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Error 12005 Trying to Call WINHTTPCONNECT Function in WINHTTP DLL from VB

Posted on 2008-06-25
Medium Priority
Last Modified: 2013-12-20
I am trying to call Winhttp.dll from a VB app. I specifically need to carry out this process using windows native DLL's, not COM objects.
When I run the attached code, I get the error 12005, could someone explain why, and offer a solution.
Please note my final solution will be adapted to run in an uncommon language (Omnis 7), so please keep this in mind for your replies.
Public Declare Function WinHttpOpen Lib "WinHttp.dll" (ByVal pwszUserAgent As String, ByVal dwAccessType As Int32, ByVal pwszProxyName As String, ByVal pwszProxyBypass As String, ByVal dwFlags As Int32) As Int32
    Public Declare Function WinHttpConnect Lib "WinHttp.dll" (ByVal Hsession As Int32, ByVal SiteAddress As String, ByVal Port_Number As Int32, ByVal dwvalue As Int32) As Int32
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim hsession As Int32
        Dim hconnect As Int32
        Dim Herror As Int32
        'Dim Exception As String
        Dim URL As String
        URL = "www.google.co.uk"
        hsession = WinHttpOpen("Visual Basic", 0, "", "", 0)
        hconnect = WinHttpConnect(hsession, URL, 80, 0)
        Herror = Err.LastDllError
        If Herror = 12005 Then
            MsgBox("Bad Url")
        End If
    End Sub

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Question by:lonefox_illuminus
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Author Comment

ID: 21866513
points changed
LVL 38

Expert Comment

ID: 21978407
Try using

URL = "http://www.google.co.uk"

Some of the low level APIs can be picky about the URL format.  Google doesn't like being screen scraped either, so you might change to a different site for testing.

Accepted Solution

lonefox_illuminus earned 0 total points
ID: 21980735
I managed to acheive what I was looking for by using Wininet.dll instead, never had any success with winhttp.dll in the end, despite asking on numerous boards, and scouring the web for answers.
MSDN is quite clear in it's definition for the URL to be in the format of my original question, and having tried all combinations including with and without protocol prefix, suffixing / characters etc, all with no success, the most likely reason I can deduce is something to do with the string handling between VB and C++.
This question is closed, my suggestion for anyone else with the same problem.
Use Wininet.dll instead.
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LVL 38

Expert Comment

ID: 21982179
Suggest that since there is no solution to the OP problem that the question be deleted instead.

Author Comment

ID: 21983171
Solution is to not use winhttp.dll when calling from VB, and to use wininet.dll instead. IMO this is worthy information that might have saved me weeks of head scratching, had I found a reference to it online.
LVL 38

Expert Comment

ID: 21983194
As this is VB.NET I'm unclear why you would not want to use the .NET framework tools (not COM objects) instead of an API.
LVL 38

Expert Comment

ID: 21983197
(Note that I only just realized that the question targetted .NET framework...)

Author Comment

ID: 21983296
As per my question,

"I specifically need to carry out this process using windows native DLL's, not COM objects."

"Please note my final solution will be adapted to run in an uncommon language (Omnis 7),"

I think u realised that now though.

Omnis 7 doesn't support COM objects, after testing in VB to conclude the same error occured, I opted to ask my question targetting VB to increase the likelyhood of a response. There's only a handful of us out here coding in Omnis.
LVL 38

Expert Comment

ID: 21983316
Anyway, no objection to PAQ... I'll get a moderator to close the question with your solution.

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