Have multiple guard contexts we can switch between.

Currently, this code doesn't actually have the contexts behave
differently, (except for the legacy context), but it does switch
back and forth between them nicely.

1 files changed, 43 insertions, 7 deletions

diff --git a/src/or/entrynodes.h b/src/or/entrynodes.h
index a0f4c2e3f1..0164667d22 100644
--- a/src/or/entrynodes.h
+++ b/src/or/entrynodes.h
@@ -195,6 +195,26 @@ struct entry_guard_t {
 };
 
 /**
+ * Possible rules for a guard selection to follow
+ */
+typedef enum guard_selection_type_t {
+  /** Infer the type of this selection from its name. */
+  GS_TYPE_INFER=0,
+  /** Use the normal guard selection algorithm, taking our sample from the
+   * complete list of guards in the consensus. */
+  GS_TYPE_NORMAL=1,
+  /** Use the normal guard selection algorithm, taking our sample from the
+   * configured bridges, and allowing it to grow as large as all the configured
+   * bridges */
+  GS_TYPE_BRIDGE,
+  /** Use the normal guard selection algorithm, taking our sample from the
+   * set of filtered nodes. */
+  GS_TYPE_RESTRICTED,
+  /** Use the legacy (pre-prop271) guard selection algorithm and fields */
+  GS_TYPE_LEGACY,
+} guard_selection_type_t;
+
+/**
  * All of the the context for guard selection on a particular client.
  *
  * (XXXX prop271 this paragraph below is not actually implemented yet.)
@@ -213,6 +233,11 @@ struct guard_selection_s {
   char *name;
 
   /**
+   * What rules does this guard-selection object follow?
+   */
+  guard_selection_type_t type;
+
+  /**
    * A value of 1 means that primary_entry_guards is up-to-date; 0
    * means we need to recalculate it before using primary_entry_guards
    * or the is_primary flag on any guard.
@@ -340,6 +365,8 @@ int entry_guards_upgrade_waiting_circuits(guard_selection_t *gs,
 int entry_guard_state_should_expire(circuit_guard_state_t *guard_state);
 void entry_guards_note_internet_connectivity(guard_selection_t *gs);
 
+int update_guard_selection_choice(const or_options_t *options);
+
 /* Used by bridges.c only. */
 void add_bridge_as_entry_guard(guard_selection_t *gs,
                                const node_t *chosen);
@@ -396,15 +423,17 @@ int num_bridges_usable(void);
  * If a circuit has been sitting around in 'waiting for better guard' state
  * for at least this long, we'll expire it.
  */
-#define DLFT_NONPRIMARY_GUARD_IDLE_TIMEOUT (10*60)
+#define DFLT_NONPRIMARY_GUARD_IDLE_TIMEOUT (10*60)
 /**
- * DOCDOC. not yet used; see prop271.
+ * If our configuration retains fewer than this fraction of guards from the
+ * torrc, we are in a restricted setting.
  */
-#define DFLT_MEANINGFUL_RESTRICTION_FRAC 0.2
+#define DFLT_MEANINGFUL_RESTRICTION_PERCENT 20
 /**
- * DOCDOC. not yet used. see prop271.
+ * If our configuration retains fewer than this fraction of guards from the
+ * torrc, we are in an extremely restricted setting, and should warn.
  */
-#define DFLT_EXTREME_RESTRICTION_FRAC 0.01
+#define DFLT_EXTREME_RESTRICTION_PERCENT 1
 /**@}*/
 
 STATIC double get_max_sample_threshold(void);
@@ -416,13 +445,20 @@ STATIC int get_n_primary_guards(void);
 STATIC int get_internet_likely_down_interval(void);
 STATIC int get_nonprimary_guard_connect_timeout(void);
 STATIC int get_nonprimary_guard_idle_timeout(void);
+STATIC double get_meaningful_restriction_threshold(void);
+STATIC double get_extreme_restriction_threshold(void);
 
 // ---------- XXXX these functions and definitions are post-prop271.
 HANDLE_DECL(entry_guard, entry_guard_t, STATIC)
-STATIC guard_selection_t *guard_selection_new(const char *name);
+STATIC guard_selection_t *guard_selection_new(const char *name,
+                                              guard_selection_type_t type);
 STATIC guard_selection_t *get_guard_selection_by_name(
-                                    const char *name, int create_if_absent);
+          const char *name, guard_selection_type_t type, int create_if_absent);
 STATIC void guard_selection_free(guard_selection_t *gs);
+STATIC const char *choose_guard_selection(const or_options_t *options,
+                                          const networkstatus_t *ns,
+                                          const char *old_selection,
+                                          guard_selection_type_t *type_out);
 STATIC entry_guard_t *get_sampled_guard_with_id(guard_selection_t *gs,
                                                 const uint8_t *rsa_id);