CHttpFile::ErrorDlg
Jim McCabe -- jmccabe@mail.portup.com
Friday, October 11, 1996
Environment: MSVC 4.2 with first patch, Win95, 24MB RAM, Win95 PPP
I'm having trouble with the CHttpFile::ErrorDlg function. The TEAR
sample program uses this function when responding to an authentication
challenge from a web server, and although undocumented, it seems to be a
very minimal wrapper for the InternetErrorDlg function.
I am able to access web pages just fine if they don't require
authentication. But when I get a HTTP_STATUS_DENIED status code after a
CHttpFile::SendRequest, I would like to respond with a userid and
password. I've already got these stored myself, and would rather not
even use the dialog UI presented by InternetErrorDlg. (There is an
option for that but it produces the same error, which I'll describe in a
bit.)
Here's my code:
if (pHttpFile->SendRequest("", 0, pszPost, cchPost))
{
DWORD dwStatus = 0;
pHttpFile->QueryInfoStatusCode(dwStatus);
if (dwStatus == HTTP_STATUS_DENIED)
{
DWORD dwVal = pHttpFile->ErrorDlg(0,
ERROR_INTERNET_INCORRECT_PASSWORD,
(FLAGS_ERROR_UI_FLAGS_CHANGE_OPTIONS |
FLAGS_ERROR_UI_FLAGS_GENERATE_DATA
/* | FLAGS_ERROR_UI_FLAGS_NO_UI*/ ));
if (dwVal == ERROR_INTERNET_FORCE_RETRY)
pHttpFile->SendRequest(0, 0, pszPost, cchPost);
pHttpFile->QueryInfoStatusCode(dwStatus);
}
// Now read the actual data, if successful
// ...
}
The problem is that in the call to InternetErrorDlg, a
CInternetException is thrown, with error 126 and context 126. The error
string is "The specified module could not be found." I thought that
perhaps I needed to link to some special DLL with the error dialog, but
the TEAR example doesn't seem to do anything like this. Now my specific
questions:
a) What usually causes this exception?
b) If I get rid of the exception and am able to call ErrorDlg without
problems, how can I predefine the userid and password so the dialog
never appears? (My app needs to run without user intervention, and
I already store the information. In fact, I even pass the userid and
password to GetHttpConnection.)
Thanks for any clues,
Jim
jmccabe@mail.portup.com
Mike Blaszczak -- mikeblas@nwlink.com
Sunday, October 13, 1996
At 12:43 10/11/96 -0400, Jim McCabe wrote:
>Environment: MSVC 4.2 with first patch, Win95, 24MB RAM, Win95 PPP
>I'm having trouble with the CHttpFile::ErrorDlg function.
What's "the first patch"? Do you mean MFC 4.2a? If so, that's your
problem--this was a beta and didn't correctly load the
InternetErrorDlg() import from the golden builds of WININET.DLL.
Specifically, MFC 4.2-flat and MFC 4.2a try to load a routine named
InternetErrorDlg(), but the final release of WININET.DLL doesn't export
such a function. Instead, it exports InternetErrorDlgA() and
InternetErrorDlgW().
(So, maybe you have a build of MFC that correctly tries to load the
function with the right name, but it can't be found because your machine
doesn't have a correct version of WININET.DLL properly installed.)
If you're really using MFC 4.2b, you should provide a stack trace showing
where the exception was thrown... it means there's some other problem,
as MFC 4.2b fixes the import-name problem.
>a) What usually causes this exception?
The number comes directly from the GetLastError() API, and the error text
comes directly from the system via FormatMessage() API. MFC will throw
a CInternetException with this error code if it can't load a routine
it needs from a system DLL.
>b) If I get rid of the exception and am able to call ErrorDlg without
> problems, how can I predefine the userid and password so the dialog
> never appears?
You need to set them in the header for your request. Information on
doing this are in the HTTP specification, which you can get from
http://www.w3.org.
.B ekiM
http://www.nwlink.com/~mikeblas/
Don't look at my hands: look at my _shoulders_!
These words are my own. I do not speak on behalf of Microsoft.
Jim McCabe -- jmccabe@mail.portup.com
Monday, October 14, 1996
MikeB helped me with my question regarding InternetErrorDlg:
>>Environment: MSVC 4.2 with first patch, Win95, 24MB RAM, Win95 PPP
>>I'm having trouble with the CHttpFile::ErrorDlg function.
>
>Specifically, MFC 4.2-flat and MFC 4.2a try to load a routine named
>InternetErrorDlg(), but the final release of WININET.DLL doesn't export
>such a function. Instead, it exports InternetErrorDlgA() and
>InternetErrorDlgW().
Thanks. I downloaded the 4.2b patch this morning but it didn't install
a newer WININET.DLL -- mine is dated 8/21/96 and has the older
InternetErrorDlg() export instead of the newer -W() and -A() exports.
First I installed the patch for users who already applied 4.2a (I had).
Then I tried again with the SDK component patch (which was included in
the first one anyway), thinking I might have missed the new WININET.DLL
somehow.
When I installed the 4.2b patch, my msvc\include\wininet.h still only
lists one InternetErrorDlg -- that is, it doesn't show the two versions
you describe. My wininet.h is dated 09/06/96, 78840 bytes.
Where can one get this new WININET.DLL? The latest MS IE 3.0r keeps the
8/21/96 version, and the latest ActiveX SDK from the MS web site is also
dated August.
(Not that it matters, but... when I run my program using the new MFC,
the new MFC detects the lack of InternetErrorDlgA() and bails out
cleanly. This is a nice way to handle it. But now I need to find the
new WININET.DLL.)
>>b) If I get rid of the exception and am able to call ErrorDlg without
>> problems, how can I predefine the userid and password so the dialog
>> never appears?
>
>You need to set them in the header for your request. Information on
>doing this are in the HTTP specification, which you can get from
>http://www.w3.org.
Actually, after I posted my original message, I changed my code to call
the non-MFC ::InternetErrorDlg and it automatically used the userid and
password that were originally passed to GetHttpConnection(). If I then
resend the request, there is a pause while the network activity begins
and then I get a successful status code (200):
if (pHttpFile->SendRequest("", 0, pszPost, cchPost))
{
DWORD dwStatus = 0;
pHttpFile->QueryInfoStatusCode(dwStatus);
if (dwStatus == HTTP_STATUS_DENIED)
{
DWORD dwVal = ::InternetErrorDlg(0,
ERROR_INTERNET_INCORRECT_PASSWORD,
(FLAGS_ERROR_UI_FLAGS_CHANGE_OPTIONS |
FLAGS_ERROR_UI_FLAGS_GENERATE_DATA |
FLAGS_ERROR_UI_FLAGS_NO_UI));
if (dwVal == ERROR_INTERNET_FORCE_RETRY)
pHttpFile->SendRequest(0, 0, pszPost, cchPost);
pHttpFile->QueryInfoStatusCode(dwStatus);
}
// Read the file here
//...
}
But when I read the text from the CHttpFile, I get the following message
instead of the expected HTML file: "Message from VB/VFP interface:
fails to read form data from Web server!" I couldn't find the string
"VB/VFP" in any of the files (*.*) in my Windows or MSVC directories, so
I'm assuming it's not an MFC problem but rather something I need to work
out with the server on the other end. I just wanted to mention it just
in case anyone recognizes this kind of message.
| Вернуться в корень Архива
|