diff options
Diffstat (limited to 'src/feature/dircommon/voting_schedule.c')
| -rw-r--r-- | src/feature/dircommon/voting_schedule.c | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/src/feature/dircommon/voting_schedule.c b/src/feature/dircommon/voting_schedule.c new file mode 100644 index 0000000000..6edde3f229 --- /dev/null +++ b/src/feature/dircommon/voting_schedule.c @@ -0,0 +1,194 @@ +/* Copyright (c) 2018-2018, The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +/** + * \file voting_schedule.c + * \brief This file contains functions that are from the directory authority + * subsystem related to voting specifically but used by many part of + * tor. The full feature is built as part of the dirauth module. + **/ + +#define VOTING_SCHEDULE_PRIVATE +#include "or/voting_schedule.h" + +#include "or/or.h" +#include "or/config.h" +#include "or/networkstatus.h" + +#include "or/networkstatus_st.h" + +/* ===== + * Vote scheduling + * ===== */ + +/** Return the start of the next interval of size <b>interval</b> (in + * seconds) after <b>now</b>, plus <b>offset</b>. Midnight always + * starts a fresh interval, and if the last interval of a day would be + * truncated to less than half its size, it is rolled into the + * previous interval. */ +time_t +voting_schedule_get_start_of_next_interval(time_t now, int interval, + int offset) +{ + struct tm tm; + time_t midnight_today=0; + time_t midnight_tomorrow; + time_t next; + + tor_gmtime_r(&now, &tm); + tm.tm_hour = 0; + tm.tm_min = 0; + tm.tm_sec = 0; + + if (tor_timegm(&tm, &midnight_today) < 0) { + // LCOV_EXCL_START + log_warn(LD_BUG, "Ran into an invalid time when trying to find midnight."); + // LCOV_EXCL_STOP + } + midnight_tomorrow = midnight_today + (24*60*60); + + next = midnight_today + ((now-midnight_today)/interval + 1)*interval; + + /* Intervals never cross midnight. */ + if (next > midnight_tomorrow) + next = midnight_tomorrow; + + /* If the interval would only last half as long as it's supposed to, then + * skip over to the next day. */ + if (next + interval/2 > midnight_tomorrow) + next = midnight_tomorrow; + + next += offset; + if (next - interval > now) + next -= interval; + + return next; +} + +/* Populate and return a new voting_schedule_t that can be used to schedule + * voting. The object is allocated on the heap and it's the responsibility of + * the caller to free it. Can't fail. */ +static voting_schedule_t * +get_voting_schedule(const or_options_t *options, time_t now, int severity) +{ + int interval, vote_delay, dist_delay; + time_t start; + time_t end; + networkstatus_t *consensus; + voting_schedule_t *new_voting_schedule; + + new_voting_schedule = tor_malloc_zero(sizeof(voting_schedule_t)); + + consensus = networkstatus_get_live_consensus(now); + + if (consensus) { + 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; + dist_delay = options->TestingV3AuthInitialDistDelay; + } + + tor_assert(interval > 0); + + if (vote_delay + dist_delay > interval/2) + vote_delay = dist_delay = interval / 4; + + start = new_voting_schedule->interval_starts = + voting_schedule_get_start_of_next_interval(now,interval, + options->TestingV3AuthVotingStartOffset); + end = voting_schedule_get_start_of_next_interval(start+1, interval, + options->TestingV3AuthVotingStartOffset); + + tor_assert(end > start); + + new_voting_schedule->fetch_missing_signatures = start - (dist_delay/2); + new_voting_schedule->voting_ends = start - dist_delay; + new_voting_schedule->fetch_missing_votes = + start - dist_delay - (vote_delay/2); + new_voting_schedule->voting_starts = start - dist_delay - vote_delay; + + { + char tbuf[ISO_TIME_LEN+1]; + format_iso_time(tbuf, new_voting_schedule->interval_starts); + tor_log(severity, LD_DIR,"Choosing expected valid-after time as %s: " + "consensus_set=%d, interval=%d", + tbuf, consensus?1:0, interval); + } + + return new_voting_schedule; +} + +#define voting_schedule_free(s) \ + FREE_AND_NULL(voting_schedule_t, voting_schedule_free_, (s)) + +/** Frees a voting_schedule_t. This should be used instead of the generic + * tor_free. */ +static void +voting_schedule_free_(voting_schedule_t *voting_schedule_to_free) +{ + if (!voting_schedule_to_free) + return; + tor_free(voting_schedule_to_free); +} + +voting_schedule_t voting_schedule; + +/* Using the time <b>now</b>, return the next voting valid-after time. */ +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))) { + 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; +} + +/** Set voting_schedule to hold the timing for the next vote we should be + * doing. All type of tor do that because HS subsystem needs the timing as + * well to function properly. */ +void +voting_schedule_recalculate_timing(const or_options_t *options, time_t now) +{ + voting_schedule_t *new_voting_schedule; + + /* get the new voting schedule */ + new_voting_schedule = get_voting_schedule(options, now, LOG_INFO); + tor_assert(new_voting_schedule); + + /* Fill in the global static struct now */ + memcpy(&voting_schedule, new_voting_schedule, sizeof(voting_schedule)); + voting_schedule_free(new_voting_schedule); +} + |