Microsoft KB Archive/171271

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

Article ID: 171271

Article Last Modified on 8/20/2007

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APPLIES TO


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

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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.</li></ol>

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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

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Steps to Reproduce Behavior
<ol> 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.</li> From the Project menu, choose Components, and select the Internet Transfer Control 5.0 into the project if it is not already loaded.</li> Place a Internet Transfer Control 5.0(Inet1) on Form1.</li> Place a ListBox Control(List1) on Form1.</li>  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

</li> 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.</li></ol>

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