带有 WinSock2 的 VBA : send() sends wrong data

Question

我正在尝试在 VBA 中使用 WinSock2 从本地主机 TCP 流发送(以及稍后接收)数据。

目前，我主要尝试从此处复制客户端示例，https://msdn.microsoft.com/en-us/library/windows/desktop/ms738630(v=vs.85).aspx

我的代码“几乎”可以工作；我可以创建一个套接字并建立到我的服务器的连接。不过，发送数据(例如调用 ws2_32.dll 的 send() 函数)很奇怪。

在下面的示例中，服务器确实会收到一个长度为 10 的字节数组，但其内容是奇数。数组的前 4 个字节已设置(但随每次调用而变化)，后 6 个字节始终为 0。

我不太确定发生了什么；假设我在 32 位 Excel 中运行它 = 指针将有 4 个字节长，看起来有点像只发送了某个变量的地址。

当我尝试调用此函数来传递数据的显式地址(被注释掉的 SendWithPtr() 调用)时，会出现同样的问题，所以这也无济于事。

有人知道那里发生了什么吗？我需要以任何不同的方式调用 send() 函数吗？!

谢谢

---

VBA代码:

Option Explicit

' Constants ----------------------------------------------------------
Const INVALID_SOCKET = -1
Const WSADESCRIPTION_LEN = 256
Const SOCKET_ERROR = -1

' Typ definitions ----------------------------------------------------

Private Type WSADATA
wVersion As Integer
wHighVersion As Integer
szDescription(0 To WSADESCRIPTION_LEN) As Byte
szSystemStatus(0 To WSADESCRIPTION_LEN) As Byte
iMaxSockets As Integer
iMaxUdpDg As Integer
lpVendorInfo As Long
End Type

Private Type ADDRINFO
    ai_flags As Long
    ai_family As Long
    ai_socktype As Long
    ai_protocol As Long
    ai_addrlen As Long
    ai_canonName As LongPtr 'strptr
    ai_addr As LongPtr 'p sockaddr
    ai_next As LongPtr 'p addrinfo
End Type


' Enums ---------------------------------------------------------------

Enum AF
AF_UNSPEC = 0
AF_INET = 2
AF_IPX = 6
AF_APPLETALK = 16
AF_NETBIOS = 17
AF_INET6 = 23
AF_IRDA = 26
AF_BTH = 32
End Enum

Enum sock_type
SOCK_STREAM = 1
SOCK_DGRAM = 2
SOCK_RAW = 3
SOCK_RDM = 4
SOCK_SEQPACKET = 5
End Enum

' External functions --------------------------------------------------

Public Declare Function WSAStartup Lib "ws2_32.dll" (ByVal wVersionRequested As Integer, ByRef data As WSADATA) As Long
Public Declare Function connect Lib "ws2_32.dll" (ByVal socket As Long, ByVal SOCKADDR As Long, ByVal namelen As Long) As Long
Public Declare Sub WSACleanup Lib "ws2_32.dll" ()
Private Declare PtrSafe Function GetAddrInfo Lib "ws2_32.dll" Alias "getaddrinfo" (ByVal NodeName As String, ByVal ServName As String, ByVal lpHints As LongPtr, lpResult As LongPtr) As Long
Public Declare Function ws_socket Lib "ws2_32.dll" Alias "socket" (ByVal AF As Long, ByVal stype As Long, ByVal Protocol As Long) As Long
Public Declare Function closesocket Lib "ws2_32.dll" (ByVal socket As Long) As Long
Private Declare PtrSafe Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal length As Long)
Public Declare Function Send Lib "ws2_32.dll" Alias "send" (ByVal s As Long, ByRef buf() As Byte, ByVal buflen As Long, ByVal flags As Long) As Long
Public Declare Function SendWithPtr Lib "ws2_32.dll" Alias "send" (ByVal s As Long, ByVal bufPtr As Long, ByVal buflen As Long, ByVal flags As Long) As Long
Private Declare PtrSafe Function WSAGetLastError Lib "ws2_32.dll" () As Long
Private Declare Function VarPtrArray Lib "VBE7" Alias "VarPtr" (var() As Any) As Long

Sub TestWinsock()
    Dim m_wsaData As WSADATA
    Dim m_RetVal As Integer
    Dim m_Hints As ADDRINFO
    Dim m_ConnSocket As Long: m_ConnSocket = INVALID_SOCKET
    Dim Server As String
    Dim port As String
    Dim pAddrInfo As LongPtr
    Dim RetVal As Long
    Dim lastError As Long

    RetVal = WSAStartup(MAKEWORD(2, 2), m_wsaData)
    If (RetVal <> 0) Then
        LogError "WSAStartup failed with error " & RetVal, WSAGetLastError()
        Call WSACleanup
        Exit Sub
    End If

    m_Hints.ai_family = AF.AF_UNSPEC
    m_Hints.ai_socktype = sock_type.SOCK_STREAM
    Server = "localhost"
    port = "5001"

    RetVal = GetAddrInfo(Server, port, VarPtr(m_Hints), pAddrInfo)
    If (RetVal <> 0) Then
        LogError "Cannot resolve address " & Server & " and port " & port & ", error " & RetVal, WSAGetLastError()
        Call WSACleanup
        Exit Sub
    End If

    m_Hints.ai_next = pAddrInfo
    Dim connected As Boolean: connected = False
    Do While m_Hints.ai_next > 0
        CopyMemory m_Hints, ByVal m_Hints.ai_next, LenB(m_Hints)

        m_ConnSocket = ws_socket(m_Hints.ai_family, m_Hints.ai_socktype, m_Hints.ai_protocol)

        If (m_ConnSocket = INVALID_SOCKET) Then
            LogError "Error opening socket, error " & RetVal
        Else
            Dim connectionResult As Long

            connectionResult = connect(m_ConnSocket, m_Hints.ai_addr, m_Hints.ai_addrlen)

            If connectionResult <> SOCKET_ERROR Then
                connected = True
                Exit Do
            End If

            LogError "connect() to socket failed"
            closesocket (m_ConnSocket)
        End If
    Loop

    If Not connected Then
        LogError "Fatal error: unable to connect to the server", WSAGetLastError()
        Call WSACleanup
        Exit Sub
    End If

    Dim SendBuf() As Byte
    SendBuf = StrConv("Message #1", vbFromUnicode)

    Dim buflen As Integer
    buflen = UBound(SendBuf) - LBound(SendBuf) + 1

    ' !!!!!!!!!!!
    ' !! Send() does not seem to send the right bytes !!
    ' !!!!!!!!!!!
    RetVal = Send(m_ConnSocket, SendBuf, buflen, 0)

    ' The following does not work either:
    ' RetVal = SendWithPtr(m_ConnSocket, VarPtrArray(SendBuf), buflen, 0)
    If RetVal = SOCKET_ERROR Then
        LogError "send() failed", WSAGetLastError()
        Call WSACleanup
        Exit Sub
    Else
        Debug.Print "sent " & RetVal & " bytes"
    End If

    RetVal = closesocket(m_ConnSocket)
    If RetVal <> 0 Then
    LogError "closesocket() failed", WSAGetLastError()
    Call WSACleanup
    Else
        Debug.Print "closed socket"
    End If
End Sub

Public Function MAKEWORD(Lo As Byte, Hi As Byte) As Integer
MAKEWORD = Lo + Hi * 256& Or 32768 * (Hi > 127)
End Function

Private Sub LogError(msg As String, Optional ErrorCode As Long = -1)
    If ErrorCode > -1 Then
        msg = msg & " (error code " & ErrorCode & ")"
    End If

    Debug.Print msg
End Sub

服务器代码，仅供引用:

using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;

namespace Server
{
class Program
{
    static void Main(string[] args)
    {
        var address = Dns.GetHostEntry("localhost").AddressList[0];
        var addressBytes = address.GetAddressBytes();
        var port = 5001;
        var ipEndpoint = new IPEndPoint(address, port);

        var listener = new TcpListener(ipEndpoint);
        listener.Start();

        bool done = false;

        TcpClient tcpClient = null;

        try
        {
            while (!done)
            {
                Thread.Sleep(10);
                Console.WriteLine("Waiting for broadcast");

                tcpClient = listener.AcceptTcpClient();

                byte[] bytes = new byte[10];
                NetworkStream stream = tcpClient.GetStream();

                var bytesRead = stream.Read(bytes, 0, bytes.Length);
                // when called via the VBA sample, "bytes" will contain odd values.
                // when called through Microsoft's C++ sample, everything works fine
            }
        }
    finally {
            tcpClient?.Close();
        }
    }
}
}

Answer 1

您需要传递数组内数据的地址 - 即第一个元素的地址(因为变量本身的地址是封闭 SAFEARRAY 的地址)

• 将 send 参数更改为 ByRef buf As Any

• 传入第一个数组元素的地址:

  RetVal = Send(m_ConnSocket, SendBuf(0), buflen, 0)