How to find auto-config proxy for http AND ftp protocol with WPAD

[Torbjörn Håkansson]

Hi

 

I wonder if somebody have some experience with how to get proxy-servers auto-configurable addresses.

 

I and our company develop a software which depends on http and ftp i VB6. Some of our customers use automatic detect proxy servers in IE6. I need to develop the same functions for our software ( our components from IP-works needs this settings to work). I have tested different server software to learn how this WPAD magic works. At this moment my test-server is a win2000 server with a DNS and a DHCP server configured to answer for incoming request, and I use MS Proxy 2 as proxy server.  My wpad.dat file is like this:

 

function FindProxyForURL(url, host)
{
 if (url.substring(0, 5) == "http:")
 {
  return "PROXY 192.168.1.1:80";
 }
 else if (url.substring(0, 4) == "ftp:")
 {
  //If I use SOCKS server for FTP like UNIX do   
  //return "SOCKS 192.168.1.1:1080";
 
  // If I use MS Proxy2 server and use the client use winsock - go directly
  return "DIRECT";
 }
 else
 {
  // Some other protocol - for test only
  return "PROXY 192.168.1.2:80";
  //return "DIRECT";
 }
}     

 

This wpad.dat file works perfectly in IE6, do I use ftp://some-server  in the adressbar  it connects perfectly.

 

Now to the problem, I have tried to get this info for some time now ( some weeks ) , I have used wininet.h functions to find out this.  The function DetectAutoProxyUrl perfect finds the address for my WPAD file , but the pfnInternetGetProxyInfo in the jsproxy.dll can't resolve the correct answer:

 

the code snippet:

 

 if( !pInternetGetProxyInfo(  (LPSTR)url ,  sizeof( url ),
         (LPSTR) host, sizeof( host ),
         &proxy, &dwProxyHostNameLength ) )
 {
  reportFuncErr( "InternetGetProxyInfo", myError );
  *bstrFTPProxy =A2BSTR(myError);
  *lResult = -1;
  return S_OK;
 }
 else
 {
  ATLTRACE( "\n  Proxy is: %s\n", proxy );
  *bstrHttpProxy = A2BSTR(proxy);
 }

 

If I use http or ftp for my url it always report back PROXY 192.168.1.2:80 which is a wrong answer, IE6 solves this, why not this function?

 

The second solution is to use the new function WinHttpGetProxyForUrl in winhttp.dll 5.1 , this function seems to resolve the correct server-address for http addresses. But if I use some url for ftp like ftp://some-server  it answer 12006 - ERROR_WINHTTP_UNRECOGNIZED_SCHEME. If I understands correctly winhttp don't support ftp ?

 

Some info, All our code is in VB6 but this I have made in ATL/VC++ as a object.

 

Is there somebody who can solve my problem. The best solution would be to use the old functions in wininet.h mostly for our customers use win98 , NT4 and you have to use win2k sp3 or winxp sp1 to use winhttp.dll 5.1.

 

In worst case I have to interp the info in the WPAD file myself.

 

Regards

 

Torbjörn Håkansson
Developer
Introibis
http://introibis.com
Sweden

 

 

 

 

 

 

 

 

 

 

[Stephen Sulzer]

Hello.

 

The fact that InternetGetProxyInfo is returning "192.168.1.2:80" suggests that, at least, the WPAD script code is being loaded into JSPROXY successfully and executing. So I would be suspicious of the value of the url string parameter being passed to FindProxyForUrl.

 

It looks like you are using the sample WinInet autoproxy code from <http://msdn.microsoft.com/library/default.asp?url=/library/en-us/wininet/wininet/autoproxy_support_in_wininet.asp>.

 

When you integrated this sample code into your component, did you change the types of the url (and/or host) string variables (that are passed to the pInternetGetProxyInfo function)?

 

The WinInet sample code assumes the types of these variables are character arrays, and uses the sizeof compile-time function to determine their string lengths. But if you changed the types of these variables to character pointers (char *), then you must use the strlen function instead to compute the string lengths. Using sizeof on a char* type of course returns the size of a pointer (e.g., 4 bytes) and not the length of the string the pointer points to.  So I would change the sizeof(url) and sizeof(host) to strlen(url) and strlen(host) in your code. That is the only thing I can think of that would explain the problem.

 

Regarding WinHttpGetProxyForUrl, it is true that it accepts only http: and https: URLs. Which likely means you will still need to use WinInet/JSPROXY autoproxy functions (at least for ftp: URLs) on all platforms.

 

 

Hope that helps.

 

 

    Stephen

 

 

"Torbjörn Håkansson" <torb...@introibis.com> wrote in message news:eOGKQyC...@tk2msftngp13.phx.gbl...

[Torbjörn Håkansson]

 

Thanks Steven for your reply

 

Yes , I saw my mistake a hour later , when I debugged my VB test client program. The conversion from BSTR to LPSTR was incorrect. Only the first character was sent to JSPROXY, if I test http://something I sent only "h". So the JSPROXY interped the url correct.

 

My problem was that MS sample didn't work also, from MS sample
char url[1025] = "<http://www.microsoft.com/windows/default.mspx>";

 

I don't no why MS use "<" ">" , this extra char did that my wpad.dat file don't work, and I could not see why.

 

But now all works

 

 

Torbjörn