networkstatus.c

关于tor匿名通信的源代码

      } else {
        rs->need_to_mirror = 1;
      }
    });
  }

  log_info(LD_DIR, "Setting networkstatus %s %s (published %s)",
           source == NS_FROM_CACHE?"cached from":
           ((source == NS_FROM_DIR_BY_FP || source == NS_FROM_DIR_ALL) ?
             "downloaded from":"generated for"),
           trusted_dir->description, published);
  networkstatus_v2_list_has_changed = 1;
  router_dir_info_changed();

  smartlist_sort(networkstatus_v2_list,
                 _compare_networkstatus_v2_published_on);

  if (!skewed)
    add_networkstatus_to_cache(s, source, ns);

  return 0;
}

/** Remove all very-old network_status_t objects from memory and from the
 * disk cache. */
void
networkstatus_v2_list_clean(time_t now)
{
  int i;
  if (!networkstatus_v2_list)
    return;

  for (i = 0; i < smartlist_len(networkstatus_v2_list); ++i) {
    networkstatus_v2_t *ns = smartlist_get(networkstatus_v2_list, i);
    char *fname = NULL;
    if (ns->published_on + MAX_NETWORKSTATUS_AGE > now)
      continue;
    /* Okay, this one is too old.  Remove it from the list, and delete it
     * from the cache. */
    smartlist_del(networkstatus_v2_list, i--);
    fname = networkstatus_get_cache_filename(ns->identity_digest);
    if (file_status(fname) == FN_FILE) {
      log_info(LD_DIR, "Removing too-old networkstatus in %s", fname);
      unlink(fname);
    }
    tor_free(fname);
    if (directory_caches_v2_dir_info(get_options())) {
      dirserv_set_cached_networkstatus_v2(NULL, ns->identity_digest, 0);
    }
    networkstatus_v2_free(ns);
    router_dir_info_changed();
  }

  /* And now go through the directory cache for any cached untrusted
   * networkstatuses and other network info. */
  dirserv_clear_old_networkstatuses(now - MAX_NETWORKSTATUS_AGE);
  dirserv_clear_old_v1_info(now);
}

/** Helper for bsearching a list of routerstatus_t pointers: compare a
 * digest in the key to the identity digest of a routerstatus_t. */
static int
_compare_digest_to_routerstatus_entry(const void *_key, const void **_member)
{
  const char *key = _key;
  const routerstatus_t *rs = *_member;
  return memcmp(key, rs->identity_digest, DIGEST_LEN);
}

/** Return the entry in <b>ns</b> for the identity digest <b>digest</b>, or
 * NULL if none was found. */
routerstatus_t *
networkstatus_v2_find_entry(networkstatus_v2_t *ns, const char *digest)
{
  return smartlist_bsearch(ns->entries, digest,
                           _compare_digest_to_routerstatus_entry);
}

/** Return the entry in <b>ns</b> for the identity digest <b>digest</b>, or
 * NULL if none was found. */
routerstatus_t *
networkstatus_vote_find_entry(networkstatus_t *ns, const char *digest)
{
  return smartlist_bsearch(ns->routerstatus_list, digest,
                           _compare_digest_to_routerstatus_entry);
}

/*XXXX make this static once functions are moved into this file. */
/** Search the routerstatuses in <b>ns</b> for one whose identity digest is
 * <b>digest</b>.  Return value and set *<b>found_out</b> as for
 * smartlist_bsearch_idx(). */
int
networkstatus_vote_find_entry_idx(networkstatus_t *ns,
                                  const char *digest, int *found_out)
{
  return smartlist_bsearch_idx(ns->routerstatus_list, digest,
                               _compare_digest_to_routerstatus_entry,
                               found_out);
}

/** Return a list of the v2 networkstatus documents. */
const smartlist_t *
networkstatus_get_v2_list(void)
{
  if (!networkstatus_v2_list)
    networkstatus_v2_list = smartlist_create();
  return networkstatus_v2_list;
}

/** Return the consensus view of the status of the router whose current
 * <i>descriptor</i> digest is <b>digest</b>, or NULL if no such router is
 * known. */
routerstatus_t *
router_get_consensus_status_by_descriptor_digest(const char *digest)
{
  if (!current_consensus) return NULL;
  if (!current_consensus->desc_digest_map) {
    digestmap_t * m = current_consensus->desc_digest_map = digestmap_new();
    SMARTLIST_FOREACH(current_consensus->routerstatus_list,
                      routerstatus_t *, rs,
     {
       digestmap_set(m, rs->descriptor_digest, rs);
     });
  }
  return digestmap_get(current_consensus->desc_digest_map, digest);
}

/** Given the digest of a router descriptor, return its current download
 * status, or NULL if the digest is unrecognized. */
download_status_t *
router_get_dl_status_by_descriptor_digest(const char *d)
{
  routerstatus_t *rs;
  if ((rs = router_get_consensus_status_by_descriptor_digest(d)))
    return &rs->dl_status;
  if (v2_download_status_map)
    return digestmap_get(v2_download_status_map, d);

  return NULL;
}

/** Return the consensus view of the status of the router whose identity
 * digest is <b>digest</b>, or NULL if we don't know about any such router. */
routerstatus_t *
router_get_consensus_status_by_id(const char *digest)
{
  if (!current_consensus)
    return NULL;
  return smartlist_bsearch(current_consensus->routerstatus_list, digest,
                           _compare_digest_to_routerstatus_entry);
}

/** Given a nickname (possibly verbose, possibly a hexadecimal digest), return
 * the corresponding routerstatus_t, or NULL if none exists.  Warn the
 * user if <b>warn_if_unnamed</b> is set, and they have specified a router by
 * nickname, but the Named flag isn't set for that router. */
routerstatus_t *
router_get_consensus_status_by_nickname(const char *nickname,
                                        int warn_if_unnamed)
{
  char digest[DIGEST_LEN];
  routerstatus_t *best=NULL;
  smartlist_t *matches=NULL;
  const char *named_id=NULL;

  if (!current_consensus || !nickname)
    return NULL;

  /* Is this name really a hexadecimal identity digest? */
  if (nickname[0] == '$') {
    if (base16_decode(digest, DIGEST_LEN, nickname+1, strlen(nickname+1))<0)
      return NULL;
    return networkstatus_vote_find_entry(current_consensus, digest);
  } else if (strlen(nickname) == HEX_DIGEST_LEN &&
       (base16_decode(digest, DIGEST_LEN, nickname, strlen(nickname))==0)) {
    return networkstatus_vote_find_entry(current_consensus, digest);
  }

  /* Is there a server that is Named with this name? */
  if (named_server_map)
    named_id = strmap_get_lc(named_server_map, nickname);
  if (named_id)
    return networkstatus_vote_find_entry(current_consensus, named_id);

  /* Okay; is this name listed as Unnamed? */
  if (unnamed_server_map &&
      strmap_get_lc(unnamed_server_map, nickname)) {
    log_info(LD_GENERAL, "The name %s is listed as Unnamed; it is not the "
             "canonical name of any server we know.", escaped(nickname));
    return NULL;
  }

  /* This name is not canonical for any server; go through the list and
   * see who it matches. */
  /*XXXX021 This is inefficient. */
  matches = smartlist_create();
  SMARTLIST_FOREACH(current_consensus->routerstatus_list,
                    routerstatus_t *, lrs,
    {
      if (!strcasecmp(lrs->nickname, nickname)) {
        if (lrs->is_named) {
          tor_fragile_assert() /* This should never happen. */
          smartlist_free(matches);
          return lrs;
        } else {
          if (lrs->is_unnamed) {
            tor_fragile_assert(); /* nor should this. */
            smartlist_clear(matches);
            best=NULL;
            break;
          }
          smartlist_add(matches, lrs);
          best = lrs;
        }
      }
    });

  if (smartlist_len(matches)>1 && warn_if_unnamed) {
    int any_unwarned=0;
    SMARTLIST_FOREACH(matches, routerstatus_t *, lrs,
      {
        if (! lrs->name_lookup_warned) {
          lrs->name_lookup_warned=1;
          any_unwarned=1;
        }
      });
    if (any_unwarned) {
      log_warn(LD_CONFIG,"There are multiple matches for the nickname \"%s\","
               " but none is listed as named by the directory authorites. "
               "Choosing one arbitrarily.", nickname);
    }
  } else if (warn_if_unnamed && best && !best->name_lookup_warned) {
    char fp[HEX_DIGEST_LEN+1];
    base16_encode(fp, sizeof(fp),
                  best->identity_digest, DIGEST_LEN);
    log_warn(LD_CONFIG,
         "When looking up a status, you specified a server \"%s\" by name, "
         "but the directory authorities do not have any key registered for "
         "this nickname -- so it could be used by any server, "
         "not just the one you meant. "
         "To make sure you get the same server in the future, refer to "
         "it by key, as \"$%s\".", nickname, fp);
    best->name_lookup_warned = 1;
  }
  smartlist_free(matches);
  return best;
}

/** Return the identity digest that's mapped to officially by
 * <b>nickname</b>. */
const char *
networkstatus_get_router_digest_by_nickname(const char *nickname)
{
  if (!named_server_map)
    return NULL;
  return strmap_get_lc(named_server_map, nickname);
}

/** Return true iff <b>nickname</b> is disallowed from being the nickname
 * of any server. */
int
networkstatus_nickname_is_unnamed(const char *nickname)
{
  if (!unnamed_server_map)
    return 0;
  return strmap_get_lc(unnamed_server_map, nickname) != NULL;
}

/** How frequently do directory authorities re-download fresh networkstatus
 * documents? */
#define AUTHORITY_NS_CACHE_INTERVAL (10*60)

/** How frequently do non-authority directory caches re-download fresh
 * networkstatus documents? */
#define NONAUTHORITY_NS_CACHE_INTERVAL (60*60)

/** We are a directory server, and so cache network_status documents.
 * Initiate downloads as needed to update them.  For v2 authorities,
 * this means asking each trusted directory for its network-status.
 * For caches, this means asking a random v2 authority for all
 * network-statuses.
 */
static void
update_v2_networkstatus_cache_downloads(time_t now)
{
  int authority = authdir_mode_v2(get_options());
  int interval =
    authority ? AUTHORITY_NS_CACHE_INTERVAL : NONAUTHORITY_NS_CACHE_INTERVAL;
  const smartlist_t *trusted_dir_servers = router_get_trusted_dir_servers();

  if (last_networkstatus_download_attempted + interval >= now)
    return;

  last_networkstatus_download_attempted = now;

  if (authority) {
    /* An authority launches a separate connection for everybody. */
    SMARTLIST_FOREACH(trusted_dir_servers, trusted_dir_server_t *, ds,
       {
         char resource[HEX_DIGEST_LEN+6]; /* fp/hexdigit.z\0 */
         if (!(ds->type & V2_AUTHORITY))
           continue;
         if (router_digest_is_me(ds->digest))
           continue;
         if (connection_get_by_type_addr_port_purpose(
                CONN_TYPE_DIR, ds->addr, ds->dir_port,
                DIR_PURPOSE_FETCH_NETWORKSTATUS)) {
           /* XXX020 the above dir_port won't be accurate if we're
            * doing a tunneled conn. In that case it should be or_port.
            * How to guess from here? Maybe make the function less general
            * and have it know that it's looking for dir conns. -RD */
           /* Only directory caches download v2 networkstatuses, and they
            * don't use tunneled connections.  I think it's okay to ignore
            * this. */
           continue;
         }
         strlcpy(resource, "fp/", sizeof(resource));
         base16_encode(resource+3, sizeof(resource)-3, ds->digest, DIGEST_LEN);
         strlcat(resource, ".z", sizeof(resource));
         directory_initiate_command_routerstatus(
               &ds->fake_status, DIR_PURPOSE_FETCH_NETWORKSTATUS,
               ROUTER_PURPOSE_GENERAL,
               0, /* Not private */
               resource,
               NULL, 0 /* No payload. */,
               0 /* No I-M-S. */);
       });
  } else {
    /* A non-authority cache launches one connection to a random authority. */
    /* (Check whether we're currently fetching network-status objects.) */
    if (!connection_get_by_type_purpose(CONN_TYPE_DIR,
                                        DIR_PURPOSE_FETCH_NETWORKSTATUS))
      directory_get_from_dirserver(DIR_PURPOSE_FETCH_NETWORKSTATUS,
                                   ROUTER_PURPOSE_GENERAL, "all.z",1);
  }
}

/** How many times will we try to fetch a consensus before we give up? */
#define CONSENSUS_NETWORKSTATUS_MAX_DL_TRIES 8
/** How long will we hang onto a possibly live consensus for which we're
 * fetching certs before we check whether there is a better one? */
#define DELAY_WHILE_FETCHING_CERTS (20*60)

/** If we want to download a fresh consensus, launch a new download as
 * appropriate. */
static void
update_consensus_networkstatus_downloads(time_t now)
{
  or_options_t *options = get_options();
  if (!networkstatus_get_live_consensus(now))
    time_to_download_next_consensus = now; /* No live consensus? Get one now!*/
  if (time_to_download_next_consensus > now)
    return; /* Wait until the current consensus is older. */
  if (authdir_mode_v3(options))
    return; /* Authorities never fetch a consensus */
  if (!download_status_is_ready(&consensus_dl_status, now,