dirserv.c

关于tor匿名通信的源代码

/* Return 1 if we should fetch new networkstatuses, descriptors, etc
 * on the "mirror" schedule rather than the "client" schedule.
 */
int
directory_fetches_dir_info_early(or_options_t *options)
{
  return directory_fetches_from_authorities(options);
}

/* Return 1 if we should fetch new networkstatuses, descriptors, etc
 * on a very passive schedule -- waiting long enough for ordinary clients
 * to probably have the info we want. These would include bridge users,
 * and maybe others in the future e.g. if a Tor client uses another Tor
 * client as a directory guard.
 */
int
directory_fetches_dir_info_later(or_options_t *options)
{
  return options->UseBridges != 0;
}

/** Return 1 if we want to cache v2 dir info (each status file).
 */
int
directory_caches_v2_dir_info(or_options_t *options)
{
  return options->DirPort != 0;
}

/** Return 1 if we want to keep descriptors, networkstatuses, etc around
 * and we're willing to serve them to others. Else return 0.
 */
int
directory_caches_dir_info(or_options_t *options)
{
  return options->BridgeRelay != 0 || options->DirPort != 0;
}

/** Return 1 if we want to allow remote people to ask us directory
 * requests via the "begin_dir" interface, which doesn't require
 * having any separate port open. */
int
directory_permits_begindir_requests(or_options_t *options)
{
  return options->BridgeRelay != 0 || options->DirPort != 0;
}

/** Return 1 if we want to allow controllers to ask us directory
 * requests via the controller interface, which doesn't require
 * having any separate port open. */
int
directory_permits_controller_requests(or_options_t *options)
{
  return options->DirPort != 0;
}

/** Return 1 if we have no need to fetch new descriptors. This generally
 * happens when we're not a dir cache and we haven't built any circuits
 * lately.
 */
int
directory_too_idle_to_fetch_descriptors(or_options_t *options, time_t now)
{
  return !options->DirPort && !options->FetchUselessDescriptors &&
         rep_hist_circbuilding_dormant(now);
}

/********************************************************************/

/* Used only by non-v1-auth dirservers: The v1 directory and
 * runningrouters we'll serve when requested. */
static cached_dir_t *cached_directory = NULL;
static cached_dir_t cached_runningrouters = { NULL, NULL, 0, 0, 0, -1 };

/** Used for other dirservers' v2 network statuses.  Map from hexdigest to
 * cached_dir_t. */
static digestmap_t *cached_v2_networkstatus = NULL;

/** The v3 consensus network status that we're currently serving. */
static cached_dir_t *cached_v3_networkstatus = NULL;

/** Possibly replace the contents of <b>d</b> with the value of
 * <b>directory</b> published on <b>when</b>, unless <b>when</b> is older than
 * the last value, or too far in the future.
 *
 * Does not copy <b>directory</b>; frees it if it isn't used.
 */
static void
set_cached_dir(cached_dir_t *d, char *directory, time_t when)
{
  time_t now = time(NULL);
  if (when<=d->published) {
    log_info(LD_DIRSERV, "Ignoring old directory; not caching.");
    tor_free(directory);
  } else if (when>=now+ROUTER_MAX_AGE_TO_PUBLISH) {
    log_info(LD_DIRSERV, "Ignoring future directory; not caching.");
    tor_free(directory);
  } else {
    /* if (when>d->published && when<now+ROUTER_MAX_AGE) */
    log_debug(LD_DIRSERV, "Caching directory.");
    tor_free(d->dir);
    d->dir = directory;
    d->dir_len = strlen(directory);
    tor_free(d->dir_z);
    if (tor_gzip_compress(&(d->dir_z), &(d->dir_z_len), d->dir, d->dir_len,
                          ZLIB_METHOD)) {
      log_warn(LD_BUG,"Error compressing cached directory");
    }
    d->published = when;
  }
}

/** Decrement the reference count on <b>d</b>, and free it if it no longer has
 * any references. */
void
cached_dir_decref(cached_dir_t *d)
{
  if (!d || --d->refcnt > 0)
    return;
  clear_cached_dir(d);
  tor_free(d);
}

/** Allocate and return a new cached_dir_t containing the string <b>s</b>,
 * published at <b>published</b>. */
cached_dir_t *
new_cached_dir(char *s, time_t published)
{
  cached_dir_t *d = tor_malloc_zero(sizeof(cached_dir_t));
  d->refcnt = 1;
  d->dir = s;
  d->dir_len = strlen(s);
  d->published = published;
  if (tor_gzip_compress(&(d->dir_z), &(d->dir_z_len), d->dir, d->dir_len,
                        ZLIB_METHOD)) {
    log_warn(LD_BUG, "Error compressing directory");
  }
  return d;
}

/** Remove all storage held in <b>d</b>, but do not free <b>d</b> itself. */
static void
clear_cached_dir(cached_dir_t *d)
{
  tor_free(d->dir);
  tor_free(d->dir_z);
  memset(d, 0, sizeof(cached_dir_t));
}

/** Free all storage held by the cached_dir_t in <b>d</b>. */
static void
_free_cached_dir(void *_d)
{
  cached_dir_t *d = (cached_dir_t *)_d;
  cached_dir_decref(d);
}

/** If we have no cached directory, or it is older than <b>published</b>,
 * then replace it with <b>directory</b>, published at <b>published</b>.
 *
 * If <b>published</b> is too old, do nothing.
 *
 * If <b>is_running_routers</b>, this is really a v1 running_routers
 * document rather than a v1 directory.
 */
void
dirserv_set_cached_directory(const char *directory, time_t published,
                             int is_running_routers)
{
  time_t now = time(NULL);

  if (is_running_routers) {
    if (published >= now - MAX_V1_RR_AGE)
      set_cached_dir(&cached_runningrouters, tor_strdup(directory), published);
  } else {
    if (published >= now - MAX_V1_DIRECTORY_AGE) {
      cached_dir_decref(cached_directory);
      cached_directory = new_cached_dir(tor_strdup(directory), published);
    }
  }
}

/** If <b>networkstatus</b> is non-NULL, we've just received a v2
 * network-status for an authoritative directory with identity digest
 * <b>identity</b> published at <b>published</b> -- store it so we can
 * serve it to others.
 *
 * If <b>networkstatus</b> is NULL, remove the entry with the given
 * identity fingerprint from the v2 cache.
 */
void
dirserv_set_cached_networkstatus_v2(const char *networkstatus,
                                    const char *identity,
                                    time_t published)
{
  cached_dir_t *d, *old_d;
  smartlist_t *trusted_dirs;
  if (!cached_v2_networkstatus)
    cached_v2_networkstatus = digestmap_new();

  old_d = digestmap_get(cached_v2_networkstatus, identity);
  if (!old_d && !networkstatus)
    return;

  if (networkstatus) {
    if (!old_d || published > old_d->published) {
      d = new_cached_dir(tor_strdup(networkstatus), published);
      digestmap_set(cached_v2_networkstatus, identity, d);
      if (old_d)
        cached_dir_decref(old_d);
    }
  } else {
    if (old_d) {
      digestmap_remove(cached_v2_networkstatus, identity);
      cached_dir_decref(old_d);
    }
  }

  /* Now purge old entries. */
  trusted_dirs = router_get_trusted_dir_servers();
  if (digestmap_size(cached_v2_networkstatus) >
      smartlist_len(trusted_dirs) + MAX_UNTRUSTED_NETWORKSTATUSES) {
    /* We need to remove the oldest untrusted networkstatus. */
    const char *oldest = NULL;
    time_t oldest_published = TIME_MAX;
    digestmap_iter_t *iter;

    for (iter = digestmap_iter_init(cached_v2_networkstatus);
         !digestmap_iter_done(iter);
         iter = digestmap_iter_next(cached_v2_networkstatus, iter)) {
      const char *ident;
      void *val;
      digestmap_iter_get(iter, &ident, &val);
      d = val;
      if (d->published < oldest_published &&
          !router_digest_is_trusted_dir(ident)) {
        oldest = ident;
        oldest_published = d->published;
      }
    }
    tor_assert(oldest);
    d = digestmap_remove(cached_v2_networkstatus, oldest);
    if (d)
      cached_dir_decref(d);
  }
}

/** Replace the v3 consensus networkstatus that we're serving with
 * <b>networkstatus</b>, published at <b>published</b>.  No validation is
 * performed. */
void
dirserv_set_cached_networkstatus_v3(const char *networkstatus,
                                    time_t published)
{
  if (cached_v3_networkstatus)
    cached_dir_decref(cached_v3_networkstatus);
  cached_v3_networkstatus = new_cached_dir(
                                  tor_strdup(networkstatus), published);
}

/** Remove any v2 networkstatus from the directory cache that was published
 * before <b>cutoff</b>. */
void
dirserv_clear_old_networkstatuses(time_t cutoff)
{
  if (!cached_v2_networkstatus)
    return;

  DIGESTMAP_FOREACH_MODIFY(cached_v2_networkstatus, id, cached_dir_t *, dir) {
    if (dir->published < cutoff) {
      char *fname;
      fname = networkstatus_get_cache_filename(id);
      if (file_status(fname) == FN_FILE) {
        log_info(LD_DIR, "Removing too-old untrusted networkstatus in %s",
                 fname);
        unlink(fname);
      }
      tor_free(fname);
      cached_dir_decref(dir);
      MAP_DEL_CURRENT(id);
    }
  } DIGESTMAP_FOREACH_END
}

/** Remove any v1 info from the directory cache that was published
 * too long ago. */
void
dirserv_clear_old_v1_info(time_t now)
{
  if (cached_directory &&
      cached_directory->published < (now - MAX_V1_DIRECTORY_AGE)) {
    cached_dir_decref(cached_directory);
    cached_directory = NULL;
  }
  if (cached_runningrouters.published < (now - MAX_V1_RR_AGE)) {
    clear_cached_dir(&cached_runningrouters);
  }
}

/** Helper: If we're an authority for the right directory version (v1 or v2)
 * (based on <b>auth_type</b>), try to regenerate
 * auth_src as appropriate and return it, falling back to cache_src on
 * failure.  If we're a cache, simply return cache_src.
 */
static cached_dir_t *
dirserv_pick_cached_dir_obj(cached_dir_t *cache_src,
                            cached_dir_t *auth_src,
                            time_t dirty, cached_dir_t *(*regenerate)(void),
                            const char *name,
                            authority_type_t auth_type)
{
  or_options_t *options = get_options();
  int authority = (auth_type == V1_AUTHORITY && authdir_mode_v1(options)) ||
                  (auth_type == V2_AUTHORITY && authdir_mode_v2(options));

  if (!authority || authdir_mode_bridge(options)) {
    return cache_src;
  } else {
    /* We're authoritative. */
    if (regenerate != NULL) {
      if (dirty && dirty + DIR_REGEN_SLACK_TIME < time(NULL)) {
        if (!(auth_src = regenerate())) {
          log_err(LD_BUG, "Couldn't generate %s?", name);
          exit(1);
        }
      } else {
        log_info(LD_DIRSERV, "The %s is still clean; reusing.", name);
      }
    }
    return auth_src ? auth_src : cache_src;
  }
}

/** Return the most recently generated encoded signed v1 directory,
 * generating a new one as necessary.  If not a v1 authoritative directory
 * may return NULL if no directory is yet cached. */
cached_dir_t *
dirserv_get_directory(void)
{
  return dirserv_pick_cached_dir_obj(cached_directory, the_directory,
                                     the_directory_is_dirty,
                                     dirserv_regenerate_directory,
                                     "server directory", V1_AUTHORITY);
}

/** Only called by v1 auth dirservers.
 * Generate a fresh v1 directory; set the_directory and return a pointer
 * to the new value.
 */
static cached_dir_t *
dirserv_regenerate_directory(void)
{
  char *new_directory=NULL;

  if (dirserv_dump_directory_to_string(&new_directory, get_identity_key())) {
    log_warn(LD_BUG, "Error creating directory.");
    tor_free(new_directory);
    return NULL;
  }
  cached_dir_decref(the_directory);
  the_directory = new_cached_dir(new_directory, time(NULL));
  log_info(LD_DIRSERV,"New directory (size %d) has been built.",
           (int)the_directory->dir_len);
  log_debug(LD_DIRSERV,"New directory (size %d):\n%s",
            (int)the_directory->dir_len, the_directory->dir);

  the_directory_is_dirty = 0;

  /* Save the directory to disk so we re-load it quickly on startup.
   */
  dirserv_set_cached_directory(the_directory->dir, time(NULL), 0);

  return the_directory;
}

/** Only called by v1 auth dirservers.
 * Replace the current running-routers list with a newly generated one. */
static cached_dir_t *
generate_runningrouters(void)