# 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

      other entities that control, are controlled by, or are under common
      control with that entity. For the purposes of this definition,
      "control" means (i) the power, direct or indirect, to cause the
      direction or management of such entity, whether by contract or
      otherwise, or (ii) ownership of fifty percent (50%) or more of the