Commit 02da24f8 authored by Nick Mathewson's avatar Nick Mathewson 🤹
Browse files

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.
parent 26957a12

src/or/entrynodes.c

+24 −1
Original line number Diff line number Diff line
@@ -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;

src/or/entrynodes.h

+1 −0
Original line number Diff line number Diff line
@@ -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,