void add()

in lib/src/copy/web_socket_impl.dart [123:229]
95 lines of code
32 McCabe index (conditional complexity)

  void add(List<int> bytes) {
    final buffer = bytes is Uint8List ? bytes : Uint8List.fromList(bytes);
    var index = 0;
    final lastIndex = buffer.length;
    if (_state == CLOSED) {
      throw WebSocketChannelException('Data on closed connection');
    }
    if (_state == FAILURE) {
      throw WebSocketChannelException('Data on failed connection');
    }
    while ((index < lastIndex) && _state != CLOSED && _state != FAILURE) {
      final byte = buffer[index];
      if (_state <= LEN_REST) {
        if (_state == START) {
          _fin = (byte & FIN) != 0;

          if ((byte & (RSV2 | RSV3)) != 0) {
            // The RSV2, RSV3 bits must both be zero.
            throw WebSocketChannelException('Protocol error');
          }

          _opcode = byte & OPCODE;

          if (_opcode <= _WebSocketOpcode.BINARY) {
            if (_opcode == _WebSocketOpcode.CONTINUATION) {
              if (_currentMessageType == _WebSocketMessageType.NONE) {
                throw WebSocketChannelException('Protocol error');
              }
            } else {
              assert(_opcode == _WebSocketOpcode.TEXT ||
                  _opcode == _WebSocketOpcode.BINARY);
              if (_currentMessageType != _WebSocketMessageType.NONE) {
                throw WebSocketChannelException('Protocol error');
              }
              _currentMessageType = _opcode;
            }
          } else if (_opcode >= _WebSocketOpcode.CLOSE &&
              _opcode <= _WebSocketOpcode.PONG) {
            // Control frames cannot be fragmented.
            if (!_fin) throw WebSocketChannelException('Protocol error');
          } else {
            throw WebSocketChannelException('Protocol error');
          }
          _state = LEN_FIRST;
        } else if (_state == LEN_FIRST) {
          _masked = (byte & 0x80) != 0;
          _len = byte & 0x7F;
          if (_isControlFrame() && _len > 125) {
            throw WebSocketChannelException('Protocol error');
          }
          if (_len == 126) {
            _len = 0;
            _remainingLenBytes = 2;
            _state = LEN_REST;
          } else if (_len == 127) {
            _len = 0;
            _remainingLenBytes = 8;
            _state = LEN_REST;
          } else {
            assert(_len < 126);
            _lengthDone();
          }
        } else {
          assert(_state == LEN_REST);
          _len = _len << 8 | byte;
          _remainingLenBytes--;
          if (_remainingLenBytes == 0) {
            _lengthDone();
          }
        }
      } else {
        if (_state == MASK) {
          _maskingBytes[4 - _remainingMaskingKeyBytes--] = byte;
          if (_remainingMaskingKeyBytes == 0) {
            _maskDone();
          }
        } else {
          assert(_state == PAYLOAD);
          // The payload is not handled one byte at a time but in blocks.
          final payloadLength = min(lastIndex - index, _remainingPayloadBytes);
          _remainingPayloadBytes -= payloadLength;
          // Unmask payload if masked.
          if (_masked) {
            _unmask(index, payloadLength, buffer);
          }
          // Control frame and data frame share _payloads.
          _payload.add(Uint8List.view(buffer.buffer, index, payloadLength));
          index += payloadLength;
          if (_isControlFrame()) {
            if (_remainingPayloadBytes == 0) _controlFrameEnd();
          } else {
            if (_currentMessageType != _WebSocketMessageType.TEXT &&
                _currentMessageType != _WebSocketMessageType.BINARY) {
              throw WebSocketChannelException('Protocol error');
            }
            if (_remainingPayloadBytes == 0) _messageFrameEnd();
          }

          // Hack - as we always do index++ below.
          index--;
        }
      }

      // Move to the next byte.
      index++;
    }
  }