circuitlist.c

关于tor匿名通信的源代码

origin_circuit_t *
circuit_find_to_cannibalize(uint8_t purpose, extend_info_t *info,
                            int flags)
{
  /*XXXX021 arma: The purpose argument is ignored.  Can that possibly be
   * right? */
  /* XXXX <arma> i don't know of any actual bugs that this causes. since i
   * think we only call the function for purposes where we want it to do what
   * the function does. somebody should check this though. */

  circuit_t *_circ;
  origin_circuit_t *best=NULL;
  int need_uptime = (flags & CIRCLAUNCH_NEED_UPTIME) != 0;
  int need_capacity = (flags & CIRCLAUNCH_NEED_CAPACITY) != 0;
  int internal = (flags & CIRCLAUNCH_IS_INTERNAL) != 0;

  log_debug(LD_CIRC,
            "Hunting for a circ to cannibalize: purpose %d, uptime %d, "
            "capacity %d, internal %d",
            purpose, need_uptime, need_capacity, internal);

  for (_circ=global_circuitlist; _circ; _circ = _circ->next) {
    if (CIRCUIT_IS_ORIGIN(_circ) &&
        _circ->state == CIRCUIT_STATE_OPEN &&
        !_circ->marked_for_close &&
        _circ->purpose == CIRCUIT_PURPOSE_C_GENERAL &&
        !_circ->timestamp_dirty) {
      origin_circuit_t *circ = TO_ORIGIN_CIRCUIT(_circ);
#if 0 /* XXX here while roger investigates a reported RendNodes bug */
      if (_circ->purpose == CIRCUIT_PURPOSE_C_ESTABLISH_REND &&
          options->RendNodes) {
        routerinfo_t *exit = build_state_get_exit_router(circ->build_state);
        if (exit && !router_nickname_is_in_list(exit, options->RendNodes))
          continue; /* not one of our allowed RendNodes */
      }
#endif
      if ((!need_uptime || circ->build_state->need_uptime) &&
          (!need_capacity || circ->build_state->need_capacity) &&
          (internal == circ->build_state->is_internal)) {
        if (info) {
          /* need to make sure we don't duplicate hops */
          crypt_path_t *hop = circ->cpath;
          routerinfo_t *ri1 = router_get_by_digest(info->identity_digest);
          do {
            routerinfo_t *ri2;
            if (!memcmp(hop->extend_info->identity_digest,
                        info->identity_digest, DIGEST_LEN))
              goto next;
            if (ri1 &&
                (ri2 = router_get_by_digest(hop->extend_info->identity_digest))
                && routers_in_same_family(ri1, ri2))
              goto next;
            hop=hop->next;
          } while (hop!=circ->cpath);
        }
        if (!best || (best->build_state->need_uptime && !need_uptime))
          best = circ;
      next: ;
      }
    }
  }
  return best;
}

/** Return the number of hops in circuit's path. */
int
circuit_get_cpath_len(origin_circuit_t *circ)
{
  int n = 0;
  if (circ && circ->cpath) {
    crypt_path_t *cpath, *cpath_next = NULL;
    for (cpath = circ->cpath; cpath_next != circ->cpath; cpath = cpath_next) {
      cpath_next = cpath->next;
      ++n;
    }
  }
  return n;
}

/** Return the <b>hopnum</b>th hop in <b>circ</b>->cpath, or NULL if there
 * aren't that many hops in the list. */
crypt_path_t *
circuit_get_cpath_hop(origin_circuit_t *circ, int hopnum)
{
  if (circ && circ->cpath && hopnum > 0) {
    crypt_path_t *cpath, *cpath_next = NULL;
    for (cpath = circ->cpath; cpath_next != circ->cpath; cpath = cpath_next) {
      cpath_next = cpath->next;
      if (--hopnum <= 0)
        return cpath;
    }
  }
  return NULL;
}

/** Go through the circuitlist; mark-for-close each circuit that starts
 *  at us but has not yet been used. */
void
circuit_mark_all_unused_circs(void)
{
  circuit_t *circ;

  for (circ=global_circuitlist; circ; circ = circ->next) {
    if (CIRCUIT_IS_ORIGIN(circ) &&
        !circ->marked_for_close &&
        !circ->timestamp_dirty)
      circuit_mark_for_close(circ, END_CIRC_REASON_FINISHED);
  }
}

/** Go through the circuitlist; for each circuit that starts at us
 * and is dirty, frob its timestamp_dirty so we won't use it for any
 * new streams.
 *
 * This is useful for letting the user change pseudonyms, so new
 * streams will not be linkable to old streams.
 */
void
circuit_expire_all_dirty_circs(void)
{
  circuit_t *circ;
  or_options_t *options = get_options();

  for (circ=global_circuitlist; circ; circ = circ->next) {
    if (CIRCUIT_IS_ORIGIN(circ) &&
        !circ->marked_for_close &&
        circ->timestamp_dirty)
      circ->timestamp_dirty -= options->MaxCircuitDirtiness;
  }
}

/** Mark <b>circ</b> to be closed next time we call
 * circuit_close_all_marked(). Do any cleanup needed:
 *   - If state is onionskin_pending, remove circ from the onion_pending
 *     list.
 *   - If circ isn't open yet: call circuit_build_failed() if we're
 *     the origin, and in either case call circuit_rep_hist_note_result()
 *     to note stats.
 *   - If purpose is C_INTRODUCE_ACK_WAIT, remove the intro point we
 *     just tried from our list of intro points for that service
 *     descriptor.
 *   - Send appropriate destroys and edge_destroys for conns and
 *     streams attached to circ.
 *   - If circ->rend_splice is set (we are the midpoint of a joined
 *     rendezvous stream), then mark the other circuit to close as well.
 */
void
_circuit_mark_for_close(circuit_t *circ, int reason, int line,
                        const char *file)
{
  int orig_reason = reason; /* Passed to the controller */
  assert_circuit_ok(circ);
  tor_assert(line);
  tor_assert(file);

  if (circ->marked_for_close) {
    log(LOG_WARN,LD_BUG,
        "Duplicate call to circuit_mark_for_close at %s:%d"
        " (first at %s:%d)", file, line,
        circ->marked_for_close_file, circ->marked_for_close);
    return;
  }
  if (reason == END_CIRC_AT_ORIGIN) {
    if (!CIRCUIT_IS_ORIGIN(circ)) {
      log_warn(LD_BUG, "Specified 'at-origin' non-reason for ending circuit, "
               "but circuit was not at origin. (called %s:%d, purpose=%d)",
               file, line, circ->purpose);
    }
    reason = END_CIRC_REASON_NONE;
  }
  if (CIRCUIT_IS_ORIGIN(circ)) {
    /* We don't send reasons when closing circuits at the origin. */
    reason = END_CIRC_REASON_NONE;
  }

  if (reason & END_CIRC_REASON_FLAG_REMOTE)
    reason &= ~END_CIRC_REASON_FLAG_REMOTE;

  if (reason < _END_CIRC_REASON_MIN || reason > _END_CIRC_REASON_MAX) {
    if (!(orig_reason & END_CIRC_REASON_FLAG_REMOTE))
      log_warn(LD_BUG, "Reason %d out of range at %s:%d", reason, file, line);
    reason = END_CIRC_REASON_NONE;
  }

  if (circ->state == CIRCUIT_STATE_ONIONSKIN_PENDING) {
    onion_pending_remove(TO_OR_CIRCUIT(circ));
  }
  /* If the circuit ever became OPEN, we sent it to the reputation history
   * module then.  If it isn't OPEN, we send it there now to remember which
   * links worked and which didn't.
   */
  if (circ->state != CIRCUIT_STATE_OPEN) {
    if (CIRCUIT_IS_ORIGIN(circ)) {
      origin_circuit_t *ocirc = TO_ORIGIN_CIRCUIT(circ);
      circuit_build_failed(ocirc); /* take actions if necessary */
      circuit_rep_hist_note_result(ocirc);
    }
  }
  if (circ->state == CIRCUIT_STATE_OR_WAIT) {
    if (circuits_pending_or_conns)
      smartlist_remove(circuits_pending_or_conns, circ);
  }
  if (CIRCUIT_IS_ORIGIN(circ)) {
    control_event_circuit_status(TO_ORIGIN_CIRCUIT(circ),
     (circ->state == CIRCUIT_STATE_OPEN)?CIRC_EVENT_CLOSED:CIRC_EVENT_FAILED,
     orig_reason);
  }
  if (circ->purpose == CIRCUIT_PURPOSE_C_INTRODUCE_ACK_WAIT) {
    origin_circuit_t *ocirc = TO_ORIGIN_CIRCUIT(circ);
    tor_assert(circ->state == CIRCUIT_STATE_OPEN);
    tor_assert(ocirc->build_state->chosen_exit);
    /* treat this like getting a nack from it */
    log_info(LD_REND, "Failed intro circ %s to %s (awaiting ack). "
             "Removing from descriptor.",
             safe_str(ocirc->rend_query),
             safe_str(build_state_get_exit_nickname(ocirc->build_state)));
    rend_client_remove_intro_point(ocirc->build_state->chosen_exit,
                                   ocirc->rend_query);
  }
  if (circ->n_conn)
    connection_or_send_destroy(circ->n_circ_id, circ->n_conn, reason);

  if (! CIRCUIT_IS_ORIGIN(circ)) {
    or_circuit_t *or_circ = TO_OR_CIRCUIT(circ);
    edge_connection_t *conn;
    for (conn=or_circ->n_streams; conn; conn=conn->next_stream)
      connection_edge_destroy(or_circ->p_circ_id, conn);

    while (or_circ->resolving_streams) {
      conn = or_circ->resolving_streams;
      or_circ->resolving_streams = conn->next_stream;
      if (!conn->_base.marked_for_close) {
        /* The client will see a DESTROY, and infer that the connections
         * are closing because the circuit is getting torn down.  No need
         * to send an end cell. */
        conn->_base.edge_has_sent_end = 1;
        conn->end_reason = END_STREAM_REASON_DESTROY;
        conn->end_reason |= END_STREAM_REASON_FLAG_ALREADY_SENT_CLOSED;
        connection_mark_for_close(TO_CONN(conn));
      }
      conn->on_circuit = NULL;
    }

    if (or_circ->p_conn)
      connection_or_send_destroy(or_circ->p_circ_id, or_circ->p_conn, reason);
  } else {
    origin_circuit_t *ocirc = TO_ORIGIN_CIRCUIT(circ);
    edge_connection_t *conn;
    for (conn=ocirc->p_streams; conn; conn=conn->next_stream)
      connection_edge_destroy(circ->n_circ_id, conn);
  }

  circ->marked_for_close = line;
  circ->marked_for_close_file = file;

  if (!CIRCUIT_IS_ORIGIN(circ)) {
    or_circuit_t *or_circ = TO_OR_CIRCUIT(circ);
    if (or_circ->rend_splice) {
      if (!or_circ->rend_splice->_base.marked_for_close) {
        /* do this after marking this circuit, to avoid infinite recursion. */
        circuit_mark_for_close(TO_CIRCUIT(or_circ->rend_splice), reason);
      }
      or_circ->rend_splice = NULL;
    }
  }
}

/** Verify that cpath layer <b>cp</b> has all of its invariants
 * correct. Trigger an assert if anything is invalid.
 */
void
assert_cpath_layer_ok(const crypt_path_t *cp)
{
//  tor_assert(cp->addr); /* these are zero for rendezvous extra-hops */
//  tor_assert(cp->port);
  tor_assert(cp);
  tor_assert(cp->magic == CRYPT_PATH_MAGIC);
  switch (cp->state)
    {
    case CPATH_STATE_OPEN:
      tor_assert(cp->f_crypto);
      tor_assert(cp->b_crypto);
      /* fall through */
    case CPATH_STATE_CLOSED:
      tor_assert(!cp->dh_handshake_state);
      break;
    case CPATH_STATE_AWAITING_KEYS:
      /* tor_assert(cp->dh_handshake_state); */
      break;
    default:
      log_fn(LOG_ERR, LD_BUG, "Unexpected state %d", cp->state);
      tor_assert(0);
    }
  tor_assert(cp->package_window >= 0);
  tor_assert(cp->deliver_window >= 0);
}

/** Verify that cpath <b>cp</b> has all of its invariants
 * correct. Trigger an assert if anything is invalid.
 */
static void
assert_cpath_ok(const crypt_path_t *cp)
{
  const crypt_path_t *start = cp;

  do {
    assert_cpath_layer_ok(cp);
    /* layers must be in sequence of: "open* awaiting? closed*" */
    if (cp != start) {
      if (cp->state == CPATH_STATE_AWAITING_KEYS) {
        tor_assert(cp->prev->state == CPATH_STATE_OPEN);
      } else if (cp->state == CPATH_STATE_OPEN) {
        tor_assert(cp->prev->state == CPATH_STATE_OPEN);
      }
    }
    cp = cp->next;
    tor_assert(cp);
  } while (cp != start);
}

/** Verify that circuit <b>c</b> has all of its invariants
 * correct. Trigger an assert if anything is invalid.
 */
void
assert_circuit_ok(const circuit_t *c)
{
  edge_connection_t *conn;
  const or_circuit_t *or_circ = NULL;
  const origin_circuit_t *origin_circ = NULL;

  tor_assert(c);
  tor_assert(c->magic == ORIGIN_CIRCUIT_MAGIC || c->magic == OR_CIRCUIT_MAGIC);
  tor_assert(c->purpose >= _CIRCUIT_PURPOSE_MIN &&
             c->purpose <= _CIRCUIT_PURPOSE_MAX);

  {
    /* Having a separate variable for this pleases GCC 4.2 in ways I hope I
     * never understand. -NM. */
    circuit_t *nonconst_circ = (circuit_t*) c;
    if (CIRCUIT_IS_ORIGIN(c))
      origin_circ = TO_ORIGIN_CIRCUIT(nonconst_circ);
    else
      or_circ = TO_OR_CIRCUIT(nonconst_circ);
  }

  if (c->n_conn) {
    tor_assert(!memcmp(c->n_conn->identity_digest, c->n_conn_id_digest,
                       DIGEST_LEN));
    if (c->n_circ_id)
      tor_assert(c == circuit_get_by_circid_orconn(c->n_circ_id, c->n_conn));
  }
  if (or_circ && or_circ->p_conn) {
    if (or_circ->p_circ_id)
      tor_assert(c == circuit_get_by_circid_orconn(or_circ->p_circ_id,
                                                   or_circ->p_conn));
  }
#if 0 /* false now that rendezvous exits are attached to p_streams */
  if (origin_circ)
    for (conn = origin_circ->p_streams; conn; conn = conn->next_stream)
      tor_assert(conn->_base.type == CONN_TYPE_AP);
#endif
  if (or_circ)
    for (conn = or_circ->n_streams; conn; conn = conn->next_stream)
      tor_assert(conn->_base.type == CONN_TYPE_EXIT);

  tor_assert(c->deliver_window >= 0);
  tor_assert(c->package_window >= 0);
  if (c->state == CIRCUIT_STATE_OPEN) {
    tor_assert(!c->n_conn_onionskin);
    if (or_circ) {
      tor_assert(or_circ->n_crypto);
      tor_assert(or_circ->p_crypto);
      tor_assert(or_circ->n_digest);
      tor_assert(or_circ->p_digest);
    }
  }
  if (c->state == CIRCUIT_STATE_OR_WAIT && !c->marked_for_close) {
    tor_assert(circuits_pending_or_conns &&
               smartlist_isin(circuits_pending_or_conns, c));
  } else {
    tor_assert(!circuits_pending_or_conns ||
               !smartlist_isin(circuits_pending_or_conns, c));
  }
  if (origin_circ && origin_circ->cpath) {
    assert_cpath_ok(origin_circ->cpath);
  }
  if (c->purpose == CIRCUIT_PURPOSE_REND_ESTABLISHED) {
    tor_assert(or_circ);
    if (!c->marked_for_close) {
      tor_assert(or_circ->rend_splice);
      tor_assert(or_circ->rend_splice->rend_splice == or_circ);
    }
    tor_assert(or_circ->rend_splice != or_circ);
  } else {
    tor_assert(!or_circ || !or_circ->rend_splice);
  }
}