networkstatus.c

关于tor匿名通信的源代码

    voter->bad_signature = 1;
  } else {
    voter->good_signature = 1;
  }
  tor_free(signed_digest);
  return 0;
}

/** Given a v3 networkstatus consensus in <b>consensus</b>, check every
 * as-yet-unchecked signature on <b>consensus</b>.  Return 1 if there is a
 * signature from every recognized authority on it, 0 if there are
 * enough good signatures from recognized authorities on it, -1 if we might
 * get enough good signatures by fetching missing certificates, and -2
 * otherwise.  Log messages at INFO or WARN: if <b>warn</b> is over 1, warn
 * about every problem; if warn is at least 1, warn only if we can't get
 * enough signatures; if warn is negative, log nothing at all. */
int
networkstatus_check_consensus_signature(networkstatus_t *consensus,
                                        int warn)
{
  int n_good = 0;
  int n_missing_key = 0;
  int n_bad = 0;
  int n_unknown = 0;
  int n_no_signature = 0;
  int n_v3_authorities = get_n_authorities(V3_AUTHORITY);
  int n_required = n_v3_authorities/2 + 1;
  smartlist_t *need_certs_from = smartlist_create();
  smartlist_t *unrecognized = smartlist_create();
  smartlist_t *missing_authorities = smartlist_create();
  int severity;

  tor_assert(! consensus->is_vote);

  SMARTLIST_FOREACH(consensus->voters, networkstatus_voter_info_t *, voter,
  {
    if (!voter->good_signature && !voter->bad_signature && voter->signature) {
      /* we can try to check the signature. */
      authority_cert_t *cert =
        authority_cert_get_by_digests(voter->identity_digest,
                                      voter->signing_key_digest);
      if (! cert) {
        if (!trusteddirserver_get_by_v3_auth_digest(voter->identity_digest)) {
          smartlist_add(unrecognized, voter);
          ++n_unknown;
        } else {
          smartlist_add(need_certs_from, voter);
          ++n_missing_key;
        }
        continue;
      }
      if (networkstatus_check_voter_signature(consensus, voter, cert) < 0) {
        smartlist_add(need_certs_from, voter);
        ++n_missing_key;
        continue;
      }
    }
    if (voter->good_signature)
      ++n_good;
    else if (voter->bad_signature)
      ++n_bad;
    else
      ++n_no_signature;
  });

  /* Now see whether we're missing any voters entirely. */
  SMARTLIST_FOREACH(router_get_trusted_dir_servers(),
                    trusted_dir_server_t *, ds,
    {
      if ((ds->type & V3_AUTHORITY) &&
          !networkstatus_get_voter_by_id(consensus, ds->v3_identity_digest))
        smartlist_add(missing_authorities, ds);
    });

  if (warn > 1 || (warn >= 0 && n_good < n_required))
    severity = LOG_WARN;
  else
    severity = LOG_INFO;

  if (warn >= 0) {
    SMARTLIST_FOREACH(unrecognized, networkstatus_voter_info_t *, voter,
      {
        log_info(LD_DIR, "Consensus includes unrecognized authority '%s' "
                 "at %s:%d (contact %s; identity %s)",
                 voter->nickname, voter->address, (int)voter->dir_port,
                 voter->contact?voter->contact:"n/a",
                 hex_str(voter->identity_digest, DIGEST_LEN));
      });
    SMARTLIST_FOREACH(need_certs_from, networkstatus_voter_info_t *, voter,
      {
        log_info(LD_DIR, "Looks like we need to download a new certificate "
                 "from authority '%s' at %s:%d (contact %s; identity %s)",
                 voter->nickname, voter->address, (int)voter->dir_port,
                 voter->contact?voter->contact:"n/a",
                 hex_str(voter->identity_digest, DIGEST_LEN));
      });
    SMARTLIST_FOREACH(missing_authorities, trusted_dir_server_t *, ds,
      {
        log_info(LD_DIR, "Consensus does not include configured "
                 "authority '%s' at %s:%d (identity %s)",
                 ds->nickname, ds->address, (int)ds->dir_port,
                 hex_str(ds->v3_identity_digest, DIGEST_LEN));
      });
    log(severity, LD_DIR,
        "%d unknown, %d missing key, %d good, %d bad, %d no signature, "
        "%d required", n_unknown, n_missing_key, n_good, n_bad,
        n_no_signature, n_required);
  }

  smartlist_free(unrecognized);
  smartlist_free(need_certs_from);
  smartlist_free(missing_authorities);

  if (n_good == n_v3_authorities)
    return 1;
  else if (n_good >= n_required)
    return 0;
  else if (n_good + n_missing_key >= n_required)
    return -1;
  else
    return -2;
}

/** Helper: return a newly allocated string containing the name of the filename
 * where we plan to cache the network status with the given identity digest. */
char *
networkstatus_get_cache_filename(const char *identity_digest)
{
  char fp[HEX_DIGEST_LEN+1];
  base16_encode(fp, HEX_DIGEST_LEN+1, identity_digest, DIGEST_LEN);
  return get_datadir_fname2("cached-status", fp);
}

/** Helper for smartlist_sort: Compare two networkstatus objects by
 * publication date. */
static int
_compare_networkstatus_v2_published_on(const void **_a, const void **_b)
{
  const networkstatus_v2_t *a = *_a, *b = *_b;
  if (a->published_on < b->published_on)
    return -1;
  else if (a->published_on > b->published_on)
    return 1;
  else
    return 0;
}

/** Add the parsed v2 networkstatus in <b>ns</b> (with original document in
 * <b>s</b>) to the disk cache (and the in-memory directory server cache) as
 * appropriate. */
static int
add_networkstatus_to_cache(const char *s,
                           networkstatus_source_t source,
                           networkstatus_v2_t *ns)
{
  if (source != NS_FROM_CACHE) {
    char *fn = networkstatus_get_cache_filename(ns->identity_digest);
    if (write_str_to_file(fn, s, 0)<0) {
      log_notice(LD_FS, "Couldn't write cached network status to \"%s\"", fn);
    }
    tor_free(fn);
  }

  if (directory_caches_v2_dir_info(get_options()))
    dirserv_set_cached_networkstatus_v2(s,
                                        ns->identity_digest,
                                        ns->published_on);

  return 0;
}

/** How far in the future do we allow a network-status to get before removing
 * it? (seconds) */
#define NETWORKSTATUS_ALLOW_SKEW (24*60*60)

/** Given a string <b>s</b> containing a network status that we received at
 * <b>arrived_at</b> from <b>source</b>, try to parse it, see if we want to
 * store it, and put it into our cache as necessary.
 *
 * If <b>source</b> is NS_FROM_DIR or NS_FROM_CACHE, do not replace our
 * own networkstatus_t (if we're an authoritative directory server).
 *
 * If <b>source</b> is NS_FROM_CACHE, do not write our networkstatus_t to the
 * cache.
 *
 * If <b>requested_fingerprints</b> is provided, it must contain a list of
 * uppercased identity fingerprints.  Do not update any networkstatus whose
 * fingerprint is not on the list; after updating a networkstatus, remove its
 * fingerprint from the list.
 *
 * Return 0 on success, -1 on failure.
 *
 * Callers should make sure that routers_update_all_from_networkstatus() is
 * invoked after this function succeeds.
 */
int
router_set_networkstatus_v2(const char *s, time_t arrived_at,
            networkstatus_source_t source, smartlist_t *requested_fingerprints)
{
  networkstatus_v2_t *ns;
  int i, found;
  time_t now;
  int skewed = 0;
  trusted_dir_server_t *trusted_dir = NULL;
  const char *source_desc = NULL;
  char fp[HEX_DIGEST_LEN+1];
  char published[ISO_TIME_LEN+1];

  if (!directory_caches_v2_dir_info(get_options()))
    return 0; /* Don't bother storing it. */

  ns = networkstatus_v2_parse_from_string(s);
  if (!ns) {
    log_warn(LD_DIR, "Couldn't parse network status.");
    return -1;
  }
  base16_encode(fp, HEX_DIGEST_LEN+1, ns->identity_digest, DIGEST_LEN);
  if (!(trusted_dir =
        router_get_trusteddirserver_by_digest(ns->identity_digest)) ||
      !(trusted_dir->type & V2_AUTHORITY)) {
    log_info(LD_DIR, "Network status was signed, but not by an authoritative "
             "directory we recognize.");
    source_desc = fp;
  } else {
    source_desc = trusted_dir->description;
  }
  now = time(NULL);
  if (arrived_at > now)
    arrived_at = now;

  ns->received_on = arrived_at;

  format_iso_time(published, ns->published_on);

  if (ns->published_on > now + NETWORKSTATUS_ALLOW_SKEW) {
    char dbuf[64];
    long delta = now - ns->published_on;
    format_time_interval(dbuf, sizeof(dbuf), delta);
    log_warn(LD_GENERAL, "Network status from %s was published %s in the "
             "future (%s GMT). Check your time and date settings! "
             "Not caching.",
             source_desc, dbuf, published);
    control_event_general_status(LOG_WARN,
                       "CLOCK_SKEW MIN_SKEW=%ld SOURCE=NETWORKSTATUS:%s:%d",
                       delta, ns->source_address, ns->source_dirport);
    skewed = 1;
  }

  if (!networkstatus_v2_list)
    networkstatus_v2_list = smartlist_create();

  if ( (source == NS_FROM_DIR_BY_FP || source == NS_FROM_DIR_ALL) &&
       router_digest_is_me(ns->identity_digest)) {
    /* Don't replace our own networkstatus when we get it from somebody else.*/
    networkstatus_v2_free(ns);
    return 0;
  }

  if (requested_fingerprints) {
    if (smartlist_string_isin(requested_fingerprints, fp)) {
      smartlist_string_remove(requested_fingerprints, fp);
    } else {
      if (source != NS_FROM_DIR_ALL) {
        char *requested =
          smartlist_join_strings(requested_fingerprints," ",0,NULL);
        log_warn(LD_DIR,
               "We received a network status with a fingerprint (%s) that we "
               "never requested. (We asked for: %s.) Dropping.",
               fp, requested);
        tor_free(requested);
        return 0;
      }
    }
  }

  if (!trusted_dir) {
    if (!skewed) {
      /* We got a non-trusted networkstatus, and we're a directory cache.
       * This means that we asked an authority, and it told us about another
       * authority we didn't recognize. */
      log_info(LD_DIR,
               "We do not recognize authority (%s) but we are willing "
               "to cache it.", fp);
      add_networkstatus_to_cache(s, source, ns);
      networkstatus_v2_free(ns);
    }
    return 0;
  }

  found = 0;
  for (i=0; i < smartlist_len(networkstatus_v2_list); ++i) {
    networkstatus_v2_t *old_ns = smartlist_get(networkstatus_v2_list, i);

    if (!memcmp(old_ns->identity_digest, ns->identity_digest, DIGEST_LEN)) {
      if (!memcmp(old_ns->networkstatus_digest,
                  ns->networkstatus_digest, DIGEST_LEN)) {
        /* Same one we had before. */
        networkstatus_v2_free(ns);
        tor_assert(trusted_dir);
        log_info(LD_DIR,
                 "Not replacing network-status from %s (published %s); "
                 "we already have it.",
                 trusted_dir->description, published);
        if (old_ns->received_on < arrived_at) {
          if (source != NS_FROM_CACHE) {
            char *fn;
            fn = networkstatus_get_cache_filename(old_ns->identity_digest);
            /* We use mtime to tell when it arrived, so update that. */
            touch_file(fn);
            tor_free(fn);
          }
          old_ns->received_on = arrived_at;
        }
        download_status_failed(&trusted_dir->v2_ns_dl_status, 0);
        return 0;
      } else if (old_ns->published_on >= ns->published_on) {
        char old_published[ISO_TIME_LEN+1];
        format_iso_time(old_published, old_ns->published_on);
        tor_assert(trusted_dir);
        log_info(LD_DIR,
                 "Not replacing network-status from %s (published %s);"
                 " we have a newer one (published %s) for this authority.",
                 trusted_dir->description, published,
                 old_published);
        networkstatus_v2_free(ns);
        download_status_failed(&trusted_dir->v2_ns_dl_status, 0);
        return 0;
      } else {
        networkstatus_v2_free(old_ns);
        smartlist_set(networkstatus_v2_list, i, ns);
        found = 1;
        break;
      }
    }
  }

  if (source != NS_FROM_CACHE && trusted_dir) {
    download_status_reset(&trusted_dir->v2_ns_dl_status);
  }

  if (!found)
    smartlist_add(networkstatus_v2_list, ns);

/*XXXX021 magic. */
/*DOCDOC */
#define V2_NETWORKSTATUS_LIFETIME (3*60*60)

  {
    time_t live_until = ns->published_on + V2_NETWORKSTATUS_LIFETIME;
    SMARTLIST_FOREACH(ns->entries, routerstatus_t *, rs,
    {
      signed_descriptor_t *sd =
        router_get_by_descriptor_digest(rs->descriptor_digest);
      if (sd) {
        if (sd->last_listed_as_valid_until < live_until)
          sd->last_listed_as_valid_until = live_until;