NumDirectoryGuards now tracks NumEntryGuards by default

Now a user who changes only NumEntryGuards will get the behavior she
expects. Fixes bug 9354; bugfix on 0.2.4.8-alpha.

3 files changed, 16 insertions, 6 deletions

diff --git a/src/or/config.c b/src/or/config.c
index bf82643b91..72ceea395e 100644
--- a/src/or/config.c
+++ b/src/or/config.c
@@ -314,7 +314,7 @@ static config_var_t option_vars_[] = {
   OBSOLETE("NoPublish"),
   VAR("NodeFamily",              LINELIST, NodeFamilies,         NULL),
   V(NumCPUs,                     UINT,     "0"),
-  V(NumDirectoryGuards,          UINT,     "3"),
+  V(NumDirectoryGuards,          UINT,     "0"),
   V(NumEntryGuards,              UINT,     "3"),
   V(ORListenAddress,             LINELIST, NULL),
   VPORT(ORPort,                      LINELIST, NULL),
diff --git a/src/or/entrynodes.c b/src/or/entrynodes.c
index 7a1f67d16a..f1af75aefb 100644
--- a/src/or/entrynodes.c
+++ b/src/or/entrynodes.c
@@ -415,14 +415,24 @@ add_an_entry_guard(const node_t *chosen, int reset_status, int prepend,
   return node;
 }
 
+/** Choose how many entry guards or directory guards we'll use. If
+ * <b>for_directory</b> is true, we return how many directory guards to
+ * use; else we return how many entry guards to use. */
+static int
+decide_num_guards(const or_options_t *options, int for_directory)
+{
+  if (for_directory && options->NumDirectoryGuards != 0)
+    return options->NumDirectoryGuards;
+  return options->NumEntryGuards;
+}
+
 /** If the use of entry guards is configured, choose more entry guards
  * until we have enough in the list. */
 static void
 pick_entry_guards(const or_options_t *options, int for_directory)
 {
   int changed = 0;
-  const int num_needed = for_directory ? options->NumDirectoryGuards :
-    options->NumEntryGuards;
+  const int num_needed = decide_num_guards(options, for_directory);
 
   tor_assert(entry_guards);
 
@@ -962,8 +972,7 @@ choose_random_entry_impl(cpath_build_state_t *state, int for_directory,
   int need_capacity = state ? state->need_capacity : 0;
   int preferred_min, consider_exit_family = 0;
   int need_descriptor = !for_directory;
-  const int num_needed = for_directory ? options->NumDirectoryGuards :
-    options->NumEntryGuards;
+  const int num_needed = decide_num_guards(options, for_directory);
 
   if (chosen_exit) {
     nodelist_add_node_and_family(exit_family, chosen_exit);
diff --git a/src/or/or.h b/src/or/or.h
index 0b8d057aaf..3dc96b9a9d 100644
--- a/src/or/or.h
+++ b/src/or/or.h
@@ -3769,7 +3769,8 @@ typedef struct {
   int NumEntryGuards; /**< How many entry guards do we try to establish? */
   int UseEntryGuardsAsDirGuards; /** Boolean: Do we try to get directory info
                                   * from a smallish number of fixed nodes? */
-  int NumDirectoryGuards; /**< How many dir guards do we try to establish? */
+  int NumDirectoryGuards; /**< How many dir guards do we try to establish?
+                           * If 0, use value from NumEntryGuards. */
   int RephistTrackTime; /**< How many seconds do we keep rephist info? */
   int FastFirstHopPK; /**< If Tor believes it is safe, should we save a third
                        * of our PK time by sending CREATE_FAST cells? */