RdmaMemoryRegion region = provider.registerMemory(buffer, access);
        assertNotNull(region, "Memory region should not be null");
        assertEquals(buffer, region.getBuffer(), "Buffer should match");
        assertEquals(1024, region.getSize(), "Size should match buffer size");
        assertTrue(region.hasAccess(RdmaAccess.LOCAL_READ), "Should have local read access");

        if (minSize <= sendBufferSize) {
            RdmaMemoryRegion region = availableSendRegions.poll();
            if (region != null) {
                region.getBuffer().clear();
                return region;
            }
        }

        // Allocate new buffer
        ByteBuffer buffer = ByteBuffer.allocateDirect(Math.max(minSize, sendBufferSize));

        if (this.state == 0) {
            bind();
        }
        final byte[] inB = this.transportContext.getBufferCache().getBuffer();
        final byte[] out = this.transportContext.getBufferCache().getBuffer();
        try {
            final NdrBuffer buf = encodeMessage(msg, out);
            final int off = sendFragments(msg, out, buf);

            alignmentBytes = 1; // Need 1 byte of padding for 2-byte alignment
        }

        // The value 0xCD should be encoded as a 16-bit value (0x00CD) in little-endian
        byte[] bufferData = buf.getBuffer();
        assertEquals((byte) 0xCD, bufferData[startIndex + alignmentBytes], "Least significant byte should be first");

        resp.reset();

        long k;

        /*
         * First request w/ interim response
         */
        try {
            req.setBuffer(getContext().getBufferCache().getBuffer());
            req.nextElement();
            if (req.hasMoreElements()) {
                final SmbComBlankResponse interim = new SmbComBlankResponse(getContext().getConfig());

                        // Test allocation performance
                        long allocStart = System.nanoTime();
                        byte[] buffer = BufferCache.getBuffer();
                        long allocEnd = System.nanoTime();
                        totalAllocTime.addAndGet(allocEnd - allocStart);
                        allocations.incrementAndGet();

        boolean isDirect;
        DcerpcException de;

        if (state == 0) {
            bind();
        }

        isDirect = true;

        stub = jcifs.smb1.smb1.BufferCache.getBuffer();
        try {
            int off, tot, n;

            buf = new NdrBuffer(stub, 0);

            msg.flags = DCERPC_FIRST_FRAG | DCERPC_LAST_FRAG;
            msg.call_id = call_id++;

    public int getTailSpace() {
        return buf.length - index;
    }

    /**
     * Returns the underlying byte buffer.
     *
     * @return the byte buffer
     */
    public byte[] getBuffer() {
        return buf;
    }

    /**
     * Aligns the buffer index to the specified boundary with a fill value.
     *
     * @param boundary the alignment boundary

            // In real implementation, this would receive using DiSNI:
            // RdmaCompletionEvent event = endpoint.getCqProcessor().getCqEvent(timeout);
            // if (event != null) {
            //     return event.getBuffer();
            // }
            // return null;

            // For skeleton implementation, return null (timeout)
            return null;

        } catch (Exception e) {

        lenient().when(mockContext.getBufferCache()).thenReturn(mockBufferCache);

        // Setup buffer cache to return buffers for sendrecv operations
        lenient().when(mockBufferCache.getBuffer()).thenReturn(new byte[8192]);
    }

    /**
     * Helper method to create a DcerpcPipeHandle with injected mocks
     * Uses mock to avoid constructor issues while allowing real method calls
     */