FIX: Crash in INET Control Downloading Page Multiple Times (171824)

SYMPTOMS

The Internet Transfer Control crashes if you call the Execute method that causes the GetChunk function to be called repeatedly.

This problem only occurs with the Execute method when GetChunk is called repeatedly, asking for small buffers (for instance, 1K), until the total download is retrieved. If GetChunk is called only once and asks for a very large buffer (for instance, 100K), the problem disappears.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug has been fixed in Visual Studio 97 Service Pack 2.

For more information on the Visual Studio 97 Service Pack 2, please see the following article in the Microsoft Knowledge Base:

170365 : INFO: Visual Studio 97 Service Packs - What, Where, and Why

For a list of the Visual Basic 5.0 bugs that were fixed in the Visual Studio 97 Service Pack 2, please see the following article in the Microsoft Knowledge Base:

171554 : INFO: Visual Basic 5.0 Fixes in Visual Studio 97 Service Pack 2

MORE INFORMATION

Steps to Reproduce Behavior

Run Visual Basic or, if Visual Basic is already running, choose New Project from the File menu (ALT, F, N). Form1 is created by default.

Place an Internet Transfer Control (Inet1) on Form1 and add the following code:

     Private Sub Inet1_StateChanged(ByVal State As Integer)
        Dim strMess As String ' Message variable.
        Select Case State
        ' ... Other cases not shown.

        Case icResponseCompleted ' 12
            Dim vtData As Variant ' Data variable.
            Dim strData As String: strData = ""
            Dim bDone As Boolean: bDone = False

            ' Get first chunk.
            vtData = Inet1.GetChunk(1024, icString)

            Do While Not bDone
                strData = Data & vtData
                ' Get next chunk.
                vtData = Inet1.GetChunk(1024, icString)
                If Len(vtData) = 0 Then
                    bDone = True
                End If
            Loop

            txtdata.Text = strData

      End Sub

Place a CommandButton (Command1) on Form1, and add the following code:

      Private Sub Command4_Click()
         Inet1.Execute "ftp://Tony's Server", "dir"
      End Sub

From the Run menu, click Start (ALT, R, S), or press the F5 key to run the program. Press the Command1 button multiple time to see the crash.