guard->is_usable_filtered_guard && ! guard->is_pending) { + if (need_descriptor && !guard_has_descriptor(guard)) + continue; /* not a bug */ guard->is_pending = 1; guard->last_tried_to_connect = approx_time(); *state_out = GUARD_CIRC_STATE_USABLE_IF_NO_BETTER_GUARD; @@ -1836,11 +1855,15 @@ select_entry_guard_for_circuit(guard_selection_t *gs, random from {USABLE_FILTERED_GUARDS}." */ { entry_guard_t *guard; + unsigned flags = 0; + if (need_descriptor) + flags |= SAMPLE_EXCLUDE_NO_DESCRIPTOR; guard = sample_reachable_filtered_entry_guards(gs, rst, SAMPLE_EXCLUDE_CONFIRMED | SAMPLE_EXCLUDE_PRIMARY | - SAMPLE_EXCLUDE_PENDING); + SAMPLE_EXCLUDE_PENDING | + flags); if (guard == NULL) { log_info(LD_GUARD, "Absolutely no sampled guards were available."); return NULL; diff --git a/src/or/entrynodes.h b/src/or/entrynodes.h index d469df7..0c29292 100644 --- a/src/or/entrynodes.h +++ b/src/or/entrynodes.h @@ -498,6 +498,7 @@ STATIC int entry_guards_all_primary_guards_are_down(guard_selection_t *gs); #define SAMPLE_EXCLUDE_PRIMARY (1u<<1) #define SAMPLE_EXCLUDE_PENDING (1u<<2) #define SAMPLE_NO_UPDATE_PRIMARY (1u<<3) +#define SAMPLE_EXCLUDE_NO_DESCRIPTOR (1u<<4) /**@}*/ STATIC entry_guard_t *sample_reachable_filtered_entry_guards( guard_selection_t *gs,