prop224: Add hsdir consensus parameters

Signed-off-by: David Goulet <dgoulet@torproject.org>

src/or/hs_common.c

@@ -857,6 +857,36 @@ hs_get_previous_srv(uint64_t time_period_num)
   return sr_value;
 }
 
+/* Return the number of replicas defined by a consensus parameter or the
+ * default value. */
+int32_t
+hs_get_hsdir_n_replicas(void)
+{
+  /* The [1,16] range is a specification requirement. */
+  return networkstatus_get_param(NULL, "hsdir_n_replicas",
+                                 HS_DEFAULT_HSDIR_N_REPLICAS, 1, 16);
+}
+
+/* Return the spread fetch value defined by a consensus parameter or the
+ * default value. */
+int32_t
+hs_get_hsdir_spread_fetch(void)
+{
+  /* The [1,128] range is a specification requirement. */
+  return networkstatus_get_param(NULL, "hsdir_spread_fetch",
+                                 HS_DEFAULT_HSDIR_SPREAD_FETCH, 1, 128);
+}
+
+/* Return the spread store value defined by a consensus parameter or the
+ * default value. */
+int32_t
+hs_get_hsdir_spread_store(void)
+{
+  /* The [1,128] range is a specification requirement. */
+  return networkstatus_get_param(NULL, "hsdir_spread_store",
+                                 HS_DEFAULT_HSDIR_SPREAD_STORE, 1, 128);
+}
+
 /* Initialize the entire HS subsytem. This is called in tor_init() before any
  * torrc options are loaded. Only for >= v3. */
 void

src/or/hs_common.h

@@ -113,6 +113,13 @@
 #define HS_SRV_DISASTER_PREFIX "shared-random-disaster"
 #define HS_SRV_DISASTER_PREFIX_LEN (sizeof(HS_SRV_DISASTER_PREFIX) - 1)
 
+/* Default value of number of hsdir replicas (hsdir_n_replicas). */
+#define HS_DEFAULT_HSDIR_N_REPLICAS 2
+/* Default value of hsdir spread store (hsdir_spread_store). */
+#define HS_DEFAULT_HSDIR_SPREAD_STORE 3
+/* Default value of hsdir spread fetch (hsdir_spread_fetch). */
+#define HS_DEFAULT_HSDIR_SPREAD_FETCH 3
+
 /* Type of authentication key used by an introduction point. */
 typedef enum {
   HS_AUTH_KEY_TYPE_LEGACY  = 1,
@@ -203,6 +210,10 @@ void hs_build_hs_index(uint64_t replica,
                        const ed25519_public_key_t *blinded_pk,
                        uint64_t period_num, uint8_t *hs_index_out);
 
+int32_t hs_get_hsdir_n_replicas(void);
+int32_t hs_get_hsdir_spread_fetch(void);
+int32_t hs_get_hsdir_spread_store(void);
+
 #ifdef HS_COMMON_PRIVATE
 
 #ifdef TOR_UNIT_TESTS