}
      else -> {
        throw ProtocolException("Unknown control opcode: " + opcode.toHexString())
      }
    }
  }

  @Throws(IOException::class)
  private fun readMessageFrame() {
    val opcode = this.opcode
    if (opcode != OPCODE_TEXT && opcode != OPCODE_BINARY) {
      throw ProtocolException("Unknown opcode: ${opcode.toHexString()}")
    }

    readMessage()

        // Test other opCode, resultCode, questionType, recordType branches
        packet.opCode = NameServicePacket.WACK;
        packet.resultCode = NameServicePacket.SRV_ERR;
        packet.questionType = NameServicePacket.NBSTAT;
        packet.recordType = NameServicePacket.NBSTAT;
        expectedString =

    public String toString() {
        String opCodeString, resultCodeString, questionTypeString, recordTypeString;

        opCodeString = switch (this.opCode) {
        case QUERY -> "QUERY";
        case WACK -> "WACK";
        default -> Integer.toString(this.opCode);
        };
        resultCodeString = switch (this.resultCode) {
        case FMT_ERR -> "FMT_ERR";
        case SRV_ERR -> "SRV_ERR";

        final String questionClassString;
        String recordTypeString;
        final String recordClassString;

        opCodeString = switch (opCode) {
        case QUERY -> "QUERY";
        case WACK -> "WACK";
        default -> Integer.toString(opCode);
        };
        resultCodeString = switch (resultCode) {
        case FMT_ERR -> "FMT_ERR";
        case SRV_ERR -> "SRV_ERR";

        // Set 'opCode' field in superclass to a value other than QUERY (0)
        Field opCodeField = NameServicePacket.class.getDeclaredField("opCode");
        opCodeField.setAccessible(true);
        opCodeField.set(nameQueryResponse, 7); // WACK opCode, which is not QUERY (0)

        // Ensure 'resultCode' is 0 for this test to isolate opCode condition

  internal const val B0_FLAG_RSV2 = 32

  /** Byte 0 reserved flag 3. Must be 0 unless negotiated otherwise. */
  internal const val B0_FLAG_RSV3 = 16

  /** Byte 0 mask for the frame opcode. */
  internal const val B0_MASK_OPCODE = 15

  /** Flag in the opcode which indicates a control frame. */
  internal const val OPCODE_FLAG_CONTROL = 8

  /**
   * Byte 1 flag for whether the payload data is masked.
   *

  @Throws(IOException::class)
  private fun writeControlFrame(
    opcode: Int,
    payload: ByteString,
  ) {
    if (writerClosed) throw IOException("closed")

    val length = payload.size
    require(length <= PAYLOAD_BYTE_MAX) {
      "Payload size must be less than or equal to $PAYLOAD_BYTE_MAX"
    }

    val b0 = B0_FLAG_FIN or opcode
    sinkBuffer.writeByte(b0)

    var b1 = length

    @Override
    int writeRDataWireFormat(final byte[] dst, final int dstIndex) {
        return 0;
    }

    @Override
    int readRDataWireFormat(final byte[] src, int srcIndex) {
        if (resultCode != 0 || opCode != QUERY) {
            return 0;
        }
        final boolean groupName = ((src[srcIndex] & 0x80) == 0x80) == true;
        final int nodeType = (src[srcIndex] & 0x60) >> 5;
        srcIndex += 2;

    int writeRDataWireFormat(final byte[] dst, final int dstIndex) {
        return 0;
    }

    @Override
    int readRDataWireFormat(final byte[] src, int srcIndex) {
        if (this.resultCode != 0 || this.opCode != QUERY) {
            return 0;
        }
        final boolean groupName = ((src[srcIndex] & 0x80) == 0x80) == true;
        final int nodeType = (src[srcIndex] & 0x60) >> 5;
        srcIndex += 2;

            throw new IOException("Connection not established");
        }

        try {
            // In real implementation, this would perform RDMA write:
            // Similar to rdmaRead but with IBV_WR_RDMA_WRITE opcode

            log.debug("DiSNI RDMA write completed, {} bytes", length);

        } catch (Exception e) {
            state = RdmaConnectionState.ERROR;