directory.c

关于tor匿名通信的源代码

/* Copyright (c) 2001-2004, Roger Dingledine.
 * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
 * Copyright (c) 2007-2008, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/* $Id$ */
const char directory_c_id[] =
  "$Id$";

#include "or.h"
#if defined(EXPORTMALLINFO) && defined(HAVE_MALLOC_H) && defined(HAVE_MALLINFO)
#include <malloc.h>
#endif

/**
 * \file directory.c
 * \brief Code to send and fetch directories and router
 * descriptors via HTTP.  Directories use dirserv.c to generate the
 * results; clients use routers.c to parse them.
 **/

/* In-points to directory.c:
 *
 * - directory_post_to_dirservers(), called from
 *   router_upload_dir_desc_to_dirservers() in router.c
 *   upload_service_descriptor() in rendservice.c
 * - directory_get_from_dirserver(), called from
 *   rend_client_refetch_renddesc() in rendclient.c
 *   run_scheduled_events() in main.c
 *   do_hup() in main.c
 * - connection_dir_process_inbuf(), called from
 *   connection_process_inbuf() in connection.c
 * - connection_dir_finished_flushing(), called from
 *   connection_finished_flushing() in connection.c
 * - connection_dir_finished_connecting(), called from
 *   connection_finished_connecting() in connection.c
 */
static void directory_send_command(dir_connection_t *conn,
                             int purpose, int direct, const char *resource,
                             const char *payload, size_t payload_len,
                             int supports_conditional_consensus,
                             time_t if_modified_since);
static int directory_handle_command(dir_connection_t *conn);
static int body_is_plausible(const char *body, size_t body_len, int purpose);
static int purpose_needs_anonymity(uint8_t dir_purpose,
                                   uint8_t router_purpose);
static char *http_get_header(const char *headers, const char *which);
static void http_set_address_origin(const char *headers, connection_t *conn);
static void connection_dir_download_networkstatus_failed(
                               dir_connection_t *conn, int status_code);
static void connection_dir_download_routerdesc_failed(dir_connection_t *conn);
static void connection_dir_download_cert_failed(
                               dir_connection_t *conn, int status_code);
static void dir_networkstatus_download_failed(smartlist_t *failed,
                                              int status_code);
static void dir_routerdesc_download_failed(smartlist_t *failed,
                                           int status_code,
                                           int router_purpose,
                                           int was_extrainfo,
                                           int was_descriptor_digests);
static void note_request(const char *key, size_t bytes);
static int client_likes_consensus(networkstatus_t *v, const char *want_url);

/********* START VARIABLES **********/

/** How far in the future do we allow a directory server to tell us it is
 * before deciding that one of us has the wrong time? */
#define ALLOW_DIRECTORY_TIME_SKEW (30*60)

#define X_ADDRESS_HEADER "X-Your-Address-Is: "

/** HTTP cache control: how long do we tell proxies they can cache each
 * kind of document we serve? */
#define FULL_DIR_CACHE_LIFETIME (60*60)
#define RUNNINGROUTERS_CACHE_LIFETIME (20*60)
#define NETWORKSTATUS_CACHE_LIFETIME (5*60)
#define ROUTERDESC_CACHE_LIFETIME (30*60)
#define ROUTERDESC_BY_DIGEST_CACHE_LIFETIME (48*60*60)
#define ROBOTS_CACHE_LIFETIME (24*60*60)

/********* END VARIABLES ************/

/** Return true iff the directory purpose 'purpose' must use an
 * anonymous connection to a directory. */
static int
purpose_needs_anonymity(uint8_t dir_purpose, uint8_t router_purpose)
{
  if (get_options()->AllDirActionsPrivate)
    return 1;
  if (router_purpose == ROUTER_PURPOSE_BRIDGE && has_completed_circuit)
    return 1; /* if no circuits yet, we may need this info to bootstrap. */
  if (dir_purpose == DIR_PURPOSE_FETCH_DIR ||
      dir_purpose == DIR_PURPOSE_UPLOAD_DIR ||
      dir_purpose == DIR_PURPOSE_UPLOAD_VOTE ||
      dir_purpose == DIR_PURPOSE_UPLOAD_SIGNATURES ||
      dir_purpose == DIR_PURPOSE_FETCH_RUNNING_LIST ||
      dir_purpose == DIR_PURPOSE_FETCH_NETWORKSTATUS ||
      dir_purpose == DIR_PURPOSE_FETCH_STATUS_VOTE ||
      dir_purpose == DIR_PURPOSE_FETCH_DETACHED_SIGNATURES ||
      dir_purpose == DIR_PURPOSE_FETCH_CONSENSUS ||
      dir_purpose == DIR_PURPOSE_FETCH_CERTIFICATE ||
      dir_purpose == DIR_PURPOSE_FETCH_SERVERDESC ||
      dir_purpose == DIR_PURPOSE_FETCH_EXTRAINFO)
    return 0;
  return 1;
}

/** Return a newly allocated string describing <b>auth</b>. */
char *
authority_type_to_string(authority_type_t auth)
{
  char *result;
  smartlist_t *lst = smartlist_create();
  if (auth & V1_AUTHORITY)
    smartlist_add(lst, (void*)"V1");
  if (auth & V2_AUTHORITY)
    smartlist_add(lst, (void*)"V2");
  if (auth & BRIDGE_AUTHORITY)
    smartlist_add(lst, (void*)"Bridge");
  if (auth & HIDSERV_AUTHORITY)
    smartlist_add(lst, (void*)"Hidden service");
  if (smartlist_len(lst)) {
    result = smartlist_join_strings(lst, ", ", 0, NULL);
  } else {
    result = tor_strdup("[Not an authority]");
  }
  smartlist_free(lst);
  return result;
}

/** Return a string describing a given directory connection purpose. */
static const char *
dir_conn_purpose_to_string(int purpose)
{
  switch (purpose)
    {
    case DIR_PURPOSE_FETCH_DIR:
      return "v1 directory fetch";
    case DIR_PURPOSE_FETCH_RENDDESC:
      return "hidden-service descriptor fetch";
    case DIR_PURPOSE_UPLOAD_DIR:
      return "server descriptor upload";
    case DIR_PURPOSE_UPLOAD_RENDDESC:
      return "hidden-service descriptor upload";
    case DIR_PURPOSE_UPLOAD_VOTE:
      return "server vote upload";
    case DIR_PURPOSE_UPLOAD_SIGNATURES:
      return "consensus signature upload";
    case DIR_PURPOSE_FETCH_RUNNING_LIST:
      return "running-routers fetch";
    case DIR_PURPOSE_FETCH_NETWORKSTATUS:
      return "network-status fetch";
    case DIR_PURPOSE_FETCH_SERVERDESC:
      return "server descriptor fetch";
    case DIR_PURPOSE_FETCH_EXTRAINFO:
      return "extra-info fetch";
    case DIR_PURPOSE_FETCH_CONSENSUS:
      return "consensus network-status fetch";
    case DIR_PURPOSE_FETCH_CERTIFICATE:
      return "authority cert fetch";
    case DIR_PURPOSE_FETCH_STATUS_VOTE:
      return "status vote fetch";
    case DIR_PURPOSE_FETCH_DETACHED_SIGNATURES:
      return "consensus signature fetch";
    case DIR_PURPOSE_FETCH_RENDDESC_V2:
      return "hidden-service v2 descriptor fetch";
    case DIR_PURPOSE_UPLOAD_RENDDESC_V2:
      return "hidden-service v2 descriptor upload";
    }

  log_warn(LD_BUG, "Called with unknown purpose %d", purpose);
  return "(unknown)";
}

/** Return true iff <b>identity_digest</b> is the digest of a router we
 * believe to support extrainfo downloads.  (If <b>is_authority</b> we do
 * additional checking that's only valid for authorities.) */
int
router_supports_extrainfo(const char *identity_digest, int is_authority)
{
  routerinfo_t *ri = router_get_by_digest(identity_digest);

  if (ri) {
    if (ri->caches_extra_info)
      return 1;
    if (is_authority && ri->platform &&
        tor_version_as_new_as(ri->platform, "Tor 0.2.0.0-alpha-dev (r10070)"))
      return 1;
  }
  if (is_authority) {
    routerstatus_t *rs = router_get_consensus_status_by_id(identity_digest);
    if (rs && rs->version_supports_extrainfo_upload)
      return 1;
  }
  return 0;
}

/** Return true iff any trusted directory authority has accepted our
 * server descriptor.
 *
 * We consider any authority sufficient because waiting for all of
 * them means it never happens while any authority is down; we don't
 * go for something more complex in the middle (like \>1/3 or \>1/2 or
 * \>=1/2) because that doesn't seem necessary yet.
 */
int
directories_have_accepted_server_descriptor(void)
{
  smartlist_t *servers = router_get_trusted_dir_servers();
  or_options_t *options = get_options();
  SMARTLIST_FOREACH(servers, trusted_dir_server_t *, d, {
    if ((d->type & options->_PublishServerDescriptor) &&
        d->has_accepted_serverdesc) {
      return 1;
    }
  });
  return 0;
}

/** Start a connection to every suitable directory authority, using
 * connection purpose 'purpose' and uploading the payload 'payload'
 * (length 'payload_len').  The purpose should be one of
 * 'DIR_PURPOSE_UPLOAD_DIR' or 'DIR_PURPOSE_UPLOAD_RENDDESC'.
 *
 * <b>type</b> specifies what sort of dir authorities (V1, V2,
 * HIDSERV, BRIDGE) we should upload to.
 *
 * If <b>extrainfo_len</b> is nonzero, the first <b>payload_len</b> bytes of
 * <b>payload</b> hold a router descriptor, and the next <b>extrainfo_len</b>
 * bytes of <b>payload</b> hold an extra-info document.  Upload the descriptor
 * to all authorities, and the extra-info document to all authorities that
 * support it.
 */
void
directory_post_to_dirservers(uint8_t dir_purpose, uint8_t router_purpose,
                             authority_type_t type,
                             const char *payload,
                             size_t payload_len, size_t extrainfo_len)
{
  int post_via_tor;
  smartlist_t *dirservers = router_get_trusted_dir_servers();
  int found = 0;
  tor_assert(dirservers);
  /* This tries dirservers which we believe to be down, but ultimately, that's
   * harmless, and we may as well err on the side of getting things uploaded.
   */
  SMARTLIST_FOREACH(dirservers, trusted_dir_server_t *, ds,
    {
      routerstatus_t *rs = &(ds->fake_status);
      size_t upload_len = payload_len;

      if ((type & ds->type) == 0)
        continue;

      found = 1; /* at least one authority of this type was listed */
      if (dir_purpose == DIR_PURPOSE_UPLOAD_DIR)
        ds->has_accepted_serverdesc = 0;

      if (extrainfo_len && router_supports_extrainfo(ds->digest, 1)) {
        upload_len += extrainfo_len;
        log_info(LD_DIR, "Uploading an extrainfo (length %d)",
                 (int) extrainfo_len);
      }
      post_via_tor = purpose_needs_anonymity(dir_purpose, router_purpose) ||
              !fascist_firewall_allows_address_dir(ds->addr, ds->dir_port);
      directory_initiate_command_routerstatus(rs, dir_purpose,
                                              router_purpose,
                                              post_via_tor,
                                              NULL, payload, upload_len, 0);
    });
  if (!found) {
    char *s = authority_type_to_string(type);
    log_warn(LD_DIR, "Publishing server descriptor to directory authorities "
             "of type '%s', but no authorities of that type listed!", s);
    tor_free(s);
  }
}

/** Start a connection to a random running directory server, using
 * connection purpose <b>dir_purpose</b>, intending to fetch descriptors
 * of purpose <b>router_purpose</b>, and requesting <b>resource</b>.
 * If <b>retry_if_no_servers</b>, then if all the possible servers seem
 * down, mark them up and try again.
 */
void
directory_get_from_dirserver(uint8_t dir_purpose, uint8_t router_purpose,
                             const char *resource, int retry_if_no_servers)
{
  routerstatus_t *rs = NULL;
  or_options_t *options = get_options();
  int prefer_authority = directory_fetches_from_authorities(options);
  int get_via_tor = purpose_needs_anonymity(dir_purpose, router_purpose);
  authority_type_t type;
  int flags = retry_if_no_servers ? PDS_RETRY_IF_NO_SERVERS : 0;
  time_t if_modified_since = 0;

  /* FFFF we could break this switch into its own function, and call
   * it elsewhere in directory.c. -RD */
  switch (dir_purpose) {
    case DIR_PURPOSE_FETCH_EXTRAINFO:
      type = EXTRAINFO_CACHE |
             (router_purpose == ROUTER_PURPOSE_BRIDGE ? BRIDGE_AUTHORITY :
                                                        V2_AUTHORITY);
      break;
    case DIR_PURPOSE_FETCH_NETWORKSTATUS:
    case DIR_PURPOSE_FETCH_SERVERDESC:
      type = (router_purpose == ROUTER_PURPOSE_BRIDGE ? BRIDGE_AUTHORITY :
                                                        V2_AUTHORITY);
      break;
    case DIR_PURPOSE_FETCH_DIR:
    case DIR_PURPOSE_FETCH_RUNNING_LIST:
      type = V1_AUTHORITY;
      break;
    case DIR_PURPOSE_FETCH_RENDDESC:
      type = HIDSERV_AUTHORITY;
      break;
    case DIR_PURPOSE_FETCH_STATUS_VOTE:
    case DIR_PURPOSE_FETCH_DETACHED_SIGNATURES:
      type = V3_AUTHORITY;
      break;
    case DIR_PURPOSE_FETCH_CONSENSUS:
    case DIR_PURPOSE_FETCH_CERTIFICATE:
      type = V3_AUTHORITY;
      break;
    default:
      log_warn(LD_BUG, "Unexpected purpose %d", (int)dir_purpose);
      return;
  }

  if (DIR_PURPOSE_FETCH_CONSENSUS) {
    networkstatus_t *v = networkstatus_get_latest_consensus();
    if (v)
      if_modified_since = v->valid_after + 180;
  }

  if (!options->FetchServerDescriptors && type != HIDSERV_AUTHORITY)