relay.c

关于tor匿名通信的源代码

             safe_str(conn->socks_request->address),
             connection_edge_end_reason_str(reason));
    exitrouter =
      router_get_by_digest(circ->build_state->chosen_exit->identity_digest);
    switch (reason) {
      case END_STREAM_REASON_EXITPOLICY:
        if (rh->length >= 5) {
          uint32_t addr = ntohl(get_uint32(cell->payload+RELAY_HEADER_SIZE+1));
          int ttl;
          if (!addr) {
            log_info(LD_APP,"Address '%s' resolved to 0.0.0.0. Closing,",
                     safe_str(conn->socks_request->address));
            connection_mark_unattached_ap(conn, END_STREAM_REASON_TORPROTOCOL);
            return 0;
          }
          if (rh->length >= 9)
            ttl = (int)ntohl(get_uint32(cell->payload+RELAY_HEADER_SIZE+5));
          else
            ttl = -1;
          client_dns_set_addressmap(conn->socks_request->address, addr,
                                    conn->chosen_exit_name, ttl);
        }
        /* check if he *ought* to have allowed it */
        if (exitrouter &&
            (rh->length < 5 ||
             (tor_inet_aton(conn->socks_request->address, &in) &&
              !conn->chosen_exit_name))) {
          log_info(LD_APP,
                 "Exitrouter '%s' seems to be more restrictive than its exit "
                 "policy. Not using this router as exit for now.",
                 exitrouter->nickname);
          policies_set_router_exitpolicy_to_reject_all(exitrouter);
        }
        /* rewrite it to an IP if we learned one. */
        if (addressmap_rewrite(conn->socks_request->address,
                               sizeof(conn->socks_request->address),
                               NULL)) {
          control_event_stream_status(conn, STREAM_EVENT_REMAP, 0);
        }
        if (conn->_base.chosen_exit_optional ||
            conn->_base.chosen_exit_retries) {
          /* stop wanting a specific exit */
          conn->_base.chosen_exit_optional = 0;
          /* A non-zero chosen_exit_retries can happen if we set a
           * TrackHostExits for this address under a port that the exit
           * relay allows, but then try the same address with a different
           * port that it doesn't allow to exit. We shouldn't unregister
           * the mapping, since it is probably still wanted on the
           * original port. But now we give away to the exit relay that
           * we probably have a TrackHostExits on it. So be it. */
          conn->_base.chosen_exit_retries = 0;
          tor_free(conn->chosen_exit_name); /* clears it */
        }
        if (connection_ap_detach_retriable(conn, circ, control_reason) >= 0)
          return 0;
        /* else, conn will get closed below */
        break;
      case END_STREAM_REASON_CONNECTREFUSED:
        if (!conn->_base.chosen_exit_optional)
          break; /* break means it'll close, below */
        /* Else fall through: expire this circuit, clear the
         * chosen_exit_name field, and try again. */
      case END_STREAM_REASON_RESOLVEFAILED:
      case END_STREAM_REASON_TIMEOUT:
      case END_STREAM_REASON_MISC:
        if (client_dns_incr_failures(conn->socks_request->address)
            < MAX_RESOLVE_FAILURES) {
          /* We haven't retried too many times; reattach the connection. */
          circuit_log_path(LOG_INFO,LD_APP,circ);
          tor_assert(circ->_base.timestamp_dirty);
          circ->_base.timestamp_dirty -= get_options()->MaxCircuitDirtiness;

          if (conn->_base.chosen_exit_optional) {
            /* stop wanting a specific exit */
            conn->_base.chosen_exit_optional = 0;
            tor_free(conn->chosen_exit_name); /* clears it */
          }
          if (connection_ap_detach_retriable(conn, circ, control_reason) >= 0)
            return 0;
          /* else, conn will get closed below */
        } else {
          log_notice(LD_APP,
                     "Have tried resolving or connecting to address '%s' "
                     "at %d different places. Giving up.",
                     safe_str(conn->socks_request->address),
                     MAX_RESOLVE_FAILURES);
          /* clear the failures, so it will have a full try next time */
          client_dns_clear_failures(conn->socks_request->address);
        }
        break;
      case END_STREAM_REASON_HIBERNATING:
      case END_STREAM_REASON_RESOURCELIMIT:
        if (exitrouter) {
          policies_set_router_exitpolicy_to_reject_all(exitrouter);
        }
        if (conn->_base.chosen_exit_optional) {
          /* stop wanting a specific exit */
          conn->_base.chosen_exit_optional = 0;
          tor_free(conn->chosen_exit_name); /* clears it */
        }
        if (connection_ap_detach_retriable(conn, circ, control_reason) >= 0)
          return 0;
        /* else, will close below */
        break;
    } /* end switch */
    log_info(LD_APP,"Giving up on retrying; conn can't be handled.");
  }

  log_info(LD_APP,
           "Edge got end (%s) before we're connected. Marking for close.",
       connection_edge_end_reason_str(rh->length > 0 ? reason : -1));
  if (conn->_base.type == CONN_TYPE_AP) {
    circuit_log_path(LOG_INFO,LD_APP,circ);
    /* need to test because of detach_retriable*/
    if (!conn->_base.marked_for_close)
      connection_mark_unattached_ap(conn, control_reason);
  } else {
    /* we just got an 'end', don't need to send one */
    conn->_base.edge_has_sent_end = 1;
    conn->end_reason = control_reason;
    connection_mark_for_close(TO_CONN(conn));
  }
  return 0;
}

/** Helper: change the socks_request-&gt;address field on conn to the
 * dotted-quad representation of <b>new_addr</b> (given in host order),
 * and send an appropriate REMAP event. */
static void
remap_event_helper(edge_connection_t *conn, uint32_t new_addr)
{
  struct in_addr in;

  in.s_addr = htonl(new_addr);
  tor_inet_ntoa(&in, conn->socks_request->address,
                sizeof(conn->socks_request->address));
  control_event_stream_status(conn, STREAM_EVENT_REMAP,
                              REMAP_STREAM_SOURCE_EXIT);
}

/** An incoming relay cell has arrived from circuit <b>circ</b> to
 * stream <b>conn</b>.
 *
 * The arguments here are the same as in
 * connection_edge_process_relay_cell() below; this function is called
 * from there when <b>conn</b> is defined and not in an open state.
 */
static int
connection_edge_process_relay_cell_not_open(
    relay_header_t *rh, cell_t *cell, circuit_t *circ,
    edge_connection_t *conn, crypt_path_t *layer_hint)
{
  if (rh->command == RELAY_COMMAND_END) {
    if (CIRCUIT_IS_ORIGIN(circ))
      return connection_edge_process_end_not_open(rh, cell,
                                                 TO_ORIGIN_CIRCUIT(circ), conn,
                                                 layer_hint);
    else
      return 0;
  }

  if (conn->_base.type == CONN_TYPE_AP &&
      rh->command == RELAY_COMMAND_CONNECTED) {
    tor_assert(CIRCUIT_IS_ORIGIN(circ));
    if (conn->_base.state != AP_CONN_STATE_CONNECT_WAIT) {
      log_fn(LOG_PROTOCOL_WARN, LD_APP,
             "Got 'connected' while not in state connect_wait. Dropping.");
      return 0;
    }
    conn->_base.state = AP_CONN_STATE_OPEN;
    log_info(LD_APP,"'connected' received after %d seconds.",
             (int)(time(NULL) - conn->_base.timestamp_lastread));
    if (rh->length >= 4) {
      uint32_t addr = ntohl(get_uint32(cell->payload+RELAY_HEADER_SIZE));
      int ttl;
      if (!addr || (get_options()->ClientDNSRejectInternalAddresses &&
                    is_internal_IP(addr, 0))) {
        char buf[INET_NTOA_BUF_LEN];
        struct in_addr a;
        a.s_addr = htonl(addr);
        tor_inet_ntoa(&a, buf, sizeof(buf));
        log_info(LD_APP,
                 "...but it claims the IP address was %s. Closing.", buf);
        connection_edge_end(conn, END_STREAM_REASON_TORPROTOCOL);
        connection_mark_unattached_ap(conn, END_STREAM_REASON_TORPROTOCOL);
        return 0;
      }
      if (rh->length >= 8)
        ttl = (int)ntohl(get_uint32(cell->payload+RELAY_HEADER_SIZE+4));
      else
        ttl = -1;
      client_dns_set_addressmap(conn->socks_request->address, addr,
                                conn->chosen_exit_name, ttl);

      remap_event_helper(conn, addr);
    }
    circuit_log_path(LOG_INFO,LD_APP,TO_ORIGIN_CIRCUIT(circ));
    /* don't send a socks reply to transparent conns */
    if (!conn->socks_request->has_finished)
      connection_ap_handshake_socks_reply(conn, NULL, 0, 0);
    /* handle anything that might have queued */
    if (connection_edge_package_raw_inbuf(conn, 1) < 0) {
      /* (We already sent an end cell if possible) */
      connection_mark_for_close(TO_CONN(conn));
      return 0;
    }
    return 0;
  }
  if (conn->_base.type == CONN_TYPE_AP &&
      rh->command == RELAY_COMMAND_RESOLVED) {
    int ttl;
    int answer_len;
    uint8_t answer_type;
    if (conn->_base.state != AP_CONN_STATE_RESOLVE_WAIT) {
      log_fn(LOG_PROTOCOL_WARN, LD_APP, "Got a 'resolved' cell while "
             "not in state resolve_wait. Dropping.");
      return 0;
    }
    tor_assert(SOCKS_COMMAND_IS_RESOLVE(conn->socks_request->command));
    answer_len = cell->payload[RELAY_HEADER_SIZE+1];
    if (rh->length < 2 || answer_len+2>rh->length) {
      log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
             "Dropping malformed 'resolved' cell");
      connection_mark_unattached_ap(conn, END_STREAM_REASON_TORPROTOCOL);
      return 0;
    }
    answer_type = cell->payload[RELAY_HEADER_SIZE];
    if (rh->length >= answer_len+6)
      ttl = (int)ntohl(get_uint32(cell->payload+RELAY_HEADER_SIZE+
                                  2+answer_len));
    else
      ttl = -1;
    if (answer_type == RESOLVED_TYPE_IPV4 && answer_len >= 4) {
      uint32_t addr = ntohl(get_uint32(cell->payload+RELAY_HEADER_SIZE+2));
      if (get_options()->ClientDNSRejectInternalAddresses &&
          is_internal_IP(addr, 0)) {
        char buf[INET_NTOA_BUF_LEN];
        struct in_addr a;
        a.s_addr = htonl(addr);
        tor_inet_ntoa(&a, buf, sizeof(buf));
        log_info(LD_APP,"Got a resolve with answer %s.  Rejecting.", buf);
        connection_ap_handshake_socks_resolved(conn,
                                               RESOLVED_TYPE_ERROR_TRANSIENT,
                                               0, NULL, 0, TIME_MAX);
        connection_mark_unattached_ap(conn, END_STREAM_REASON_TORPROTOCOL);
        return 0;
      }
    }
    connection_ap_handshake_socks_resolved(conn,
                   answer_type,
                   cell->payload[RELAY_HEADER_SIZE+1], /*answer_len*/
                   cell->payload+RELAY_HEADER_SIZE+2, /*answer*/
                   ttl,
                   -1);
    if (answer_type == RESOLVED_TYPE_IPV4) {
      uint32_t addr = ntohl(get_uint32(cell->payload+RELAY_HEADER_SIZE+2));
      remap_event_helper(conn, addr);
    }
    connection_mark_unattached_ap(conn,
                              END_STREAM_REASON_DONE |
                              END_STREAM_REASON_FLAG_ALREADY_SOCKS_REPLIED);
    return 0;
  }

  log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
         "Got an unexpected relay command %d, in state %d (%s). Dropping.",
         rh->command, conn->_base.state,
         conn_state_to_string(conn->_base.type, conn->_base.state));
  return 0; /* for forward compatibility, don't kill the circuit */
//  connection_edge_end(conn, END_STREAM_REASON_TORPROTOCOL);
//  connection_mark_for_close(conn);
//  return -1;
}

/** An incoming relay cell has arrived on circuit <b>circ</b>. If
 * <b>conn</b> is NULL this is a control cell, else <b>cell</b> is
 * destined for <b>conn</b>.
 *
 * If <b>layer_hint</b> is defined, then we're the origin of the
 * circuit, and it specifies the hop that packaged <b>cell</b>.
 *
 * Return -reason if you want to warn and tear down the circuit, else 0.
 */
static int
connection_edge_process_relay_cell(cell_t *cell, circuit_t *circ,
                                   edge_connection_t *conn,
                                   crypt_path_t *layer_hint)
{
  static int num_seen=0;
  relay_header_t rh;
  unsigned domain = layer_hint?LD_APP:LD_EXIT;
  int reason;

  tor_assert(cell);
  tor_assert(circ);

  relay_header_unpack(&rh, cell->payload);
//  log_fn(LOG_DEBUG,"command %d stream %d", rh.command, rh.stream_id);
  num_seen++;
  log_debug(domain, "Now seen %d relay cells here.", num_seen);

  if (rh.length > RELAY_PAYLOAD_SIZE) {
    log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
           "Relay cell length field too long. Closing circuit.");
    return - END_CIRC_REASON_TORPROTOCOL;
  }

  /* either conn is NULL, in which case we've got a control cell, or else
   * conn points to the recognized stream. */

  if (conn && !connection_state_is_open(TO_CONN(conn)))
    return connection_edge_process_relay_cell_not_open(
             &rh, cell, circ, conn, layer_hint);

  switch (rh.command) {
    case RELAY_COMMAND_DROP:
//      log_info(domain,"Got a relay-level padding cell. Dropping.");
      return 0;
    case RELAY_COMMAND_BEGIN:
    case RELAY_COMMAND_BEGIN_DIR:
      if (layer_hint &&
          circ->purpose != CIRCUIT_PURPOSE_S_REND_JOINED) {
        log_fn(LOG_PROTOCOL_WARN, LD_APP,
               "Relay begin request unsupported at AP. Dropping.");
        return 0;
      }
      if (conn) {
        log_fn(LOG_PROTOCOL_WARN, domain,
               "Begin cell for known stream. Dropping.");
        return 0;
      }
      return connection_exit_begin_conn(cell, circ);
    case RELAY_COMMAND_DATA:
      ++stats_n_data_cells_received;
      if (( layer_hint && --layer_hint->deliver_window < 0) ||
          (!layer_hint && --circ->deliver_window < 0)) {
        log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
               "(relay data) circ deliver_window below 0. Killing.");
        connection_edge_end(conn, END_STREAM_REASON_TORPROTOCOL);
        connection_mark_for_close(TO_CONN(conn));
        return -END_CIRC_REASON_TORPROTOCOL;
      }
      log_debug(domain,"circ deliver_window now %d.", layer_hint ?
                layer_hint->deliver_window : circ->deliver_window);

      circuit_consider_sending_sendme(circ, layer_hint);

      if (!conn) {
        log_info(domain,"data cell dropped, unknown stream.");
        return 0;
      }

      if (--conn->deliver_window < 0) { /* is it below 0 after decrement? */
        log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
               "(relay data) conn deliver_window below 0. Killing.");
        return -END_CIRC_REASON_TORPROTOCOL;
      }

      stats_n_data_bytes_received += rh.length;
      connection_write_to_buf(cell->payload + RELAY_HEADER_SIZE,
                              rh.length, TO_CONN(conn));
      connection_edge_consider_sending_sendme(conn);
      return 0;
    case RELAY_COMMAND_END:
      reason = rh.length > 0 ?
        *(uint8_t *)(cell->payload+RELAY_HEADER_SIZE) : END_STREAM_REASON_MISC;
      if (!conn) {