prop224: Make client and service pick same HSDir

With the latest change on how we use the HSDir index, the client and service
need to pick their responsible HSDir differently that is depending on if they
are before or after a new time period.

The overlap mode is active function has been renamed for this and test added.

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

1 files changed, 31 insertions, 20 deletions

diff --git a/src/or/hs_common.c b/src/or/hs_common.c
index 3bf423f855..ee08aff7b3 100644
--- a/src/or/hs_common.c
+++ b/src/or/hs_common.c
@@ -589,7 +589,7 @@ compute_disaster_srv(uint64_t time_period_num, uint8_t *srv_out)
  *  would have to do it thousands of times in a row, we always cache the
  *  computer disaster SRV (and its corresponding time period num) in case we
  *  want to reuse it soon after. We need to cache two SRVs, one for each active
- *  time period (in case of overlap mode).
+ *  time period.
  */
 static uint8_t cached_disaster_srv[2][DIGEST256_LEN];
 static uint64_t cached_time_period_nums[2] = {0};
@@ -1034,10 +1034,22 @@ hs_build_blinded_keypair(const ed25519_keypair_t *kp,
   memwipe(param, 0, sizeof(param));
 }
 
-/* Return true if overlap mode is active given the date in consensus. If
- * consensus is NULL, then we use the latest live consensus we can find. */
+/* Return true if we are currently in the time segment between a new time
+ * period and a new SRV (in the real network that happens between 12:00 and
+ * 00:00 UTC). Here is a diagram showing exactly when this returns true:
+ *
+ *    +------------------------------------------------------------------+
+ *    |                                                                  |
+ *    | 00:00      12:00       00:00       12:00       00:00       12:00 |
+ *    | SRV#1      TP#1        SRV#2       TP#2        SRV#3       TP#3  |
+ *    |                                                                  |
+ *    |  $==========|-----------$===========|-----------$===========|    |
+ *    |             ^^^^^^^^^^^^            ^^^^^^^^^^^^                 |
+ *    |                                                                  |
+ *    +------------------------------------------------------------------+
+ */
 MOCK_IMPL(int,
-hs_overlap_mode_is_active, (const networkstatus_t *consensus, time_t now))
+hs_time_between_tp_and_srv, (const networkstatus_t *consensus, time_t now))
 {
   time_t valid_after;
   time_t srv_start_time, tp_start_time;
@@ -1049,19 +1061,18 @@ hs_overlap_mode_is_active, (const networkstatus_t *consensus, time_t now))
     }
   }
 
-  /* We consider to be in overlap mode when we are in the period of time
-   * between a fresh SRV and the beginning of the new time period (in the
-   * normal network this is between 00:00 (inclusive) and 12:00 UTC
-   * (exclusive)) */
+  /* Get start time of next TP and of current SRV protocol run, and check if we
+   * are between them. */
   valid_after = consensus->valid_after;
-  srv_start_time =sr_state_get_start_time_of_current_protocol_run(valid_after);
+  srv_start_time =
+    sr_state_get_start_time_of_current_protocol_run(valid_after);
   tp_start_time = hs_get_start_time_of_next_time_period(srv_start_time);
 
   if (valid_after >= srv_start_time && valid_after < tp_start_time) {
-    return 1;
+    return 0;
   }
 
-  return 0;
+  return 1;
 }
 
 /* Return 1 if any virtual port in ports needs a circuit with good uptime.
@@ -1267,9 +1278,9 @@ node_has_hsdir_index(const node_t *node)
 /* For a given blinded key and time period number, get the responsible HSDir
  * and put their routerstatus_t object in the responsible_dirs list. If
  * is_next_period is true, the next hsdir_index of the node_t is used. If
- * is_client is true, the spread fetch consensus parameter is used else the
- * spread store is used which is only for upload. This function can't fail but
- * it is possible that the responsible_dirs list contains fewer nodes than
+ * 'for_fetching' is true, the spread fetch consensus parameter is used else
+ * the spread store is used which is only for upload. This function can't fail
+ * but it is possible that the responsible_dirs list contains fewer nodes than
  * expected.
  *
  * This function goes over the latest consensus routerstatus list and sorts it
@@ -1277,8 +1288,8 @@ node_has_hsdir_index(const node_t *node)
  * node. All of this makes it a bit CPU intensive so use it wisely. */
 void
 hs_get_responsible_hsdirs(const ed25519_public_key_t *blinded_pk,
-                          uint64_t time_period_num, int is_next_period,
-                          int is_client, smartlist_t *responsible_dirs)
+                          uint64_t time_period_num, int is_new_tp,
+                          int for_fetching, smartlist_t *responsible_dirs)
 {
   smartlist_t *sorted_nodes;
   /* The compare function used for the smartlist bsearch. We have two
@@ -1322,10 +1333,10 @@ hs_get_responsible_hsdirs(const ed25519_public_key_t *blinded_pk,
   /* First thing we have to do is sort all node_t by hsdir_index. The
    * is_next_period tells us if we want the current or the next one. Set the
    * bsearch compare function also while we are at it. */
-  if (is_client) {
+  if (for_fetching) {
     smartlist_sort(sorted_nodes, compare_node_fetch_hsdir_index);
     cmp_fct = compare_digest_to_fetch_hsdir_index;
-  } else if (is_next_period) {
+  } else if (is_new_tp) {
     smartlist_sort(sorted_nodes, compare_node_store_second_hsdir_index);
     cmp_fct = compare_digest_to_store_second_hsdir_index;
   } else {
@@ -1341,8 +1352,8 @@ hs_get_responsible_hsdirs(const ed25519_public_key_t *blinded_pk,
     uint8_t hs_index[DIGEST256_LEN] = {0};
     /* Number of node to add to the responsible dirs list depends on if we are
      * trying to fetch or store. A client always fetches. */
-    int n_to_add = (is_client) ? hs_get_hsdir_spread_fetch() :
-                                 hs_get_hsdir_spread_store();
+    int n_to_add = (for_fetching) ? hs_get_hsdir_spread_fetch() :
+                                    hs_get_hsdir_spread_store();
 
     /* Get the index that we should use to select the node. */
     hs_build_hs_index(replica, blinded_pk, time_period_num, hs_index);