Finally FTP Wininet Async Callback, BUT...

Hi Da Weasel,

FTPAsync.cls is an ActiveX.DLL marked for apartment-model threading which correct me if I am wrong will handle all the serialization so that a call is never interrupted by a call from another thread.  I am just concerned about why the callback needs to yield control of the processor. There must be another way to handle this correctly.

Here is my complete source code, I couldn't get InternetReadFile to work Async But I got everything else to work Async. I suppose its because I am not passing the bytes in chunks rather than passing the entire filesize at once. If possible I need someone to help me implement the InternetReadFile in Async mode. My Current project code below, evertyhing is copy and paste, if you need to see download progress then add progressbar to form. Also if anyone try this project could you let me know of any bugs, I appreciate it


'-----------------------------------------------------
'                   AsyncAPI.BAS
'-----------------------------------------------------

Option Explicit
'===========================================
'           WinInet Async CallBack
'===========================================
'       Author: (Erik L)
'       Init.   (EGL)
'       Email:  egl1044@gmail.com
'
'===========================================
'             FTP ASYNC TYPE
'===========================================

Public Type INERNET_ASYNC_RESULT
    dwResult        As Long
    dwError         As Long
    dwAddress       As Long        'Address Handle created by callback
    dwSize          As Long        'Obtained FileSize from FtpGetFileSize
    dwBytesR        As Long        'Number of received bytes
    dwDownloading   As Boolean
End Type

'===========================================
'             FTP INTERNET ASYNC API
'===========================================
Public Declare Function InternetOpenA Lib "WININET.DLL" ( _
  ByVal lpszAgent As String, _
  ByVal dwAccessType As Long, _
  ByVal lpszProxyName As String, _
  ByVal lpszProxyBypass As String, _
  ByVal dwFlags As Long) As Long

Public Declare Function InternetSetStatusCallback Lib "WININET.DLL" ( _
  ByVal hInternet As Long, _
  ByVal lpfnInternetCallback As Long) As Long
 
Public Declare Function InternetConnectA Lib "WININET.DLL" ( _
  ByVal hConnect As Long, _
  ByVal lpszServerName As String, _
  ByVal nServerPort As Long, _
  ByVal lpszUsername As String, _
  ByVal lpszPassword As String, _
  ByVal dwService As Long, _
  ByVal dwFlags As Long, _
  ByVal dwContext As Long) As Long
 
Public Declare Function InternetReadFile Lib "WININET.DLL" ( _
  ByVal hFile As Long, _
  ByVal sBuffer As Long, _
  ByVal lNumBytesToRead As Long, _
  lNumberOfBytesRead As Long) As Long

Public Declare Function InternetCloseHandle Lib "WININET.DLL" ( _
  ByVal hInternet As Long) As Long

Public mOpen        As Long     '// InternetOpen         Handle
Public mConn        As Long     '// InternetConnect      Handle
Public mBuffer()    As Byte     '// InernetReadFile      Buffer
Public mBytesR      As Long     '// Received Bytes       Array
Public mDownload    As Boolean  '// Downloading          Helper

Public Function RipNulls(ByVal AnyBuffer As String) As String
    RipNulls = Left$(AnyBuffer, InStr(AnyBuffer, vbNullChar) - 1)
End Function



'-----------------------------------------------------
'                   CallBackProc.BAS
'-----------------------------------------------------


Option Explicit

Private Declare Sub BalanceMemoryAny Lib "kernel32" Alias "RtlMoveMemory" ( _
  lpDest As Any, _
  lpSource As Any, _
  ByVal nBytes As Long)

Public Enum InternetStatusVals
  ResolvingName = 10
  NameResolved = 11
  ConnectingToServer = 20
  ConnectedToServer = 21
  SendingRequest = 30
  RequestSent = 31
  ReceivingResponse = 40
  ResponseReceived = 41
  PreFetch = 43
  ClosingConnection = 50
  ConnectionClosed = 51
  HandleCreated = 60
  HandleClosing = 70
  DetectingProxy = 80
  RequestComplete = 100
  Redirecting = 110
  IntermediateResponse = 120
  UserInputRequired = 140
  StateChange = 200
End Enum

Private mIAR As INERNET_ASYNC_RESULT

Public Sub INTERNET_STATUS_CALLBACK( _
    ByVal hInternet As Long, _
    ByVal dwContext As Long, _
    ByVal dwInternetStatus As InternetStatusVals, _
    ByVal lpvStatusInformation As Long, _
    ByVal dwStatusInformationLength As Long)
'InternetStatusCallback:
'   Prototype for an application-defined status callback function.

Dim dwRead As Long
Dim cBuffer As String
Dim Prg As Long

        cBuffer = Space$(dwStatusInformationLength)

    Select Case dwInternetStatus
   
  Case ResolvingName
  'Looking up the IP address of the name contained in lpvStatusInformation
    BalanceMemoryAny ByVal cBuffer, ByVal lpvStatusInformation, dwStatusInformationLength
    Debug.Print RipNulls(cBuffer)

  Case NameResolved
  'Successfully found the IP address of the name contained in lpvStatusInformation.
    BalanceMemoryAny ByVal cBuffer, ByVal lpvStatusInformation, dwStatusInformationLength
    Debug.Print RipNulls(cBuffer)
   
  Case ConnectingToServer
  'Connecting to the socket address (SOCKADDR) pointed to by lpvStatusInformation.
  Debug.Print "Connecting"
 
  Case ConnectedToServer
  'Successfully connected to the socket address (SOCKADDR) pointed to by lpvStatusInformation.
  Debug.Print "Connected"
 
  Case SendingRequest
  'Sending the information request to the server.
  'The lpvStatusInformation parameter is NULL.

  Case RequestSent
  'An asynchronous operation has been completed.
  'The lpvStatusInformation parameter contains the
  'address of an INTERNET_ASYNC_RESULT structure.
  BalanceMemoryAny dwRead, ByVal lpvStatusInformation, dwStatusInformationLength
   
  Case ReceivingResponse
  'Waiting for the server to respond to a request.
  'The lpvStatusInformation parameter is NULL.

  Case ResponseReceived
  'Successfully received a response from the server.
  'The lpvStatusInformation parameter points to a DWORD
  'value that contains the number, in bytes, received.
        Dim Success As Boolean
           
        If mBytesR > 4095 Then
            Success = SetEvent(hEvent)
                BalanceMemoryAny dwRead, ByVal lpvStatusInformation, dwStatusInformationLength
                    mBytesR = mBytesR + dwRead
                        mBytesR = mBytesR
                           
                            'Total bytes transfered
                            With mIAR
                                .dwBytesR = mBytesR - dwRead
                            End With
                           
                        'Used to indicate a download
                        'otherwise don't initiate the
                        'progress bar.
                        If mDownload = True Then
                           Form1.ProgressBar1.Value = mIAR.dwBytesR
                          End If

        Else
            BalanceMemoryAny dwRead, ByVal lpvStatusInformation, dwStatusInformationLength
                    mBytesR = dwRead
                       
                End If
               
  Case ClosingConnection
  'Closing the connection to the server.
  'The lpvStatusInformation parameter is NULL.
  Debug.Print "Closing Connection"
 
  Case ConnectionClosed
  'Successfully closed the connection to the server.
  'The lpvStatusInformation parameter is NULL.
  Debug.Print "Closed Connection"
 
  Case HandleCreated
    'Used by InternetConnect to indicate it has created the new handle.
    'This lets the application call InternetCloseHandle from another thread,
    'if the connect is taking too long. The lpvStatusInformation parameter
    'contains the address of an INTERNET_ASYNC_RESULT structure.
    BalanceMemoryAny mIAR.dwAddress, ByVal lpvStatusInformation, dwStatusInformationLength
   
  Case HandleClosing
  'This handle value has been terminated.
 
  Case RequestComplete
  'An asynchronous operation has been completed.
  'The lpvStatusInformation parameter contains the
  'address of an INTERNET_ASYNC_RESULT structure.
 
  Case Else
    End Select
        DoEvents
   
End Sub

Public Function ReturnAddress() As Long
    'This function holds the Address structure
    'which can be passed back to the application.
    ReturnAddress = mIAR.dwAddress
End Function


'-----------------------------------------------------
'                   IOPending.BAS
'-----------------------------------------------------

Option Explicit

Private Const WAIT_OBJECT_0& = 0
Private Const INFINITE = &HFFFF

Private Const QS_HOTKEY& = &H80
Private Const QS_KEY& = &H1
Private Const QS_MOUSEBUTTON& = &H4
Private Const QS_MOUSEMOVE& = &H2
Private Const QS_PAINT& = &H20
Private Const QS_POSTMESSAGE& = &H8
Private Const QS_SENDMESSAGE& = &H40
Private Const QS_TIMER& = &H10
Private Const QS_MOUSE& = (QS_MOUSEMOVE _
                            Or QS_MOUSEBUTTON)
Private Const QS_INPUT& = (QS_MOUSE _
                            Or QS_KEY)
Private Const QS_ALLEVENTS& = (QS_INPUT _
                            Or QS_POSTMESSAGE _
                            Or QS_TIMER _
                            Or QS_PAINT _
                            Or QS_HOTKEY)

Private Const QS_ALLINPUT& = (QS_SENDMESSAGE _
                            Or QS_PAINT _
                            Or QS_TIMER _
                            Or QS_POSTMESSAGE _
                            Or QS_MOUSEBUTTON _
                            Or QS_MOUSEMOVE _
                            Or QS_HOTKEY _
                            Or QS_KEY)

       
Private Declare Function MsgWaitForMultipleObjects Lib "user32" ( _
    ByVal nCount As Long, _
    pHandles As Long, _
    ByVal fWaitAll As Long, _
    ByVal dwMilliseconds As Long, _
    ByVal dwWakeMask As Long) As Long
   
Private Declare Function CreateEvent Lib "kernel32" Alias "CreateEventA" ( _
    lpEventAttributes As Any, _
    ByVal bManualReset As Long, _
    ByVal bInitialState As Long, _
    ByVal lpName As String) As Long

Private Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long
Private Declare Function ResetEvent Lib "kernel32" (ByVal hEvent As Long) As Long
Public Declare Function SetEvent Lib "kernel32" (ByVal hEvent As Long) As Long

Public hEvent As Long

Public Function Async_IO_Pending() As Boolean
    'This is my attempt at IO_Pend function
    'the function is used to wait until the
    'callback function is ready for available
    'data
    Dim Success As Boolean
    Dim lBusy As Long
   
    hEvent = CreateEvent(ByVal 0&, Abs(False), Abs(True), vbNullString)
    Success = ResetEvent(hEvent)

    Do
    lBusy = MsgWaitForMultipleObjects(1, hEvent, False, INFINITE, QS_ALLINPUT&)
    DoEvents
    Loop Until lBusy = WAIT_OBJECT_0
   
    mBytesR = 0
    hEvent = CloseHandle(hEvent)
    hEvent = 0
     
End Function



'-----------------------------------------------------
'                  WinInetAsync.CLS
'-----------------------------------------------------



Option Explicit
Option Base 0

'===========================================
'             FTP ASYNC CONST
'===========================================
    Private Const FTP_RELOADS& = &H80000000
    Private Const FTP_PASSIVE& = &H8000000
    Private Const FTP_SERVICE& = 1
    Private Const FTP_PORTNUM& = 21
    Private Const FTP_DIRECT& = 1
    Private Const FTP_READ& = &H80000000
    Private Const FTP_ASYNC& = &H1
   
    Private Const DW_CONTEXT& = 2
    Private Const INVALID_CALLBACK& = -1
    Private Const MAX_PATH As String = 260
   
'===========================================
'             FTP ASYNC API
'===========================================
Private Declare Function FtpGetFile Lib "WININET.DLL" Alias "FtpGetFileA" ( _
  ByVal hConnect As Long, _
  ByVal lpszRemoteFile As String, _
  ByVal lpszNewFile As String, _
  ByVal fFailIfExists As Long, _
  ByVal dwFlagsAndAttributes As Long, _
  ByVal dwFlags As Long, _
  ByVal dwContext As Long) As Long
 
Private Declare Function FtpPutFileA Lib "WININET.DLL" ( _
  ByVal hConnect As Long, _
  ByVal lpszLocalFile As String, _
  ByVal lpszNewRemoteFile As String, _
  ByVal dwFlags As Long, _
  ByVal dwContext As Long) As Long

Private Declare Function FtpSetCurrentDirectoryA Lib "WININET.DLL" ( _
  ByVal hConnect As Long, _
  ByVal lpszDirectory As String) As Long

Private Declare Function FtpGetCurrentDirectoryA Lib "WININET.DLL" ( _
  ByVal hConnect As Long, _
  ByVal lpszCurrentDirectory As String, _
  ByRef lpdwCurrentDirectory As Long) As Long

Private Declare Function FtpOpenFile Lib "WININET.DLL" Alias "FtpOpenFileA" ( _
  ByVal hConnect As Long, _
  ByVal lpszFileName As String, _
  ByVal dwAccess As Long, _
  ByVal dwFlags As Long, _
  ByVal dwContext As Long) As Long
 
Private Declare Function FtpGetFileSize Lib "WININET.DLL" ( _
  ByVal hFile As Long, _
  ByRef lpdwFileSizeHigh As Long) As Long

Private Declare Function FtpDeleteFileA Lib "WININET.DLL" ( _
  ByVal hConnect As Long, _
  ByVal lpszFileName As String) As Long

Private Declare Function FtpCreateDirectoryA Lib "WININET.DLL" ( _
  ByVal hConnect As Long, _
  ByVal lpszDirectory As String) As Long

Private Declare Function FtpRemoveDirectory Lib "WININET.DLL" Alias "FtpRemoveDirectoryA" ( _
  ByVal hFtpSession As Long, _
  ByVal lpszDirectory As String) As Long

Private Declare Function FtpRenameFileA Lib "WININET.DLL" ( _
  ByVal hConnect As Long, _
  ByVal lpszExisting As String, _
  ByVal lpNewFileName As String) As Long

'===========================================
'         FTP ASYNC TRANSFER ENUM
'===========================================
Public Enum FtpTransferTypes
    FTP_TRANSFER_TYPE_UNKNOWN = &H0
    FTP_TRANSFER_TYPE_ASCII = &H1
    FTP_TRANSFER_TYPE_BINARY = &H2
End Enum

    Public Server$         '// Ftp Servername
    Public UserName$       '// Ftp Username
    Public Password$       '// Ftp Password
   
    Public AmIRegistered$
   
    Private m_AsyncResult As INERNET_ASYNC_RESULT
   
Public Sub Connect(Optional AsyncMode As Boolean = True)

    '   AsynchronousMode, otherwise the call is blocked
    '   and marked for Synchronous operations.
   
        '   NOTE: If AsyncMode is False, no CallBack status
        '       will be displayed upon ftp requests
       
    Dim Result As Long
    'InternetOpen:
    '   Initializes an application's use of the WinINet functions.
    mOpen = InternetOpenA( _
                    App.ProductName, _
                    FTP_DIRECT, _
                    vbNullString, _
                    vbNullString, FTP_ASYNC&)
   
    If AsyncMode = True Then
    'InternetSetStatusCallback:
    '   Sets up a callback function that WinINet functions can call as progress is made during an operation.
    Result = InternetSetStatusCallback(mOpen, AddressOf INTERNET_STATUS_CALLBACK)
    End If
   
    'InternetConnect:
    '   Opens an File Transfer Protocol (FTP), Gopher, or HTTP session for a given site.
    mConn = InternetConnectA( _
                    mOpen, _
                    Server, _
                    FTP_PORTNUM&, _
                    UserName, _
                    Password, _
                    FTP_SERVICE&, _
                    FTP_PASSIVE&, DW_CONTEXT&)
                   
                    Async_IO_Pending
End Sub

Public Function Disconnect() As Boolean
   
'   If asynchronous requests are pending for
'   the handle or any of its child handles
'   the handle cannot be closed immediately
'   but it will be invalidated.
   
    'Clean up
    Dim Success As Boolean
        Success = SetEvent(hEvent)
    'InternetCloseHandle
    '   Closes a single Internet handle.
    Call InternetCloseHandle(mConn)
    Call InternetCloseHandle(mOpen)
    'Close the Address Handle, this handle
    'is the same as the handle returned
    'from InternetopenA
    Call InternetCloseHandle(ReturnAddress)
   
     mConn = 0
     mOpen = 0
     
End Function

Public Function FtpDownload(ByVal RemoteFile As String, _
                    ByVal LocalFile As String, _
                    ByVal TransferMode As FtpTransferTypes, _
                    Optional ProgressB As Object) As Boolean
   
    'Let callback know we are downloading
    'and set up the progressbar status.
    mDownload = True
   
    Call FtpReadFile(RemoteFile, TransferMode)
    ProgressB.Max = m_AsyncResult.dwSize
   
    'FtpGetFile:
    '   Retrieves a file from the FTP serverand stores
    '   it under the specified file name, creating a
    '   new local file in the process.
    Dim Success As Boolean
        Success = FtpGetFile(mConn, RemoteFile, LocalFile, False, ByVal 0&, TransferMode, DW_CONTEXT&)
            FtpDownload = Success
End Function

Public Function FtpUpload(ByVal RemoteFile As String, _
                    ByVal LocalFile As String, _
                    ByVal TransferMode As FtpTransferTypes) As Boolean
                   
    'FtpPutFile:
    '   Stores a file on the FTP server
    Dim Success As Boolean
        Success = FtpPutFileA(mConn, LocalFile, RemoteFile, TransferMode, DW_CONTEXT&)
            FtpUpload = Success
End Function

Public Function FtpGetDirectory() As String
'FtpGetCurrentDirectory:
    '   Retrieves the current directory for the specified FTP session.
    Dim DirBuff As String
    Dim strTemp As String
    Dim Success As Boolean
   
    DirBuff = String$(MAX_PATH, vbNullChar)
        Success = FtpGetCurrentDirectoryA(mConn, DirBuff, Len(DirBuff))
            FtpGetDirectory = RipNulls(DirBuff)
End Function

Private Function FtpReadFile(ByVal FtpFileName As String, _
                            ByVal TransferMode As FtpTransferTypes) As Boolean
   
    Dim lHandle As Long
    Dim llowSize As Long
    Dim lHighSize As Long
    Dim lOpen As Long
    Dim lConn As Long
    Dim Dummy As Long
    Dim Result As Long
   
    '   After calling FtpOpenFile and until calling
    '   InternetCloseHandle, all other calls to FTP
    '   functions on the same FTP session handle
    '   will fail.
   
    '   Objective:  Initialize a new temporary session handle
    '               used only to obtain the information
    '               then close all handles immediately.
       
        lOpen = InternetOpenA( _
                    "Temp", _
                    FTP_DIRECT, _
                    vbNullString, _
                    vbNullString, FTP_ASYNC&)
                   
        Result = InternetSetStatusCallback(mOpen, AddressOf INTERNET_STATUS_CALLBACK)
       
        lConn = InternetConnectA( _
                    lOpen, _
                    Server, _
                    FTP_PORTNUM&, _
                    UserName, _
                    Password, _
                    FTP_SERVICE&, _
                    FTP_PASSIVE&, DW_CONTEXT&)
                   
            'FtpOpenFile:
            '   Initiates access to a remote file on an
            '   FTP server for reading or writing.
        lHandle = FtpOpenFile(lConn, FtpFileName, FTP_READ, TransferMode, DW_CONTEXT&)
            'FtpGetFileSize:
            '   Retrieves the file size of the requested FTP resource.
        llowSize = FtpGetFileSize(lHandle, lHighSize)
           
            'Add the filesize to the structure
            m_AsyncResult.dwSize = llowSize
           
            ' Close the temporary handles
            lHandle = InternetCloseHandle(lConn)
            lHandle = InternetCloseHandle(lOpen)
            lConn = 0
            lOpen = 0
End Function

Public Function InternetFileReadDownload(ByVal sFileName As String, ByVal sOutputFile As String, _
                                 ByVal TransferMode As FtpTransferTypes)
       
        'I couldn't get InternetReadFile to work
        'async, however FtpGetFile, and FtpPutFile
        'work async below demonstrates how to read
        'entire file into a byte array for output.

        Dim lHandle As Long
        Dim lFree As Long
       
        'Get the filesize in bytes
        Call FtpReadFile(sFileName, TransferMode)
        'Debug.Print m_AsyncResult.dwsize

ReDim mBuffer(0 To m_AsyncResult.dwSize)

    'FtpOpenFile:
    '   Initiates access to a remote file on an FTP server for reading or writing.
   
    lHandle = FtpOpenFile(mConn, sFileName, FTP_READ, TransferMode Or FTP_RELOADS&, DW_CONTEXT&)
    'InternetReadFile:
    '   Reads data from a handle opened by the
    '   InternetOpenUrl, FtpOpenFile, GopherOpenFile,
    '   or HttpOpenRequest function.

        If (lHandle) > 0 Then
    ' Read the entire file
    InternetReadFile lHandle, _
            ByVal VarPtr(mBuffer(0)), _
            ByVal m_AsyncResult.dwSize, _
            ByVal VarPtr(mBuffer(m_AsyncResult.dwSize))
           
                Else
            Debug.Print "FtpOpenFile Error"
            lHandle = InternetCloseHandle(lHandle)
                Exit Function
            End If
       
        'Output the file to hard disk
        lFree = FreeFile
        Open sOutputFile For Binary As #lFree
            Put #lFree, , mBuffer
        Close #lFree

        'Reset byte size
        Erase mBuffer()
           'Reset structure size
           m_AsyncResult.dwSize = 0
            lHandle = 0
       
End Function

Friend Function FtpSetDirectory(ByVal SSetDir As String) As Boolean
    'FtpSetCurrentDirectory:
    '   Changes to a different working directory on the FTP server.
    Dim Success As Boolean
        Success = FtpSetCurrentDirectoryA(mConn, SSetDir)
            FtpSetDirectory = Success
End Function

Friend Function FtpFileDelete(ByVal sFileName As String) As Boolean
    'FtpDeleteFile:
    '   Deletes a file stored on the FTP server.
    Dim Success As Boolean
        Success = FtpDeleteFileA(mConn, sFileName)
            FtpFileDelete = Success
End Function

Friend Function FtpFileRename(ByVal ExistingFileName As String, _
                                ByVal RenameFile As String) As Boolean
'FtpRemoveDirectory:
'   Removes the specified directory on the FTP server.
    Dim Success As Boolean
        Success = FtpRenameFileA(mConn, ExistingFileName, RenameFile)
            FtpFileRename = Success
End Function

Friend Function FtpDirectoryCreate(ByVal CreateNewDirName As String) As Boolean
'FtpCreateDirectory:
'   Creates a new directory on the FTP server.
    Dim Success As Boolean
        Success = FtpCreateDirectoryA(mConn, CreateNewDirName)
            FtpDirectoryCreate = Success
End Function

Friend Function FtpDirectoryRemove(ByVal RemoveDirectoryName As String) As Boolean
'FtpRemoveDirectory
'   Removes the specified directory on the FTP server.
    Dim Success As Boolean
        Success = FtpRemoveDirectory(mConn, RemoveDirectoryName)
            FtpDirectoryRemove = Success
End Function




'-----------------------------------------------------
'                   Form Code Example
'-----------------------------------------------------

'Add 3 Command Buttons, default names


Option Explicit

Dim w As WinInetAsync
   
Private Sub Command1_Click()
    'This performs sync
    'w.InternetFileReadDownload "calc.exe", "D:\calc.exe", FTP_TRANSFER_TYPE_BINARY
   
    'This performs async with progress display
    w.FtpDownload "calc.exe", "D:\calc.exe", FTP_TRANSFER_TYPE_BINARY, ProgressBar1
End Sub

Private Sub Command2_Click()
    w.Server = "ftp.server.com"
    w.UserName = "user id"
    w.Password = "password"
    w.Connect True
End Sub

Private Sub Command3_Click()
    w.Disconnect
End Sub

Private Sub Form_Load()
Set w = New WinInetAsync

Command1.Caption = "Download"
Command2.Caption = "Connect"
Command3.Caption = "Disconnect"
End Sub

Private Sub Form_Unload(Cancel As Integer)
    If ReturnAddress > 0 Then w.Disconnect
    Set w = Nothing
End Sub

have you thing about this?

http://vbnet.mvps.org/index.html?code/internet/ftpdownloadcallback.htm

Hi EDDYKT, Thats a good resource but it doesn't use InternetReadFile, if possible I need to read 4096 chunks at a time and just run it in a loop, but I have trouble shifting the bytes correctly. I can't use a string buffer so I need to use a byte array with varptr because my decleration of InternetReadFile needs to be Long() in order to be passed into the callback function.

That link might help a little, I was just looking for a strait forward example on how to shift the bytes.

And example is something like this...For instance say the file is 114688 bytes which is the size of Calc.exe which is = 112 KB but we will only use the bytes.

First I pull the total bytes of the file from the ftp which I can do with no problems, The problem I am having is that I can get it to work if I specify the entire length of the file like this...

Dim FileSize as Long  'Long pointer
Dim mBuffer() as Byte 'This is the byte array

'Which holds a buffer for the file..
ReDim mBuffer(0 To FileSize)

'Internet ReadFile will now use the buffer from the byte array and download the file
InternetReadFile lHandle, _
            ByVal VarPtr(mBuffer(0)), _
            ByVal FileSize, _
            ByVal VarPtr(mBuffer(FileSize))


The problem is I want to read in chunks, say 4096 bytes each loop until it reaches the size of the file.