Introduce new guard restriction and use it to skip outdated dirs.

1 files changed, 27 insertions, 10 deletions

diff --git a/src/or/entrynodes.h b/src/or/entrynodes.h
index 735c7738ba..29de627de0 100644
--- a/src/or/entrynodes.h
+++ b/src/or/entrynodes.h
@@ -272,22 +272,28 @@ struct guard_selection_s {
 
 struct entry_guard_handle_t;
 
+/** Types of restrictions we impose when picking guard nodes */
+typedef enum guard_restriction_type_t {
+  /* Don't pick the same guard node as our exit node (or its family) */
+  RST_EXIT_NODE = 0,
+  /* Don't pick dirguards that have previously shown to be outdated */
+  RST_OUTDATED_MD_DIRSERVER = 1
+} guard_restriction_type_t;
+
 /**
  * A restriction to remember which entry guards are off-limits for a given
  * circuit.
  *
- * Right now, we only use restrictions to block a single guard and its family
- * from being selected; this mechanism is designed to be more extensible in
- * the future, however.
- *
  * Note: This mechanism is NOT for recording which guards are never to be
  * used: only which guards cannot be used on <em>one particular circuit</em>.
  */
 struct entry_guard_restriction_t {
-  /**
-   * The guard's RSA identity digest must not equal this; and it must not
-   * be in the same family as any node with this digest.
-   */
+  /* What type of restriction are we imposing? */
+  guard_restriction_type_t type;
+
+  /* In case of restriction type RST_EXIT_NODE, the guard's RSA identity
+   * digest must not equal this; and it must not be in the same family as any
+   * node with this digest. */
   uint8_t exclude_id[DIGEST_LEN];
 };
 
@@ -316,7 +322,8 @@ struct circuit_guard_state_t {
 int guards_update_all(void);
 const node_t *guards_choose_guard(cpath_build_state_t *state,
                                   circuit_guard_state_t **guard_state_out);
-const node_t *guards_choose_dirguard(circuit_guard_state_t **guard_state_out);
+const node_t *guards_choose_dirguard(uint8_t dir_purpose,
+                                     circuit_guard_state_t **guard_state_out);
 
 #if 1
 /* XXXX NM I would prefer that all of this stuff be private to
@@ -550,7 +557,17 @@ STATIC unsigned entry_guards_note_guard_success(guard_selection_t *gs,
                                                 unsigned old_state);
 STATIC int entry_guard_has_higher_priority(entry_guard_t *a, entry_guard_t *b);
 STATIC char *getinfo_helper_format_single_entry_guard(const entry_guard_t *e);
-#endif
+
+STATIC entry_guard_restriction_t *
+guard_create_exit_restriction(const uint8_t *exit_id);
+
+STATIC entry_guard_restriction_t *
+guard_create_dirserver_md_restriction(void);
+
+STATIC void
+entry_guard_restriction_free(entry_guard_restriction_t *rst);
+
+#endif /* defined(ENTRYNODES_PRIVATE) */
 
 void remove_all_entry_guards_for_guard_selection(guard_selection_t *gs);
 void remove_all_entry_guards(void);