[tor-commits] [tor/master] Recreate voting schedule before use if it's outdated.

[nickm at torproject.org]

commit a686464420801c5aa58bde1babbf96d3b8520b00
Author: George Kadianakis <desnacked at riseup.net>
Date:   Tue Jun 12 14:29:06 2018 +0300

    Recreate voting schedule before use if it's outdated.
---
 src/or/voting_schedule.c | 26 +++++++++++++++++++++++++-
 src/or/voting_schedule.h |  4 ++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/src/or/voting_schedule.c b/src/or/voting_schedule.c
index 1d66b5e22..d230a6dbc 100644
--- a/src/or/voting_schedule.c
+++ b/src/or/voting_schedule.c
@@ -83,6 +83,10 @@ get_voting_schedule(const or_options_t *options, time_t now, int severity)
     interval = (int)( consensus->fresh_until - consensus->valid_after );
     vote_delay = consensus->vote_seconds;
     dist_delay = consensus->dist_seconds;
+
+    /* Note down the consensus valid after, so that we detect outdated voting
+     * schedules in case of skewed clocks etc. */
+    new_voting_schedule->live_consensus_valid_after = consensus->valid_after;
   } else {
     interval = options->TestingV3AuthInitialVotingInterval;
     vote_delay = options->TestingV3AuthInitialVoteDelay;
@@ -138,14 +142,34 @@ voting_schedule_t voting_schedule;
 time_t
 voting_schedule_get_next_valid_after_time(void)
 {
+  time_t now = approx_time();
+  bool need_to_recalculate_voting_schedule = false;
+
   /* This is a safe guard in order to make sure that the voting schedule
    * static object is at least initialized. Using this function with a zeroed
    * voting schedule can lead to bugs. */
   if (tor_mem_is_zero((const char *) &voting_schedule,
                       sizeof(voting_schedule))) {
-    voting_schedule_recalculate_timing(get_options(), time(NULL));
+    need_to_recalculate_voting_schedule = true;
+    goto done; /* no need for next check if we have to recalculate anyway */
+  }
+
+  /* Also make sure we are not using an outdated voting schedule. If we have a
+   * newer consensus, make sure we recalculate the voting schedule. */
+  const networkstatus_t *ns = networkstatus_get_live_consensus(now);
+  if (ns && ns->valid_after != voting_schedule.live_consensus_valid_after) {
+    log_info(LD_DIR, "Voting schedule is outdated: recalculating (%d/%d)",
+             (int) ns->valid_after,
+             (int) voting_schedule.live_consensus_valid_after);
+    need_to_recalculate_voting_schedule = true;
+  }
+
+ done:
+  if (need_to_recalculate_voting_schedule) {
+    voting_schedule_recalculate_timing(get_options(), now);
     voting_schedule.created_on_demand = 1;
   }
+
   return voting_schedule.interval_starts;
 }
 
diff --git a/src/or/voting_schedule.h b/src/or/voting_schedule.h
index 4f9d58403..087701408 100644
--- a/src/or/voting_schedule.h
+++ b/src/or/voting_schedule.h
@@ -43,6 +43,10 @@ typedef struct {
    * timings only for the first vote even though this object was initilized
    * prior to voting. */
   int created_on_demand;
+
+  /** The valid-after time of the last live consensus that filled this voting
+   *  schedule.  It's used to detect outdated voting schedules. */
+  time_t live_consensus_valid_after;
 } voting_schedule_t;
 
 /* Public API. */