* The header is prepared as a synchronous response with server-to-redirector flag.
     */
    private void buildHeader(byte[] buf, int start, int status, int command, long sessionId) {
        System.arraycopy(SMBUtil.SMB2_HEADER, 0, buf, start, SMBUtil.SMB2_HEADER.length);
        // Status at +8
        SMBUtil.writeInt4(status, buf, start + 8);
        // Command at +12
        SMBUtil.writeInt2(command, buf, start + 12);

            }

            System.arraycopy(txn_buf, bufParameterOffset, dst, dstIndex, parameterCount);
            dstIndex += parameterCount;
        }

        if (dataCount > 0) {
            p = pad1;
            while (p-- > 0) {
                dst[dstIndex] = (byte) 0x00; // Pad1
                dstIndex++;
            }
            System.arraycopy(txn_buf, bufDataOffset, dst, dstIndex, dataCount);

        }
        bufferIndex += 4;
        this.ctlCode = SMBUtil.readInt4(buffer, bufferIndex);
        bufferIndex += 4;

        this.fileId = new byte[16];
        System.arraycopy(buffer, bufferIndex, this.fileId, 0, 16);
        bufferIndex += 16;

        final int inputOffset = SMBUtil.readInt4(buffer, bufferIndex) + getHeaderStart();
        bufferIndex += 4;

            byte[] buffer = new byte[256];
            int offset = 100;
            byte[] responseData = createValidCopyChunkResponse(10, 131072, 1310720);
            System.arraycopy(responseData, 0, buffer, offset, responseData.length);

            int bytesDecoded = response.decode(buffer, offset, responseData.length);

            assertEquals(12, bytesDecoded);

        // Verify capabilities (4 bytes)
        assertEquals(DEFAULT_CAPABILITIES, SMBUtil.readInt4(buffer, 0));

        // Verify client GUID (16 bytes)
        byte[] extractedGuid = new byte[16];
        System.arraycopy(buffer, 4, extractedGuid, 0, 16);
        assertArrayEquals(defaultClientGuid, extractedGuid);

        // Verify security mode (2 bytes)
        assertEquals(DEFAULT_SECURITY_MODE, SMBUtil.readInt2(buffer, 20));

            // Write name if present
            if (name != null && name.length > 0) {
                System.arraycopy(name, 0, dst, offset, name.length);
                offset += name.length;
            }

            // Write data if present
            if (data != null && data.length > 0) {
                System.arraycopy(data, 0, dst, offset, data.length);
                offset += data.length;
            }

        s.getChars(lastEscape, index, dest, destIndex);
        destIndex += charsSkipped;
      }

      // Copy the replacement string into the dest buffer as needed.
      if (rlen > 0) {
        System.arraycopy(r, 0, dest, destIndex, rlen);
        destIndex += rlen;
      }
      lastEscape = index + 1;
    }

    // Copy leftover characters if there are any.
    int charsLeft = slen - lastEscape;

        byte[] buffer = new byte[512];
        int headerStart = 0;
        int bodyStart = Smb2Constants.SMB2_HEADER_LENGTH;

        // Write SMB2 header (64 bytes)
        // Protocol ID
        System.arraycopy(new byte[] { (byte) 0xFE, 'S', 'M', 'B' }, 0, buffer, headerStart, 4);
        // Structure size (64)
        SMBUtil.writeInt2(64, buffer, headerStart + 4);
        // Credit charge

            System.arraycopy(buffer, bufferIndex, this.txn_buf, this.bufParameterStart + this.parameterDisplacement, this.parameterCount);
            bufferIndex += this.parameterCount;
        }
        if (this.dataCount > 0) {
            bufferIndex += this.pad1 = this.dataOffset - (bufferIndex - this.headerStart);

        int pos = 0;
        System.arraycopy(baseKey, 0, input, pos, baseKey.length);
        pos += baseKey.length;
        System.arraycopy(labelBytes, 0, input, pos, labelBytes.length);
        pos += labelBytes.length;
        if (context != null) {
            System.arraycopy(context, 0, input, pos, context.length);
        }