Make sure bridges are definitely running before delaying directory fetches

Retry directory downloads when we get our first bridge descriptor
during bootstrap or while reconnecting to the network. Keep retrying
every time we get a bridge descriptor, until we have a reachable bridge.

Stop delaying bridge descriptor fetches when we have cached bridge
descriptors. Instead, only delay bridge descriptor fetches when we
have at least one reachable bridge.

Fixes bug 24367; bugfix on 0.2.0.3-alpha.

1 files changed, 9 insertions, 2 deletions

diff --git a/src/or/entrynodes.c b/src/or/entrynodes.c
index 100286f103..90b728726d 100644
--- a/src/or/entrynodes.c
+++ b/src/or/entrynodes.c
@@ -3135,13 +3135,16 @@ entry_list_is_constrained(const or_options_t *options)
 }
 
 /** Return the number of bridges that have descriptors that are marked with
- * purpose 'bridge' and are running.
+ * purpose 'bridge' and are running. If use_maybe_reachable is
+ * true, include bridges that might be reachable in the count.
+ * Otherwise, if it is false, only include bridges that have recently been
+ * found running in the count.
  *
  * We use this function to decide if we're ready to start building
  * circuits through our bridges, or if we need to wait until the
  * directory "server/authority" requests finish. */
 MOCK_IMPL(int,
-num_bridges_usable,(void))
+num_bridges_usable,(int use_maybe_reachable))
 {
   int n_options = 0;
 
@@ -3154,8 +3157,12 @@ num_bridges_usable,(void))
   }
 
   SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) {
+    /* Definitely not usable */
     if (guard->is_reachable == GUARD_REACHABLE_NO)
       continue;
+    /* If we want to be really sure the bridges will work, skip maybes */
+    if (!use_maybe_reachable && guard->is_reachable == GUARD_REACHABLE_MAYBE)
+      continue;
     if (tor_digest_is_zero(guard->identity))
       continue;
     const node_t *node = node_get_by_id(guard->identity);