dirvote.c

关于tor匿名通信的源代码

  out->cache_info.signed_descriptor_body =
    tor_strndup(cert->cache_info.signed_descriptor_body,
                cert->cache_info.signed_descriptor_len);
  out->cache_info.saved_location = SAVED_NOWHERE;
  out->identity_key = crypto_pk_dup_key(cert->identity_key);
  out->signing_key = crypto_pk_dup_key(cert->signing_key);

  return out;
}

/* =====
 * Vote scheduling
 * ===== */

/** Set *<b>timing_out</b> to the intervals at which we would like to vote.
 * Note that these aren't the intervals we'll use to vote; they're the ones
 * that we'll vote to use. */
void
dirvote_get_preferred_voting_intervals(vote_timing_t *timing_out)
{
  or_options_t *options = get_options();

  tor_assert(timing_out);

  timing_out->vote_interval = options->V3AuthVotingInterval;
  timing_out->n_intervals_valid = options->V3AuthNIntervalsValid;
  timing_out->vote_delay = options->V3AuthVoteDelay;
  timing_out->dist_delay = options->V3AuthDistDelay;
}

/** Return the start of the next interval of size <b>interval</b> (in seconds)
 * after <b>now</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
dirvote_get_start_of_next_interval(time_t now, int interval)
{
  struct tm tm;
  time_t midnight_today;
  time_t midnight_tomorrow;
  time_t next;

  tor_gmtime_r(&now, &tm);
  tm.tm_hour = 0;
  tm.tm_min = 0;
  tm.tm_sec = 0;

  midnight_today = tor_timegm(&tm);
  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;

  return next;
}

/** Scheduling information for a voting interval. */
static struct {
  /** When do we generate and distribute our vote for this interval? */
  time_t voting_starts;
  /** When do we send an HTTP request for any votes that we haven't
   * been posted yet?*/
  time_t fetch_missing_votes;
  /** When do we give up on getting more votes and generate a consensus? */
  time_t voting_ends;
  /** When do we send an HTTP request for any signatures we're expecting to
   * see on the consensus? */
  time_t fetch_missing_signatures;
  /** When do we publish the consensus? */
  time_t interval_starts;

  /* True iff we have generated and distributed our vote. */
  int have_voted;
  /* True iff we've requested missing votes. */
  int have_fetched_missing_votes;
  /* True iff we have built a consensus and sent the signatures around. */
  int have_built_consensus;
  /* True iff we've fetched missing signatures. */
  int have_fetched_missing_signatures;
  /* True iff we have published our consensus. */
  int have_published_consensus;
} voting_schedule = {0,0,0,0,0,0,0,0,0,0};

/** Set voting_schedule to hold the timing for the next vote we should be
 * doing. */
void
dirvote_recalculate_timing(or_options_t *options, time_t now)
{
  int interval, vote_delay, dist_delay;
  time_t start;
  time_t end;
  networkstatus_t *consensus;

  if (!authdir_mode_v3(options))
    return;

  consensus = networkstatus_get_live_consensus(now);

  memset(&voting_schedule, 0, sizeof(voting_schedule));

  if (consensus) {
    interval = (int)( consensus->fresh_until - consensus->valid_after );
    vote_delay = consensus->vote_seconds;
    dist_delay = consensus->dist_seconds;
  } else {
    interval = DEFAULT_VOTING_INTERVAL_WHEN_NO_CONSENSUS;
    vote_delay = dist_delay = 300;
  }

  tor_assert(interval > 0);

  if (vote_delay + dist_delay > interval/2)
    vote_delay = dist_delay = interval / 4;

  start = voting_schedule.interval_starts =
    dirvote_get_start_of_next_interval(now,interval);
  end = dirvote_get_start_of_next_interval(start+1, interval);

  tor_assert(end > start);

  voting_schedule.fetch_missing_signatures = start - (dist_delay/2);
  voting_schedule.voting_ends = start - dist_delay;
  voting_schedule.fetch_missing_votes = start - dist_delay - (vote_delay/2);
  voting_schedule.voting_starts = start - dist_delay - vote_delay;

  {
    char tbuf[ISO_TIME_LEN+1];
    format_iso_time(tbuf, voting_schedule.interval_starts);
    log_notice(LD_DIR,"Choosing expected valid-after time as %s: "
               "consensus_set=%d, interval=%d",
               tbuf, consensus?1:0, interval);
  }
}

/** Entry point: Take whatever voting actions are pending as of <b>now</b>. */
void
dirvote_act(or_options_t *options, time_t now)
{
  if (!authdir_mode_v3(options))
    return;
  if (!voting_schedule.voting_starts) {
    char *keys = list_v3_auth_ids();
    authority_cert_t *c = get_my_v3_authority_cert();
    log_notice(LD_DIR, "Scheduling voting.  Known authority IDs are %s. "
               "Mine is %s.",
               keys, hex_str(c->cache_info.identity_digest, DIGEST_LEN));
    tor_free(keys);
    dirvote_recalculate_timing(options, now);
  }
  if (voting_schedule.voting_starts < now && !voting_schedule.have_voted) {
    log_notice(LD_DIR, "Time to vote.");
    dirvote_perform_vote();
    voting_schedule.have_voted = 1;
  }
  if (voting_schedule.fetch_missing_votes < now &&
      !voting_schedule.have_fetched_missing_votes) {
    log_notice(LD_DIR, "Time to fetch any votes that we're missing.");
    dirvote_fetch_missing_votes();
    voting_schedule.have_fetched_missing_votes = 1;
  }
  if (voting_schedule.voting_ends < now &&
      !voting_schedule.have_built_consensus) {
    log_notice(LD_DIR, "Time to compute a consensus.");
    dirvote_compute_consensus();
    /* XXXX We will want to try again later if we haven't got enough
     * votes yet.  Implement this if it turns out to ever happen. */
    voting_schedule.have_built_consensus = 1;
  }
  if (voting_schedule.fetch_missing_signatures < now &&
      !voting_schedule.have_fetched_missing_signatures) {
    log_notice(LD_DIR, "Time to fetch any signatures that we're missing.");
    dirvote_fetch_missing_signatures();
    voting_schedule.have_fetched_missing_signatures = 1;
  }
  if (voting_schedule.interval_starts < now &&
      !voting_schedule.have_published_consensus) {
    log_notice(LD_DIR, "Time to publish the consensus and discard old votes");
    dirvote_publish_consensus();
    dirvote_clear_votes(0);
    voting_schedule.have_published_consensus = 1;
    /* XXXX We will want to try again later if we haven't got enough
     * signatures yet.  Implement this if it turns out to ever happen. */
    dirvote_recalculate_timing(options, now);
  }
}

/** A vote networkstatus_t and its unparsed body: held around so we can
 * use it to generate a consensus (at voting_ends) and so we can serve it to
 * other authorities that might want it. */
typedef struct pending_vote_t {
  cached_dir_t *vote_body;
  networkstatus_t *vote;
} pending_vote_t;

/** List of pending_vote_t for the current vote.  Before we've used them to
 * build a consensus, the votes go here. */
static smartlist_t *pending_vote_list = NULL;
/** List of pending_vote_t for the previous vote.  After we've used them to
 * build a consensus, the votes go here for the next period. */
static smartlist_t *previous_vote_list = NULL;
/** The body of the consensus that we're currently building.  Once we
 * have it built, it goes into dirserv.c */
static char *pending_consensus_body = NULL;
/** The detached signatures for the consensus that we're currently
 * building. */
static char *pending_consensus_signatures = NULL;
/** The parsed in-progress consensus document. */
static networkstatus_t *pending_consensus = NULL;
/** List of ns_detached_signatures_t: hold signatures that get posted to us
 * before we have generated the consensus on our own. */
static smartlist_t *pending_consensus_signature_list = NULL;

/** Generate a networkstatus vote and post it to all the v3 authorities.
 * (V3 Authority only) */
static int
dirvote_perform_vote(void)
{
  crypto_pk_env_t *key = get_my_v3_authority_signing_key();
  authority_cert_t *cert = get_my_v3_authority_cert();
  networkstatus_t *ns;
  char *contents;
  pending_vote_t *pending_vote;

  int status;
  const char *msg = "";

  if (!cert || !key) {
    log_warn(LD_NET, "Didn't find key/certificate to generate v3 vote");
    return -1;
  }
  if (!(ns = dirserv_generate_networkstatus_vote_obj(key, cert)))
    return -1;

  contents = format_networkstatus_vote(key, ns);
  networkstatus_vote_free(ns);
  if (!contents)
    return -1;

  pending_vote = dirvote_add_vote(contents, &msg, &status);
  tor_free(contents);
  if (!pending_vote) {
    log_warn(LD_DIR, "Couldn't store my own vote! (I told myself, '%s'.)",
             msg);
    return -1;
  }

  directory_post_to_dirservers(DIR_PURPOSE_UPLOAD_VOTE,
                               ROUTER_PURPOSE_GENERAL,
                               V3_AUTHORITY,
                               pending_vote->vote_body->dir,
                               pending_vote->vote_body->dir_len, 0);
  log_notice(LD_DIR, "Vote posted.");
  return 0;
}

/** Send an HTTP request to every other v3 authority, for the votes of every
 * authority for which we haven't received a vote yet in this period. (V3
 * authority only) */
static void
dirvote_fetch_missing_votes(void)
{
  smartlist_t *missing_fps = smartlist_create();
  char *resource;

  SMARTLIST_FOREACH(router_get_trusted_dir_servers(),
                    trusted_dir_server_t *, ds,
    {
      if (!(ds->type & V3_AUTHORITY))
        continue;
      if (!dirvote_get_vote(ds->v3_identity_digest,
                            DGV_BY_ID|DGV_INCLUDE_PENDING)) {
        char *cp = tor_malloc(HEX_DIGEST_LEN+1);
        base16_encode(cp, HEX_DIGEST_LEN+1, ds->v3_identity_digest,
                      DIGEST_LEN);
        smartlist_add(missing_fps, cp);
      }
    });

  if (!smartlist_len(missing_fps)) {
    smartlist_free(missing_fps);
    return;
  }
  log_notice(LOG_NOTICE, "We're missing votes from %d authorities. Asking "
             "every other authority for a copy.", smartlist_len(missing_fps));
  resource = smartlist_join_strings(missing_fps, "+", 0, NULL);
  directory_get_from_all_authorities(DIR_PURPOSE_FETCH_STATUS_VOTE,
                                     0, resource);
  tor_free(resource);
  SMARTLIST_FOREACH(missing_fps, char *, cp, tor_free(cp));
  smartlist_free(missing_fps);
}

/** Send a request to every other authority for its detached signatures,
 * unless we have signatures from all other v3 authorities already. */
static void
dirvote_fetch_missing_signatures(void)
{
  if (!pending_consensus)
    return;
  if (networkstatus_check_consensus_signature(pending_consensus, -1) == 1)
    return; /* we have a signature from everybody. */

  directory_get_from_all_authorities(DIR_PURPOSE_FETCH_DETACHED_SIGNATURES,
                                     0, NULL);
}

/** Drop all currently pending votes, consensus, and detached signatures. */
static void
dirvote_clear_votes(int all_votes)
{
  if (!previous_vote_list)
    previous_vote_list = smartlist_create();
  if (!pending_vote_list)
    pending_vote_list = smartlist_create();

  /* All "previous" votes are now junk. */
  SMARTLIST_FOREACH(previous_vote_list, pending_vote_t *, v, {
      cached_dir_decref(v->vote_body);
      v->vote_body = NULL;
      networkstatus_vote_free(v->vote);
      tor_free(v);
    });
  smartlist_clear(previous_vote_list);

  if (all_votes) {
    /* If we're dumping all the votes, we delete the pending ones. */
    SMARTLIST_FOREACH(pending_vote_list, pending_vote_t *, v, {
        cached_dir_decref(v->vote_body);
        v->vote_body = NULL;
        networkstatus_vote_free(v->vote);
        tor_free(v);
      });
  } else {
    /* Otherwise, we move them into "previous". */
    smartlist_add_all(previous_vote_list, pending_vote_list);
  }
  smartlist_clear(pending_vote_list);

  if (pending_consensus_signature_list) {
    SMARTLIST_FOREACH(pending_consensus_signature_list, char *, cp,
                      tor_free(cp));
    smartlist_clear(pending_consensus_signature_list);
  }
  tor_free(pending_consensus_body);
  tor_free(pending_consensus_signatures);
  if (pending_consensus) {
    networkstatus_vote_free(pending_consensus);
    pending_consensus = NULL;
  }
}

/** Return a newly allocated string containing the hex-encoded v3 authority
    identity digest of every recognized v3 authority. */
static char *
list_v3_auth_ids(void)
{
  smartlist_t *known_v3_keys = smartlist_create();
  char *keys;
  SMARTLIST_FOREACH(router_get_trusted_dir_servers(),
                    trusted_dir_server_t *, ds,
    if ((ds->type & V3_AUTHORITY) &&
        !tor_digest_is_zero(ds->v3_identity_digest))
      smartlist_add(known_v3_keys,