tor

commit 7217bdacb50e6934abdf9bb43b4c9b1073155647
parent 4c3b43604b7dedf3456136a1ad71fa0802744b2e
Author: Nick Mathewson <nickm@torproject.org>
Date:   Fri, 24 Aug 2018 12:57:18 -0400

Merge remote-tracking branch 'tor-github/pr/289'

Diffstat:
M
src/feature/hs_common/shared_random_client.c
 | 
21
+++++++++++++++++----
M
src/test/test_shared_random.c
 | 
34
++++++++++++++++++++++++++++++++++

2 files changed, 51 insertions(+), 4 deletions(-)
diff --git a/src/feature/hs_common/shared_random_client.c b/src/feature/hs_common/shared_random_client.c
@@ -51,9 +51,13 @@ get_voting_interval(void)
   return interval;
 }
 
-/* Given the time <b>now</b>, return the start time of the current round of
+/* Given the current consensus, return the start time of the current round of
  * the SR protocol. For example, if it's 23:47:08, the current round thus
- * started at 23:47:00 for a voting interval of 10 seconds. */
+ * started at 23:47:00 for a voting interval of 10 seconds.
+ *
+ * This function uses the consensus voting schedule to derive its results,
+ * instead of the actual consensus we are currently using, so it should be used
+ * for voting purposes. */
 time_t
 get_start_time_of_current_round(void)
 {
@@ -231,8 +235,17 @@ sr_state_get_start_time_of_current_protocol_run(void)
 {
   int total_rounds = SHARED_RANDOM_N_ROUNDS * SHARED_RANDOM_N_PHASES;
   int voting_interval = get_voting_interval();
-  /* Find the time the current round started. */
-  time_t beginning_of_curr_round = get_start_time_of_current_round();
+  time_t beginning_of_curr_round;
+
+  /* This function is not used for voting purposes, so if we have a live
+     consensus, use its valid-after as the beginning of the current round,
+     otherwise resort to the voting schedule which should always exist. */
+  networkstatus_t *ns = networkstatus_get_live_consensus(approx_time());
+  if (ns) {
+    beginning_of_curr_round = ns->valid_after;
+  } else {
+    beginning_of_curr_round = get_start_time_of_current_round();
+  }
 
   /* Get current SR protocol round */
   int curr_round_slot;
diff --git a/src/test/test_shared_random.c b/src/test/test_shared_random.c
@@ -290,6 +290,40 @@ test_get_start_time_of_current_run(void *arg)
     tt_str_op("2015-04-20 00:00:00", OP_EQ, tbuf);
   }
 
+  {
+    /* We want the local time to be past midnight, but the current consensus to
+     * have valid-after 23:00 (e.g. this can happen if we fetch a new consensus
+     * at 00:08 before dircaches have a chance to get the midnight consensus).
+     *
+     * Basically, we want to cause a desynch between ns->valid_after (23:00)
+     * and the voting_schedule.interval_starts (01:00), to make sure that
+     * sr_state_get_start_time_of_current_protocol_run() handles it gracefully:
+     * It should actually follow the local consensus time and not the voting
+     * schedule (which is designed for authority voting purposes). */
+    retval = parse_rfc1123_time("Mon, 20 Apr 2015 00:00:00 UTC",
+                                &mock_consensus.fresh_until);
+    tt_int_op(retval, OP_EQ, 0);
+
+    retval = parse_rfc1123_time("Mon, 19 Apr 2015 23:00:00 UTC",
+                                &mock_consensus.valid_after);
+
+    retval = parse_rfc1123_time("Mon, 20 Apr 2015 00:08:00 UTC",
+                                &current_time);
+    tt_int_op(retval, OP_EQ, 0);
+    update_approx_time(current_time);
+    voting_schedule_recalculate_timing(get_options(), current_time);
+
+    run_start_time = sr_state_get_start_time_of_current_protocol_run();
+
+    /* Compare it with the correct result */
+    format_iso_time(tbuf, run_start_time);
+    tt_str_op("2015-04-19 00:00:00", OP_EQ, tbuf);
+    /* Check that voting_schedule.interval_starts is at 01:00 (see above) */
+    time_t interval_starts = voting_schedule_get_next_valid_after_time();
+    format_iso_time(tbuf, interval_starts);
+    tt_str_op("2015-04-20 01:00:00", OP_EQ, tbuf);
+  }
+
   /* Next test is testing it without a consensus to use the testing voting
    * interval . */
   UNMOCK(networkstatus_get_live_consensus);