# 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

   * corresponding response body stream. This is necessary if we want servers to be able to stop
   * inbound data and send an early 400 before the request body completes.
   *
   * This test sends a slow request that is canceled by the server. It expects the response to still
   * be readable after the request stream is canceled.
   */
  @Disabled
  @Test
  fun serverCancelsRequestBodyAndSendsResponseBody() {

     * execute Queue#drainTo is not added *on top* of waiting for the timeout (which could make
     * the timeout arbitrarily inaccurate, given a queue that is slow to drain).
     */
    long deadline = System.nanoTime() + unit.toNanos(timeout);
    int added = 0;
    while (added < numElements) {

        // Prepare buffer with specific type value
        testBuffer[0] = 0x01; // revision
        testBuffer[1] = 0x00; // padding
        testBuffer[2] = 0x04; // type low byte
        testBuffer[3] = (byte) 0x80; // type high byte (0x8004)
        // Set all offsets to 0
        for (int i = 4; i < 20; i++) {
            testBuffer[i] = 0;
        }

    }

    /*
     * These methods "should" call checkNotNull. However, I'm wary of accidentally introducing
     * anything that might slow down execution on such a hot path. Given that the methods are only
     * package-private, I feel OK with just not testing them for NPE.
     *

import org.junit.jupiter.api.Tag
import org.junit.jupiter.api.Test
import org.junit.jupiter.api.Timeout
import org.junit.jupiter.api.extension.RegisterExtension

@Suppress("deprecation")
@Timeout(30)
@Tag("Slow")
class MockWebServerTest {
  @RegisterExtension
  var platform = PlatformRule()

  private val server = MockWebServer()

  @BeforeEach
  fun setUp() {
    server.start()
  }

  @AfterEach

      // Don't cache non-GET and non-QUERY responses. We're technically allowed to cache HEAD
      // requests and some POST requests, but the complexity of doing so is high and the benefit
      // is low.
      return null
    }

    if (response.hasVaryAll()) {
      return null
    }

    val entry = Entry(response)
    var editor: DiskLruCache.Editor? = null
    try {

import jcifs.smb1.util.transport.Transport;
import jcifs.smb1.util.transport.TransportException;

/**
 * Legacy SMB transport implementation for SMB1 protocol communication.
 * Handles the low-level transport layer for SMB1 protocol messages.
 */
public class SmbTransport extends Transport implements SmbConstants {

    static final byte[] BUF = new byte[0xFFFF];

import org.junit.jupiter.api.Tag
import org.junit.jupiter.api.Test
import org.junit.jupiter.api.Timeout
import org.junit.jupiter.api.extension.RegisterExtension

@Flaky // STDOUT logging enabled for test
@Timeout(30)
@Tag("Slow")
class EventListenerTest {
  @RegisterExtension
  val platform = PlatformRule()

  @RegisterExtension
  val clientTestRule = OkHttpClientTestRule()

  @StartStop
  private val server = MockWebServer()

  /**
   * Contains the logical entries, in the range of [0, size()). The high bits of each int are the
   * part of the smeared hash of the key not covered by the hashtable mask, whereas the low bits are
   * the "next" pointer (pointing to the next entry in the bucket chain), which will always be less
   * than or equal to the hashtable mask.
   *
   * <pre>
   * hash  = aaaaaaaa
   * mask  = 00000fff