assertTrue(len > 0);
            assertEquals(0, testMessage.getHeaderStart());
            assertTrue(testMessage.getLength() > 0);

            // Verify SMB2 header
            assertEquals((byte) 0xFE, buffer[0]);
            assertEquals((byte) 'S', buffer[1]);
            assertEquals((byte) 'M', buffer[2]);
            assertEquals((byte) 'B', buffer[3]);
        }

        @Test

        byte[] buffer = new byte[1024];
        int bufferIndex = 0;

        // Prepare SMB2 header (64 bytes)
        // Protocol ID
        System.arraycopy(new byte[] { (byte) 0xFE, 'S', 'M', 'B' }, 0, buffer, bufferIndex, 4);
        // Header length
        SMBUtil.writeInt2(64, buffer, bufferIndex + 4);
        // Credit charge
        SMBUtil.writeInt2(1, buffer, bufferIndex + 6);

                throw new SmbException("Invalid SMB1 header size: " + structureSize);
            }
        }
        // Check SMB2/3 signature
        else if (protocolId == 0x424D53FE) { // 0xFE 'S' 'M' 'B'
            // SMB2/3
            if (structureSize != 64) {
                failedValidations.incrementAndGet();
                throw new SmbException("Invalid SMB2 header size: " + structureSize);

        assertEquals(68, SMBUtil.SMB2_HEADER.length);

        // Verify SMB2 header signature
        assertEquals((byte) 0xFE, SMBUtil.SMB2_HEADER[0]);
        assertEquals((byte) 'S', SMBUtil.SMB2_HEADER[1]);
        assertEquals((byte) 'M', SMBUtil.SMB2_HEADER[2]);
        assertEquals((byte) 'B', SMBUtil.SMB2_HEADER[3]);

        // Random but realistic GUID
        byte[] testGuid = { (byte) 0x01, (byte) 0x23, (byte) 0x45, (byte) 0x67, (byte) 0x89, (byte) 0xAB, (byte) 0xCD, (byte) 0xEF,
                (byte) 0xFE, (byte) 0xDC, (byte) 0xBA, (byte) 0x98, (byte) 0x76, (byte) 0x54, (byte) 0x32, (byte) 0x10 };

        // Security mode with signing required

        String name = "TESTFLAGS       ";
        System.arraycopy(name.getBytes("US-ASCII"), 0, src, srcIndex + 1, 16);
        src[srcIndex + 16] = 0x00; // hex code
        src[srcIndex + 17] = (byte) 0xFE; // All flags except one: 11111110
        // Bit 7: group (1)
        // Bits 6-5: owner node type (11 = 3)
        // Bit 4: being deleted (1)
        // Bit 3: in conflict (1)
        // Bit 2: active (1)

        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
        SMBUtil.writeInt2(1, buffer, headerStart + 6);