# RDMA (SMB Direct) Feature - Detailed Design Document

## 1. Overview

SMB Direct enables high-performance data transfer using Remote Direct Memory Access (RDMA) technology. This provides ultra-low latency and high bandwidth data transfer by bypassing the traditional TCP/IP stack and allowing direct memory-to-memory transfers between client and server.

## 2. Protocol Specification Reference

- **MS-SMBD**: SMB2 Remote Direct Memory Access (RDMA) Transport Protocol

package jcifs.internal.smb2.rdma;

import jcifs.internal.util.SMBUtil;

/**
 * SMB Direct Negotiate Response message.
 *
 * As per MS-SMBD 2.2.2 - SMB_DIRECT_NEGOTIATE_RESPONSE
 * This message is sent in response to negotiate SMB Direct protocol parameters.
 */
public class SmbDirectNegotiateResponse {

    // Protocol constants
    /** SMB Direct negotiate response message type */
    public static final int NEGOTIATE_RESPONSE = 0x02;

/**
 * SMB Direct Negotiate Request message.
 *
 * As per MS-SMBD 2.2.1 - SMB_DIRECT_NEGOTIATE_REQUEST
 * This message is sent to negotiate SMB Direct protocol parameters.
 */
public class SmbDirectNegotiateRequest {

    // Protocol constants
    /** Minimum supported SMB Direct protocol version (1.0) */
    public static final int MIN_VERSION = 0x0100; // SMB Direct 1.0

/**
 * RDMA capability flags indicating what operations are supported
 * by an RDMA provider implementation.
 */
public enum RdmaCapability {
    /**
     * Remote direct read operations
     */
    RDMA_READ,

    /**
     * Remote direct write operations
     */
    RDMA_WRITE,

    /**
     * Traditional send/receive with RDMA
     */
    RDMA_SEND_RECEIVE,

    /**

 * FILE_WRITE_DATA</code>) and the target file has the following security
 * descriptor ACEs:
 *
 * <pre>
 * Allow WNET\alice     0x001200A9  Direct
 * Allow Administrators 0x001F01FF  Inherited
 * Allow SYSTEM         0x001F01FF  Inherited
 * </pre>
 *
 * the access check would fail because the direct ACE has an access mask
 * of <code>0x001200A9</code> which doesn't have the

 * FILE_WRITE_DATA</code>) and the target file has the following security
 * descriptor ACEs:
 *
 * <pre>
 * Allow WNET\alice     0x001200A9  Direct
 * Allow Administrators 0x001F01FF  Inherited
 * Allow SYSTEM         0x001F01FF  Inherited
 * </pre>
 *
 * the access check would fail because the direct ACE has an access mask
 * of <code>0x001200A9</code> which doesn't have the

 */
package jcifs.internal.smb2.rdma;

/**
 * RDMA channel information for SMB Direct operations.
 *
 * This class encapsulates RDMA channel metadata including remote memory keys,
 * addresses, and lengths for direct memory access operations.
 */
public class RdmaChannelInfo {

    private final Smb2RdmaTransform transform;

    /**

 * FILE_WRITE_DATA</code>) and the target file has the following security
 * descriptor ACEs:
 * <pre>
 * Allow WNET\alice     0x001200A9  Direct
 * Allow Administrators 0x001F01FF  Inherited
 * Allow SYSTEM         0x001F01FF  Inherited
 * </pre>
 * the access check would fail because the direct ACE has an access mask
 * of <code>0x001200A9</code> which doesn't have the

        }
    }

    /**
     * Allocate a direct buffer for temporary use
     *
     * @param size buffer size in bytes
     * @return direct byte buffer
     */
    public ByteBuffer allocateBuffer(int size) {
        return ByteBuffer.allocateDirect(size);
    }

    /**
     * Release a temporary buffer
     *
     * For direct buffers, we rely on GC. A more sophisticated

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