Pick guards on the order they were sampled (prop310).

Co-authored-by: Florentin Rochet <florentin.rochet@uclouvain.be>

1 files changed, 18 insertions, 4 deletions

diff --git a/src/feature/client/entrynodes.h b/src/feature/client/entrynodes.h
index 6eede2c8d4..a478b92d75 100644
--- a/src/feature/client/entrynodes.h
+++ b/src/feature/client/entrynodes.h
@@ -117,6 +117,13 @@ struct entry_guard_t {
    * confirmed guard. */
   time_t confirmed_on_date; /* 0 if not confirmed */
   /**
+   * In what order was this guard sampled? Guards with
+   * lower indices appear earlier on the sampled list, the confirmed list and
+   * the primary list as a result of Prop 310
+   */
+  int sampled_idx;
+
+  /**
    * In what order was this guard confirmed? Guards with lower indices
    * appear earlier on the confirmed list.  If the confirmed list is compacted,
    * this field corresponds to the index of this guard on the confirmed list.
@@ -242,8 +249,9 @@ struct guard_selection_t {
    * Ordered list (from highest to lowest priority) of guards that we
    * have successfully contacted and decided to use. Every member of
    * this list is a member of sampled_entry_guards. Every member should
-   * have confirmed_on_date set, and have confirmed_idx greater than
-   * any earlier member of the list.
+   * have confirmed_on_date set.
+   * The ordering of the list should be by sampled idx. The reasoning behind
+   * it is linked to Proposal 310.
    *
    * This list is persistent. It is a subset of the elements in
    * sampled_entry_guards, and its pointers point to elements of
@@ -271,6 +279,12 @@ struct guard_selection_t {
    * confirmed_entry_guards receive? */
   int next_confirmed_idx;
 
+  /** What sampled_idx value should the next-added member of
+   * sampled_entry_guards receive? This should follow the size of the sampled
+   * list until sampled relays get pruned for some reason
+   */
+  int next_sampled_idx;
+
 };
 
 struct entry_guard_handle_t;
@@ -523,7 +537,7 @@ STATIC void entry_guard_free_(entry_guard_t *e);
 STATIC void entry_guards_update_filtered_sets(guard_selection_t *gs);
 STATIC int entry_guards_all_primary_guards_are_down(guard_selection_t *gs);
 /**
- * @name Flags for sample_reachable_filtered_entry_guards()
+ * @name Flags for first_reachable_filtered_entry_guard()
  */
 /**@{*/
 #define SAMPLE_EXCLUDE_CONFIRMED   (1u<<0)
@@ -532,7 +546,7 @@ STATIC int entry_guards_all_primary_guards_are_down(guard_selection_t *gs);
 #define SAMPLE_NO_UPDATE_PRIMARY   (1u<<3)
 #define SAMPLE_EXCLUDE_NO_DESCRIPTOR (1u<<4)
 /**@}*/
-STATIC entry_guard_t *sample_reachable_filtered_entry_guards(
+STATIC entry_guard_t *first_reachable_filtered_entry_guard(
                                     guard_selection_t *gs,
                                     const entry_guard_restriction_t *rst,
                                     unsigned flags);