Microsoft KB Archive/171271

From BetaArchive Wiki
The printable version is no longer supported and may have rendering errors. Please update your browser bookmarks and please use the default browser print function instead.

Article ID: 171271

Article Last Modified on 8/20/2007



APPLIES TO

  • 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:


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

  1. 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.
  2. 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
    
                            
  3. From the Project menu, choose Components, and select the Internet Transfer Control 5.0 into the project if it is not already loaded.
  4. Place a Internet Transfer Control 5.0(Inet1) on Form1.
  5. Place a ListBox Control(List1) on Form1.
  6. 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)
                       '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
    
                            
  7. 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

  1. 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.
  2. From the Project menu, choose Components, and select the Internet Transfer Control 5.0 into the project if it is not already loaded.
  3. Place a Internet Transfer Control 5.0(Inet1) on Form1.
  4. Place a ListBox Control(List1) on Form1.
  5. 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
    
                            
  6. 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