func: static int protocol_client_auth_sasl_start_len(VncState *vs, uint8_t *data, size_t len)
  
  {
  
      uint32_t startlen = read_u32(data, 0);
  
      VNC_DEBUG("Got client start len %d\n", startlen);
  
      if (startlen > SASL_DATA_MAX_LEN) {
  
          VNC_DEBUG("Too much SASL data %d\n", startlen);
  
          vnc_client_error(vs);
  
          return -1;
  
      }
  
  
  
      if (startlen == 0)
  
          return protocol_client_auth_sasl_start(vs, NULL, 0);
  
  
  
      vnc_read_when(vs, protocol_client_auth_sasl_start, startlen);
  
      return 0;
  
  }
  