KB171271 - FIX: Internet Transfer Control 5.0 Has Bug with "HEAD" Request

Article ID: 171271

Article Last Modified on 8/20/2007

Microsoft Visual Basic 5.0 Control Creation Edition
Microsoft Visual Basic 5.0 Professional Edition

This article was previously published under Q171271

SYMPTOMS

The Internet Transfer Control 5.0 "HEAD" request does not work based on the documentation provided by Microsoft. There is no header information being returned when the Execute method and "HEAD" request are sent to the web server.

RESOLUTION

The Internet Transfer Control 5.0 "HEAD" request does not work from Visual Basic 5.0. You need to use the WinInet APIs that are included with the ActiveX SDK to get header information from your server. Specifically the InternetOpen, InternetConnect, HttpOpenRequest, HttpSendRequest, and HttpQueryInfo are the WinInet APIs you need to use. In the sample code below, get the header information from:

http://www.microsoft.com

The following code can be used to work around this problem:

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.

Add the following code to the general declarations section of Form1:

      Private Declare Function InternetOpen Lib "wininet.dll" _
                                           Alias "InternetOpenA" _
                  (ByVal lpszCallerName As String, _
                  ByVal dwAccessType As Long, _
                  ByVal lpszProxyName As String, _
                  ByVal lpszProxyBypass As String, _
                  ByVal dwFlags As Long) As Long

      Private Declare Function InternetConnect Lib "wininet.dll" _
                                          Alias "InternetConnectA" _
                  (ByVal hInternetSession As Long, _
                  ByVal lpszServerName As String, _
                  ByVal nProxyPort As Integer, _
                  ByVal lpszUsername As String, _
                  ByVal lpszPassword As String, _
                  ByVal dwService As Long, _
                  ByVal dwFlags As Long, _
                  ByVal dwContext As Long) As Long

      Private Declare Function HttpOpenRequest Lib "wininet.dll" _
                                            Alias "HttpOpenRequestA" _
                  (ByVal hInternetSession As Long, _
                  ByVal lpszVerb As String, _
                  ByVal lpszObjectName As String, _
                  ByVal lpszVersion As String, _
                  ByVal lpszReferer As String, _
                  ByVal lpszAcceptTypes As Long, _
                  ByVal dwFlags As Long, _
                  ByVal dwContext As Long) As Long

      Private Declare Function HttpSendRequest Lib "wininet.dll" _
                                            Alias "HttpSendRequestA" _
                  (ByVal hHttpRequest As Long, _
                  ByVal sHeaders As String, _
                  ByVal lHeadersLength As Long, _
                  ByVal sOptional As String, _
                  ByVal lOptionalLength As Long) As Boolean

      Private Declare Function HttpQueryInfo Lib "wininet.dll" _
                                                 Alias "HttpQueryInfoA" _
                  (ByVal hHttpRequest As Long, _
                  ByVal lInfoLevel As Long, _
                  ByVal sBuffer As Any, _
                  ByRef lBufferLength As Long, _
                  ByRef lIndex As Long) As Boolean

      Private Declare Function InternetCloseHandle Lib "wininet.dll" _
                   (ByVal hInternetHandle As Long) As Boolean

From the Project menu, choose Components, and select the Internet Transfer Control 5.0 into the project if it is not already loaded.
Place a Internet Transfer Control 5.0(Inet1) on Form1.
Place a ListBox Control(List1) on Form1.

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

      Private Sub Command1_Click()

            Dim hInternetOpen As Long
            Dim hInternetConnect As Long
            Dim hHttpOpenRequest As Long
            Dim bRet As Boolean

            hInternetOpen = 0
            hInternetConnect = 0
            hHttpOpenRequest = 0

         ' Use registry access settings.
         Const INTERNET_OPEN_TYPE_PRECONFIG = 0

         hInternetOpen = InternetOpen("http generic", _
                               INTERNET_OPEN_TYPE_PRECONFIG, _
                               vbNullString, _
                               vbNullString, _
                               0)

         If hInternetOpen <> 0 Then
            ' Type of service to access.
            Const INTERNET_SERVICE_HTTP = 3
            Const INTERNET_DEFAULT_HTTP_PORT = 80

            hInternetConnect = InternetConnect(hInternetOpen, _
                               "www.microsoft.com", _
                               INTERNET_DEFAULT_HTTP_PORT, _
                               vbNullString, _ 
                               "HTTP/1.0", _ 
                               INTERNET_SERVICE_HTTP, _ 
                               0, _
                               0)
           If hInternetConnect <> 0 Then
            ' Brings the data across the wire even if it locally cached.
            Const INTERNET_FLAG_RELOAD = &H80000000

           hHttpOpenRequest = HttpOpenRequest(hInternetConnect, _ 
                              "HEAD", _ 
                              "default.htm", _ 
                              vbNullString, _ 
                              vbNullString, _ 
                              0, _
                              INTERNET_FLAG_RELOAD, _ 
                              0)

             If hHttpOpenRequest <> 0 Then


               bRet = HttpSendRequest(hHttpOpenRequest, _
                               vbNullString, _
                               0, _
                               vbNullString, _
                               0)

            ' Headers to query
             Const HTTP_QUERY_CONTENT_TYPE = 1
             Const HTTP_QUERY_VERSION = 18
             Const HTTP_QUERY_SERVER = 37
             Const HTTP_QUERY_REQUEST_METHOD = 45

               If bRet Then
                   Dim sBuff  As String * 1024
                   Dim lBuffLen   As Long
                      lBuffLen = Len(sBuff)
                   &apos;response headers
                      If (HttpQueryInfo(hHttpOpenRequest, _
                          HTTP_QUERY_CONTENT_TYPE, sBuff, lBuffLen, 0) _
                        = 1) Then
                        List1.AddItem sBuff
                      End If

                      If (HttpQueryInfo(hHttpOpenRequest, _
                               HTTP_QUERY_VERSION, sBuff, lBuffLen, 0) _
                        = 1) Then
                        List1.AddItem sBuff
                      End If

                      If (HttpQueryInfo(hHttpOpenRequest, _
                                HTTP_QUERY_SERVER, sBuff, lBuffLen, 0) _
                        = 1) Then
                        List1.AddItem sBuff
                      End If

                      If (HttpQueryInfo(hHttpOpenRequest, _
                        HTTP_QUERY_REQUEST_METHOD, sBuff, lBuffLen, 0) _
                        = 1) Then
                        List1.AddItem sBuff
                      End If"?> Dim sBuff As String * 1024 
Dim lBuffLen As Long 
lBuffLen = Len(sBuff) 
'response headers 
If (HttpQueryInfo(hHttpOpenRequest, _ HTTP_QUERY_CONTENT_TYPE, sBuff, lBuffLen, 0) _ = 1) Then 
	List1.AddItem sBuff 
End If

lBuffLen = Len(sBuff) 
If (HttpQueryInfo(hHttpOpenRequest, _ HTTP_QUERY_VERSION, sBuff, lBuffLen, 0) _ = 1) Then 
	List1.AddItem sBuff 
End If 

lBuffLen = Len(sBuff) 
If (HttpQueryInfo(hHttpOpenRequest, _ HTTP_QUERY_SERVER, sBuff, lBuffLen, 0) _ = 1) Then 
	List1.AddItem sBuff 
End If 

lBuffLen = Len(sBuff) 
If (HttpQueryInfo(hHttpOpenRequest, _ HTTP_QUERY_REQUEST_METHOD, sBuff, lBuffLen, 0) _ = 1) Then 
	List1.AddItem sBuff 
End If 

               End If
             End If
           End If
         End If

         ' Close all handles
         If hInternetOpen <> 0 Then
           bRet = InternetCloseHandle(hInternetOpen)
         End If

         If hInternetConnect <> 0 Then
           bRet = InternetCloseHandle(hInternetConnect)
         End If

         If hHttpOpenRequest <> 0 Then
           bRet = InternetCloseHandle(hHttpOpenRequest)
         End If

      End Sub

From the Run menu, choose Start (ALT, R, S), or press the F5 key to run the program. Press the Command1 button and garbage will be posted to your server.

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.
From the Project menu, choose Components, and select the Internet Transfer Control 5.0 into the project if it is not already loaded.
Place a Internet Transfer Control 5.0(Inet1) on Form1.
Place a ListBox Control(List1) on Form1.

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

      Private Sub Command1_Click()
        Dim strURL As String
        strURL = "http://www.microsoft.com"
        Inet2.Execute URL:=strURL, Operation:="HEAD"
      End Sub

From the Run menu, choose Start (ALT, R, S) or press the F5 key to run the program. Press the Command1 button and garbage will be posted to your server.

REFERENCES

ActiveX SDK

Keywords: kbbug kbfix kbvbp500sp2fix kbvs97sp2fix KB171271