dirserv.c

关于tor匿名通信的源代码

               platform ? escaped(platform) : "");
      tor_free(esc_contact);
    }
    if (msg)
      *msg = "Rejected: There is already a named server with this nickname "
        "and a different fingerprint.";
  }

  status_by_digest = digestmap_get(fingerprint_list->status_by_digest,
                                   id_digest);
  if (status_by_digest)
    result |= (status_by_digest->status & ~FP_NAMED);

  if (result & FP_REJECT) {
    if (msg)
      *msg = "Fingerprint is marked rejected";
    return FP_REJECT;
  } else if (result & FP_INVALID) {
    if (msg)
      *msg = "Fingerprint is marked invalid";
  }

  if (authdir_policy_baddir_address(addr, or_port)) {
    if (should_log)
      log_info(LD_DIRSERV,
               "Marking '%s' as bad directory because of address '%s'",
               nickname, address);
    result |= FP_BADDIR;
  }

  if (authdir_policy_badexit_address(addr, or_port)) {
    if (should_log)
      log_info(LD_DIRSERV, "Marking '%s' as bad exit because of address '%s'",
               nickname, address);
    result |= FP_BADEXIT;
  }

  if (!(result & FP_NAMED)) {
    if (!authdir_policy_permits_address(addr, or_port)) {
      if (should_log)
        log_info(LD_DIRSERV, "Rejecting '%s' because of address '%s'",
                 nickname, address);
      if (msg)
        *msg = "Authdir is rejecting routers in this range.";
      return FP_REJECT;
    }
    if (!authdir_policy_valid_address(addr, or_port)) {
      if (should_log)
        log_info(LD_DIRSERV, "Not marking '%s' valid because of address '%s'",
                 nickname, address);
      result |= FP_INVALID;
    }
    if (reject_unlisted) {
      if (msg)
        *msg = "Authdir rejects unknown routers.";
      return FP_REJECT;
    }
    /* 0.1.0.2-rc was the first version that did enough self-testing that
     * we're willing to take its word about whether it's running. */
    if (platform && !tor_version_as_new_as(platform,"0.1.0.2-rc"))
      result |= FP_INVALID;
  }

  return result;
}

/** If we are an authoritative dirserver, and the list of approved
 * servers contains one whose identity key digest is <b>digest</b>,
 * return that router's nickname.  Otherwise return NULL. */
const char *
dirserv_get_nickname_by_digest(const char *digest)
{
  router_status_t *status;
  if (!fingerprint_list)
    return NULL;
  tor_assert(digest);

  status = digestmap_get(fingerprint_list->status_by_digest, digest);
  return status ? status->nickname : NULL;
}

/** Clear the current fingerprint list. */
void
dirserv_free_fingerprint_list(void)
{
  if (!fingerprint_list)
    return;

  strmap_free(fingerprint_list->fp_by_name, _tor_free);
  digestmap_free(fingerprint_list->status_by_digest, _tor_free);
  tor_free(fingerprint_list);
}

/*
 *    Descriptor list
 */

/** Return -1 if <b>ri</b> has a private or otherwise bad address,
 * unless we're configured to not care. Return 0 if all ok. */
static int
dirserv_router_has_valid_address(routerinfo_t *ri)
{
  struct in_addr iaddr;
  if (get_options()->DirAllowPrivateAddresses)
    return 0; /* whatever it is, we're fine with it */
  if (!tor_inet_aton(ri->address, &iaddr)) {
    log_info(LD_DIRSERV,"Router '%s' published non-IP address '%s'. Refusing.",
             ri->nickname, ri->address);
    return -1;
  }
  if (is_internal_IP(ntohl(iaddr.s_addr), 0)) {
    log_info(LD_DIRSERV,
             "Router '%s' published internal IP address '%s'. Refusing.",
             ri->nickname, ri->address);
    return -1; /* it's a private IP, we should reject it */
  }
  return 0;
}

/** Check whether we, as a directory server, want to accept <b>ri</b>.  If so,
 * set its is_valid,named,running fields and return 0.  Otherwise, return -1.
 *
 * If the router is rejected, set *<b>msg</b> to an explanation of why.
 *
 * If <b>complain</b> then explain at log-level 'notice' why we refused
 * a descriptor; else explain at log-level 'info'.
 */
int
authdir_wants_to_reject_router(routerinfo_t *ri, const char **msg,
                               int complain)
{
  /* Okay.  Now check whether the fingerprint is recognized. */
  uint32_t status = dirserv_router_get_status(ri, msg);
  time_t now;
  int severity = complain ? LOG_NOTICE : LOG_INFO;
  tor_assert(msg);
  if (status & FP_REJECT)
    return -1; /* msg is already set. */

  /* Is there too much clock skew? */
  now = time(NULL);
  if (ri->cache_info.published_on > now+ROUTER_ALLOW_SKEW) {
    log_fn(severity, LD_DIRSERV, "Publication time for nickname '%s' is too "
           "far (%d minutes) in the future; possible clock skew. Not adding "
           "(%s)",
           ri->nickname, (int)((ri->cache_info.published_on-now)/60),
           esc_router_info(ri));
    *msg = "Rejected: Your clock is set too far in the future, or your "
      "timezone is not correct.";
    return -1;
  }
  if (ri->cache_info.published_on < now-ROUTER_MAX_AGE_TO_PUBLISH) {
    log_fn(severity, LD_DIRSERV,
           "Publication time for router with nickname '%s' is too far "
           "(%d minutes) in the past. Not adding (%s)",
           ri->nickname, (int)((now-ri->cache_info.published_on)/60),
           esc_router_info(ri));
    *msg = "Rejected: Server is expired, or your clock is too far in the past,"
      " or your timezone is not correct.";
    return -1;
  }
  if (dirserv_router_has_valid_address(ri) < 0) {
    log_fn(severity, LD_DIRSERV,
           "Router with nickname '%s' has invalid address '%s'. "
           "Not adding (%s).",
           ri->nickname, ri->address,
           esc_router_info(ri));
    *msg = "Rejected: Address is not an IP, or IP is a private address.";
    return -1;
  }
  /* Okay, looks like we're willing to accept this one. */
  ri->is_named = (status & FP_NAMED) ? 1 : 0;
  ri->is_valid = (status & FP_INVALID) ? 0 : 1;
  ri->is_bad_directory = (status & FP_BADDIR) ? 1 : 0;
  ri->is_bad_exit = (status & FP_BADEXIT) ? 1 : 0;

  return 0;
}

/** As for dirserv_add_descriptor, but accepts multiple documents, and
 * returns the most severe error that occurred for any one of them. */
int
dirserv_add_multiple_descriptors(const char *desc, uint8_t purpose,
                                 const char *source,
                                 const char **msg)
{
  int r=100; /* higher than any actual return value. */
  int r_tmp;
  const char *msg_out;
  smartlist_t *list;
  const char *s;
  int n_parsed = 0;
  time_t now = time(NULL);
  char annotation_buf[ROUTER_ANNOTATION_BUF_LEN];
  char time_buf[ISO_TIME_LEN+1];
  int general = purpose == ROUTER_PURPOSE_GENERAL;
  tor_assert(msg);

  format_iso_time(time_buf, now);
  if (tor_snprintf(annotation_buf, sizeof(annotation_buf),
                   "@uploaded-at %s\n"
                   "@source %s\n"
                   "%s%s%s", time_buf, escaped(source),
                   !general ? "@purpose " : "",
                   !general ? router_purpose_to_string(purpose) : "",
                   !general ? "\n" : "")<0) {
    *msg = "Couldn't format annotations";
    return -1;
  }

  s = desc;
  list = smartlist_create();
  if (!router_parse_list_from_string(&s, NULL, list, SAVED_NOWHERE, 0, 0,
                                     annotation_buf)) {
    SMARTLIST_FOREACH(list, routerinfo_t *, ri, {
        msg_out = NULL;
        tor_assert(ri->purpose == purpose);
        r_tmp = dirserv_add_descriptor(ri, &msg_out);
        if (r_tmp < r) {
          r = r_tmp;
          *msg = msg_out;
        }
      });
  }
  n_parsed += smartlist_len(list);
  smartlist_clear(list);

  s = desc;
  if (!router_parse_list_from_string(&s, NULL, list, SAVED_NOWHERE, 1, 0,
                                     NULL)) {
    SMARTLIST_FOREACH(list, extrainfo_t *, ei, {
        msg_out = NULL;

        r_tmp = dirserv_add_extrainfo(ei, &msg_out);
        if (r_tmp < r) {
          r = r_tmp;
          *msg = msg_out;
        }
      });
  }
  n_parsed += smartlist_len(list);
  smartlist_free(list);

  if (! *msg) {
    if (!n_parsed) {
      *msg = "No descriptors found in your POST.";
      if (r > -1)
        r = -1;
    } else {
      *msg = "(no message)";
    }
  }

  return r <= 2 ? r : 2;
}

/** Examine the parsed server descriptor in <b>ri</b> and maybe insert it into
 * the list of server descriptors. Set *<b>msg</b> to a message that should be
 * passed back to the origin of this descriptor.
 *
 * Return 2 if descriptor is well-formed and accepted;
 *  1 if well-formed and accepted but origin should hear *msg;
 *  0 if well-formed but redundant with one we already have;
 * -1 if it is rejected and origin should hear *msg;
 *
 * This function is only called when fresh descriptors are posted, not when
 * we re-load the cache.
 */
int
dirserv_add_descriptor(routerinfo_t *ri, const char **msg)
{
  int r;
  routerinfo_t *ri_old;
  char *desc = NULL;
  size_t desclen = 0;

  /* If it's too big, refuse it now. Otherwise we'll cache it all over the
   * network and it'll clog everything up. */
  if (ri->cache_info.signed_descriptor_len > MAX_DESCRIPTOR_UPLOAD_SIZE) {
    log_notice(LD_DIR, "Somebody attempted to publish a router descriptor "
               "with size %d. Either this is an attack, or the "
               "MAX_DESCRIPTOR_UPLOAD_SIZE (%d) constant is too low.",
               (int)ri->cache_info.signed_descriptor_len,
               MAX_DESCRIPTOR_UPLOAD_SIZE);
    *msg = "Router descriptor was too large";
    control_event_or_authdir_new_descriptor("REJECTED",
               ri->cache_info.signed_descriptor_body,
               ri->cache_info.signed_descriptor_len, *msg);
    routerinfo_free(ri);
    return -1;
  }

  /* Check whether this descriptor is semantically identical to the last one
   * from this server.  (We do this here and not in router_add_to_routerlist
   * because we want to be able to accept the newest router descriptor that
   * another authority has, so we all converge on the same one.) */
  ri_old = router_get_by_digest(ri->cache_info.identity_digest);
  if (ri_old && ri_old->cache_info.published_on < ri->cache_info.published_on
      && router_differences_are_cosmetic(ri_old, ri)
      && !router_is_me(ri)) {
    log_info(LD_DIRSERV,
             "Not replacing descriptor from '%s'; differences are cosmetic.",
             ri->nickname);
    *msg = "Not replacing router descriptor; no information has changed since "
      "the last one with this identity.";
    control_event_or_authdir_new_descriptor("DROPPED",
                         ri->cache_info.signed_descriptor_body,
                         ri->cache_info.signed_descriptor_len, *msg);
    routerinfo_free(ri);
    return 0;
  }
  if (control_event_is_interesting(EVENT_AUTHDIR_NEWDESCS)) {
    /* Make a copy of desc, since router_add_to_routerlist might free
     * ri and its associated signed_descriptor_t. */
    desclen = ri->cache_info.signed_descriptor_len;
    desc = tor_strndup(ri->cache_info.signed_descriptor_body, desclen);
  }

  if ((r = router_add_to_routerlist(ri, msg, 0, 0))<0) {
    if (r < -1 && desc) /* unless the routerinfo was fine, just out-of-date */
      control_event_or_authdir_new_descriptor("REJECTED", desc, desclen, *msg);
    tor_free(desc);
    return r == -1 ? 0 : -1;
  } else {
    smartlist_t *changed;
    control_event_or_authdir_new_descriptor("ACCEPTED", desc, desclen, *msg);

    changed = smartlist_create();
    smartlist_add(changed, ri);
    control_event_descriptors_changed(changed);
    smartlist_free(changed);
    if (!*msg) {
      *msg =  ri->is_valid ? "Descriptor for valid server accepted" :
        "Descriptor for invalid server accepted";
    }
    tor_free(desc);
    return r == 0 ? 2 : 1;
  }
}

/** As dirserv_add_descriptor, but for an extrainfo_t <b>ei</b>. */
static int
dirserv_add_extrainfo(extrainfo_t *ei, const char **msg)
{
  routerinfo_t *ri;
  int r;
  tor_assert(msg);
  *msg = NULL;

  ri = router_get_by_digest(ei->cache_info.identity_digest);
  if (!ri) {
    *msg = "No corresponding router descriptor for extra-info descriptor";
    extrainfo_free(ei);
    return -1;
  }

  /* If it's too big, refuse it now. Otherwise we'll cache it all over the
   * network and it'll clog everything up. */
  if (ei->cache_info.signed_descriptor_len > MAX_EXTRAINFO_UPLOAD_SIZE) {
    log_notice(LD_DIR, "Somebody attempted to publish an extrainfo "
               "with size %d. Either this is an attack, or the "
               "MAX_EXTRAINFO_UPLOAD_SIZE (%d) constant is too low.",
               (int)ei->cache_info.signed_descriptor_len,
               MAX_EXTRAINFO_UPLOAD_SIZE);
    *msg = "Extrainfo document was too large";
    extrainfo_free(ei);
    return -1;
  }

  if ((r = routerinfo_incompatible_with_extrainfo(ri, ei, NULL, msg))) {
    extrainfo_free(ei);
    return r < 0 ? 0 : -1;
  }
  router_add_extrainfo_to_routerlist(ei, msg, 0, 0);
  return 2;
}

/** Remove all descriptors whose nicknames or fingerprints no longer
 * are allowed by our fingerprint list. (Descriptors that used to be